- A nickelacycle as propionic acid equivalent for carbon-carbon coupling reactions; application to the synthesis of C25 steroid carboxylic acids
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β-Substituted propionic acids are prepared in good yields by carbon-carbon coupling reaction of the nickelacycle 1 with organic iodides and anhydrous manganese(II) iodide. This new reaction is used to the synthesis of C25 steroid carboxylic acids from C22 steroid iodides.
- Schonecker,Walther,Fischer,Nestler,Braunlich,Eibisch,Droescher
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- The plant pathogen enzyme AldC is a long-chain aliphatic aldehyde dehydrogenase
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Aldehyde dehydrogenases are versatile enzymes that serve a range of biochemical functions. Although traditionally considered metabolic housekeeping enzymes because of their ability to detoxify reactive aldehydes, like those generated from lipid peroxidation damage, the contributions of these enzymes to other biological processes are widespread. For example, the plant pathogen Pseudomonas syringae strain PtoDC3000 uses an indole-3-acetaldehyde dehydrogenase to synthesize the phytohormone indole-3-acetic acid to elude host responses. Here we investigate the biochemical function of AldC from PtoDC3000. Analysis of the substrate profile of AldC suggests that this enzyme functions as a long-chain aliphatic aldehyde dehydrogenase. The 2.5 ? resolution X-ray crystal of the AldC C291A mutant in a dead-end complex with octanal and NAD1 reveals an apolar binding site primed for aliphatic aldehyde substrate recognition. Functional characterization of site-directed mutants targeting the substrate- and NAD(H)-binding sites identifies key residues in the active site for ligand interactions, including those in the “aromatic box” that define the aldehyde-binding site. Overall, this study provides molecular insight for understanding the evolution of the prokaryotic aldehyde dehydrogenase superfamily and their diversity of function.
- Lee, Soon Goo,Harline, Kate,Abar, Orchid,Akadri, Sakirat O.,Bastian, Alexander G.,Chen, Hui-Yuan S.,Duan, Michael,Focht, Caroline M.,Groziak, Amanda R.,Kao, Jesse,Kottapalli, Jagdeesh S.,Leong, Matthew C.,Lin, Joy J.,Liu, Regina,Luo, Joanna E.,Meyer, Christine M.,Mo, Albert F.,Pahng, Seong Ho,Penna, Vinay,Raciti, Chris D.,Srinath, Abhinav,Sudhakar, Shwetha,Tang, Joseph D.,Cox, Brian R.,Holland, Cynthia K.,Cascella, Barrie,Cruz, Wilhelm,McClerkin, Sheri A.,Kunkel, Barbara N.,Jez, Joseph M.
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- Synthesis of (E)-1-Aryl-1-alkenes via a Novel BF3·OEt2-Catalyzed Aldol-Grob Reaction Sequence
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The reactions of aromatic aldehydes with ketones in the presence of various acids were examined. The reactions generate (E)-1-aryl-1-alkenes in the presence of boron trifluoride diethyl etherate in nonnucleophilic solvents.
- Kabalka, George W.,Li, Nan-Sheng,Tejedor, David,Malladi, Rama R.,Trotman, Sarah
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- Polyanhydride networks from thiol-ene polymerizations
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Thiol-ene photopolymerization was used in the synthesis of elastomeric polyanhydrides. Side reactions involving the addition of thiol to the anhydride were observed but take place at a much slower rate than photoinitiated thiol-ene polymerization. The thermomechanical properties, including the glass transition temperature (Tg) as well as tensile and compressive modulus, of the cross-linked material were studied using dynamic mechanical analysis. T g values ranged from -15 to approximately -50 °C and were dependent on the degree of cross-linking. The Young's and compressive modulus measurements confirm that these types of networks are a soft rubber-like material at room and body temperature and become softer as the cross-linking density is reduced. The hydrophobicity/hydrophilicity of these networks was analyzed by water contact angle measurements. The polyanhydrides were moderately hydrophobic, with water contact angle averages ranging from 82° to 92°. This hydrophobicity, coupled with the high reactivity of the anhydride groups, results in the material eroding via the surface erosion mechanism.
- Rutherglen, Broden G.,McBath, Ryan A.,Huang, Yu Ling,Shipp, Devon A.
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- Oxidation of valeraldehyde by chlorine dioxide
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The product of the reaction of valeraldehyde with chlorine dioxide was determined, and the solvent effect on the reaction kinetics was studied. The major oxidation product is valeric acid. The reaction rate is described by the second-order equation w = k[RCHO]?[ClO2]. The rate constants were measured in the 297-328 K interval, and the activation parameters of the reaction were determined.
- Ganieva,Ganiev,Grabovskiy,Kabalnova
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- A novel montmorillonite - KMnO4 system for the oxidation of alkenes under triphase conditions
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A very simple oxidation of alkenes to dicarboxylic acids using H-montmorillonite-KMnO4 system has been described for the first time.
- Choudary,Valli,Prasad
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- Bi(III)-mandelate/DMSO : A New Oxidizing System for the Catalyzed C-C Cleavage of Epoxides
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Bi(III)-mandelate was found to be an effective catalyst for the oxidative C-C bond cleavage of epoxides and their transformation into carboxylic acids in anhydrous DMSO medium.
- Zevaco, Thomas,Dunach, Elisabet,Postel, Michele
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- Controlling product selectivity by surface defects over MoOx-decorated Ni-based nanocatalysts for γ-valerolactone hydrogenolysis
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Currently, highly efficient biomass upgrading over non-noble metal catalysts is of vital importance for reducing equipment and operation expenses in biorefinery industries. In this respect, the related heterogeneous catalysis demands the design and construction of mutual cooperative microstructure of catalysts to improve their catalytic performances. Here, an efficient catalytic process for selective hydrogenolysis of biomass-derived γ-valerolactone (GVL) to produce 1,4-pentanediol (1,4-PDO) and 2-methyltetrahydrofuran (2-MTHF) was developed by earth-abundant nickel-based catalysts, which were derived from a molybdate intercalated Ni-Al layered double hydroxide precursor. It was found that with the elevated reduction temperature, the amount of surface defective MoOx species (0 x/Al2O3 catalyst obtained at the reduction temperature of 600 °C delivered a 94.0% combined yield of 1,4-PDO and 2-MTHF under mild reaction conditions. It was demonstrated that over the present Ni-MoOx/Al2O3 catalyst system, surface defective MoOx species could greatly facilitate the adsorption and activation of carbonyl group in GVL and thus significantly promote the cleavage of C[dbnd]O bond and its adjacent C[sbnd]O bond. This finding opens a promising door to engineer surface defective structure of high-performance supported metal catalysts.
- Zhang, Guangcheng,Li, Wei,Fan, Guoli,Yang, Lan,Li, Feng
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- Catalytic Oxidation of Alcohol to Carboxylic Acid with a Hydrophobic Cobalt Catalyst in Hydrocarbon Solvent
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A hydrophobic cobalt catalyst was synthesized and proved to be effective in alcohol oxidation under the assistance of hydrocarbon solvent with oxygen as the terminal oxidant. A series of catalysts with different water contact angles was applied to investigate the hydrophobic effect. Further insight into the reaction process was gained by reaction kinetics, isotopic effect, etc. It showed that the hydrocarbon solvent participated in the alcohol oxidation, and with the aid of the in situ generated free radicals, the α-C?H bond was smoothly activated and the alcohol was converted to carbonyl compounds. The hydrophobic effect promoted the alcohol oxidation by affecting the solvent oxidation.
- Shi, Song,Liu, Meng,Zhao, Li,Wang, Min,Chen, Chen,Gao, Jin,Xu, Jie
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- Two-Phase Flow Oxidation of Valeraldehyde with O2 in a Microstructured Reactor
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Microstructured reactors are the ideal device for highly exothermic reactions. In this work, the highly exothermic two-phase reaction of valeraldehyde with oxygen to valeric acid was carried out in a microreactor. The used device from one-A Engineering Austria GmbH is designed for process development and intensification and can be applied in the scale-up process to small-scale commercial production. The atom economic oxidation of valeraldehyde is performed at 0 to 40 °C with a catalytic amount of manganese(II) acetate. A continuous flow oxidation of aldehydes in such reactors can be a safe and beneficial alternative to commercial batch processes.
- Baumeister, Tobias,Kitzler, Hannes,Obermaier, Klemens,Zikeli, Stefan,R?der, Thorsten
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- Hybrid polyoxotungstates as second-generation POM-based catalysts for microwave-assisted H2O2 activation
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Organic-inorganic hybrids synthesized from lacunary polyoxotungstates (POMs) have been screened as oxidation catalysts with H2O2 under MW irradiation. Yields up to 99% have been obtained in 25-50 min depending both on the POM structure and on the organic moiety. The reaction scope, optimized with the best performing catalyst [γ-SiW 10O36(PhPO)2]4-, includes epoxidation of terminal and internal double bonds, alcohol oxidation, and sulfoxidation, as well as oxygen transfer to electron-deficient substrates as chalcone, ketones, and sulfoxides.
- Carraro, Mauro,Sandei, Luca,Sartorel, Andrea,Scorrano, Gianfranco,Bonchio, Marcella
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- Boron trifluoride induced fragmentation of β-Aryl-β-hydroxyketones
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β-Aryl-β-hydroxy ketones are readily cleaved by boron trifluoride in non-protic solvents. The reaction appears to proceed via a non-synchronous Grobe fragmentation pathway.
- Kabalka, George W.,Tejedor, David,Li, Nan-Sheng,Reddy, Malladi,Trotman, Sarah
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- New norterpenoids and a sphingolipid from Carissa opaca
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Chemical investigations on the aerial parts of Carissa opaca resulted in the isolation and characterization of two new nor-triterpenoids (compounds 1 and 2) and a new sphingolipid (compound 3) together with six known compounds. The structures of all the isolates were established using spectral data. All the isolated compounds showed DPPH radical scavenging and enzyme inhibitory activities against enzymes acetylcholinesterase, butyrylcholinesterase, and lipoxygenase.
- Parveen, Shehla,Saleem, Muhammad,Riaz, Naheed,Ashraf, Muhammad,Qurat-Ul-Ain,Nisar, Muhammad Farrukh,Jabbar, Abdul
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- Experimental and computational studies on substituent effects in reactions of peracid-aldehyde adducts
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Liquid phase oxidation of six branched and four linear aldehydes by dioxygen and m-chloroperbenzoic acid was studied experimentally. 2-Substituted (α-branched) aldehydes reacted to give formates (via Bayer-Villiger mechanism) whereas the related linear saturated aldehydes were converted to the corresponding carboxylic acids. Formation of both these products can be rationalized via rearrangement reactions of peracid-aldehyde adducts 1. Computational studies employing DFT methods at the DNPP level with the Spartan program (v5.0) were carried out in order to understand properties of those adducts. Conformational properties of the adducts 1 were found to shed light on the differences observed in the reactions of linear and branched adducts. (C) 2000 Elsevier Science Ltd.
- Lehtinen, Christel,Nevalainen, Vesa,Brunow, G?sta
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- Valeronitrile hydrolysis in supercritical water
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Nitriles act as important intermediates for the chemical industry and are accessible on a large scale through hydrocyanation or ammonoxidation. Nitrile hydrolysis yields amides and acids used in various applications. The conventional nitrile hydrolysis process relies on stoichiometric amounts of mineral acid or base which inherently deliver great amounts of waste brine. Improving this process towards green chemistry would require reaction conditions which can provide technically significant results without the use of catalysts. Under these conditions, the hydrolysis of valeronitrile in pure supercritical water was investigated. The experiments were performed in a continuous high pressure laboratory-scale apparatus at a temperature between 400 and 5008C, 30 MPa pressure and maximal residence time of 100 s. Nitrile conversion and valeric acid selectivity greater than 90% were achieved.
- Sarlea, Michael,Kohl, Sabine,Blickhan, Nina,Vogel, Herbert
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- Enabling industrial biocatalytic processes by application of silicone-coated enzyme preparations
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Composite particles of the commercial lipase preparation NZ435 and silicone (silcoat-NZ435) have recently been described as promising biocatalysts for synthetic use. In this study, their actual potential for enhanced performance in industrial applications was evaluated, focusing on scenarios where carrier disintegration and catalyst leaching constitute key limitations. All three investigated model reactions, the syntheses of myristyl myristate, poly(ethylene glycol) 400-coconut fatty acid monoester and ethylene oxide and propylene oxide copolymer (EO/PO)-oleic acid diester, were considerably improved in terms of the maximal number of reaction cycles performed with the same batch of catalyst, and consequently in terms of the obtainable product amount. The total turnover numbers (TTN) increased by a factor up to 50, making the realization of this type of reactions in an industrial process more feasible. The utility of silcoat-NZ435 for stereoselective transformations was demonstrated with the enantioselective acylation of 1-phenylethanol with vinyl butyrate, in which full retention of the excellent stereoselectivity of native NZ435 was observed. Moreover, it was demonstrated for the first time that the methodology by which silcoat-catalysts are obtained can be successfully transferred to alternative carriers and enzymes (e.g., protease, esterase and laccase), opening a broad field for the implementation and advancement of biocatalysis in industrial processes. Copyright
- Nieguth,Eckstein,Wiemann,Thum,Ansorge-Schumacher
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- Hydrophobic interactions in the pillar[5]arene-based host-guest complexation and their application in the inhibition of acetylcholine hydrolysis
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The host-guest complexations between a water-soluble pillar[5]arenes (WP5) and choline derivatives with different alkyl chain lengths were investigated. The hydrophobic interactions played a significant role in these pillar[5]arene-based host-guest complexations. By taking advantage of hydrophobic interactions, the cavity of WP5 could be further employed to inhibit the hydrolysis of acetylcholine in the presence of acetylcholinesterase.
- Hua, Bin,Zhou, Jiong,Yu, Guocan
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- Conversion of γ-Valerolactone to Ethyl Valerate over Metal Promoted Ni/ZSM-5 Catalysts: Influence of Ni0/Ni2+ Heterojunctions on Activity and Product Selectivity
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Promoter (Cr, Mo and W) modified Ni/ZSM-5 catalysts were explored in the vapor phase conversion of γ-valerolactone (GVL) to ethyl valerate (EV; gasoline blender) at atmospheric pressure. Among the three different promoters (Cr, Mo and W) tested the Mo-modified catalyst was found to be the best candidate. In addition, this catalyst was found to be stable up to 50 h reaction time with an insignificant decrease in activity. The good catalytic performance is related to an optimal ratio of acid and hydrogenation functions provided by Ni2+ and Ni0, respectively. In situ FTIR spectroscopic studies revealed a strong adsorption of GVL on all catalysts which quickly reacts with dosed ethanol by formation of EV, most pronounced on the Mo-modified catalyst, while VA was identified as side product. These findings suggest the preferred GVL ring opening by cracking the C?O bond on the methyl side of the GVL molecule on this type of catalysts leading to pentenoic acid as intermediate, which is quickly hydrogenated and esterified.
- Akula, Venugopal,Bentrup, Ursula,Bhargava, Suresh K.,Brückner, Angelika,Gutta, Naresh,Jampaiah, Deshetti,Velisoju, Vijay Kumar
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- The aldol-Grob reaction: Regioselective synthesis of (E)-alkenes from aldehydes and ketones with ytterbium triflate catalysis
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A simple, good yielding and solvent-free aldol-Grob reaction sequence, catalysed by Yb(OTf)3 hydrate, affording (E)-alkenes regioselectively from aldehydes and ketones is described. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Curini, Massimo,Epifano, Francesco,Maltese, Federica,Marcotullio, Maria Carla
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- DIRECT REMOTE OXIDATION OF ALIPHATIC KETONES TO γ- AND δ-DIKETONES
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Aliphatic ketones are converted into γ- and δ-diketones in onepot oxidation reaction on treatment with Na2S2O8 in presence of Fe(II)ions.
- Nikishin, Gennady I.,Troyansky Emmanuil I.,Lazareva, Margarita I.
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- Improved procedure for ruthenium-catalyzed oxidative cleavage of alkenes with IG(OH)5
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Oxidative cleavage of alkenes to carboxylic acids catalyzed by cis-[RuCl2-(bipy)2]·2H2O in the presence of IO(OH)5 has been studied in a biphasic (CH3CN-CCl 4-H2O; 1:1:2 v/v) solvent system. Ruthenium tetraoxide seems to be the active catalyst species. Copyright Taylor & Francis LLC.
- Shoair, Abdel Ghany F.,Mohamed, Ramadan H.
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- Role of surfactants on metal mediated cerium(IV) oxidation of valeraldehyde at room temperature and pressure
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Abstract The short chain straight fatty acid, valeric or pentanoic acid is chemically significant for its huge applications in variety of industrial target compounds including plasticizers, lubricants, biodegradable solvents, perfumery and pharmaceuticals. Synthesis of valeric acid has been achieved by the cerium(IV) oxidation of a straight C5 chain valeraldehyde which is a precursor of organic compounds. Ce(IV) is selected as an alternative oxidizing agent in place of higher valent metals. The oxidation kinetics of valeraldehyde has been investigated under pseudo-first-order conditions in acidic medium at 30 °C. Several transition metal salts: Cr(III), Mn(II), Cu(II), Ir(III) and Ru(III) have been introduced to observe their effect on reaction rate6. Three different representative non-functional surfactants: Cetyltrimethylammonium bromide (CTAB; cationic), Sodium dodecylsulphate (SDS; anionic) and 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS; zwitterionic) catalyze the reaction significantly. Ir(III) and Ru(III) enhance the oxidation rate in the presence and absence of surfactant. Cr(III), Mn(II) and Cu(II) interestingly inhibit the reaction rate. CMC values of the surfactants have been determined by spectrofluorometry and conductometry. The oxidized product valeric acid has been characterized by NMR and FTIR spectroscopy. Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) experiments support the aggregation of surfactants Ru(III) in association with CTAB micellar catalyst that exhibited a dramatic ～ 330 fold rate enhancement compared to the uncatalyzed reaction path.
- Ghosh, Aniruddha,Sar, Pintu,Malik, Susanta,Saha, Bidyut
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- Molecular oxygen oxidative carbon-carbon bond cleavage of α-ketols catalysed by Bi(III) carboxylates
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Bi(III)-mandelate catalyses the oxidative carbon-carbon bond cleavage, by molecular oxygen, of a series of α-ketols into the corresponding carboxylic acids. The reaction is accelerated in the presence of DMSO.
- Le Boisselier, Veronique,Coin, Christine,Postel, Michele,Dunach, Elisabet
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- Ce promoted Pd-Nb catalysts for γ-valerolactone ring-opening and hydrogenation
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γ-Valerolactone (GVL) has been catalytically transformed into pentanoic acid (PA), a molecule of growing importance in the search for alternative green fuels and chemical feedstocks. The GVL conversion process goes through ring-opening and hydrogenation reactions over well dispersed Pd-NbCe oxides on an activated carbon support.
- Buitrago-Sierra,Serrano-Ruiz,Rodriguez-Reinoso,Sepulveda-Escribano,Dumesic
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- Production of C5 carboxylic acids in engineered Escherichia coli
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Valeric acid and 2-methylbutyric acid serve as chemical intermediates for a variety of applications such as plasticizers, lubricants and pharmaceuticals. The commercial process for their production uses toxic intermediates like synthesis gas and relies on non-renewable petroleum-based feedstock. In this work, synthetic metabolic pathways were constructed in Escherichia coli for the renewable production of these chemicals directly from glucose. The native leucine and isoleucine biosynthetic pathways in E. coli were expanded for the synthesis of valeric acid and 2-methylbutyric acid (2MB) respectively by the introduction of aldehyde dehydrogenases and 2-ketoacid decarboxylases. Various aldehyde dehydrogenases and 2-ketoacid decarboxylases were investigated for their activities in the constructed pathways. Highest titers of 2.59 g/L for 2-mthylbutyric acid and 2.58 g/L for valeric acid were achieved in shake flask experiments through optimal combinations of these enzymes. This work demonstrates the feasibility of renewable production of these high volume aliphatic carboxylic acids.
- Dhande, Yogesh K.,Xiong, Mingyong,Zhang, Kechun
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- Exploring the charged nature of supramolecular micelles based on p-sulfonatocalix[6]arene and dodecyltrimethylammonium bromide
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The aggregation of supramolecular amphiphiles formed from hexamethylated p-sulfonatocalix[6]arene (SC6HM) and dodecyltrimethylammonium bromide (C12TAB) was studied by capillary electrophoresis experiments and by kinetic probes. The hydrolysis of 4-methoxybenzenesulfonyl chloride (MBSC) was used to investigate the micropolarity of the micellar aggregates and their ability to solubilize and stabilize labile organic compounds against hydrolysis. Further insights were obtained using a more sophisticated kinetic probe: the basic hydrolysis of p-nitrophenylvalerate (NPV). This probe provides information on the ionic composition of the micellar interface and on the potential of the aggregates to be used as nanoreactors. The results obtained revealed that the charge of the micellar aggregates can be tuned from anionic to cationic through the adjustment of the C12TAB : SC6HM molar ratio and confirmed that these micelles have good solubilization properties. On the other hand, the kinetics of the p-nitrophenylvalerate basic hydrolysis suggest that, in the concentration range comprised between the first and second CMCs, Br- anions do not take part in the micellar structure.
- Basílio, Nuno,Spudeit, Daniel Alfonso,Bastos, Juliana,Scorsin, Leandro,Fiedler, Haidi D.,Nome, Faruk,García-Río, Luis
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- Proton Acidity and Chemical Reactivity in Molten Salt Hydrates
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Molten Ca(NO3)2*4H2O has been used as a model system for studies of proton acidity and chemical reactions (including ester hydrolyses and aromatic nitrations) in molten salt hydrates.Increases in proton acidity caused by addition of acidic hydrates such as AlCl3*6H2O and Cd(NO3)2*4H2O or of aqueous HNO3 can be quantified in terms of changes in Hammett acidity H0, but usually not by the downfield shifts observed in the NMR spectrum.The rates of hydrolysis of selected primary esters (e.g., n-octyl acetate) were found to be linearly dependent on nitric acid concentration, indicating that the acidity of these melts can be changed with little change in water activity.The measurement of kinetic parameters is complicated, however, by side reactions between the organic substrates and HNO2, NO2 (or NO2+) and other species originating from the nitrate ions in the melt.
- Franzyshen, S. K.,Schiavelli, M. D.,Stocker, K. D.,Ingram, M. D.
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- Reduction of Isopropylidene Acylmalonates, 5-Acylbarbituric Acids, and 3-Acyl-4-hydroxycoumarins to the Corresponding Alkyl Derivatives by Sodium Cyanoborohydride-Acetic Acid
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Isopropylidene acylmalonates, 5-acylbarbituric acids, and 3-acyl-4-hydroxycoumarins are readily reduced to the corresponding alkyl derivatives by sodium cyanoborohydride-acetic acid.The cyclic substrates are readily prepared by the acylation of isopropylidene malonate, barbituric acid (or its N,N'-dimethyl derivative), and 4-hydroxycoumarin, according to procedures developed by other workers.The reductions take place upon addition of a 2 mol equiv of sodium cyanoborohydride to a mixture of the acyl compound and acetic acid.This reductive transformation completes a synthetic method for the preparation of the alkyl derivatives starting from the parent compound.
- Nutaitis, Charles F.,Schultz, Rose Ann,Obaza, Judy,Smith, Francis X.
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- Radical-mediated Carbonylation of Alkyl Iodides in Aqueous Media
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Radical-mediated single carbonylation of alkyl iodides furnishing carboxylic acids proceeded in water using phosphinic acid as a radical initiator in the presence of a surfactant (CTAB). On the other hand, formation of double carbonylation product (α-keto carboxylic acid) along with single carbonylation product was observed for the first time, when the reaction was carried out in aqueous ethanol without any surfactants.
- Sugiura, Masaharu,Hagio, Hiroyuki,Kobayashi, Shu
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- Experimental and computational studies on solvent effects in reactions of peracid-aldehyde adducts
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Solvent effects on liquid phase oxidation of aldehydes by dioxygen and m-chloroperbenzoic acid were studied experimentally. The main products were the corresponding carboxylic acid and a formate ester formed by Baeyer-Villiger rearrangement. In alcohol solvents (particularly methanol) substantially higher acid to formate ratios were formed than in solvents not capable of forming hydrogen bonds. Formation of both main products can be rationalised via rearrangement reactions of two epimeric peracid-aldehyde adducts, of which the interactions with methanol were studied computationally employing DFT methods at the DNPP level with the Spartan program (v5.0). The calculations indicate that structures of the adducts rearranging to give two equivalents of acid resemble the transition state of the reaction more than structures of the epimeric adducts rearranging to the acid and formate ester in 1:1 ratio. Therefore, the enhanced favor of the formation of acid in the presence of methanol can be explained in the light of Hammond's postulate.
- Lehtinen, Christel,Nevalainen, Vesa,Brunow, G?sta
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- Cavitation-induced radical-chain oxidation of valeric aldehyde
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The application of high-amplitude ultrasound to liquids triggers cavitation. By the collapse of the thereby appearing vacuum cavities, high temperatures can be reached in a transient manner. The high temperatures in these hot-spots can lead to homolytic scission of chemical bonds. The thereby generated radicals are usually utilized in aqueous systems for the degeneration of organic pollutants. In this contribution, we demonstrate that the radicals can also be used for synthetic purposes: under an oxygen atmosphere, they trigger the oxidation of an aldehyde substrate.
- Neuenschwander, Ulrich,Neuenschwander, Jürg,Hermans, Ive
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- Transformation of Thioacids into Carboxylic Acids via a Visible-Light-Promoted Atomic Substitution Process
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A visible-light-promoted atomic substitution reaction for transforming thiocacids into carboxylic acids with dimethyl sulfoxide (DMSO) as the oxygen source has been developed, affording various alkyl and aryl carboxylic acids in over 90% yields. The atomic substitution process proceeds smoothly through the photochemical reactivity of the formed hydrogen-bonding adduct between thioacids and DMSO. A DMSO-involved proton-coupled electron transfer (PCET) and the simultaneous generation of thiyl and hydroxyl radicals are proposed to be key steps for realizing the transformation.
- Fu, Qiang,Liang, Fu-Shun,Lou, Da-Wei,Pan, Gao-Feng,Wang, Rui,Wu, Min,Xie, Kai-Jun
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p. 2020 - 2024
(2022/03/31)
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- Controlling Chemoselectivity of Catalytic Hydroboration with Light
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The ability to selectively react one functional group in the presence of another underpins efficient reaction sequences. Despite many designer catalytic systems being reported for hydroboration reactions, which allow introduction of a functional handle fo
- Bergamaschi, Enrico,Chen, Yi-Kai,Hohenadel, Melissa,Lunic, Danijela,McLean, Liam A.,Teskey, Christopher J.
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supporting information
(2022/01/13)
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- Green, homogeneous oxidation of alcohols by dimeric copper(II) complexes
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Three pyrazole derivatives, 3,5-dimethyl-1H-pyrazole (DMPz) (I), 3-methyl-5-phenyl-1H-pyrazole (MPPz) (II), and 3,5-diphenyl-1H-pyrazole (DPPz) (III), were prepared via reacting semicarbazide hydrochloride with the acetylacetone, 1-phenylbutane-1,3-dione, and 1,3-diphenylpropane-1,3-dione, respectively. Complexes 1–3 were isolated by reacting CuCl2·2H2O with I–III, respectively, and characterized by CHNS elemental analyses, FT-IR, UV-Vis, 1H and 13C NMR, EPR spectra, and TGA/DTA. Molecular structures of the pyrazole derivatives I–III and copper(II) complexes 2 and 3 were studied through single-crystal XRD analysis to confirm their molecular structures. Overlapping of hyperfine splitting in the EPR spectra of the dimeric copper(II) complexes 1–3 indicates that both copper centers do not possess the same electronic environment in solution. The copper(II) complexes are dimeric in solid state as well as in solution and catalyze the oxidation of various primary and secondary alcohols selectively. Catalysts 1–3 show more than 92% product selectivity toward ketones during the oxidation of secondary alcohols. Surprisingly primary alcohols, which are relatively difficult to oxidize, produce carboxylic acid as a major product (48%–90% selectivity) irrespective of catalytic systems. The selectivity for carboxylic acid rises with decreasing the carbon chain length of the alcohols. An eco-friendly and affordable catalytic system for oxidation of alcohols is developed by the utilization of H2O2, a green oxidant, and water, a clean and greener solvent, which is a notable aspect of the study.
- Maurya, Abhishek,Haldar, Chanchal
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p. 885 - 904
(2020/12/18)
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- In Situ Generated Nickel Phosphide Based Catalysts for Hydroprocessing of Levulinic Acid
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Abstract: This article describes the production of unsupported nickel phosphide catalysts generated in situ in а reaction mixture from water-soluble and oil-soluble precursors during the hydroconversion of levulinic acid. These catalysts contain crystalline phases, specifically Ni12P5 and Ni(PO3)2. During the hydrogenation of levulinic acid in toluene in the presence of NiP–TOP, a lower temperature and a shorter reaction time contribute to the formation of γ-valerolactone (100% selectivity). A higher temperature and a longer reaction time favor the formation of valeric acid (94% selectivity). In the hydrogenation of levulinic acid in ethanol in the presence of NiP–H3PO2, the main reaction product is ethyl levulinate (95% selectivity).
- Golubeva
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p. 670 - 675
(2021/03/29)
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- Zeolite-Tailored Active Site Proximity for the Efficient Production of Pentanoic Biofuels
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Biofuel production can alleviate reliance on fossil resources and thus carbon dioxide emission. Hydrodeoxygenation (HDO) refers collectively to a series of important biorefinery processes to produce biofuels. Here, well-dispersed and ultra-small Ru metal nanoclusters (ca. 1 nm), confined within the micropores of zeolite Y, provide the required active site intimacy, which significantly boosts the chemoselectivity towards the production of pentanoic biofuels in the direct, one-pot HDO of neat ethyl levulinate. Crucial for improving catalyst stability is the addition of La, which upholds the confined proximity by preventing zeolite lattice deconstruction during catalysis. We have established and extended an understanding of the “intimacy criterion” in catalytic biomass valorization. These findings bring new understanding of HDO reactions over confined proximity sites, leading to potential application for pentanoic biofuels in biomass conversion.
- Chen, Shaohua,Chen, Tiehong,Chu, Shengqi,Gu, Qingqing,He, Jiang,Liu, Yuanshuai,Luo, Wenhao,Wang, Aiqin,Weckhuysen, Bert M.,Wu, Zhijie,Yang, Bing,Zhang, Tao,Zhang, Yafeng
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supporting information
p. 23713 - 23721
(2021/09/22)
-
- Suppressing carboxylate nucleophilicity with inorganic salts enables selective electrocarboxylation without sacrificial anodes
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Although electrocarboxylation reactions use CO2as a renewable synthon and can incorporate renewable electricity as a driving force, the overall sustainability and practicality of this process is limited by the use of sacrificial anodes such as magnesium and aluminum. Replacing these anodes for the carboxylation of organic halides is not trivial because the cations produced from their oxidation inhibit a variety of undesired nucleophilic reactions that form esters, carbonates, and alcohols. Herein, a strategy to maintain selectivity without a sacrificial anode is developed by adding a salt with an inorganic cation that blocks nucleophilic reactions. Using anhydrous MgBr2as a low-cost, soluble source of Mg2+cations, carboxylation of a variety of aliphatic, benzylic, and aromatic halides was achieved with moderate to good (34-78%) yields without a sacrificial anode. Moreover, the yields from the sacrificial-anode-free process were often comparable or better than those from a traditional sacrificial-anode process. Examining a wide variety of substrates shows a correlation between known nucleophilic susceptibilities of carbon-halide bonds and selectivity loss in the absence of a Mg2+source. The carboxylate anion product was also discovered to mitigate cathodic passivation by insoluble carbonates produced as byproducts from concomitant CO2reduction to CO, although this protection can eventually become insufficient when sacrificial anodes are used. These results are a key step toward sustainable and practical carboxylation by providing an electrolyte design guideline to obviate the need for sacrificial anodes.
- Corbin, Nathan,Lazouski, Nikifar,Manthiram, Karthish,Steinberg, Katherine,Yang, Deng-Tao
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p. 12365 - 12376
(2021/10/08)
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- Disproportionation of aliphatic and aromatic aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions
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Disproportionation of aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions often requires the application of high temperatures, equimolar or excess quantities of strong bases, and is mostly limited to the aldehydes with no CH2 or CH3 adjacent to the carbonyl group. Herein, we developed an efficient, mild, and multifunctional catalytic system consisting AlCl3/Et3N in CH2Cl2, that can selectively convert a wide range of not only aliphatic, but also aromatic aldehydes to the corresponding alcohols, acids, and dimerized esters at room temperature, and in high yields, without formation of the side products that are generally observed. We have also shown that higher AlCl3 content favors the reaction towards Cannizzaro reaction, yet lower content favors Tishchenko reaction. Moreover, the presence of hydride donor alcohols in the reaction mixture completely directs the reaction towards the Meerwein–Ponndorf–Verley reaction. Graphic abstract: [Figure not available: see fulltext.].
- Sharifi, Sina,Sharifi, Hannah,Koza, Darrell,Aminkhani, Ali
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p. 803 - 808
(2021/07/20)
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- Solvent-free oxidation of straight-chain aliphatic primary alcohols by polymer-grafted vanadium complexes
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Oxidovanadium(IV) complexes [VO(tertacac)2] (1), [VO(dipd)2] (2), and [VO(phbd)2] (3) were synthesized by reacting [VO(acac)2] with 2,2,6,6-tetramethyl-3,5-hepatanedione, 1,3-diphenyl-1,3-propanedione, and 1-phenyl-1,3-butanedione, respectively. Imidazole-modified Merrifield resin was used for the heterogenization of complexes 1–3. During the process of heterogenization, the V4+ center in complex 2 converts into V5+, whereas the other two complexes 1 and 3 remain in the oxidovanadium(IV) state in the polymer matrix. Theoretically, calculated IPA values of 1–3 suggest that 2 is prone to oxidation compared with 1 and 3, which was also supported by the absence of EPR lines in 5. Polymer-supported complexes Ps-Im-[VIVO(tertacac)2] (4), Ps-Im-[VVO2(dipd)2] (5), and Ps-Im-[VIVO(phbd)2] (6) were applied for the solvent-free heterogenous oxidation of a series of straight-chain aliphatic alcohols in the presence of H2O2 at 60°C and showed excellent substrate conversion specially for the alcohols with fewer carbon atoms. Higher reaction temperature improves the substrate conversion significantly for the alcohols containing more carbon atoms such as 1-pentanol, 1-hexanol, and 1-heptanol while using optimized reaction conditions. However, alcohols with fewer carbon atoms seem less affected by reaction temperatures higher than the optimized temperature. A decreasing trend in the selectivity(%) of carboxylic acid was observed with increasing carbon atoms among the examined alcohols, whereas the selectivity towards aldehydes increased. The order of efficiency of the supported catalysts is 4 > 6 > 5 in terms of turnover frequency (TOF) values and substrate conversion, further supported by theoretical calculations.
- Chaudhary, Nikita,Haldar, Chanchal,Kachhap, Payal
-
-
- Tuning the selectivity of electrochemical levulinic acid reduction to 4-hydroxyvaleric acid: A monomer for biocompatible and biodegradable plastics
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Levulinic acid (LA) is a biomass-derived feedstock that can be converted to a wide array of value-added products; several of these can be accessed efficiently by electrochemical conversion. Herein, we present a study of factors governing LA conversion in electrochemical environments. Most notably, we identify an unprecedentedly efficient pathway forming 4-hydroxyvaleric acid (HVA), a valuable monomer that can be used for production of bio-polyesters - specifically, poly(hydroxy acids) - as well as γ-valerolactone (GVL) (a green fuel/solvent) and other fine chemicals. This method shows >99.9% selectivity and >80% faradaic efficiency for conversion above 80%. Production rates higher than 40 g L-1 h-1 (or 200 kg L-1 mgeom.-2 h-1) were achieved; these are substantially higher than reports for compatible biochemical methods. We further identify mechanistic insights regarding the steering of selectivity toward this new pathway in comparison to known electrochemical routes toward valeric acid (VA) or to GVL. Finally, we provide a fast, sequential one-pot synthesis route to transform electrochemically-produced HVA to GVL with higher overall selectivity and faradaic efficiency than can be achieved by direct aqueous electrochemical conversion of LA to GVL (96% conversion and >99.9% selectivity, giving a total yield of 93% from LA). This journal is
- Fishler, Yuval,Holewinski, Adam,Lucas, Francisco W. S.
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supporting information
p. 9154 - 9164
(2021/11/27)
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- Nucleophilic reactivity of a mononuclear cobalt(iii)-bis(: Tert -butylperoxo) complex
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A mononuclear cobalt(III)-bis(tert-butylperoxo) adduct (CoIII-(OOtBu)2) bearing a tetraazamacrocyclic ligand was synthesized and characterized using various physicochemical methods, such as X-ray, UV-vis, ESI-MS, EPR, and NMR analyses. The crystal structure of the CoIII-(OOtBu)2 complex clearly showed that two OOtBu ligands bound to the equatorial position of the cobalt(iii) center. Kinetic studies and product analyses indicate that the CoIII-(OOtBu)2 intermediate exhibits nucleophilic oxidative reactivity toward external organic substrates.
- Cho, Jaeheung,Jeong, Donghyun,Park, Younwoo,Shin, Bongki
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supporting information
p. 9449 - 9452
(2020/09/07)
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- Method for preparing carboxylic acid by catalyzing aldehyde oxidation with N-heterocyclic carbene
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The invention discloses a method for preparing carboxylic acid by catalyzing aldehyde oxidation with N-heterocyclic carbene, and relates to the field of catalytic technology. The method comprises thefollowing steps: taking deionized water as a solvent and aldehyde as a reaction substrate, adding alkali into a reaction system, taking air as an oxidant and N-heterocyclic carbene as a catalyst required by the reaction, and carrying out catalytic oxidation on aldehyde at room temperature to 80 DEG C to generate a corresponding reaction product. The method has the beneficial effects that the N-heterocyclic carbene is used as the catalyst, no organic solvent is needed in the reaction process, the reaction process is green and safe, and the reaction yield is high.
- -
-
Paragraph 0039-0043; 0088-0089; 0090-0091; 0092-0109
(2020/11/25)
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- Oxidation of aromatic and aliphatic aldehydes to carboxylic acids by Geotrichum candidum aldehyde dehydrogenase
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Oxidation reaction is one of the most important and indispensable organic reactions, so that green and sustainable catalysts for oxidation are necessary to be developed. Herein, biocatalytic oxidation of aldehydes was investigated, resulted in the synthesis of both aromatic and aliphatic carboxylic acids using a Geotrichum candidum aldehyde dehydrogenase (GcALDH). Moreover, selective oxidation of dialdehydes to aldehydic acids by GcALDH was also successful.
- Hoshino, Tomoyasu,Yamabe, Emi,Hawari, Muhammad Arisyi,Tamura, Mayumi,Kanamaru, Shuji,Yoshida, Keisuke,Koesoema, Afifa Ayu,Matsuda, Tomoko
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- One-pot direct conversion of levulinic acid into high-yield valeric acid over a highly stable bimetallic Nb-Cu/Zr-doped porous silica catalyst
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The direct conversion of levulinic acid (LA) to valeric biofuel is highly promising for the development of biorefineries. Herein, LA is converted into valeric acid (VA) via one-pot direct cascade conversion over non-noble metal-based Nb-doped Cu on Zr-doped porous silica (Nb-Cu/ZPS). Under mild reaction conditions (150 °C and 3.0 MPa H2 for 4 h), LA was completely converted into VA in high yield (99.8%) in aqueous medium with a high turnover frequency of 0.038 h-1. The Lewis acid sites of ZPS enhanced the adsorption of LA on the catalyst surface, and both the Lewis and Br?nsted acidity associated with Nb2O5 and the metallic Cu0 sites promoted catalysis of the cascade hydrogenation, ring cyclization, ring-opening, and hydrogenation reactions to produce VA from LA. The bimetallic Nb-Cu/ZPS catalyst was also effective for the conversion of VA into various valeric esters in C1-C5 alcohol media. The presence of Nb2O5 effectively suppressed metal leaching and coke formation, which are serious issues in the liquid-phase conversion of highly acidic LA during the reaction. The catalyst could be used for up to five consecutive cycles with marginal loss of activity, even without catalyst re-activation.
- Karanwal, Neha,Verma, Deepak,Butolia, Paresh,Kim, Seung Min,Kim, Jaehoon
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supporting information
p. 766 - 787
(2020/02/25)
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- Expanding the repertoire of nitrilases with broad substrate specificity and high substrate tolerance for biocatalytic applications
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Enzymatic conversion of nitriles to carboxylic acids by nitrilases has gained significance in the green synthesis of several pharmaceutical precursors and fine chemicals. Although nitrilases from several sources have been characterized, there exists a scope for identifying broad spectrum nitrilases exhibiting higher substrate tolerance and better thermostability to develop industrially relevant biocatalytic processes. Through genome mining, we have identified nine novel nitrilase sequences from bacteria and evaluated their activity on a broad spectrum of 23 industrially relevant nitrile substrates. Nitrilases from Zobellia galactanivorans, Achromobacter insolitus and Cupriavidus necator were highly active on varying classes of nitriles and applied as whole cell biocatalysts in lab scale processes. Z. galactanivorans nitrilase could convert 4-cyanopyridine to achieve yields of 1.79 M isonicotinic acid within 3 h via fed-batch substrate addition. The nitrilase from A. insolitus could hydrolyze 630 mM iminodiacetonitrile at a fast rate, effecting 86 % conversion to iminodiacetic acid within 1 h. The arylaliphatic nitrilase from C. necator catalysed enantioselective hydrolysis of 740 mM mandelonitrile to (R)-mandelic acid in 4 h. Significantly high product yields suggest that these enzymes would be promising additions to the suite of nitrilases for upscale biocatalytic application.
- Rayavarapu, Pratima,Shah, Shikha,Sunder, Avinash Vellore,Wangikar, Pramod P.
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p. 289 - 296
(2020/05/18)
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- METHOD FOR PRODUCING CARBONYL COMPOUND
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PROBLEM TO BE SOLVED: To allow a method that oxidizes a first or second alcohol compound to obtain a carbonyl compound to be conducted with a higher yield than that of a method that uses sodium hypochlorite as an oxidizer. SOLUTION: A first or second alcohol compound is oxidized, in the presence of tetraalkylammonium hypochlorite and, preferably, in coexistence with a nitroxy radical catalyst and a metal halide cocatalyst, to produce a carbonyl compound composed of an aldehyde compound, a carboxylic acid compound, and a ketone compound. SELECTED DRAWING: None COPYRIGHT: (C)2021,JPO&INPIT
- -
-
Paragraph 0066-0067
(2021/02/04)
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- METHOD FOR THE HYDRODEOXYGENATION OF OXYGENATED COMPOUNDS TO UNSATURATED PRODUCTS
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The invention relates to methods of hydrodeoxygenation of oxygenated compounds into compounds with unsaturated carbon-carbon bonds, comprising the steps of: a) providing a reaction mixture comprising, an oxygenated compound containing one or more of a hydroxyl, keto or aldehyde group, an ionic liquid, a homogeneous metal catalyst, and carbon monoxide or a carbon monoxide releasing compound, b) reacting said reaction mixture under a H2 atmosphere at acidic conditions at a temperature between 180 and 250 °C and a pressure between 10 and 200 bar.
- -
-
Page/Page column 16-17
(2021/01/23)
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- PROCESSES FOR PREPARING 4-METHYL-5-NONANONE AND 4-METHYL-5-NONANOL
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The present invention provides a process for preparing 4-methyl-5-nonanone of the following formula (3), the process comprising at least a step of subjecting pentanoic anhydride of the following formula (1) and a 2-pentyl nucleophilic reagent of the following general formula (2), in which M represents Li, MgZ1, or ZnZ1, wherein Z1 represents a halogen atom or a 2-pentyl group, to a nucleophilic substitution reaction to produce 4-methyl-5-nonanone (3), as well as a process for preparing 4-methyl-5-nonanol of the following formula (7), the process comprising at least steps of preparing 4-methyl-5-nonanone and subjecting the obtained 4-methyl-5-nonanone and a reducing agent to a reduction reaction to produce 4-methyl-5-nonanol (7).
- -
-
Paragraph 0177-0182
(2020/07/14)
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- Production of isobutyric acid from methanol by: Clostridium luticellarii
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Renewable methanol can be used as a feedstock to generate value-added multicarbon components through fermentation technologies. Recently, researchers reported the production of isobutyric acid using methanol as an electron donor with open culture systems dominated by Eubacterium sp. and Clostridium sp. Here we report the ability of Clostridium luticellarii wild-type strain to produce isobutyric acid from methanol and CO2 & H2. When growing on methanol, the supplementation of acetic and butyric acid enhanced isobutyric acid final concentration, selectivity and production rate. A maximum of 5.04 ± 0.08 g L-1 isobutyric acid was produced at a rate of 0.420 ± 0.012 g L-1 d-1and selectivity of 0.70 electron per electron of total products in batch with acetic and butyric acid as electron acceptors. The pH was also found to be a major factor influencing isobutyric acid formation with maximal production at pH 6.50. Finally, in addition to its ability to produce isomers, C. luticellarii was able to perform C2-unit elongation from methanol. Overall, this study positions C. luticellarii as a promising platform for the production of isocarboxylic acids.
- Petrognani, Camille,Boon, Nico,Ganigué, Ramon
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p. 8389 - 8402
(2020/12/31)
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- METHOD FOR PRODUCING ALCOHOL
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PROBLEM TO BE SOLVED: To provide a method for producing selectively alcohol from carboxylic acid under mild conditions. SOLUTION: In the presence of a catalyst with M1 and M2 as metal species supported on a support, a substrate is reduced to produce a corresponding alcohol. (M1 is Rh, Pt, Ru, Ir, or Pd; M2 is Sn, V, Mo, W, or Re; the support is ZrO2, hydroxyapatite, Nb2O5, fluoroapatite, or hydrotalcite; the substrate is the formula 1a, 1b, or 1c). SELECTED DRAWING: None COPYRIGHT: (C)2020,JPO&INPIT
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-
Paragraph 0101-0110
(2020/11/26)
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- PRODUCTION METHOD OF AMIDE COMPOUND
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PROBLEM TO BE SOLVED: To provide a production method of an amide compound, which can use a variety of carboxylic acid halides and can produce a desired amide compound at a yield higher than a batch process by suppressing a side reaction. SOLUTION: Provided is a production method of an amide compound using a flow type reactor, in which the flow type reactor includes: a first flow path; a second flow path; a first mixing means provided at a confluent part of the first flow path and the second flow path; and a third flow path that is connected to the first mixing means and arranged on a down stream side of the first mixing means, the production method comprising: a mixing step of obtaining a mixed liquid by circulating a first liquid containing the carboxylic acid halide in the first flow path, circulating a second liquid containing an amine compound having a molecular weight of 1,000 or less, an inorganic alkali and water in the second flow path, and mixing the first liquid and the second liquid by the first mixing means to obtain a mixture; and a reaction step of obtaining an amide compound by circulating the mixed liquid in the third flow path and reacting the carboxylic acid halide and the amine compound in the third flow path. SELECTED DRAWING: Figure 1 COPYRIGHT: (C)2020,JPO&INPIT
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-
Paragraph 0134-0137
(2020/10/08)
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- Metal-free Photocatalytic Aerobic Oxidative Cleavage of C?C Bonds in 1,2-Diols
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The preparation of carbonyl compounds by the aerobic oxidative cleavage of C?C bonds in 1,2-diols under mild reaction conditions is a very significant reaction and is widely employed in various scenarios. Avoiding the use of harmful stoichiometric oxidants and adopting a greener chemical process remain a challenge for this reaction to date. In this manuscript, a heterogeneous metal-free photocatalytic strategy without any additive was developed for aerobic oxidative cleavage of C?C bonds in 1,2-diols at ambient conditions with visible light. The reaction mechanism was further studied through a series of control experiments and density functional theory (DFT) calculations. In addition, the catalytic system showed a broad substrates scope, including aliphatic (linear or cyclic) 1,2-diols, benzylic, alkenyl 1,2-diols, and α-hydroxy acids (such as lactic acid). Thus, this strategy could serve as a method for the transformation of 1,2-diols to corresponding carbonyl compounds by the aerobic oxidative cleavage of C?C bonds.
- Zhu, Rui,Zhou, Gongyu,Teng, Jia-nan,Li, Xinglong,Fu, Yao
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p. 5248 - 5255
(2020/08/21)
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- Rhodium porphyrin molecule-based catalysts for the hydrogenation of biomass derived levulinic acid to biofuel additive γ-valerolactone
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Rhodium-meso-tetraphenylporphyrin (RhTPP) and rhodium-meso-tetrakis(4-carboxyphenyl)porphyrin (RhTCPP) complexes were synthesized and surface grafted on amine-functional mesoporous molecular sieves. The formation of ligands (TPP and TCPP) and their rhodium complexes (RhTPP and RhTCPP) was evident with the help of 1H NMR, 13C NMR, mass spectral and elemental (CHN) analysis. The absence of the pyrrole proton of the porphyrin units on RhTPP and RhTCPP confirmed the successful formation of metallo-macro-molecules. Further, RhTPP and RhTCPP were fixed on the surface of SBA-15 through amino-silane as the linker. The rhodium containing homogeneous (RhTPP and RhTCPP) and heterogeneous catalysts (RhTPP-SBA-AM and RhTCPP-SBA-AM) were used for biomass-derived levulinic acid hydrogenation. Further, the synthesized catalysts were utilized for the hydrogenation of various organic molecules having arene, carbonyl, and alkene functionality under moderate reaction conditions. Both homogeneous and heterogeneous catalysts showed more than 95% levulinic acid conversion even after four cycles. The homogeneous RhTPP and RhTCPP yielded γ-valerolactone (GVL) as a major product, whereas heterogeneous catalysts showed only comparable γ-valerolactone (GVL) selectivity, with improved reusability and recylability in the presence of relatively lower amounts of rhodium complexes. Among RhTPP and RhTCPP, RhTPP showed better selectivity for γ-valerolactone (GVL) compared to RhTCPP. Further, as the number of catalytic runs increased, there was a gradual increase in diol selectivity, which was predominant in the case of RhTCPP, possibly due to the presence of the hydrophilic carboxylate ion which facilitates the interaction of water by-products with γ-valerolactone and favours diol formation. The hydrophobic environment of the RhTPP catalyst facilitated the formation of γ-valerolactone as the major product even in the fifth run. This journal is
- Anjali, Kaiprathu,Christopher, Jayaraj,Sakthivel, Ayyamperumal,Venkatesha, Naragalu J.
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supporting information
p. 11064 - 11075
(2020/07/15)
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- A Remarkable Effect of Aluminum on the Novel and Efficient Aqueous-Phase Hydrogenation of Levulinic Acid into Γ-Valerolactone Using Water-Soluble Platinum Catalysts Modified with Nitrogen-Containing Ligands
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Abstract: The catalytic performance of novel water-soluble platinum catalysts modified with various nitrogen-containing and phosphine ligands in the hydrogenation reaction of levulinic acid (LA) into γ-valerolactone (GVL) has been studied in environmentally attractive, green, aqueous monophasic systems. The presence of the Lewis acid aluminum enormously increases the catalytic activity of water-soluble platinum catalysts modified with nitrogen-containing ligands in the LA hydrogenation reaction and high catalytic activities up to 3540 TOF’s per hour with a quantitative selectivity towards GVL have been achieved using Na2PtCl6·6H2O precursors modified with the bidentate bathophenanthrolinedisulfonic acid disodium salt (BPhDS) ligand and low amounts of AlCl3·6H2O promotors (molar ratio of AlCl3·6H2O/Pt = 0.17) in aqueous media. This unprecedented increase in catalytic activity with aluminum promotors for water-soluble transition metal catalytic systems in aqueous-phase hydrogenation reactions has not been described until now in the literature. The apparent activation energy of platinum catalyst modified with the monodentate nitrilotriacetic acid trisodium salt ligand in aqueous medium was calculated and amounts to a relative low value of 73.04?kJ?mol?1 when one considers that in the LA hydrogenation reaction this catalyst reduces a less reactive keto group into alcohol functionality. A recycling experiment of the Pt/BPhDS/Al catalyst from the aqueous monophasic LA hydrogenation reaction mixture followed by biphasic recovery of the catalyst in active form from organic reaction products by extraction and simple phase separation of an aqueous/organic two-phase system formed after addition of diethyl ether has shown that the Pt/BPhDS/Al catalyst is stable without loss of activity and selectivity in a consecutive run. Graphical Abstract: [Figure not available: see fulltext.].
- Krommyda, Kalliopi,Panopoulou, Christina,Moustani, Chrysavgi,Anagnostopoulou, Eleni,Makripidi, Konstantina,Papadogianakis, Georgios
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p. 1250 - 1265
(2019/03/28)
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- Nanocomposite of hydrophobic cellulose aerogel/graphene quantum dot/Pd: Synthesis, characterization, and catalytic application
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Novel hydrophobic cellulose aerogel (CA) supported graphene quantum dots (GQD)/Pd were synthesized with high lipophilicity, superior porosity as well as high catalytic activity. The nanocomposite aerogel was obtained in four steps, including transformation of cotton to CA, a silanization reaction of CA in the presence of TiO2 nanoparticles to give polysiloxane/TiO2 nanoparticles supported on CA (ST@CA), a modification of ST@CA with GQD to yield polysiloxane/TiO2 nanoparticles/graphene quantum dots supported on CA (STG@CA), and finally a deposition of Pd nanoparticles on STG@CA. The synthesized aerogel demonstrated hydrophobicity with a water contact angle of 136.2°. It also exhibited excellent oil/water selective absorption capacity with an oil absorption of up to 79 g g-1 with 134 g g-1 selectivity. Finally, the nanocomposite was used as a heterogeneous catalyst in the oxidation reaction of alcohols, ethylbenzene, and alkenes. High yields, excellent selectivities, green and mild reaction conditions, recyclability and biocompatibility of the catalyst were important features of the reactions.
- Keshipour, Sajjad,Khezerloo, Masoumeh
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p. 17129 - 17136
(2019/06/24)
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- Hydrogenation of levulinic acid to valeric acid over platinum-tungsten catalysts supported on γ-Al2O3
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To address the challenges associated with fossil fuel depletion, exploration of the sustainable energy resources is one of the most pursued research areas in this century. Valeric acid (VA) is considered as a valuable platform molecule for the production of biofuels and chemical intermediates. However, the production of VA from levulinic acid (LA) has become one of the most desirable reactions. The aim of this work was to investigate the amount of acidity, Pt loading and experimental conditions for the hydrogenation of LA into VA operated at 0.1 MPa H2 pressure and to elucidate the relationship between the active sites and the catalytic performance. The Pt-WO3 catalysts supported on γ-Al2O3 were synthesized by a simple wet impregnation method with various Pt loadings from 0.5 to 3 wt% with constant 10 wt% of WO3 and calcination at 500 °C for 4 h under air. The catalysts were characterized by powder X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), N2 adsorption-desorption, temperature programmed desorption of ammonia (NH3-TPD), pyridine Fourier transform infrared spectroscopy (Pyr.FT-IR) and CO-chemisorption studies. Under optimized reaction conditions, the 2Pt-10WO3/γ-Al2O3 catalyst exhibited the highest selectivity to VA (58%) with 91% conversion of LA. This is due to the availability of a huge number of acidic and Pt active sites on the catalyst surface. In addition, the catalytic activity, reaction parameters and stability of the catalyst are demonstrated clearly.
- Bhanuchander, Ponnala,Samudrala, Shanthi Priya,Putrakumar, Balla,Vijayanand, Perupogu,Kumar, Beepala Sateesh,Chary, Komandur V. R.
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p. 18003 - 18011
(2019/12/02)
-
- Aerobic Self-Esterification of Alcohols Assisted by Mesoporous Manganese and Cobalt Oxide
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Aerobic self-esterification of primary alcohols catalyzed by mesoporous metal oxides (manganese and cobalt oxides) is reported under base and solvent free conditions. For a range of aliphatic alcohols, up to 90 % conversions to esters was achieved. The catalytic reaction is likewise applicable to neat aldehydes as substrates with yields of up to 86 %. High pressure batch reaction for ethanol to ethyl acetate led to 22 % yield. Isotope labeling studies indicated decarboxylation on the catalyst surface. Mechanistic and kinetic experiments implicate oxygen rebound and α-carbon removal as intermediate steps. Mesoporous cobalt oxide showed about 20 % higher catalytic activity compared to mesoporous manganese oxide.
- Moharreri, Ehsan,Biswas, Sourav,Deljoo, Bahareh,Kriz, David,Lim, Seyoung,Elliott, Sarah,Dissanayake, Shanka,Dabaghian, Marina,Aindow, Mark,Suib, Steven L.
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p. 3413 - 3422
(2019/08/01)
-
- Strategic Approach to the Metamorphosis of γ-Lactones to NH γ-Lactams via Reductive Cleavage and C-H Amidation
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A new approach has elaborated on the conversion of γ-lactones to the corresponding NH γ-lactams that can serve as γ-lactone bioisosteres. This approach consists of reductive C-O cleavage and an Ir-catalyzed C-H amidation, offering a powerful synthetic tool for accessing a wide range of valuable NH γ-lactam building blocks starting from γ-lactones. The synthetic utility was further demonstrated by the late-stage transformation of complex bioactive molecules and the asymmetric transformation.
- Jung, Hoi-Yun,Chang, Sukbok,Hong, Sungwoo
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supporting information
p. 7099 - 7103
(2019/09/07)
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- Cyclohexyl-Fused, Spirobiindane-Derived, Phosphine-Catalyzed Synthesis of Tricyclic ?3-Lactams and Kinetic Resolution of ?3-Substituted Allenoates
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A C2-symmetric chiral phosphine catalyst, NUSIOC-Phos, which can be easily derived from cyclohexyl-fused spirobiindane, was introduced. A highly enantioselective domino process involving pyrrolidine-2,3-diones and γ-substituted allenoates catalyzed by NUSIOC-Phos has been disclosed. Diastereospecific tricyclic γ-lactams containing five contiguous stereogenic centers were obtained in high yields and with nearly perfect enantioselectivities. A kinetic resolution process of racemic γ-substituted allenoates was developed for the generation of optically enriched chiral allenoates.
- Wu, Mingyue,Han, Zhaobin,Li, Kaizhi,Wu, Ji'En,Ding, Kuiling,Lu, Yixin
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supporting information
p. 16362 - 16373
(2019/10/16)
-
- Insertion of CO2 Mediated by a (Xantphos)NiI–Alkyl Species
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The incorporation of CO2 into organometallic and organic molecules represents a sustainable way to prepare carboxylates. The mechanism of reductive carboxylation of alkyl halides has been proposed to proceed through the reduction of NiII to NiI by either Zn or Mn, followed by CO2 insertion into NiI-alkyl species. No experimental evidence has been previously established to support the two proposed steps. Demonstrated herein is that the direct reduction of (tBu-Xantphos)NiIIBr2 by Zn affords NiI species. (tBu-Xantphos)NiI-Me and (tBu-Xantphos)NiI-Et complexes undergo fast insertion of CO2 at 22 °C. The substantially faster rate, relative to that of NiII complexes, serves as the long-sought-after experimental support for the proposed mechanisms of Ni-catalyzed carboxylation reactions.
- Diccianni, Justin B.,Hu, Chunhua T.,Diao, Tianning
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supporting information
p. 13865 - 13868
(2019/08/26)
-
- Photoinduced Divergent Alkylation/Acylation of Pyridine N-Oxides with Alkynes under Anaerobic and Aerobic Conditions
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Ortho-alkylated and ortho-acylated pyridines have been conveniently synthesized from pyridine N-oxides and alkynes under visible-light-mediation in a metal-free manner. The alkynes served as both alkylating and acylating agents via switching between anaerobic and aerobic conditions. The overall strategy accommodates a broad scope of substituted pyridine N-oxides and alkynes, with excellent regioselectivity in a number of cases.
- Xu, Jin-Hui,Wu, Wen-Bin,Wu, Jie
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p. 5321 - 5325
(2019/07/08)
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- Role of group V elements on the hydrogenation activity of Ni/TiO2 catalyst for the vapour phase conversion of levulinic acid to Γ-valerolactone
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Influence of group V elements such as Ta, Nb and V on the product distribution in the vapour phase hydrogenation of levulinic acid (LA) over Ni/TiO2 catalyst was examined at ambient pressure. The Nb promoted Ni/TiO2 demonstrated a high selectivity towards γ-valerolactone (GVL) compared to other catalysts at 275 °C. The TPR results showed a lower H2 uptake over Ta and V modified Ni/TiO2 which was explained due to a strong interaction between these oxide species with nickel. Presence of a high ratio of ionic nickel (Ni2+) on Ta and V modified catalyst could be a possible reason for the formation of valeric acid (VA) through the ring opening of GVL. The high GVL selectivity over the Ni-Nb/TiO2 catalyst attributed to the presence of a high proportion of Lewis acid sites in conjunction with finely dispersed Ni species on the catalyst surface. This however, is accomplished by the pyridine adsorbed diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and CO-chemisorption results.
- Peddakasu, Ganga Bhavani,Velisoju, Vijay Kumar,Kandula, Manasa,Gutta, Naresh,VR Chary, Komandur,Akula, Venugopal
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- Kinetics and Mechanism of the Oxidative Conversion of n-Amyl Alcohol to Valeric Acid on a Modified Zeolite Catalyst
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The catalytic activity of natural and synthetic mordenites modified with Cu2+, Zn2+, and Pd2+ cations via ion exchange was studied in the oxidative conversion of n-amyl alcohol to valeric acid under the action of oxygen. It is established that the highest activity and selectivity in this reaction is exhibited by mordenite hydrothermally synthesized from kaolinite and containing 3.0 wt % Cu2+, 0.1 wt % Pd2+, and 2.0 wt % Zn2+. The kinetics of this catalytic reaction is studied. Based on the experimental data, a possible stepwise mechanism is proposed, and a theoretically grounded kinetic model of the process is developed.
- Aliev,Bakhmanov,Agaev,Agaev, V. Sh.,Shabanova,Safarov
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p. 656 - 662
(2018/04/12)
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- An Efficient Aerobic Oxidation Protocol of Aldehydes to Carboxylic Acids in Water Catalyzed by an Inorganic-Ligand-Supported Copper Catalyst
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A method for the aerobic oxidation of aldehydes to carboxylic acids in water by using an inorganic-ligand-supported copper catalyst was developed. This method was performed with the use of atmospheric oxygen as the sole oxidant under extremely mild aqueous conditions, and furthermore, a wide range of aldehydes with various functional groups were tolerated. The copper catalyst could be recycled and used in successive reactions at least six times without any appreciable degradation in performance. This method is operationally simple and avoids the use of high-costing, toxic, air/moisture-sensitive, and commercially unavailable organic ligands. The generality of this method gives it potential to be used on the industrial scale.
- Yu, Han,Ru, Shi,Zhai, Yongyan,Dai, Guoyong,Han, Sheng,Wei, Yongge
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p. 1253 - 1257
(2018/02/16)
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- A biocatalytic method for the chemoselective aerobic oxidation of aldehydes to carboxylic acids
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Herein, we present a study on the oxidation of aldehydes to carboxylic acids using three recombinant aldehyde dehydrogenases (ALDHs). The ALDHs were used in purified form with a nicotinamide oxidase (NOx), which recycles the catalytic NAD+ at the expense of dioxygen (air at atmospheric pressure). The reaction was studied also with lyophilised whole cell as well as resting cell biocatalysts for more convenient practical application. The optimised biocatalytic oxidation runs in phosphate buffer at pH 8.5 and at 40 °C. From a set of sixty-one aliphatic, aryl-Aliphatic, benzylic, hetero-Aromatic and bicyclic aldehydes, fifty were converted with elevated yield (up to >99%). The exceptions were a few ortho-substituted benzaldehydes, bicyclic heteroaromatic aldehydes and 2-phenylpropanal. In all cases, the expected carboxylic acid was shown to be the only product (>99% chemoselectivity). Other oxidisable functionalities within the same molecule (e.g. hydroxyl, alkene, and heteroaromatic nitrogen or sulphur atoms) remained untouched. The reaction was scaled for the oxidation of 5-(hydroxymethyl)furfural (2 g), a bio-based starting material, to afford 5-(hydroxymethyl)furoic acid in 61% isolated yield. The new biocatalytic method avoids the use of toxic or unsafe oxidants, strong acids or bases, or undesired solvents. It shows applicability across a wide range of substrates, and retains perfect chemoselectivity. Alternative oxidisable groups were not converted, and other classical side-reactions (e.g. halogenation of unsaturated functionalities, Dakin-Type oxidation) did not occur. In comparison to other established enzymatic methods such as the use of oxidases (where the concomitant oxidation of alcohols and aldehydes is common), ALDHs offer greatly improved selectivity.
- Knaus, Tanja,Tseliou, Vasilis,Humphreys, Luke D.,Scrutton, Nigel S.,Mutti, Francesco G.
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supporting information
p. 3931 - 3943
(2018/09/11)
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- Preparation of valeric acid and valerate esters from biomass-derived levulinic acid using metal triflates + Pd/C
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Recently, great attention has been paid to the study of the conversion of biomass-derived compounds to value-Added chemicals. Levulinic acid (LA) is a versatile and valuable chemical and its various applications have been described. The selective conversion of biomass-derived LA to produce valeric acid and valerate esters was successfully performed in the presence of H2, in which metal triflates and Pd/C were used as the catalysts. Under optimal conditions, a 99% conversion of LA and a 92% selectivity of valeric acid was obtained with Hf(OTf)4 and Pd/C as the catalysts at a relatively low temperature of 150 °C. Moreover, the metal center of the catalyst, the solvent, the reaction temperature and other reaction conditions were studied. In addition, the results of the recycling experiment exhibited that the catalysts continued to have a satisfactory activity after being reused 5 times.
- Zhou, Jian,Zhu, Rui,Deng, Jin,Fu, Yao
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p. 3974 - 3980
(2018/09/11)
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- Organic synthesis raw material valeric acid synthesis method
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The invention relates to an organic synthesis raw material valeric acid synthesis method, which mainly comprises: adding 3 mol methyl propyl ketone and 4-6 mol tributyl citrate solution to a reactioncontainer, controlling the stirring speed at 190-220 rpm, reducing the solution temperature to 6-9 DEG C, maintaining for 60-80 min, increasing the temperature of the solution to 10-15 DEG C, adding 3-4 mol chromium acetate in 3-6 times every 30-40 min, continuously carrying out the reaction for 2-3 h, standing for 60-80 min, adding 300 ml of a potassium nitrate solution, layering the solution, extracting 3-5 times with a 4-heptanone solution, extracting 4-6 times with a 3-methyl-2-pentanone solution, combining the oil layer and the extraction liquid, re-crystallizing in an isobutyl butyrate solution, and dehydrating with a dehydrating agent to obtain the finished product valeric acid.
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Paragraph 0006; 0009-0014
(2018/07/30)
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- Method for preparing carboxylic acid compound by oxidatively breaking carbon-carbon bond of ketone compound
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The invention relates to a method for directly preparing a carboxylic acid compound by oxidatively breaking a carbon-carbon bond of a ketone compound. The method comprises adding a ketone compound anda catalyst into an organic solvent, putting the solution into a pressure container, sealing the container, and feeding oxygen source gas under a certain pressure into the container, wherein the reaction product is a carboxylic acid compound, the oxygen source gas is oxygen or air, the catalyst is a copper salt catalyst, the organic solvent is one of acetonitrile, dimethyl sulfoxide and N, N-dimethylformamide and the corresponding carboxylic acid product highest yield after the reaction is 99%. The method has a wide application range, is free of alkali assistants and organic ligands and is easy to separate.
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Paragraph 0141; 0142
(2018/06/16)
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- An Efficient Iron(III)-Catalyzed Aerobic Oxidation of Aldehydes in Water for the Green Preparation of Carboxylic Acids
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The first example of a heterogeneous iron(III)-catalyzed aerobic oxidation of aldehydes in water was developed. This method utilizes 1 atmosphere of oxygen as the sole oxidant, proceeds under extremely mild aqueous conditions, and covers a wide range of various functionalized aldehydes. Chromatography is generally not necessary for product purification. Its operational simplicity, gram-scale oxidation, and the ability to successively reuse the catalyst, make this new methodology environmentally benign and cost effective. The generality of this methodology gives it the potential to be used on an industrial scale.
- Yu, Han,Ru, Shi,Dai, Guoyong,Zhai, Yongyan,Lin, Hualin,Han, Sheng,Wei, Yongge
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p. 3867 - 3871
(2017/03/27)
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- A levulinic acid by the method of preparation valeric acid and pentanoate (by machine translation)
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The present invention provides a process for preparing valeric acid and by levulinic acid formylvalerate ester, to levulinic acid as a starting material, the hydrogenation catalyst and trifluoromethanesulfonic acid metal salt as a catalyst, the hydrogen atmosphere catalytic hydrogenolysis reaction, to obtain the valeric acid, continue to valeric acid as the raw material, trifluoromethanesulfonic acid metal salt as catalyst, adding alcohol compound to carry out the esterification reaction, to obtain pentanoate. The invention described in the laevulinic acid preparation valeric acid and formylvalerate ester, it has simple process, mild reaction conditions, high product yield, easy to be purified, environment-friendly and the like, and is suitable for large-scale industrial production. (by machine translation)
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Paragraph 0026-0051
(2017/08/30)
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- Influence of W on the reduction behaviour and Br?nsted acidity of Ni/TiO2catalyst in the hydrogenation of levulinic acid to valeric acid: Pyridine adsorbed DRIFTS study
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Effect of W on 20 wt%Ni/TiO2catalyst is examined in the hydrogenation of levulinic acid (LA) to valeric acid at ambient H2pressure. The interaction between W and Ni had a significant influence on the hydrogenation activity and product selectivity. The H2-TPR (temperature programmed reduction) results emphasized a shift in Tmaxto very high temperatures due to W species which are in close proximity to Ni particles. The N2O decomposition measurements showed a decrease in N2O uptake with the increase in ‘W’ loadings due to a high ratio of Ni2+/Ni0species at higher tungsten content. X-ray photoelectron spectra (XPS) demonstrated a shift in binding energy to higher owing to a strong interaction between W and Ni particles by the presence of ionic Ni at the near surface region. The ionic Ni species seems to be involved in the conversion of γ-valerolactone (GVL) to valeric acid (VA). Pyridine adsorbed infrared (IR) spectra revealed an enormous increase in surface Br?nsted acidity originated from tungsten interacted Ni/TiO2are the sites responsible for ring opening of GVL to form VA.
- Kumar, V. Vijay,Naresh,Deepa,Bhavani, P. Ganga,Nagaraju,Sudhakar,Chary,Venugopal,Tardio,Bhargava
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p. 169 - 176
(2016/12/27)
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- Iodine catalyzed oxidation of alcohols and aldehydes to carboxylic acids in water: A metal-free route to the synthesis of furandicarboxylic acid and terephthalic acid
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A metal-free iodine/NaOH-catalyzed oxidation of alcohols and aldehydes has been developed for the practical synthesis of a wide range of carboxylic acids using water as the solvent. This transformation involves dehydrogenation of an alcohol, followed by a fast attack of water on an aldehyde. This method is mostly free from chromatographic purification, which makes it suitable for large-scale synthesis. The iodine species formed during the reaction as the active oxidation catalyst has been deduced as IO2- by control experiments. We also demonstrate a 10 gram scale synthesis of furandicarboxylic acid (FDCA) from HMF in good yield using our method.
- Hazra, Susanta,Deb, Mayukh,Elias, Anil J.
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supporting information
p. 5548 - 5552
(2017/12/06)
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- Structural transformation of porous polyoxometalate frameworks and highly efficient biomimetic aerobic oxidation of aliphatic alcohols
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Due to their inherent inert nature, it is difficult to oxidize unactivated aliphatic alcohols with molecular oxygen under mild conditions. Inspired by enzymatic catalysis, numerous biomimetic systems have been therefore established. However, low catalytic efficiency and easy auto-oxidative deactivation nature remain the problematic issues. To meet these challenges, we report herein a 2D porous polyoxometalate (POM) framework Gd4(H2O)26[WZn{Cu(H2O)}2(ZnW9O34)2]·24H2O (CZJ-11) and a 3D porous POM framework Gd4(H2O)24[WZn{Cu(H2O)}2(ZnW9O34)2]·11H2O (CZJ-12) transferred from CZJ-11 by partial dehydration, consisting of scaffolded redox-active Cu(II) sites in the sandwich-type POM cluster [WZn{Cu-(H2O)}2(ZnW9O34)2]12- (abbreviated as {Zn3Cu2W19}). To mimic the catalytic mechanism of enzymes, N-hydroxyphthalimide (NHPI) and tetramethylammonium bromide (TMAB) were introduced as cocatalysts, which performed as electron donor and electron-transfer mediator, respectively. The coupled catalyst systems demonstrate analogue properties with oxygenase enzymes in the aerobic oxidation of aliphatic alcohols under mild conditions. Compared with molecular POM counterpart and metalloporphyrins, the catalytic efficiency of these POM frameworks is predominant in aerobic oxidation of unactivated aliphatic alcohols by imitating the active sites and the catalytic mechanism of enzymes. Compared with metal-organic coordination complexes, such as metalloporphyrins, the pure inorganic frameworks offer significant superiority of robustness to auto-oxidation and simple recovery for recycling with retained high catalytic efficiency.
- Zhao, Min,Zhang, Xian-Wei,Wu, Chuan-De
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p. 6573 - 6580
(2017/11/09)
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- Preparation method of carboxylic acid compound
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The invention provides a preparation method of a carboxylic acid compound. The preparation method comprises the following step of taking a lactone component to react with hydrogen in the presence of a compound catalyst to obtain the carboxylic acid compound. The compound catalyst comprises a hydrogenation catalyst and Lewis acid. In the presence of the compound catalyst comprising the hydrogenation catalyst and the Lewis acid, the lactone component is subjected to hydrogenation ring-opening reaction to obtain the carboxylic acid compound. The preparation method has the advantages of moderate reaction conditions and high yield; compared with a traditional method, less byproducts are generated, green and chemical requirements are met and the industrial value is better.
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Paragraph 0113; 0121-0123
(2017/08/29)
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- A Comprehensive Study on Metal Triflate-Promoted Hydrogenolysis of Lactones to Carboxylic Acids: From Synthetic and Mechanistic Perspectives
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Direct hydrogenolysis of lactone to carboxylic acid (i.e., hydrogenolysis of the Calkoxy-O bond with the carbonyl group untouched) is generally difficult, as the current strategies employing Br?nsted acids as the catalyst usually require harsh conditions such as a high temperature and a high H2 pressure. Herein, we report a developed solvent-free catalytic transformation, in which W(OTf)6 is believed to promote the hydrogenolysis process. This strategy could efficiently hydrogenate lactones to carboxylic acids under extra mild conditions (e.g., a reaction temperature of 2) and showed a broad substrate scope. In addition, the catalytic protocol can be further applied to the hydrogenolysis of polyhydroxyalkanoate, as a renewable polymer, to the corresponding straight-chain carboxylic acids. An extensive mechanistic study was subsequently performed, and the density functional theory calculations revealed a reaction pattern, including the complete cleavage of the C=O bond with the assistance of the W(OTf)6 catalyst. Moreover, the key intermediate created in the mechanism, as an oxonium with an OTf moiety, was successfully detected by electrospray ionization mass spectra. Through a comparison with the Br?nsted acid-catalyzed system, the study confirmed that the existence of the OTf moiety can significantly lower the barriers associated with the rearrangement and elimination processes. Meanwhile, emphasis was placed on the critical role that the anion plays, as well as the fact that the anion effect is directly related to the chemoselectivity.
- Zhu, Rui,Jiang, Ju-Long,Li, Xing-Long,Deng, Jin,Fu, Yao
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p. 7520 - 7528
(2017/11/10)
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- Effect of SiO2 support properties on the performance of Cu-SiO2 catalysts for the hydrogenation of levulinic acid to gamma valerolactone using formic acid as a hydrogen source
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Vapor phase catalytic transfer hydrogenation of aqueous levulinic acid (LA) with formic acid (FA) as a hydrogen source was carried out over copper loaded on to several SiO2 supports having different physicochemical properties. The SiO2 supports and Cu-SiO2 catalysts with different support properties were characterized by XRD, TPR, XPS, NH3-TPD and UV-vis techniques to evaluate the copper species and its interaction with the support. The SiO2 support alone showed lower LA conversion and low selectivity to GVL whereas Cu-SiO2 catalysts were found to show high conversion and selectivity to the desired product with formic acid as the hydrogen source. The difference in the activities and product selectivity among different copper supported silica appears to be a complex function of acidity and the nature of copper species in the Cu-SiO2 catalysts. No direct correlation was observed between a specific catalyst property such as acidity and pore size, and the performance of the Cu-SiO2 catalysts. From the characterization, it appears that the species responsible for higher activity and selectivity to GVL are monomeric partially oxidized copper species in a strong interaction with the support in combination with a higher number of acid sites, both of which are present in Cu-SiO2-Q6. Cu-SiO2-Q6 showed the highest conversion and selectivity of 66 and 81%, respectively, under optimized conditions.
- Lomate, Samadhan,Sultana, Asima,Fujitani, Tadahiro
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p. 3073 - 3083
(2017/08/15)
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- Green technology for preparing n-valeric acid from low-purity n-valeraldehyde by air oxidation
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The invention discloses a green technology for preparing n-valeric acid from low-purity n-valeraldehyde by air oxidation. The green technology includes the steps: adding the low-purity n-valeraldehyde into a stirred bubbling tank reactor with outer circulation; bubbling into air or oxygen or oxygen-enriched air or oxygen-denuded air; decompressing, rectifying and purifying for products after oxidation reaction to obtain the n-valeric acid with purity of more than 98%. The content of the n-valeraldehyde is lower than 80%, air speed is 100-2000L/min, reaction temperature is 25-100 DEG C, reaction time is 1-30 hours, the conversion rate of the n-valeraldehyde reaches 97% or above, selectivity reaches 98% or above, single decompressing and distilling rate reaches 86% or above. By the aid of the green technology, the air serves as an oxidizing agent, any catalysts are omitted, and the green technology has the advantages of smooth reaction, high efficiency, low cost, green, environmental protection and the like and a wide application and market prospect.
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Paragraph 0015
(2017/06/14)
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