- Molybdate Stabilized Magnesium‐Iron Hydrotalcite Materials: Potential Catalysts for Isoeugenol to Vanillin and Olefin Epoxidation
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A series of molybdate-intercalated and stabilized magnesium‐iron hydrotalcite (HMFeMo) materials with different molybdate loadings were successfully prepared by an in-situ hydrothermal method. The prepared HMFeMo materials were systematically characterized using Fourier-transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), Ultraviolet-visible spectroscopy, scanning electron microscopy, thermo-gravimetric analysis, nitrogen adsorption-desorption and X-ray photoelectron spectroscopy (XPS) experiments. The XRD results demonstrated the successful intercalation of molybdate ions in the interlayer space of magnesium-iron hydrotalcite and the stabilization of the layered structure. In addition, the XPS spectra of the HMFeMo materials revealed the presence of molybdenum in a higher-valent oxidation state. The calcination of HMFeMo materials led to the formation of solid solution of mixed metal oxides. Both the as-prepared and calcined HMFeMo catalysts showed promising activity for the epoxidation of cyclooctene, as a model reaction. Furthermore, the performance of the as-prepared and calcined HMFeMo catalysts for the oxidation of a biomass model compound, namely isoeugenol to vanillin, was evaluated. The isoeugenol conversion over the as-prepared HMFeMo catalysts under solvent-free conditions and using tertiary-butyl hydroperoxide in decane as the oxidant was good. Moreover, the isoeugenol conversion and selectivity toward vanillin of HMFeMo0.1, with a molybdate loading of 0.1 mol %, were the highest (86.2% and 83.1%, respectively) of all HMFeMo catalysts in this study at 80 °C for 5 hr. HMFeMo0.1 presented the best catalytic activity for both the epoxidation of cyclooctene and oxidation of isoeugenol to vanillin, and its activity remained unchanged after several runs.
- Neethu, P. P.,Sakthivel, A.,Sreenavya, A.
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- Continuous flow study of isoeugenol to vanillin: A bio-based iron oxide catalyst
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The use of a biorefinery co-product, such as humins, in combination with an iron precursor in a solvent-free method yields a catalytic material with potential use in selective oxidative cleavage reactions. In particular, this catalyst was found active in the hydrogen-peroxide assisted oxidation of a naturally extracted molecule, isoeugenol, to high added-value flavouring agent, vanillin. By carrying out the reaction in continuous flow, not only a better understanding of the reaction mechanism and of the catalyst deactivation can be achieved, but also important insights for optimised conditions can be developed. The findings of this paper could pave the way to a more sustainable process for the production of a valuable food and perfume additive, vanillin.
- Filiciotto, Layla,Márquez-Medina, María Dolores,Pineda, Antonio,Balu, Alina M.,Romero, Antonio A.,Angelici, Carlo,de Jong, Ed,van der Waal, Jan C.,Luque, Rafael
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p. 281 - 290
(2019/12/25)
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- Structural features and antioxidant activities of Chinese quince (Chaenomeles sinensis) fruits lignin during auto-catalyzed ethanol organosolv pretreatment
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Chinese quince fruits (Chaenomeles sinensis) have an abundance of lignins with antioxidant activities. To facilitate the utilization of Chinese quince fruits, lignin was isolated from it by auto-catalyzed ethanol organosolv pretreatment. The effects of three processing conditions (temperature, time, and ethanol concentration) on yield, structural features and antioxidant activities of the auto-catalyzed ethanol organosolv lignin samples were assessed individually. Results showed the pretreatment temperature was the most significant factor; it affected the molecular weight, S/G ratio, number of β-O-4′ linkages, thermal stability, and antioxidant activities of lignin samples. According to the GPC analyses, the molecular weight of lignin samples had a negative correlation with pretreatment temperature. 2D-HSQC NMR and Py-GC/MS results revealed that the S/G ratios of lignin samples increased with temperature, while total phenolic hydroxyl content of lignin samples decreased. The structural characterization clearly indicated that the various pretreatment conditions affected the structures of organosolv lignin, which further resulted in differences in the antioxidant activities of the lignin samples. These results can be helpful for controlling and optimizing delignification during auto-catalyzed ethanol organosolv pretreatment, and they provide theoretical support for the potential applications of Chinese quince fruits lignin as a natural antioxidant in the food industry.
- Cheng, Xi-Chuang,Guo, Xin-Ran,Liu, Hua-Min,Liu, Yu-Lan,Qin, Zhao,Wang, Xue-De
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p. 4348 - 4358
(2020/09/22)
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- MnO2as a terminal oxidant in Wacker oxidation of homoallyl alcohols and terminal olefins
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Efficient and mild reaction conditions for Wacker-type oxidation of terminal olefins of less explored homoallyl alcohols to β-hydroxy-methyl ketones have been developed by using a Pd(ii) catalyst and MnO2 as a co-oxidant. The method involves mild reaction conditions and shows good functional group compatibility along with high regio- and chemoselectivity. While our earlier system of PdCl2/CrO3/HCl produced α,β-unsaturated ketones from homoallyl alcohols, the present method provided orthogonally the β-hydroxy-methyl ketones. No overoxidation or elimination of benzylic and/or β-hydroxy groups was observed. The method could be extended to the oxidation of simple terminal olefins as well, to methyl ketones, displaying its versatility. An application to the regioselective synthesis of gingerol is demonstrated.
- Fernandes, Rodney A.,Ramakrishna, Gujjula V.,Bethi, Venkati
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p. 6115 - 6125
(2020/10/27)
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- Stereoselective Synthesis of 1-Arylpropan-2-amines from Allylbenzenes through a Wacker-Tsuji Oxidation-Biotransamination Sequential Process
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Herein, a sequential and selective chemoenzymatic approach is described involving the metal-catalysed Wacker-Tsuji oxidation of allylbenzenes followed by the amine transaminase-catalysed biotransamination of the resulting 1-arylpropan-2-ones. Thus, a series of nine optically active 1-arylpropan-2-amines were obtained with good to very high conversions (74–92%) and excellent selectivities (>99% enantiomeric excess) in aqueous medium. The Wacker-Tsuji reaction has been exhaustively optimised searching for compatible conditions with the biotransamination experiments, using palladium(II) complexes as catalysts and iron(III) salts as terminal oxidants in aqueous media. The compatibility of palladium/iron systems for the chemical oxidation with commercially available and made in house amine transaminases was analysed, finding ideal conditions for the development of a general and stereoselective cascade sequence. Depending on the selectivity displayed by selected amine transaminase, it was possible to produce both 1-arylpropan-2-amines enantiomers under mild reaction conditions, compounds that present therapeutic properties or can be employed as synthetic intermediates of chiral drugs from the amphetamine family. (Figure presented.).
- González-Martínez, Daniel,Gotor, Vicente,Gotor-Fernández, Vicente
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p. 2582 - 2593
(2019/05/15)
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- Method for preparing medical intermediate 4-hydroxy-3-methoxyphenylacetone
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The invention discloses a method for preparing a medical intermediate 4-hydroxy-3-methoxyphenylacetone. The method comprises steps as follows: firstly, a catalyst containing graphene, zirconia and Ptis prepared, 2-methoxy-4-(2-nitro-1-allyl) phenol is prepared from vanillic aldehyde and nitroethane as raw materials under the catalysis of glacial acetic acid and n-butylamine, and 2-methoxy-4-(2-oximido propyl) phenol is prepared from 2-methoxy-4-(2-nitro-1-allyl) phenol as a reaction raw material by adding ammonium formate and the self-made catalyst through stirring reaction; finally, 2-methoxy-4-(2-oximido propyl) phenol and a sulfuric acid solution are subjected to the stirring reaction for 1-3 h at the room temperature, after the reaction, a reaction liquid is left to stand for layering, a xylene layer is separated out and dried with anhydrous sodium sulfate, a solvent is removed through reduced-pressure concentration, fractions at 150-151 DEG C are collected, and 4-hydroxy-3-methoxyphenylacetone is obtained. The method is simple to operate, purity of a target product is high, yield is high, and cost is low.
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Paragraph 0029-0036
(2018/06/15)
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- Benign-by-design preparation of humin-based iron oxide catalytic nanocomposites
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The current acid-catalyzed conversion of biomass feedstocks yields substantial quantities of undesired by-products called humins, for which applications are yet to be found. This work aims to provide a starting point for valorisation of humins via preparation of humin-based iron oxide catalytic nanocomposites from humins and thermally treated humins (foams) via solvent-free methodologies including ball milling and thermal degradation. The prepared materials were found to be active in the microwave-assisted selective oxidation of isoeugenol (conversions >87%) to vanillin, proving the feasibility to use humin by-products as template/composite materials.
- Filiciotto, Layla,Balu, Alina M.,Romero, Antonio A.,Rodríguez-Castellón, Enrique,Van Der Waal, Jan C.,Luque, Rafael
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p. 4423 - 4434
(2017/09/27)
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- Correlating lignin structural features to phase partitioning behavior in a novel aqueous fractionation of softwood Kraft black liquor
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In this work, a set of softwood lignins were recovered from a Kraft black liquor using a novel pH-based fractionation process involving sequential CO 2 acidification and separation of the solvated aqueous lignin fraction. These recovered lignin fractions were characterized with respect to properties that may be responsible for their phase partitioning behavior as well as properties that may render the lignins more suitable for materials applications. Lignin fractions were recovered between a pH range of 12.8 and 9.5 with the bulk of the lignin (90%) recovered between a pH of 11.1 and 10.0. While all the fractions were found to consist primarily of lignin as validated by sample methoxyl content, the first fractions to phase separated were found to be especially enriched in aliphatic extractives and polysaccharides. From the bulk of the lignin that was recovered between a pH of 11.1 and 10.0 a number of noteworthy trends were discernible from the data. Specifically, the phenolic hydroxyl content was found to exhibit a strong negative correlation to the fractionation pH and exhibited a nearly 50% increase with recovery at decreasing pH, while the GPC-estimated molecular weights and 13C NMR-estimated β-O-4 content showed strong positive correlations to the pH at recovery. The aliphatic hydroxyl content exhibited minimal differences between recovery conditions. Overall, these results suggest that this fractionation approach can generate lignin fractions enriched in select physical or structural properties that may be important for their application as feedstocks for renewable chemicals or materials.
- Stoklosa, Ryan J.,Velez, Julian,Kelkar, Shantanu,Saffron, Christopher M.,Thies, Mark C.,Hodge, David B.
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supporting information
p. 2904 - 2912
(2013/10/08)
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- DEPOLYMERIZATION OF LIGNIN USING SOLID ACID CATALYSTS
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The invention provides for a process for the depolymerization of lignin in an inert atmosphere to result in substituted phenolic monomer compounds. The process is catalysed by heterogeneous solid acid catalysts and is carried out in batch or continuous mode.
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Page/Page column 6; 7
(2012/12/13)
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- Oxidation of isoeugenol to vanillin by the "h2O 2-vanadate-pyrazine-2-carboxylic acid" reagent
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Isoeugenol [2-methoxy-4-(prop-1-en-1-yl)phenol; compound 1] can be oxidized to vanillin (4-hydroxy-3-methoxybenzaldehyde, compound 2) by H 2O2 in the presence of the n-Bu4NVO 3/pyrazine-2-carboxylic acid catalyt
- Gusevskaya, Elena V.,Menini, Luciano,Parreira, Luciana A.,Mesquita, Rafaela A.,Kozlov, Yuriy N.,Shul'Pin, Georgiy B.
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p. 140 - 147,8
(2020/08/20)
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- Oxidative cleavage of isoeugenol to vanillin under molecular oxygen catalysed by cobalt porphyrin intercalated into lithium taeniolite clay
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Three types of Co-porphyrin complexes differing in their porphyrin-ring substituents and nonionic or cationic structure were intercalated into lithium taeniolite (LiTN) using a simple cation exchange method. All the intercalated catalysts displayed expanded clearance spaces (in the range of 0.30-0.51 nm) compared with that of the parent LiTN (0.24 nm). The catalysts were applied for the oxidative cleavage of isoeugenol to vanillin with molecular oxygen as the sole oxidant, and the reaction proceeded effectively under mild reaction conditions. The highest vanillin selectivity of 72% was obtained with CoTPyP/TN, which had the widest clearance space among the three Co-porphyrin catalysts. These intercalated catalysts showed high stability during oxidation, enabling their recycling for at least three runs.
- Adilina, Indri Badria,Hara, Takayoshi,Ichikuni, Nobuyuki,Shimazu, Shogo
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experimental part
p. 72 - 79
(2012/08/08)
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- Palladium-catalyzed aerobic oxidation of naturally occurring allylbenzenes as a route to valuable fragrance and pharmaceutical compounds
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A palladium-catalyzed, aerobic oxidation of naturally occurring allylbenzenes, i.e., eugenol, methyleugenol, safrole, and estragole, in dimethylacetamide/water solutions under mild conditions has been developed, in which palladium(II) chloride is used in the absence of co-catalysts or special stabilizing ligands as the sole and recyclable catalyst. Methyl ketones that are important for the flavour and pharmaceutical industries have been obtained in good to excellent yields with low catalyst loadings (1-2 mol%) and high average turnover frequencies. This simple catalytic method represents an ecologically benign and economically attractive route to industrially valuable compounds starting from renewable substrates easily available from essential oils.
- Parreira, Luciana A.,Menini, Luciano,Da Cruz Santos, Joyce C.,Gusevskaya, Elena V.
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experimental part
p. 1533 - 1538
(2010/09/11)
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- Fe-HCl: An efficient reagent for deprotection of oximes as well as selective oxidative hydrolysis of nitroalkenes and nitroalkanes to ketones
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Fe-HCl mixture was found to selectively perform oxidative hydrolysis of the nitroalkenes 1a-j and nitroalkanes 2a-j to the ketones 3a-j. Also, the reagent was observed to deprotect the oximes 7a-j to carbonyl compounds 8a-j in excellent yields.
- Pradhan, Prasun K.,Dey, Sumit,Jaisankar, Parasuraman,Giri, Venkatachalam S.
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p. 913 - 922
(2007/10/03)
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- Methoxyphenols from burning of Scandinavian forest plant materials
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Semivolatile compounds in smoke from gram-scale incomplete burning of plant materials were assessed by gas chromatography and mass spectrometry. Gas syringe sampling was shown to be adequate by comparison with adsorbent sampling. Methoxyphenols as well as 1,6-anhydroglucose were released in amounts as large as 10 mg kg-1 of dry biomass at 90% combustion efficiency. Wood, twigs, bark and needles from the conifers Norway spruce and Scots pine emitted 12 reported 2-methoxyphenols in similar proportions. Grass, heather and birchwood released the same 2-methoxyphenols but also the corresponding 2,6-dimethoxyphenols which are characteristic of angiosperms. The methoxyphenols are formed from lignin and differ in structure by the group in para position relative to the phenolic OH group. Prominent phenols were those with trans-l-propenyl and ethenyl groups in that position. Vanillin, 4- hydroxy-3-methoxybenzaldehyde, was a prominent carbonyl compound from the conifer materials. (C) 2000 Elsevier Science Ltd.
- Kjaellstrand, Jennica,Ramnaes, Olle,Petersson, Goeran
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p. 735 - 741
(2007/10/03)
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- Clay Catalized Rearrangement of Phenyloxiranes
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The reaction of phenyloxiranes with a clay produces aldehydes, ketones and cyclic ethers. This method has the advantage that experimental conditions are simple and the reagents used are cheaper.
- Martinez, Roberte,Velasco, Micaela,Martinez, Ignacio,Menconi, Italo,Ramirez, Alberto,Angeles, Enrique,Regla, Ignacio,Lopez, Rafael
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p. 1865 - 1866
(2007/10/03)
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- The Palladium Assisted Transfer Reduction of α,β-Unsaturated Nitroalkenes to Oximes Using Ammonium Formate
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α,β-Unsaturated nitroalkenes are readily reduced to the corresponding oximes in good yields using ammonium formate in the presence of palladium.The reactions occur rapidly at room temperature in a solvent system of methanol and tetrahydrofuran.
- Kabalka, George W.,Pace, R. David,Wadgaonkar, P.P.
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p. 2453 - 2458
(2007/10/02)
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- SYNTHESIS AND REACTIONS OF 2-ARYL-8-OXABICYCLOOCT-6-EN-3-ONES
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A number of 1-aryl-1-bromopropanones have been prepared and converted into the corresponding oxyallyl carbocations.These were reacted with furan to produce the expected 2-aryl-8-oxabicyclooct-6-en-3-ones, as well as a number of interesting side-products.These included 3-aryl-propanoic acid esters produced via Favorskii rearrangements.Attempts to cleave the ether linkage in the cycloadducts using bromotrimethylsilane produced instead 1-aryl-3-furylpropanones in excellent yield.
- Mann, John,Wilde, Philip D.,Finch, Mark W.
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p. 5431 - 5442
(2007/10/02)
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- Process for producing phenylacetones
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A phenylacetone or its derivative having the general formula (I): STR1 wherein X, Y, and Z are independently a hydrogen atom, a hydroxyl group, a halogen atom, a nitro group, an amino group, a lower alkyl group having 1 to 6 carbon atoms, a lower alkoxy group having 1 to 6 carbon atoms, or a benzyloxy group and any two substituents of X, Y, and Z may form, together with the benzene ring, a heterocycling ring having 5 to 7 members including 1 or 2 oxygen atoms is produced at a high yield and a high selectivity by reacting a 3-phenylpropylene or its derivative having the general formula (II): STR2 wherein X, Y, and Z are as defined above, with an alkyl nitrite having the general formula (III): wherein R is an aliphatic, aromatic, or alicyclic saturated or unsaturated hydrocarbon group in the presence of (a) water, (b) an alcohol, (c) a palladium catalyst, and (d) an optional amine or copper compound, or by reacting the above-mentioned 3-phenylpropylene or its derivative with the above-mentioned alkyl nitrite in the presence of (a) an alcohol, (b) a palladium catalyst and (c) an optional amine or copper compound to form 1-phenyl-2,2-dialkoxypropane or it derivative having the general formula (IV): STR3 wherein X, Y, Z and R are as defined above, followed by hydrolyzing the reaction product.
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- Selective catalyzed-rearrangement of terminal epoxides to methyl ketones
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Terminal epoxides of the type {A figure is presented} have been selectively converted into methyl ketones by various catalysts. Some lanthanide derivatives, MnI2, and Co2(CO)8 gave the best results. The rearrangement of internal epoxides into ketones is much slower, allowing specific transformation of terminal epoxides. The scope of the reaction and tentative mechanisms are discussed.
- Prandi,Namy,Menoret,Kagan
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p. 449 - 460
(2007/10/02)
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