- Malononitrile as acylanion equivalent
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The oxidation of derivatives of malononitrile with peracid in methanol proceeds with loss of the cyano groups to yield methyl esters in high yield. The method was applied to a variety of malononitrile derivatives, some of which were prepared by Pd- or Ir-catalyzed asymmetric allylic substitution. Georg Thieme Verlag Stuttgart.
- F?rster, Sebastian,Tverskoy, Olena,Helmchen, Günter
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- Mechanistic Insights into Aerobic Oxidative Methyl Esterification of Primary Alcohols with Heterogeneous PdBiTe Catalysts
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Aerobic oxidative methyl esterification of primary alcohols is an important chemical transformation that converts a nucleophile (alcohol) into a versatile electrophile (methyl ester). We recently discovered a heterogeneous PdBiTe/C catalyst that exhibits the highest activity yet reported for this transformation. Bi and Te serve as synergistic promoters that enhance both the rate and yield of the reactions relative to reactions employing Pd alone or Pd in combination with Bi or with Te as the sole promoter. Here, we report a mechanistic study of the oxidative methyl esterification of benzyl alcohol and 1-octanol to provide insights into the overall multistep transformation as well as the role of the Bi and Te in the reaction. The catalytic rates of the oxidative esterification of benzyl alcohol and octanol with Pd, PdBi, PdTe, and PdBiTe catalysts exhibit a saturation dependence on [alcohol] and [K2CO3] and a first-order dependence on pO2. Hammett studies of benzyl alcohol oxidation reveal opposing electronic trends for initial rates of oxidation of alcohol to aldehyde (negative ? value) and the oxidation of aldehyde to methyl ester (positive ? value). These data and complementary kinetic isotope effect data support a Langmuir-Hinshelwood mechanism in which a surface-bound alkoxide or hemiacetal intermediate undergoes rate-limiting β-hydride elimination. Molecular oxygen participates in this process, as revealed by a first-order dependence on pO2. X-ray photoelectron and X-ray absorption spectroscopic methods show that the promoters undergo oxidation in preference to Pd, maintaining the Pd surface in the active metallic state and preventing inhibition by surface Pd-oxide formation. Collectively, these results provide valuable insights into the synergistic benefits of multiple promoters in heterogeneous catalytic oxidation reactions.
- Mannel, David S.,King, Jesaiah,Preger, Yuliya,Ahmed, Maaz S.,Root, Thatcher W.,Stahl, Shannon S.
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- Structure and catalysis of layered Nb-W oxide constructed by the self-assembly of nanofibers
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Treatment of crystalline Nb2O5-WOx fibers with an aqueous solution of oxalic or tartaric acid resulted in the formation of nanosheets with a layered structure in which fibers were self-assembled. The oxalic and tartaric acid-treated oxides had dense layered structures containing mesopores between the layers with mean diameters of 4.6 and 1.9 nm, respectively. These oxides exhibited much higher recyclability as catalysts for the Friedel-Crafts alkylation and acylation of anisole compared to untreated ones. Furthermore, no deactivation was observed in a continuous flow process for the reaction of anisole and benzyl alcohol at least over 87 days' period in which turnover number = 33,000 was obtained. The improved catalytic performance was ascribed to the formation of layered structure, which was preserved during reactions.
- Okumura, Kazu,Ishida, Soichiro,Takahata, Ryota,Katada, Naonobu
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- Hydroxylamine Reactions with Peroxide Products of Alkenes Ozonolysis
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Reactions were studied of peroxide ozonolysis products obtained from linear and cyclic alkenes with hydroxylamine prepared in situ from NH2OH·HCl by hydrogen chloride neutralization with sodium acetate. A one-pot reactions sequence was performed: alkene oxidation with ozone → reduction to a carbonyl compound with hydroxylamine → condensation of the carbonyl compound with hydroxylamine providing a possibility of direct transformation of alkenes in keto- and aldoximes excluding the stage of preparation and isolation of the carbonyl compound.
- Legostaeva, Yu. V.,Garifullina,Nazarov,Ishmuratova,Ishmuratov, G. Yu.
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- Synthesis, characterization and reactivity of (dithiolato)indium complexes
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We have synthesized indium complexes incorporating tetradentate dithiolate ligands. The 1:1 reaction of InX3 (X?=?OAc, NO3) and the corresponding dithiol or dithiolate yielded the compounds [(SOOS)In(py)(NO3)] (1), [(SNNS)In(OAc)] (2), [In(μ-SNNS)2(μ-OMe)In][NO3] (3), [(SNNSPr)In(OAc)] (4), [(NNS2)In(OAc)] (5) and [(NNS2)In(NO3)] (6) [H2(SOOS)?=?2,2′-(ethylenedioxy)diethanethiol; H2(SNNS)?=?N,N′-dimethyl-N,N′-bis(2-mercaptoethyl)ethylenediamine; H2(SNNSPr)?=?N,N′-diethyl-N,N′-bis(2-mercaptoethyl)propanediamine; H2(NNS2)?=?N,N-diethyl-N′,N′-bis(2-mercaptoethyl)ethanediamine]. The solid-state structures of 1, 2 and 4–6 are mononuclear and show a tetradentate SOOS/SNNS/NNS2 ligand and a distorted octahedral (1) or trigonal bipyramidal (2, 4–6) coordination geometry at indium. Compound 3 is dinuclear, with the indium centres bridged by a -OMe oxygen atom and a thiolate sulfur atom of chelating tetradentate ligands, respectively. InX3 (X?=?Cl, NO3) were found to be useful Lewis acid catalysts for the aldol reaction of benzaldehyde and 1-(trimethylsiloxy)cyclohexene under ambient conditions, while compounds 1–6 show moderate activity as catalysts for the esterification of stearic acid and transesterification of methyl stearate and glyceryl trioctanoate.
- Anderson, Timothy S.,Briand, Glen G.,Brüning, Ralf,Decken, Andreas,Margeson, Matthew J.,Pickard, Heidi M.,Trevors, Eric E.
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- Magnesia-supported gold nanoparticles as efficient catalysts for oxidative esterification of aldehydes or alcohols with methanol to methyl esters
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Magnesia-supported gold nanoparticles were found to be highly efficient catalysts for the oxidative esterification of methacrolein (MAL) with methanol in the presence of molecular oxygen into methyl methacrylate (MMA) under liquid base-free conditions. MAL conversion of 98% and MMA selectivity of 99% were obtained over the Au/MgO catalyst at 343 K after a 2 h reaction. Besides the Au nanoparticles, the support also played pivotal roles in the oxidative esterification of MAL. The support with higher density of basic sites, particularly stronger basic sites, showed better performances for the formation of MMA. The enhancement of the intermediate formation by the basic sites is proposed to be the key reason for the superior activity of the Au/MgO catalyst. Our studies on the size effect of Au nanoparticles reveal that smaller Au nanoparticles favor the transformation of MAL, and the turnover frequency increases with decreasing mean size of Au nanoparticles. This suggests that the Au-catalyzed oxidative esterification of MAL is a structure-sensitive reaction. We have demonstrated that the Au/MgO catalyst is also applicable to the oxidative esterification of different aldehydes and alcohols.
- Wan, Xiaoyue,Deng, Weiping,Zhang, Qinghong,Wang, Ye
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- (BDP)CuH: A "hot" Stryker's reagent for use in achiral conjugate reductions
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(Chemical Equation Presented) A ligand-modified, economical version of Stryker's reagent (SR) has been developed based on a bidentate, achiral bis-phosphine. Generated in situ, "(BDP)CuH" smoothly effects conjugate reductions of a variety of unsaturated substrates, including those that are normally unreactive toward SR. Substrate-to-ligand ratios typically on the order of 1000-10000:1 can be used leading to products in high yields.
- Baker, Benjamin A.,Boskovic, Zarko V.,Lipshutz, Bruce H.
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- Composition of lipids from sunflower pollen (Helianthus annuus)
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The contents of the pollen lipids of the sunflower Helianthus annuus are described. The major component is the seco-triterpene helianyl octanoate, followed by new β-diketones as second major group of compounds. They exhibit a shorter chain length and often other positions of the functional group compared to already known β-diketones. Of particular note are the 1-phenyl- β-diketones, not previously reported from nature. Further lipid classes present are related hydroxyketones and diols. Interestingly, new β- dioxoalkanoic acids are present in the extracts, which most likely are biogenetic precursors of the diketones. Additionally, we investigated the composition of the pollen coat which resembles the total extract, but lacks the dioxoalkanoic acids and certain estolides. (C) 2000 Elsevier Science Ltd.
- Schulz, Stefan,Arsene, Cristian,Tauber, Marianne,McNeil, Jeremy N.
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- Pore-expanded SBA-15 sulfonic acid silicas for biodiesel synthesis
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Here we present the first application of pore-expanded SBA-15 in heterogeneous catalysis. Pore expansion over the range 6-14 nm confers a striking activity enhancement towards fatty acid methyl ester (FAME) synthesis from triglycerides (TAG), and free fatty acid (FFA), attributed to improved mass transport and acid site accessibility.
- Dacquin,Lee,Pirez,Wilson
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- Hydrazides of Organic Acids in the Transformations of the Peroxide Products of Non-1-ene Ozonolysis
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The reaction of hydrazides of alicyclic capric and aromatic benzoic and p-hydroxybenzoic acids with the peroxide product of non-1-ene ozonolysis was studied. Capric acid hydrazide exhibits the strongest reducing properties in aprotic solvents (methylene chloride, THF) and leads to chemoselective and high-yield (~ 80%) formation of the corresponding acylhydrazone. p-Hydroxybenzoic acid hydrazide forms a similar derivative with a yield of 67% only in THF.
- Myasoedova, Yu. V.,Garifullina,Nurieva,Ishmuratov, G. Yu.
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- Friedel-Crafts acylation of anisole with octanoic acid over acid modified zeolites
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Friedel-Crafts acylation of anisole using octanoic acid as a green acylating agent was studied over zeolites free of solvent. It was found that a mixed organic acid, composed of tartaric acid and oxalic acid, modified Hβ (Mix-Hβ) zeolite showed the best catalytic performance among the catalysts studied. The conversion of octanoic acid and the selectivity for p-octanoyl anisole were 72.7% and 82.5%, respectively. Inductively coupled plasma analysis (ICP) and 27Al MAS NMR indicated dealumination of the parent Hβ zeolite due to the treatment of the mixed organic acid, leading to more accessible active sites and accounting for the better catalytic activity of the Mix-Hβ zeolite. Furthermore, lower strength of Lewis acid sites and Broensted acid sites of the Mix-Hβ zeolite, as demonstrated by Fourier Transform Infrared Spectrometry after adsorption of pyridine (Py-IR), are advantageous to suppress the demethylation of anisole and the subsequent esterification of thus formed phenol, accounting for its higher selectivity toward p-octanoyl anisole.
- Bai, Guoyi,Han, Jie,Zhang, Huanhuan,Liu, Chen,Lan, Xingwang,Tian, Fei,Zhao, Zhen,Jin, Hui
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- Hierarchical macroporous-mesoporous SBA-15 sulfonic acid catalysts for biodiesel synthesis
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Hierarchical macroporous-mesoporous SBA-15 silicas have been synthesised via dual-templating routes employing liquid crystalline surfactants and polystyrene beads. These offer high surface areas and well-defined, interconnecting macro- and mesopore networks with respective narrow size distributions around 300 nm and 3-5 nm for polystyrene:tetraethoxysilane ratios ≥2:1. Subsequent functionalisation with propylsulfonic acid yields the first organized, macro-mesoporous solid acid catalyst. The enhanced mass transport properties of these new bi-modal solid acid architectures confer significant rate enhancements in the transesterification of bulky glyceryl trioctanoate, and esterification of long chain palmitic acid, over pure mesoporous analogues. This paves the way to the wider application of hierarchical catalysts in biofuel synthesis and biomass conversion.
- Dhainaut, Jeremy,Dacquin, Jean-Philippe,Lee, Adam F.,Wilson, Karen
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- Graphite oxide activated zeolite NaY: Applications in alcohol dehydration
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A mixture of graphite oxide (GO) and the zeolite NaY (Si/Al = 5.1) was used to dehydrate various alcohols to their respective olefinic products. Using conditions optimized for 4-heptanol (15 wt% GO-NaY (1 : 1 wt/wt), 150°C, 30 min), a series of secondary and tertiary aliphatic alcohols were cleanly dehydrated in moderate to excellent conversions (27.5-97.2%). Several primary alcohols were also dehydrated, although higher catalyst loadings (200 wt% GO-NaY (1 : 1) and longer reaction times (3 h) were required. The enhanced dehydration activity was attributed to the ability of GO to convert NaY to an acidic form and without the need for ammonium cation exchange and/or high temperature calcination. The Royal Society of Chemistry 2013.
- Todd, Alexander D.,Bielawski, Christopher W.
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- Electrooxidative Conversion of Aldehydes into Methyl Carboxylates
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The electrolytic oxidation of methanolic solutions of aldehydes in the presence of sodium cyanide at a platinum anode was found to produce corresponding methyl carboxylates.
- Chiba, Toshiro,Okimoto, Mitsuhiro,Nagai, Hiroshi,Takata, Yoshiyuki
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- Aerobic oxidative esterification of 5-hydroxymethylfurfural to dimethyl furan-2,5-dicarboxylate by using homogeneous and heterogeneous PdCoBi/C catalysts under atmospheric oxygen
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The conversion of platform molecule 5-hydroxymethylfurfural (HMF) into many value-added derivatives has attracted significant interest. FDCA and its esters are important derivatives of HMF, which can be used as polyester monomers and pharmaceutical intermediates. In this paper, oxidative esterification of 5-HMF has been carried out by using homogeneous and heterogeneous PdCoBi/C catalysts under atmospheric oxygen. The effect of reaction conditions on product distribution has been studied under both homogeneous and heterogeneous catalytic conditions. The highest yields of oxidative esterification products are obtained at 93% and 96% by using homogeneous and heterogeneous PdCoBi/C catalysts, respectively. The catalysts are characterized by X-ray photoelectron spectroscopy (XPS) and powder X-ray diffraction (XRD). The catalytic system has better compatibility according to the expansion of the substrate. A reaction mechanism is proposed, and recycle experiments are also conducted.
- Li, Feng,Li, Xing-Long,Li, Chuang,Shi, Jing,Fu, Yao
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- Biodiesel synthesis using integrated acid and base catalysis in continuous flow
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The use of biodiesel derived from oils and fats is making an increased contribution as a renewable energy source. The synthesis of biodiesel involves transesterification of triglycerides to the monoalkyl esters, a process often made challenging by the presence of free fatty acids (FFA). Herein an integrated flow system for the synthesis of biodiesel, employing a solid supported acid catalyst for esterification of FFAs, followed by transesterification using polymer supported N-heterocycle carbene (NHC) catalyst is reported. This system delivers biodiesel in high yields from a variety of fat and oils, using robust and recyclable catalysts.
- Asadi, Mousa,Hooper, Joel F.,Lupton, David W.
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- Syntheses of novel halogen-free Br?nsted-Lewis acidic ionic liquid catalysts and their applications for synthesis of methyl caprylate
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A series of benign halogen-free ionic liquid (IL) catalysts were synthesized by combining the Br?nsted acidic ionic liquid [HSO3-pmim]+HSO4? with ZnO in different composition ratios. The IL catalysts, which possess both Br?nsted and Lewis acidities, were employed as acidic catalysts for the esterification of n-caprylic acid to methyl caprylate. The [HSO3-pmim]+(1/2Zn2+)SO42?, prepared by cooperating equimolar amounts of Br?nsted and Lewis acid sites, was found to exhibit an optimal catalytic performance and excellent durability. This is attributed to a synergy of Br?nsted and Lewis acidities manifested by the catalyst. The response surface methodology (RSM) based on the Box-Behnken design (BBD) was utilized to explore the effects of different experimental variables (viz. catalyst amount, methanol to caprylic acid molar ratio, temperature, and reaction time) on the esterification reaction. Analysis of variance (ANOVA) was also employed to study the interactions between variables and their effects on the catalytic process. Accordingly, the deduced optimal reaction conditions led to a high methyl caprylate yield of 95.4%, in good agreement with experimental results and those predicted by the BBD model. Moreover, a kinetic study performed under optimal reaction conditions revealed an apparent reaction order of 1.70 and an active energy of 33.66 kJ mol?1
- Han, Xiao-Xiang,Du, Huan,Hung, Chin-Te,Liu, Li-Li,Wu, Pei-Hao,Ren, Da-Hai,Huang, Shing-Jong,Liu, Shang-Bin
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- Synthesis, structural characterization, and reactivity of (thiolato)bismuth complexes as potential water-tolerant Lewis acid catalysts
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We have synthesized bismuth complexes incorporating polydentate mono-and di-thiolate ligands and examined their utility as water-tolerant Lewis acid catalysts. The reaction of Bi(OAc)3 or Bi(NO3)3·5H2O and the corresponding mono-or di-thiol(ate) yielded the compounds [(SNNS)Bi(OAc)] (4), [(SNNSPr)Bi(OAc)] (5), [(NNS2)Bi(OAc)] (6), [(ONS2)Bi(OAc)] (7), [(ONS2)Bi(NO3)] (8), and [(NNS)2Bi][NO3] (9) [H2(SNNS) = N,N′-dimethyl-N,N′-bis(2-mercaptoethyl)ethylenediamine; H2(SNNSPr) = N,N′-diethyl-N,N′-bis(2-mercaptoethyl)propanediamine; H2(NNS2) = N,N-diethyl-N′,N′-bis(2-mercaptoethyl)ethanediamine; H2(ONS2) = 2-methoxyethyl-bis(2-mercaptoethyl)amine; H(NNS) = N,N-diethyl-N′-(2-mercaptoethyl)ethanediamine]. The solid-state structures of 4-8 show similar distorted pentagonal pyramidal geometries at the bismuth centre with a thiolate sulfur atom in the axial site, whereas 8 shows second structural arrangement with a distorted trigonal bipyramidal geometry at bismuth. The cation of 9 shows two NNS-bonded ligands and a distorted octahedral geometry at bismuth. Two-dimensional NMR studies of 4-8 show geminal 1H coupling in-SCH2CH2N-groups and suggests strong dative Bi-N intramolecular interactions. Bi(NO3)3·5H2O and BiCl3 show high activity toward the esterification of stearic acid, Bi(NO3)3·5H2O, and 4-7 and 9 show high activity toward the transesterification of methyl stearate in butanol, and 7 shows moderate activity as a catalyst for the transesterification of glyceryl trioctanoate in methanol.
- Briand, Glen G.,Decken, Andreas,Shannon, Whitney E.M.M.,Trevors, Eric E.
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- Ozonolysis of methyl oleate monolayers at the air-water interface: Oxidation kinetics, reaction products and atmospheric implications
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Ozonolysis of methyl oleate monolayers at the air-water interface results in surprisingly rapid loss of material through cleavage of the CC bond and evaporation/dissolution of reaction products. We determine using neutron reflectometry a rate coefficient of (5.7 ± 0.9) × 10-10 cm2 molecule-1 s-1 and an uptake coefficient of ~3 × 10-5 for the oxidation of a methyl ester monolayer: the atmospheric lifetime is ~10 min. We obtained direct experimental evidence that a minor change to the structure of the molecule (fatty acid vs. its methyl ester) considerably impacts on reactivity and fate of the organic film.
- Pfrang, Christian,Sebastiani, Federica,Lucas, Claire O. M.,King, Martin D.,Hoare, Ioan D.,Chang, Debby,Campbell, Richard A.
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- The Candida rugosa lipase adsorbed onto titania as nano biocatalyst with improved thermostability and reuse potential in aqueous and organic media
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The immobilization of Candida rugosa lipase by adsorption was performed onto commercial titania powder (Degussa P25). The change of titania particles surface was diagnosed by means of FTIR and FESEM analysis, as well as by shift of zeta potential value towards that of lipase. A detailed study of the effect of immobilization on enzyme kinetic, temperature stability, as well as on potential for its reuse in aqueous organic media was undertaken. Immobilization of lipase altered enzyme affinity toward substrates with different length of carbon chain in hydrolytic reaction. The Vmax value decreased 2–8-fold, where major constraint was registered for the ester containing the longest carbon chain. Thermostability of lipase improved more than 7-fold at 60 °C. Significant potential for reuse in water solutions was also found after immobilization. In cyclohexane immobilized lipase catalyzed synthesis of amyl octanoate by ping-pong bi–bi mechanism with inhibition by amyl alcohol. Obtained kinetic constants were Vmax = 26.4 μmol min?1, KAc = 0.52 mol/L, KAl = 0.2 mol/L and Ki,Al = 0.644 mol/L. Esterification activity remained 60% after 5 reuse cycles in cyclohexane indicating moderate reuse stability.
- Izrael ?ivkovi?, Lidija T.,Gop?evi?, Kristina R.,Karad?i?, Ivanka M.,?ivkovi?, Ljiljana S.,Be?koski, Vladimir P.,Joki?, Bojan M.,Radosavljevi?, Dragoslav S.
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- Alkali- and nitrate-free synthesis of highly active Mg-Al hydrotalcite-coated alumina for FAME production
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Mg-Al hydrotalcite coatings have been grown on alumina via a novel alkali- and nitrate-free impregnation route and subsequent calcination and hydrothermal treatment. The resulting Mg-HT/Al2O3 catalysts significantly outperform conventional bulk hydrotalcites prepared via co-precipitation in the transesterification of C4-C18 triglycerides for fatty acid methyl ester (FAME) production, with rate enhancements increasing with alkyl chain length. This promotion is attributed to improved accessibility of bulky triglycerides to active surface base sites over the higher area alumina support compared to conventional hydrotalcites wherein many active sites are confined within the micropores.
- Creasey, Julia J.,Chieregato, Alessandro,Manayil, Jinesh C.,Parlett, Christopher M. A.,Wilson, Karen,Lee, Adam F.
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- Sterically hindered (pyridyl)benzamidine palladium(II) complexes: Syntheses, structural studies, and applications as catalysts in the methoxycarbonylation of olefins
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Reactions of ligands (E)-N′-(2,6-diisopropylphenyl)-N-(4-methylpyridin-2-yl)benzimidamide (L1), (E)-N′-(2,6-diisopropylphenyl)-N-(6-methylpyridin-2-yl)benzimidamide (L2), (E)-N′-(2,6-dimethylphenyl)-N-(6-methylpyridin-2-yl)benzimidamide (L3), (E)-N′-(2,6-dimethylphenyl)-N-(4-methylpyridin-2-yl)benzimidamide (L4), and (E)-N-(6-methylpyridin-2-yl)-N′-phenylbenzimidamide (L5) with [Pd(NCMe)2Cl2] furnished the corresponding palladium(II) precatalysts (Pd1–Pd5), in good yields. Molecular structures of Pd2 and Pd3 revealed that the ligands coordinate in a N^N bidentate mode to afford square planar compounds. Activation of the palladium(II) complexes with para-tolyl sulfonic acid (PTSA) afforded active catalysts in the methoxycarbonylation of a number of alkene. The resultant catalytic activities were controlled by the both the complex structure and alkene substrate. While aliphatic substrates favored the formation of linear esters (>70%), styrene substrate resulted in the formation of predominantly branched esters of up to 91%.
- Akiri, Saphan O.,Ojwach, Stephen O.
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- N-Heterocyclic Carbene/Carboxylic Acid Co-Catalysis Enables Oxidative Esterification of Demanding Aldehydes/Enals, at Low Catalyst Loading
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We report the discovery that simple carboxylic acids, such as benzoic acid, boost the activity of N-heterocyclic carbene (NHC) catalysts in the oxidative esterification of aldehydes. A simple and efficient protocol for the transformation of a wide range of sterically hindered α- and β-substituted aliphatic aldehydes/enals, catalyzed by a novel and readily accessible N-Mes-/N-2,4,6-trichlorophenyl 1,2,4-triazolium salt, and benzoic acid as co-catalyst, was developed. A whole series of α/β-substituted aliphatic aldehydes/enals hitherto not amenable to NHC-catalyzed esterification could be reacted at typical catalyst loadings of 0.02–1.0 mol %. For benzaldehyde, even 0.005 mol % of NHC catalyst proved sufficient: the lowest value ever achieved in NHC catalysis. Preliminary studies point to carboxylic acid-induced acceleration of acyl transfer from azolium enolate intermediates as the mechanistic basis of the observed effect.
- Berkessel, Albrecht,Biswas, Animesh,Harnying, Wacharee,Sudkaow, Panyapon
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supporting information
p. 19631 - 19636
(2021/08/09)
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- Esterification or Thioesterification of Carboxylic Acids with Alcohols or Thiols Using Amphipathic Monolith-SO3H Resin
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We have developed a method for the esterification of carboxylic acids with alcohols using amphipathic, monolithic-resin bearing sulfonic acid moieties as cation exchange functions (monolith-SO3H). Monolith-SO3H efficiently catalyzed the esterification of aromatic and aliphatic carboxylic acids with various primary and secondary alcohols (1.55.0 equiv) in toluene at 6080 °C without the need to remove water generated during the reaction. The amphipathic property of monolith-SO3H facilitates dehydration due to its capacity for water absorption. This reaction was also applicable to thioesterification, wherein the corresponding thioesters were obtained in excellent yield using only 2.0 equiv of thiol in toluene, although heating at 120 °C was required. Moreover, monolith-SO3H was separable from the reaction mixtures by simple filtration and reused for at least five runs without decreasing the catalytic activity.
- Ichihara, Shuta,Ishida, Moeka,Ito, Ryo,Kato, Ayumu,Monguchi, Yasunari,Nakamura, Shinji,Park, Kwihwan,Sajiki, Hironao,Takada, Hitoshi,Wakayama, Fumika,Yamada, Tsuyoshi,Yamada, Yutaro
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p. 2702 - 2710
(2022/01/19)
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- Fully recyclable Br?nsted acid catalyst systems
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Homogeneous and heterogeneous sulfonic acid catalysts are some of the most common catalysts used in organic chemistry. This work explores an alternative scheme using a fully recyclable polymeric solvent (a poly-α-olefin (PAO)) and soluble PAO-anchored polyisobutylene (PIB)-bound sulfonic acid catalysts. This PAO solvent is nonvolatile and helps to exclude water by its nonpolar nature which in turn drives reactions without the need for distillation of water, avoiding the need for excess reagents. This highly nonpolar solvent system uses polyisobutylene (PIB) bound sulfonic acid catalysts that are phase-anchored in solvents like PAO. The effectivenes of these catalysts was demonstrated by their use in esterifications, acetalizations, and multicomponent condensations. These catalysts and the PAO solvent phase show excellent recyclability in schemes where products are efficiently separated. For example, this non-volatile polymeric solvent and the PIB-bound catalyst can be recycled quantitatively when volatile products are separated and purified by distillation. In other cases, product purification can be effected by product self-separation or by extraction.
- Watson, Christopher B.,Kuechle, Adrianna,Bergbreiter, David E.
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p. 1266 - 1273
(2021/02/26)
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- Carboxylic Acid Reductase Can Catalyze Ester Synthesis in Aqueous Environments
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Most of the well-known enzymes catalyzing esterification require the minimization of water or activated substrates for activity. This work reports a new reaction catalyzed by carboxylic acid reductase (CAR), an enzyme known to transform a broad spectrum of carboxylic acids into aldehydes, with the use of ATP, Mg2+, and NADPH as co-substrates. When NADPH was replaced by a nucleophilic alcohol, CAR from Mycobacterium marinum can catalyze esterification under aqueous conditions at room temperature. Addition of imidazole, especially at pH 10.0, significantly enhanced ester production. In comparison to other esterification enzymes such as acyltransferase and lipase, CAR gave higher esterification yields in direct esterification under aqueous conditions. The scalability of CAR catalyzed esterification was demonstrated for the synthesis of cinoxate, an active ingredient in sunscreen. The CAR esterification offers a new method for green esterification under high water content conditions.
- Pongpamorn, Pornkanok,Kiattisewee, Cholpisit,Kittipanukul, Narongyot,Jaroensuk, Juthamas,Trisrivirat, Duangthip,Maenpuen, Somchart,Chaiyen, Pimchai
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supporting information
p. 5749 - 5753
(2021/02/01)
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- ZWITTERIONIC CATALYSTS FOR (TRANS)ESTERIFICATION: APPLICATION IN FLUOROINDOLE-DERIVATIVES AND BIODIESEL SYNTHESIS
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An amide/iminium zwitterion catalyst has a catalyst pocket size that promotes transesterification and dehydrative esterification. The amide/iminium zwitterions are easily prepared by reacting aziridines with aminopyridines. The reaction can be applied a wide variety of esterification processes including the large-scale synthesis of biodiesel. The amide/iminium zwitterions allow the avoidance of strongly basic or acidic condition and avoidance of metal contamination in the products. Reactions are carried out at ambient or only modestly elevated temperatures. The amide/iminium zwitterion catalyst is easily recycled and reactions proceed in high to quantitative yields.
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Paragraph 0010; 0026
(2021/01/29)
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- Transformations of Peroxide Products of Non-1-ene Ozonolysis by the Action of Carboxylic Acid Hydrazides
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Abstract: The behavior of aliphatic (cyclohexanecarboxylic) and aromatic (salicylic and isonicotinic) carboxylic acid hydrazides toward peroxide products of ozonolysis of a terminal alkene, non-1-ene, in protic (methanol) and aprotic solvents (THF, methylene chloride) has been studied. These hydrazides are capable of acting as reducing agents or decomposing intermediate peroxides. For the synthesis of N′-octylidene isoniazid derivative, it is advisable to carry out the reaction in methanol, whereas the use of THF as solvent favors formation of N′-octylidenecyclohexane-1-carbonydrazide. Salicylic acid hydrazide showed a low efficiency; in this case, mixtures of the corresponding hydrazone with octanoic acid or its methyl ester were formed in a low yield.
- Myasoedova, Yu. V.,Nurieva,Garifullina,Ishmuratova,Ishmuratov, G. Yu.
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p. 113 - 116
(2021/03/03)
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- Palladium(II) complexes of (pyridyl)imine ligands as catalysts for the methoxycarbonylation of olefins
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Reactions of 2-methoxy-N-((pyridin-2-yl)methylene)ethanamine (L1), 2-((pyridin-2-yl)methyleneamino)ethanol (L2) and 3-methoxy-N-((pyridin-2-yl)methylene)propan-1-amine (L3) ligands with either [PdCl2(COD)] or [PdCl(Me)(COD)] produced the corresponding monometallic complexes [PdCl2(L1)] (1), [PdClMe(L1)] (2), [PdCl2(L2)] (3) and [PdCl2(L3)] (4). The solid state structure of complex 1 confirmed the bidentate coordination mode of L1, giving a distorted square planar geometry. All the complexes (1–4) formed active catalysts for the methoxycarbonylation of higher olefins to give linear and branched esters. The catalytic behavior of complexes 1–4 were influenced by both the complex structure and olefin chain length.
- Zulu, Zethu,Nyamato, George S.,Tshabalala, Thandeka A.,Ojwach, Stephen O.
-
-
- MOFs based on 1D structural sub-domains with Br?nsted acid and redox active sites as effective bi-functional catalysts
-
A novel family of lamellar MOF-type materials, which contain Br?nsted acid sites together with redox active centers, based on assembled 1D organic-inorganic nanoribbons were obtained through direct solvothermal synthesis routes, using specific monotopic benzylcarboxylate spacers with thiol substituents in thepara-position like structural modulator compounds and effective post-synthesis oxidized treatments to generate accessible sulfonic groups. Low-dimensional aluminum metal-organic materials, containing free sulfonic pendant groups (Al-ITQ-SO3H), were successfully tested in several acid reactions, such as acetalization, esterification and ring opening of epoxides with a significant impact on fine chemistry processes. The direct introduction of stabilized Pd nanoparticles, cohabitating with pendant sulfonic groups, allowed the preparation of active bi-functional MOF-type hybrid materials (Al-ITQ-SO3H/Pd) capable of carrying out one-pot two-step oxidation-acetalization reactions, exhibiting high yield and high activity during consecutive catalytic cycles.
- Díaz, Urbano,Moreno, José María,Velty, Alexandra
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p. 3572 - 3585
(2020/06/25)
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- A General Approach to Deboronative Radical Chain Reactions with Pinacol Alkylboronic Esters
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The generation of carbon-centered radicals from air-sensitive organoboron compounds through nucleohomolytic substitution at boron is a general method to generate non-functionalized and functionalized radicals. Due to their reduced Lewis acidity, alkylboronic pinacol esters are not suitable substrates. We report their in situ conversion into alkylboronic catechol esters by boron-transesterification with a substoichiometric amount of catechol methyl borate combined with an array of radical chain processes. This simple one-pot radical-chain deboronative method enables the conversion of pinacol boronic esters into iodides, bromides, chlorides, and thioethers. The process is also suitable the formation of nitriles and allylated compounds through C?C bond formation using sulfonyl radical traps. The power of combining radical and classical boron chemistry is illustrated with a modular 5-membered ring formation using a combination of three-component coupling and protodeboronative cyclization.
- André-Joyaux, Emy,Kuzovlev, Andrey,Renaud, Philippe,Tappin, Nicholas D. C.
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p. 13859 - 13864
(2020/06/10)
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- Methoxycarbonylation of olefins catalysed by homogeneous palladium(II) complexes of (phenoxy)imine ligands bearing alkoxy silane groups
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The Schiff base compounds 2-phenyl-2-((3(triethoxysilyl)propyl)imino)ethanol (HL1) and 4-methyl-2-((3(triethoxysilyl)propyl)imino)methyl)phenol (HL2) were synthesized via condensation reactions of a suitable ketone or aldehyde and (3-aminopropyl) triethoxy silane (APTES). Whereas the reactions of HL1 and HL2 with [Pd(OAc)2] afforded the bis(chelated) palladium compounds [Pd(L1)2] (1) and [Pd(L2)2] (2), treatments of HL1 and HL2 with [Pd(NCMe)2Cl2] gave the mono(chelated) complexes [Pd(HL1)2Cl2] (3) and [Pd(HL2)2Cl2] (4) respectively. Structural characterization of the compounds was achieved using NMR and FT-IR spectroscopies, mass spectrometry and micro-analyses. Complexes 1–4 gave active catalysts in the methoxycarbonylation of higher olefins producing linear esters as the major products. The coordination environment around the palladium center of the complexes dictated the relative catalytic activity, where the bis(chelated) analogues 1 and 2 were more active than the mono(chelated) analogues 3 and 4. The nature of the acid promoter, phosphine groups, solvent system, olefin substrate and reactions conditions influenced the catalytic behaviour of the complexes.
- Akiri, Saphan O.,Ojwach, Stephen O.
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p. 236 - 243
(2019/03/02)
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- Oxidative esterification of aliphatic aldehydes and alcohols with ethanol over gold nanoparticle catalysts in batch and continuous flow reactors
-
Selective esterification of aliphatic aldehydes and alcohols with ethanol in the absence of a base is a more difficult reaction than that with methanol. Gold nanoparticles on ZnO were found to catalyze the oxidative esterification of octanal to ethyl octanoate with high selectivity. In addition, it was found that Au/ZnO was the most effective catalyst for yielding the desired ethyl ester without a base by direct esterification of 1-octanol with ethanol. As far as we know, this is the first report on oxidative esterification to give aliphatic ethyl esters from less reactive aliphatic alcohols and aldehydes without a base. The optimal size of gold NPs ranged from 2 to 6 nm and the presence of Au(0) was indispensable for this reaction. Au/ZnO exhibited the highest catalytic activity in both batch and flow reactors. The conversion was maintained for more than 20 h with 95% selectivity to the desired ethyl ester in the flow system.
- Taketoshi,Ishida,Murayama, Toru,Honma, Tetsuo,Haruta, Masatake
-
-
- Dehydrogenative cross-coupling of primary alcohols to form cross-esters catalyzed by a manganese pincer complex
-
Base-metal-catalyzed dehydrogenative cross-coupling of primary alcohols to form cross-esters as major products, liberating hydrogen gas, is reported. The reaction is catalyzed by a pincer complex of earth-abundant manganese in the presence of catalytic base, without any hydrogen acceptor or oxidant. Mechanistic insight indicates that a dearomatized complex is the actual catalyst, and indeed this independently prepared dearomatized complex catalyzes the reaction under neutral conditions.
- Das, Uttam Kumar,Ben-David, Yehoshoa,Leitus, Gregory,Diskin-Posner, Yael,Milstein, David
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p. 479 - 484
(2019/01/11)
-
- Method for preparing carboxylic ester by alcohol direct oxidation esterification method
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The invention discloses a method for preparing a carboxylic ester by an alcohol direct oxidation esterification method. The method comprises the following steps: taking an aromatic alcohol compound ora saturated linear aliphatic alcohol as a reaction substrate, taking an Au-Co composite particle carrier as a catalyst, adding a low catalytic amount of alkali, reacting for 0.5-15 h in a methanol solvent at the temperature of 25-150 DEG C in air or oxygen or a mixed atmosphere of the air or the oxygen, and performing aftertreatment to obtain a target product carboxylic ester. According to the preparation method disclosed by the invention, the process steps are reduced, conditions are mild, catalyst consumption is less, atom economy is high, the method is simple to operate, the application range of the substrate is wide, and industrial practicability is achieved.
- -
-
Paragraph 0076; 0077
(2019/06/30)
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- 1,3-Dibromo-5,5-dimethylhydantoin as a Precatalyst for Activation of Carbonyl Functionality
-
Activation of carbonyl moiety is one of the most rudimentary approaches in organic synthesis and is crucial for a plethora of industrial-scale condensation reactions. In esterification and aldol condensation, which represent two of the most important reactions, the susceptibility of the carbonyl group to nucleophile attack allows the construction of a variety of useful organic compounds. In this context, there is a constant need for development of and improvement in the methods for addition-elimination reactions via activation of carbonyl functionality. In this paper, an advanced methodology for the direct esterification of carboxylic acids and alcohols, and for aldol condensation of aldehydes using widely available, inexpensive, and metal-free 1,3-dibromo-5,5-dimethylhydantoin under neat reaction conditions is reported. The method is air- and moisture-tolerant, allowing simple synthetic and isolation procedures for both reactions presented in this paper. The reaction pathway for esterification is proposed and a scale-up of certain industrially important derivatives is performed.
- ?ebular, Klara,Bo?i?, Bojan ?.,Stavber, Stojan
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supporting information
(2019/08/01)
-
- Structure determination of fatty acid ester biofuels via in situ cryocrystallisation and single crystal X-ray diffraction
-
In situ cryocrystallisation in combination with a zone-melting technique enabled the crystal structure determination of a homologous series of low-melting n-alkyl methyl esters Cn-1H2n+1CO2CH3, from methyl pentanoate (n = 5) to methyl tridecanoate (n = 13), by single crystal X-ray diffraction. Two isostructural groups were identified: the odd-numbered triclinic members (C9,11,13) and the even-numbered orthorhombic members (C8,10,12). All observed structural trends, similarities and differences in intermolecular contacts, including the odd-even effect observable in melting point behaviour and unit cell parameters, were easily visualised and described by 2D fingerprint plots generated from the calculated Hirshfeld surfaces, in combination with atom-atom Coulomb-London-Pauli (AA-CLP) lattice energy calculations.
- Prathapa, Siriyara Jagannatha,Slabbert, Cara,Fernandes, Manuel A.,Lemmerer, Andreas
-
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- Amide/Iminium Zwitterionic Catalysts for (Trans)esterification: Application in Biodiesel Synthesis
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A class of zwitterionic organocatalysts based on an amide anion/iminium cation charge pair has been developed. The zwitterions are easily prepared by reacting aziridines with aminopyridines. They are catalytically applicable to transesterifications and dehydrative esterifications. Mechanistic studies reveal that the amide anion and iminium cation work synergistically in activating the reaction partners, with the iminium cationic moiety interacting with the carbonyl substrates through nonclassical hydrogen bonding. The reaction can be applied to large-scale synthesis of biodiesel under mild conditions.
- Lam, Ying-Pong,Ng, Wing-Hin,Tan, Fei,Tse, Ying-Lung Steve,Wang, Xinyan,Yeung, Ying-Yeung
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p. 8083 - 8092
(2019/08/26)
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- Structural and theoretical studies of the methoxycarbonylation of higher olefins catalysed by (Pyrazolyl-ethyl)pyridine palladium (II) complexes
-
Reactions of 2-[1-(3,5-dimethylpyrazol-1-yl)ethyl]pyridine (L1) and 2-[1-(3,5-diphenylpyrazol-1-yl)ethyl]pyridine (L2) with the [Pd (COD)Cl2] or [Pd (COD)MeCl] produced palladium (II) complexes [Pd(L1)ClMe] (1), [Pd(L1)Cl2] (C2), [Pd(L2)ClMe] (3), and [Pd(L2)Cl2] (4) in quantitative yields. Solid state structures of complexes 1, 3 and 4 established the formation of mononuclear compounds, containing one bidentate ligand unit per metal atom, to give square planar complexes. All the other spectroscopic characterization data and elemental analyses were consistent with the observed structures. All the palladium (II) complexes 1–4 gave active catalysts in the methoxycarbonylation of 1-octenes. The catalysts demonstrated 100% chemoselectivities towards esters and favored the formation of linear isomers. Reaction conditions such as the type of phosphine derivative, acid promoter, solvent system, time, pressure and temperature have been investigated and shown to affect both the catalytic activity and regio-selectivity of the catalysts. Solid-angle modelling established the comparable steric contributions from the ligands, consistent with the similar regioselectivities of the resultant catalysts.
- Zulu, Siyabonga,Alam, Mohd.G.,Alam, Mohd. G.,Ojwach, Stephen O.,Akerman, Matthew P.
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- Esterification of aryl/alkyl acids catalysed by n-bromosuccinimide under mild reaction conditions
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N-halosuccinimides (NXSs) are well-known to be convenient, easily manipulable and low-priced halogenation reagents in organic synthesis. In the present work, N-bromosuccinimide (NBS) has been promoted as the most efficient and selective catalyst among the NXSs in the reaction of direct esterification of aryl and alkyl carboxylic acids. Comprehensive esterification of substituted benzoic acids, mono-, di- and tri-carboxy alkyl derivatives has been performed under neat reaction conditions. The method is metal-free, air- and moisture-tolerant, allowing for a simple synthetic and isolation procedure as well as the large-scale synthesis of aromatic and alkyl esters with yields up to 100%. Protocol for the recycling of the catalyst has been proposed.
- ?ebular, Klara,Bo?i?, Bojan ?.,Stavber, Stojan
-
-
- LIPID DELIVERY OF THERAPEUTIC AGENTS TO ADIPOSE TISSUE
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A method of treating a disease mediated by protein expression in adipose tissue by intraperitoneally administering a composition comprising a lipid nanoparticle encapsulating or associated with a therapeutic agent (e.g., a nucleic acid), thereby delivering the therapeutic agent to adipose tissue of the subject and altering protein expression in the adipose tissue is provided herein. A method for delivering a therapeutic agent to adipose tissue of a subject in need thereof is also provided.
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Page/Page column 172
(2018/11/10)
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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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p. 3931 - 3943
(2018/09/11)
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- Formation of esters and amides via metal-free Csp2-Csp3 bond cleavage of α-nitro ketone: Mechanistic insight to the reaction pathway
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A catalyst free protocol for hucleophilic Csp2-Csp3 bond cleavage of a-nitroketone has been achieved for the formation of C-O and C-N bond. A series of differently substituted a-nitroketones could be selectively cleaved and converted into corresponding esters and tosylamides in presence of alcohols and bromamine-T respectively. Mechanism of the C-C bond cleavage has been proposed by identifying different reaction intermediates using IR and NMR spectroscopic methods.
- Sarma, Manas Jyoti,Phukan, Prodeep
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p. 523 - 533
(2019/05/21)
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- Palladium(II) complexes bearing mixed N^N^X (X?=?O and S) tridentate ligands as pre-catalysts for the methoxycarbonylation of selected 1-alkenes
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The methoxycarbonylation of selected 1-alkenes catalyzed by various neutral and cationic palladium(II) complexes, containing mixed N^N^X (X = O and S) tridentate ligands 2-[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]-6-(phenoxymethyl)pyridine (L1), 2-[(3,5-di-tert-butyl-1H-pyrazol-1-yl)methyl]-6-(phenoxymethyl)pyridine (L2), 2-[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]-6-(phenylthiomethyl)pyridine (L3), 2-[(3,5-di-tert-butyl-1H-pyrazol-1-yl)methyl]-6-(phenylthiomethyl)pyridine (L4), has been investigated. Neutral complexes, [(?2-L1)Pd(CH3)(Cl)] (1a), [(?2-L2)Pd(CH3)(Cl)] (2a), [(?2-L3)Pd(CH3)(Cl)] (3a), [(?2-L4)Pd(CH3)(Cl)] (4a), and the salts, [(?3-L3)Pd(CH3)][BAr4F] (3c) and [(?3-L4)Pd(CH3)][BAr4F] (4c), underwent complete decomposition during the reaction to palladium black and showed no catalytic activity. However, the addition of PPh3 to the reaction dramatically increased the catalytic activity. On the other hand, the salts, [(?2-L1)Pd(CH3)(PPh3)][BAr4F] (1b), [(?2-L2)Pd(CH3)(PPh3)][BAr4F] (2b), [(?2-L3)Pd(CH3)(PPh3)][BAr4F] (3b) and [(?2-L4)Pd(CH3)(PPh3)][BAr4F] (4b), showed good conversion of the selected olefins to branched and linear esters without PPh3. Addition of PPh3 to reactions with 1b-4b significantly improved catalytic activity. All decomposition of complexes led to the formation of the known palladium complexes, [Pd(PPh3)2(Cl)(CH3)] and [Pd(PPh3)2Cl2]. The decomposition of all palladium complexes could be followed by NMR studies and [Pd(PPh3)2Cl2] could be isolated from the crude methoxycarbonylation reaction.
- Kumar, Kamlesh,Darkwa, James
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p. 249 - 257
(2017/10/27)
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- Direct oxidation of aldehydes to methyl esters with urea hydrogen peroxide and p-toluenesulfonyl chloride
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Combination of urea hydrogen peroxide and p-toluenesulfonyl chloride in methanol was proved to be facile and highly efficient for the oxidative methyl esterification of various aldehydes to the corresponding carboxylic methyl esters.
- Jeong, Deuk Jun,Lee, Su Bin,Lee, Jong Chan
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p. 725 - 728
(2017/12/28)
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- One-pot oxidative bromination – Esterification of aldehydes to 2-bromoesters using cerium (IV) ammonium nitrate and lithium bromide
-
A two-step, one-pot reaction of aldehydes with the CAN/LiBr oxidation system under solvent-free conditions followed by the addition of methanol affords methyl α-bromocarboxylates. The oxidation of aldehydes with methanol using this system gives only methyl esters. A facile method, which does not require special equipment, was developed for the synthesis of 2-bromoesters from aliphatic aldehydes with carbon chain lengths of 5–10 atoms.
- Nikishin, Gennady I.,Kapustina, Nadezhda I.,Sokova, Lyubov L.,Bityukov, Oleg V.,Terent'ev, Alexander O.
-
supporting information
p. 352 - 354
(2017/01/03)
-
- Discovery of multicomponent heterogeneous catalysts via admixture screening: PdBiTe catalysts for aerobic oxidative esterification of primary alcohols
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In the present study, we demonstrate the utility of "admixture screening" for the discovery of new multicomponent heterogeneous Pd catalyst compositions that are highly effective for aerobic oxidative methyl esterification of primary alcohols. The identification of possible catalysts for this reaction was initiated by the screening of simple binary and ternary admixtures of Pd/charcoal in combination with one or two metal and/or metalloid components as the catalyst. This approach permitted rapid evaluation of over 400 admixture combinations for the oxidative methyl esterification of 1-octanol at 60°C in methanol. Product yields from these reactions varied widely, ranging from 2% to 88%. The highest yields were observed with Bi-, Te-, and Pb-based additives, and particularly from those containing both Bi and Te. Validation of the results was achieved by preparing specific PdBiTe catalyst formulations via a wet-impregnation method, followed by application of response surface methodology to identify the optimal Pd-Bi-Te catalyst stoichiometry. This approach revealed two very effective catalyst compositions: PdBi0.47Te0.09/C (PBT-1) and PdBi0.35Te0.23/C (PBT-2). The former catalyst was used in batch aerobic oxidation reactions with different primary alcohols and shown to be compatible with substrates bearing heterocycle and halide substituents. The methyl ester products were obtained in >90% yield in nearly all cases. Implementation of the PBT-2 catalyst in a continuous-flow packed-bed reactor achieved nearly 60 000 turnovers with no apparent loss of catalytic activity.
- Mannel, David S.,Ahmed, Maaz S.,Root, Thatcher W.,Stahl, Shannon S.
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supporting information
p. 1690 - 1698
(2017/02/10)
-
- Conversion of alcohols to alkyl esters and carboxylic acids using heterogeneous palladium-based catalysts
-
Disclosed are methods for synthesizing an ester or a carboxylic acid from an organic alcohol. To form the ester one reacts, in the presence of oxygen gas, the alcohol with methanol or ethanol. This reaction occurs in the presence of a catalyst comprising palladium and a co-catalyst comprising bismuth, tellurium, lead, cerium, titanium, zinc and/or niobium (most preferably at least bismuth and tellurium). Alternatively that catalyst can be used to generate an acid from that alcohol, when water is also added to the reaction mix.
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Page/Page column 17; 18; 20
(2017/04/28)
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- Efficient flow fischer esterification of carboxylic acids with alcohols using sulfonic acid-functionalized silica as supported catalyst
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Flow Fischer esterification of carboxylic acids using hydroxy-substituted sulfonic acid-functionalized silica (HOSAS) packed into a stainless steel column reactor was investigated. HO-SAS well catalyzed flow esterification of long chain carboxylic acids with methanol within 3min of residence time at 110°C, and the methyl esters were quantitatively obtained. The flow esterification protocol was applied to the synthesis of a variety of esters (19 examples) and scalable synthesis was also successful.
- Furuta, Akihiro,Fukuyama, Takahide,Ryu, Ilhyong
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p. 607 - 612
(2017/06/19)
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- Lipophilic gold(I) complexes with 1,3,4-oxadiazol-2-thione or 1,3-thiazolidine-2-thione moieties: synthesis and their cytotoxic and antimicrobial activities
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Novel lipophilic gold(I) complexes containing 1,3,4-oxadiazol-2-thione or 1,3-thiazolidine-2-thione derivatives were synthesized and characterized by IR, high resolution mass spectrometry, and 1H, 13C 31P NMR. The cytotoxicity of the compounds was evaluated considering cisplatin and/or auranofin as reference in different tumor cell lines: colon cancer (CT26WT), metastatic skin melanoma (B16F10), breast adenocarcinoma (MCF-7), cervical carcinoma (HeLa), glioblastoma (M059?J). Normal human lung fibroblasts (GM07492-A) and kidney normal cell (BHK-21) were also evaluated. The gold(I) complexes were more active than their respective free ligands and cisplatin. Furthermore, antibacterial activity was evaluated against Gram-positive bacteria Staphylococcus aureus ATCC 25213, Staphylococcus epidermidis ATCC 12228 and Gram-negative bacteria Escherichia coli ATCC 11229 and Pseudomonas aeruginosa ATCC 27853 and expressed as the minimum inhibitory concentration (MIC). The complexes exhibited lower MIC values when compared to the ligands and chloramphenicol against Gram-positive bacteria and Gram-negative bacteria. Escherichia coli was sensitive one to the action of gold(I) complexes.
- de Almeida, Angelina Maria,de Oliveira, Bruno Assis,de Castro, Pedro P?ssa,de Mendon?a, Camille Carvalho,Furtado, Ricardo Andrade,Nicolella, Heloiza Diniz,da Silva, Vania Lúcia,Diniz, Cláudio Galuppo,Tavares, Denise Crispim,Silva, Heveline,de Almeida, Mauro Vieira
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p. 841 - 857
(2017/10/07)
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- Model quinoline-sensitive ionic liquid and its catalytic preparation of long-chain fatty acid a method of esterification of
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The invention discloses a preparation method of a thermo-sensitive ionic liquid and a method for catalyzing a methyl esterification reaction of a long-chain fatty acid by adopting the thermo-sensitive ionic liquid. The structure of the thermo-sensitive ionic liquid is as shown in a general formula (I) and comprises a quinoline cation and anions such as a fluoboric acid radical, a methane sulfonic acid radical and hydrogen sulphate. The preparation method of the thermo-sensitive ionic liquid is mainly characterized in that number of phase states of a system is regulated and controlled by increasing and lowering temperature, namely the system can be in one phase at high temperature and in different phases at room temperature or low temperature after the ionic liquid is rapidly separated from products, so that the whole reaction system guarantees high catalytic efficiency in a homogeneous reaction, separation and recycling are simpler, the disadvantages of limited two-phase catalytic efficiency and difficult recycling of the ionic liquid during homogeneous catalysis are overcome, and a new thought is provided for solving the problems. The general formula (I) is as shown in the specification.
- -
-
Paragraph 0062; 0063
(2017/03/14)
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- Esterification, transesterification and hydrogenation reactions of polyunsaturated compounds catalyzed by a recyclable polymer supported palladium catalyst
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Aliphatic and aromatic carboxylic acids were converted into their corresponding esters using a polymer supported palladium(II) β-ketoesterate complex under hydrogen atmosphere in the presence of catalytic bromobenzene in alcohols. This method was also applicable to the transesterification of esters. Good to excellent yields were obtained for different aliphatic or aromatic starting materials. The esterification (or transesterification) was promoted by the in situ generation of HBr from bromobenzene, which provided a mild acidic reaction environment. Pd(II) centers were converted into polymer stabilized metal nanoparticles (the true active species) under reaction conditions. The palladium catalyst exhibited a remarkable activity and was reusable for eight consecutive cycles. The present system was also tested for the preparation of partially hydrogenated fatty acid methyl esters, starting from a mixture composed by highly polyunsaturated esters and free carboxylic acids, taken as a model acidic feedstock for biodiesel upgrading.
- Dell'Anna, Maria Michela,Capodiferro, Vito Filippo,Mali, Matilda,Mastrorilli, Piero
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p. 106 - 114
(2016/07/06)
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- Gold nanoparticles supported on metal oxides as catalysts for the direct oxidative esterification of alcohols under mild conditions
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Gold nanoparticles supported on metal oxides were used to catalyze the direct oxidative esterification of alcohols; esters were obtained using molecular oxygen as an oxidant under ambient temperature and pressure. Higher activities for the reaction between the benzyl alcohol and methanol were obtained over Au/CeO2 and Au/ZrO2 than Au/TiO2 (anatase), Au/HT (hydrotalcite) and Au/Al2O3. These catalysts were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), atomic absorption spectroscopy (AAS) and X-ray photoelectron spectroscopy (XPS). The distribution of gold nanoparticles was uniform; no change of chemical states occurred for supports and gold nanoparticles after the catalysts were reused 10 times. The oxidative esterification of various alcohols over these catalysts could also occur under optimized reaction conditions. The substituted benzyl alcohols and cinnamyl alcohols were more active than heterocyclic alcohols and aliphatic alcohols because their α-H could be eliminated more easily during the induction of adsorbed dioxygen. Self-oxidative esterification was available for benzyl alcohol in inert solvents with low polarity indexes. A reaction mechanism was proposed for the synthesis of esters from alcohols with molecular oxygen.
- Wei, Huili,Li, Jingyi,Yu, Jing,Zheng, Jianwei,Su, Haiquan,Wang, Xiaojing
-
-
- A novel aromatic carbocation-based coupling reagent for esterification and amidation reactions
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A novel tropylium-based coupling reagent has been developed to facilitate the synthesis of a series of esters, amides, lactones and peptides under mild reaction conditions. Remarkably, this reagent can be used in catalytic amounts in conjunction with a sacrificial reagent, offering a new and efficient method for nucleophilic coupling reactions of carboxylic acids.
- Nguyen, Thanh V.,Lyons, Demelza J.M.
-
supporting information
p. 3131 - 3134
(2015/06/17)
-
- Four new pentasaccharide resin glycosides from Ipomoea cairica with strong α-glucosidase inhibitory activity
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Six pentasaccharide resin glycosides from Ipomoea cairica, including four new acylated pentasaccharide resin glycosides, namely cairicoside I-IV (1-4) and the two known compounds cairicoside A (5) and cairicoside C (6), were isolated from the aerial parts of Ipomoea cairica. Their structures were established by a combination of spectroscopic, including two dimensional (2D) NMR and chemical methods. The core of the six compounds was simonic acid A, and they were esterfied the same sites, just differing in the substituent groups. The lactonization site of the aglycone was bonded to the second saccharide moiety at C-2 in 1-4, and at C-3 in 5-6. Compounds 1 and 5, 4 and 6 were two pairs of isomers. The absolute configuration of the aglycone in 1-6 which was (11S)-hydroxyhexadecanoic acid (jalapinolic acid) was established by Mosher's method. Compounds 1-4 have been evaluated for inhibitory activity against α-glucosidase, which all showed inhibitory activities.
- Pan, Jie-Tao,Yu, Bang-Wei,Yin, Yong-Qin,Li, Jie-Hong,Wang, Li,Guo, Li-Bing,Shen, Zhi-Bin
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p. 6601 - 6610
(2015/05/13)
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- Thermodynamically leveraged tandem catalysis for ester RC(O)O-R′ bond hydrogenolysis. scope and mechanism
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Rapid and selective formal hydrogenolysis of aliphatic ester RC(O)O-R′ linkages is achieved by a tandem homogeneous metal triflate + supported palladium catalytic system. The triflate catalyzes the mildly exothermic, turnover-limiting O-R′ cleavage process, whereas the exothermic hydrogenation of the intermediate alkene further drives the overall reaction to completion.
- Lohr, Tracy L.,Li, Zhi,Assary, Rajeev S.,Curtiss, Larry A.,Marks, Tobin J.
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p. 3675 - 3679
(2015/06/16)
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- Agent having neurotrophic factor-like activity
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The present invention provides a pharmaceutical agent having high safety and a neurotrophic factor-like activity, which contains, as an active ingredient, any one compound included in fatty acids each having 8 carbon atoms (C8) or having 10 carbon atoms (C10) to 12 carbon atoms (C12) or fatty acid esters thereof, such as 3,7-dimethyloctanoic acid ethyl ester, geranicacidethyl ester, and the like, eachof whichhas 8 carbonatoms (C8), decanoic acid methyl ester, trans-2-decenoic acid, trans-2-decenoic acid methyl ester, trans-2-decenoic acid ethyl ester, trans-2-decenoic acid-2-decenyl ester, trans-2-decenoic acid cyclohexyl ester, trans-2-decenoic acid isopropyl ester, trans-3-decenoic acid methyl ester, trans-9-decenoic acid methyl ester, and the like, each of which has 10 carbon atoms (C10), trans-10-undecenoic acid methyl ester, trans-10-undecenoic acid ethyl ester, and the like, each of which has 11 carbon atoms (C11), and dodecanoic acid, and the like, each of which has 12 carbon atoms (C12), or salts thereof or prodrugs thereof.
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- Biochemical Studies of Mycobacterial Fatty Acid Methyltransferase: A Catalyst for the Enzymatic Production of Biodiesel
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Summary Transesterification of fatty acids yields the essential component of biodiesel, but current processes are cost-prohibitive and generate waste. Recent efforts make use of biocatalysts that are effective in diverting products from primary metabolism to yield fatty acid methyl esters in bacteria. These biotransformations require the fatty acid O-methyltransferase (FAMT) from Mycobacterium marinum (MmFAMT). Although this activity was first reported in the literature in 1970, the FAMTs have yet to be biochemically characterized. Here, we describe several crystal structures of MmFAMT, which highlight an unexpected structural conservation with methyltransferases that are involved in plant natural product metabolism. The determinants for ligand recognition are analyzed by kinetic analysis of structure-based active-site variants. These studies reveal how an architectural fold employed in plant natural product biosynthesis is used in bacterial fatty acid O-methylation. Mycobacterial fatty acid methyltransferases are employed as biocatalysts for the production of biodiesel. Petronikolou and Nair describe structural and biochemical characterization of a mycobacterial fatty acid methyltransferase, reveal an unexpected homology to enzymes involved in plant primary metabolism, and provide insights into substrate preference.
- Petronikolou, Nektaria,Nair, Satish K.
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p. 1480 - 1490
(2015/12/01)
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- An efficient iron catalyzed regioselective acylative cleavage of ethers: Scope and mechanism
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A method involving iron catalyzed acylative cleavage of cyclic and acyclic ethers with acyl/aroyl chlorides has been studied to produce chloroesters and esters respectively. Examination of the scope revealed that less electron rich alkyl group in unsymmetric, acyclic ether was acylated while the chloride derived from the counterpart moiety was volatile and difficult to isolate. In contrast, α-branched cyclic ethers were converted to the corresponding primary ester and secondary chloride. Steric hindrance of ether also plays an important role in acylative C-O bond cleavage. The mechanism of ether cleavage is proposed to involve a single electron initiated SN1 dissociative pathway.
- Bodduri, V.D. Vijaykumar,Choi, Kyung-Min,Vaidya, Raghavender Rao,Patil, Kalpesh,Chirumarry, Sridhar,Jang, Kiwan,Yoon, Yong-Jin,Falck, John R.,Shin, Dong-Soo
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supporting information
p. 7089 - 7093
(2015/12/01)
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- Formation of new C-O and C-N bonds via base promoted Csp2-Csp3 bond cleavage of α-nitro ketone
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A catalyst free protocol has been developed for nucleophilic Csp2-Csp3 bond cleavage of α-nitroketone in the presence of potassium carbonate to create new C-O and C-N bonds. A series of different substituted α-nitroketones could be selectively cleaved and converted into corresponding esters and tosylamides in the presence of alcohols and bromamine-T, respectively.
- Sarma, Manas Jyoti,Borah, Arun Jyoti,Rajbongshi, Kamal Krishna,Phukan, Prodeep
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supporting information
p. 7008 - 7011
(2015/11/27)
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- Dimethyl sulfite a potential agent for methylation
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The synthesis of methylated ether compounds is an important challenge. A pathway for the synthesis of methyl ethers was investigated using dimethyl sulfite (DMSi). Methylation of 1-octanol was carried out in liquid phase upon different heterogeneous organic and inorganic catalysts at 130°C. Aluminium oxide gave the best result with high conversion and moderate selectivity for methyl 1-octyl ether. Reactions in gas phase at higher temperatures (200°C) were also performed. Methyl 1-octyl ether was obtained in a very high level of selectivity up to 98%. Primary and secondary ethers from unsymmetrical alkyl methyl sulfite were also performed by SO2 extrusion.
- Mouselmani, Rim,Da Silva, Eric,Lemaire, Marc
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p. 8905 - 8910
(2015/11/02)
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