- Heterogeneous catalysis in an oscillatory baffled flow reactor
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The first demonstration of heterogeneous catalysis within an oscillatory baffled flow reactor (OBR) is reported, exemplified by the solid acid catalysed esterification of organic acids, an important prototypical reaction for fine chemicals and biofuel synthesis. Suspension of a PrSO3H-SBA-15 catalyst powder is readily achieved within the OBR under an oscillatory flow, facilitating the continuous esterification of hexanoic acid. Excellent semi-quantitative agreement is obtained between OBR and conventional stirred batch reaction kinetics, demonstrating efficient mixing, and highlighting the potential of OBRs for continuous, heterogeneously catalysed liquid phase transformations. Kinetic analysis highlights acid chain length (i.e. steric factors) as a key predictor of activity. Continuous esterification offers improved ester yields compared with batch operation, due to the removal of water by-product from the catalyst, evidencing the versatility of the OBR for heterogeneous flow chemistry and potential role as a new clean catalytic technology. The Royal Society of Chemistry 2013.
- Eze, Valentine C.,Phan, Anh N.,Pirez, Cyril,Harvey, Adam P.,Lee, Adam F.,Wilson, Karen
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- Simple, rapid procedure for the synthesis of chloromethyl methyl ether and other chloro alkyl ethers
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Zinc(II) salts catalyze the reaction between acetals and acid halides to provide haloalkyl ethers in near-quantitative yield. Reactions from millimole to mole scale are typically complete in 1-4 h with 0.01 mol % catalyst. The solutions of haloalkyl ethers thus obtained can be utilized directly in reactions in which the presence of the ester byproduct does not interfere. Excess haloalkyl ether is destroyed on workup, thereby minimizing exposure to this class of carcinogenic compounds.
- Berliner, Martin A.,Belecki, Katherine
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- The Co-promotion effect of Mo and Nd on the activity and stability of sulfated zirconia-based solid acids in esterification
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SO42-/ZrO2-MoO3 (SZM), SO 42-/ZrO2-Nd2O3 (SZN) and SO42-/ZrO2-MoO3-Nd2O 3 (SZMN) solid acids catalysts were prepared and characterized by XRD, NH3-FTIR, NH3-TPD and TG-DTG. The activities and stabilities of the catalysts for the esterification of fatty acids were investigated. Experimental and characterization results show that the excellent activity and stability of SZMN are attributed to the firm combination of sulfur species with t-ZrO2. The co-addition of Mo and Nd increases the dispersion of t-ZrO2 and stabilizes the structure of small-crystallite t-ZrO2, which is favorable to increasing the acid sites amount, strengthening the acidity, and then enhancing the activity and stability of the catalyst.
- Jiang, Kanghua,Tong, Dongmei,Tang, Jinqiang,Song, Ruili,Hu, Changwei
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- Methylation of Aliphatic and Aromatic Carboxylic Acids with Dimethyl Carbonate under the Influence of Manganese and Iron Carbonyls
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The synthesis of methyl esters has been carried out via the reaction of aliphatic and aromatic carboxylic acids with dimethyl carbonate in the presence of manganese and iron carbonyls. The optimal ratio of catalyst and reagents and other conditions for the synthesis of methyl esters of carboxylic acids with high yield have been found.
- Khusnutdinov,Shchadneva,Mayakova, Yu. Yu.
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- MOFs based on 1D structural sub-domains with Br?nsted acid and redox active sites as effective bi-functional catalysts
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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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- Acylated dolabellane-type diterpenes from Nigella sativa seeds with triglyceride metabolism-promoting activity in high glucose-pretreated HepG2 cells
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Two new acylated dolabellane-type diterpenes, nigellamines B3 (9) and D (10), were isolated from Nigella sativa (Ranunculaceae) seeds using column chromatography and preparative HPLC. Their structures were determined based on chemical and physi
- Morikawa, Toshio,Ninomiya, Kiyofumi,Xu, Fengming,Okumura, Naomichi,Matsuda, Hisashi,Muraoka, Osamu,Hayakawa, Takao,Yoshikawa, Masayuki
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- A NOVEL OXO FATTY ACID IN PLANTAGO OVATA SEED OIL
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Key Word Index-Plantago ovata; Plantaginaceae; seed oil; 9-oxoocadec-cis-12-enoic acid. Plantago ovata seed oil contains two oxygenated fatty acids one of which is the known 9-hydroxyoctadec-cis-12-enoic acid.The other is 9-oxooctadec-cis-12-enoic acid a new acid.The structural elucidation of this novel compound is described.
- Jamal, Sajid,Ahmad, Ishtiaque,Agarwal, Rajiv,Ahmad, Mashood,Osman, Sheikh Mohammad
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- Ultralow-Molecular-Weight Stimuli-Responsive and Multifunctional Supramolecular Gels Based on Monomers and Trimers of Hydrazides
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The simpler, the better. A series of simple, neutral and ultralow-molecular-weight (MW: 140–200) hydrazide-derived supramolecular gelators have been designed and synthesized in two straightforward steps. For non-conjugated cyclohexane-derived hydrazides, their monomers can self-assemble to form gels through intermolecular hydrogen bonds and dipole-dipole interactions. Significantly, conjugated phthalhydrazide can self-aggregate into planar and circular trimers through intermolecular hydrogen bonds and then self-assemble to form gels through intermolecular π–π stacking interactions. It is interesting that these simple gelators exhibit unusual properties, such as self-healing, multi-response fluorescence, and visual and selective recognition of chiral (R)/(S)-1,1′-binaphthalene-2,2′-diamine and S2? through much different times of gel re-formation and blue-green color change, respectively. These results underline the importance of supramolecular gels and extend the scope of supramolecular gelators.
- Wu, Dehua,Song, Jintong,Qu, Lang,Zhou, Weilan,Wang, Lei,Zhou, Xiangge,Xiang, Haifeng
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- Optimized double kinetic resolution for the preparation of (S)-solketal
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The lipase AK (lipase from Pseudomonas sp.)-catalysed alcoholysis of racemic solketal (2,2-dimethyl-1,3-dioxolane-4-methanol) esters and acylation of solketal in organic solvents proceeded with E = 20-25. This enabled the preparation of the more reactive (S)-enantiomer with more than 30% total isolated yield (based on the racemate) and 95% ee by a double kinetic resolution strategy consisting of enzymatic acylation-chemical saponification-enzymatic acylation or enzymatic alcoholysis-enzymatic acylation sequences. Numerical calculations and theoretical plots for the optimal termination conversions for the 1st and 2nd resolution steps as well as for the find yields as the function of E is considered.
- Vaenttinen, Eero,Kanerva, Liisa T.
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- Branched Selectivity in the Pd-Catalysed Methoxycarbonylation of 1-Alkenes
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The methoxycarbonylation of alkenes by palladium(II) complexes with P,O-donor ligands [(2-methoxyphenyl)diphenylphosphine (L-2), bis(2-methoxyphenyl) phenyl phosphine (L-3) and tris(2-methoxyphenyl) phosphine (L-4)] has been investigated. The results show that the Pd complexes derived from these ligands provide high regioselectivity for the branched esters from 1-pentene and 1-hexene (>80 %). Various parameters (including temperature, pressure, acid concentration) were optimized to improve the performance of the catalyst system. Higher temperatures afforded higher regioselectivity; but effected rapid catalyst decomposition. Acceptable turnover frequencies, conversions as well as catalyst stability could be obtained at higher L/Pd ratios. The dramatic change in regioselectivity is rationalised on the basis of the hemi-lability of the o-methoxy moiety, which may lead to ligand dissociation from L2PdX2 (L=ligand, X=Cl) rather than the expected dissociation of X. In support of our hypothesis, direct evidence for the coordination of the o-methoxy to the Pd centre was demonstrated by the crystal structure. To the best of our knowledge, this work provides the first reported route to valuable branched esters through the methoxycarbonylation of alkenes at suitable rates.
- Arderne, Charmaine,Guzei, Llia A.,Holzapfel, Cedric W.,Bredenkamp, Tyler
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- Titanosilicate (TS-1) catalyzed oxidation of aromatic aldehydes to esters
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A facile conversion of aromatic aldehydes to esters using molecular sieves, TS-1, and 30% H2O2 is described.
- Chavan, Subhash P.,Dantale, Shubhada W.,Govande, Chitra A.,Venkatraman, Meenakshi S.,Praveen, Cherukupally
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- Magnetic Co3O4/reduced graphene oxide nanocomposite as a superior heterogeneous catalyst for one-pot oxidative esterification of aldehydes to methyl esters
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A magnetically separable hybrid material consisting of Co3O4 nanoparticles supported on reduced graphene oxide (Co3O4/rGO) was synthesized through a simple co-reduction process of graphene oxide (GO) and cobalt chloride (CoCl2) using sodium borohydride (NaBH4). The Co3O4/rGO heterogeneous catalyst exhibited a high-performance for the oxidative esterification of aldehydes to the corresponding methyl esters using tert-butyl hydroperoxide (TBHP) as an oxidant. Owing to the synergistic effect of rGO support, the hybrid catalyst exhibited superior catalytic activity to the corresponding cobalt oxide catalyst. Importantly, the synthesized hybrid possesses good magnetic properties, which enable facile recovery of the catalyst by using an external magnet.
- Panwar, Vineeta,Al-Nafiey, Amer,Addad, Ahmed,Sieber, Brigitte,Roussel, Pascal,Boukherroub, Rabah,Jain, Suman L.
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- Polarity of the acid chain of esters and transesterification activity of acid catalysts
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The effect of polarity of the esters on the transesterification reaction rate has been investigated. The effect was studied in homogeneous and heterogeneous catalysts. The polarity of different ethyl alkanoate esters was varied by (i) increasing the number of carbon atoms in the acid alkyl chain of the esters and (ii) introducing Br and hydroxy substituents at the end of the acid chain of ethyl hexanoate. Polarity was determined through the λmax of the UV-Vis spectrum of the betaine dye dissolved in the investigated esters (ET(30) scale). The transesterification reaction was carried out with methanol and by using sulfuric acid and a Dowex DR2030 sulfonic resin as homogeneous and heterogeneous catalysts, respectively. It was observed that, in addition to steric hindrance, the polarity of the ester chain has an effect on the reaction rate of the heterogeneous acid catalysts. It is proposed that the positive or negative effect of the polarity is due to repulsive or attractive interactions of the ester chain with the polar groups of the resin and/or with the methanol molecules present in the pores. A very positive effect is found in heterogeneous acid catalysis if H-bonds can stabilize the active intermediate participating in the rate determining step. The attractive or repulsive interactions are absent in the homogeneous case.
- Alonso, D. Martin,Granados, M. Lopez,Mariscal,Douhal
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- 'Oxenoid' oxygen insertion vs. a radical mechanism in the oxidation of alkanes and alcohols: The case of aromatic peracids
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Adamantane is oxidised by MCPBA in a free-radical process, whose selectivity is discussed; by this method, cyclohexanol can be directly oxidised to caprolactone.
- Bravo, Anna,Fontana, Francesca,Minisci, Francesco,Serri, Anna
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- Transesterification of short chain esters using sulfonic acid-functionalized hybrid silicas: Effect of silica morphology
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Sulfonic acid-functionalized hybrid silicas with different structure (amorphous, HMS, SBA-15) were synthesized by different methodologies, with a variable amount of organic moieties (propylSO3H). The obtained catalysts, characterized by X-Ray photoelectron spectroscopy, low angle X-Ray diffraction, N2 adsorption and acid capacity measurements, were tested in the transesterification reaction of short chain esters (from hexanoic to lauric ethyl ester). The optimized reaction was carried out under mild condition in the presence of 15% mol of the corresponding organic acid in order to reproduce a typical low-grade oil. A correlation between the catalytic activity of the materials and their acid capacities was found. The propyl-sulfonic SBA-15 catalyst presented the best performance in terms of activity and structural stability with no leaching of the sulfonic groups.
- Testa, Maria Luisa,La Parola, Valeria,Venezia, Anna Maria
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- Impact of Macroporosity on Catalytic Upgrading of Fast Pyrolysis Bio-Oil by Esterification over Silica Sulfonic Acids
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Fast pyrolysis bio-oils possess unfavorable physicochemical properties and poor stability, in large part, owing to the presence of carboxylic acids, which hinders their use as biofuels. Catalytic esterification offers an atom- and energy-efficient route to upgrade pyrolysis bio-oils. Propyl sulfonic acid (PrSO3H) silicas are active for carboxylic acid esterification but suffer mass-transport limitations for bulky substrates. The incorporation of macropores (200 nm) enhances the activity of mesoporous SBA-15 architectures (post-functionalized by hydrothermal saline-promoted grafting) for the esterification of linear carboxylic acids, with the magnitude of the turnover frequency (TOF) enhancement increasing with carboxylic acid chain length from 5 % (C3) to 110 % (C12). Macroporous–mesoporous PrSO3H/SBA-15 also provides a two-fold TOF enhancement over its mesoporous analogue for the esterification of a real, thermal fast-pyrolysis bio-oil derived from woodchips. The total acid number was reduced by 57 %, as determined by GC×GC–time-of-flight mass spectrometry (GC×GC–ToFMS), which indicated ester and ether formation accompanying the loss of acid, phenolic, aldehyde, and ketone components.
- Manayil, Jinesh C.,Osatiashtiani, Amin,Mendoza, Alvaro,Parlett, Christopher M.A.,Isaacs, Mark A.,Durndell, Lee J.,Michailof, Chrysoula,Heracleous, Eleni,Lappas, Angelos,Lee, Adam F.,Wilson, Karen
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- Primary alkanols: oxidative homocondensation in water and cross-condensation in methanol
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Water was used as a reaction medium and a reagent in oxidation of primary alkanols to dimeric esters and alkanoic acids using either molecular bromine or a hydrogen peroxide—hydrobromic acid mixture as the oxidants. The similar reaction in methanol produced methyl alkanoates.
- Nikishin,Sokova,Terent′ev,Kapustina
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- A facile route for synthesis of (±)-dinoprost, (±)-carboprost and its analogs
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A general synthetic approach was developed for (±)-dinoprost (1), (±)-carboprost (2) and their analogs (3-5) through a key intermediate (6). Compound 6 can be converted into the target compounds in two or three steps. Diastereomeric separation was accomplished easily for obtaining (±) dinoprost. Separation of diastereomers was difficult for (±) carboprost and their analogs. Key intermediate 6 was obtained, in turn, from (±)-corey lactone.
- Shankar,Mohan, H. Rama,Prasad, U. Viplava,Krishna, M. Hari,Rao, P. Mareswar,Lakshmikumar,Subbaraju, Gottumukkala V.
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- Facile alcoholysis of l-lactide catalysed by Group 1 and 2 metal complexes
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The application of simple metal amides MN(SiMe3)2 as effective catalysts for the alcoholysis of cyclic esters are demonstrated. Excess dry methanol and L-lactide were added to a Schlenk flask at room temperature (RT) 1 mol% of MN(SiMe3)2, where M = Li, Na or K was added. A blank test was also performed where no catalyst was added giving no reaction. The conversion of M = Li, 45% to methyl (S,S)-lactyllactatewas obtained in 10 minutes at room temperature. Similar behaviors were observed for m = Na and K, where the reactions decelerated after 20 and 30 minutes. The application also extended to other cyclic esters such as capralactone where the ring-opening product was obtained rapidly in quantitative yield.
- Phomphrai, Khamphee,Pracha, Supathana,Phonjanthuek, Phenphak,Pohmakotr, Manat
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- Structure determination of fatty acid ester biofuels via in situ cryocrystallisation and single crystal X-ray diffraction
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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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- Three step auto-tandem catalysed hydroesterification: Access to linear fruity esters from piperylene
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A convenient and selective access to saturated hexanoic esters via hydroesterification of piperylene with synthesis gas and methanol is presented. This is the first three step auto-tandem hydroesterification, which is 100% atom economic proceeding under mild conditions. Our optimisations revealed Pd2(dba)3/1,2-dtbpmb as the best catalytic system. Besides, the reaction also tolerates several alcohols, which offers a broad range of fruity esters. In addition, we present insights into the reaction sequence, investigating whether the reaction proceeds via two- or three-step reaction cascade.
- Neubert, Peter,Steffen, Matthias,Behr, Arno
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- Facile and efficient oxidative transformation of primary alcohols to methyl esters in water using hypervalent iodine(III) reagents
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A facile and direct oxidative esterification of primary alcohols in water using a combination of the hypervalent iodine(III) reagent, iodosobenzene (PhIO), and KBr has been developed. This methodology is expected to be environmentally benign since it uses a recyclable polymer-supported iodine(III) reagent in water.
- Tohma, Hirofumi,Maegawa, Tomohiro,Kita, Yasuyuki
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- PIFA-mediated esterification reaction of alkynes with alcohols via oxidative cleavage of carbon triple bonds
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A metal-free esterification of alkynes via C≡C triple bond cleavage has been developed. In the presence of phenyliodine bis(trifluoroacetate), a diverse range of alkyne and alcohol substrates undergoes triple bond cleavage to produce carboxylic ester motifs in moderate to good yields. The transformation is proposed to proceed via hydroxyethanones and ethanediones as intermediates on the basis of mechanistic studies and exhibits a broad substrate scope and good functional group tolerance.
- Jiang, Qing,Zhao, An,Xu, Bin,Jia, Jing,Liu, Xin,Guo, Cancheng
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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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- Direct Deamination of Primary Amines via Isodiazene Intermediates
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We report here a reaction that selectively deaminates primary amines and anilines under mild conditions and with remarkable functional group tolerance including a range of pharmaceutical compounds, amino acids, amino sugars, and natural products. An anomeric amide reagent is uniquely capable of facilitating the reaction through the intermediacy of an unprecedented monosubstituted isodiazene intermediate. In addition to dramatically simplifying deamination compared to existing protocols, our approach enables strategic applications of iminium and amine-directed chemistries as traceless methods. Mechanistic and computational studies support the intermedicacy of a primary isodiazene which exhibits an unexpected divergence from previously studied secondary isodiazenes, leading to cage-escaping, free radical species that engage in a chain, hydrogen-atom transfer process involving aliphatic and diazenyl radical intermediates.
- Berger, Kathleen J.,Driscoll, Julia L.,Yuan, Mingbin,Dherange, Balu D.,Gutierrez, Osvaldo,Levin, Mark D.
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supporting information
p. 17366 - 17373
(2021/11/04)
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- PCl3-mediated transesterification and aminolysis of tert-butyl esters via acid chloride formation
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A PCl3-mediated conversion of tert-butyl esters into esters and amides in one-pot under air is developed. This novel protocol is highlighted by the synthesis of skeletons of bioactive molecules and gram-scale reactions. Mechanistic studies revealed that this transformation involves the formation of an acid chloride in situ, which is followed by reactions with alcohols or amines to afford the desired products.
- Wu, Xiaofang,Zhou, Lei,Li, Fangshao,Xiao, Jing
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p. 491 - 497
(2021/01/20)
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- Efficient Catalysts for the Green Synthesis of Adipic Acid from Biomass
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Green synthesis of adipic acid from renewable biomass is a very attractive goal of sustainable chemistry. Herein, we report efficient catalysts for a two-step transformation of cellulose-derived glucose into adipic acid via glucaric acid. Carbon nanotube-supported platinum nanoparticles are found to work efficiently for the oxidation of glucose to glucaric acid. An activated carbon-supported bifunctional catalyst composed of rhenium oxide and palladium is discovered to be powerful for the removal of four hydroxyl groups in glucaric acid, affording adipic acid with a 99 % yield. Rhenium oxide functions for the deoxygenation but is less efficient for four hydroxyl group removal. The co-presence of palladium not only catalyzes the hydrogenation of olefin intermediates but also synergistically facilitates the deoxygenation. This work presents a green route for adipic acid synthesis and offers a bifunctional-catalysis strategy for efficient deoxygenation.
- Deng, Weiping,Yan, Longfei,Wang, Binju,Zhang, Qihui,Song, Haiyan,Wang, Shanshan,Zhang, Qinghong,Wang, Ye
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supporting information
p. 4712 - 4719
(2021/01/20)
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- Oxidative esterification of alcohols by a single-side organically decorated Anderson-type chrome-based catalyst
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The direct esterification of alcohols with non-noble metal-based catalytic systems faces great challenges. Here, we report a new chrome-based catalyst stabilized by a single pentaerythritol decorated Anderson-type polyoxometalate, [N(C4H9)4]3[CrMo6O18(OH)3C{(OCH2)3CH2OH}], which can realize the efficient transformation from alcohols to esters by H2O2oxidation in good yields and high selectivity without extra organic ligands. A variety of alcohols with different functionalities including some natural products and pharmaceutical intermediates are tolerated in this system. The chrome-based catalyst can be recycled several times and still keep the original configuration and catalytic activity. We also propose a reasonable catalytic mechanism and prove the potential for industrial applications.
- Wang, Jingjing,Jiang, Feng,Tao, Chaofu,Yu, Han,Ruhlmann, Laurent,Wei, Yongge
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supporting information
p. 2652 - 2657
(2021/04/21)
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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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- Ruthenium-catalyzed hydrogenation of CO2as a route to methyl esters for use as biofuels or fine chemicals
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A novel robust diphosphine-ruthenium(ii) complex has been developed that can efficiently catalyze both the hydrogenation of CO2 to methanol and its in situ condensation with carboxylic acids to form methyl esters; a TON of up to 3260 is achievable for the CO2 to methanol step. Both aromatic and aliphatic carboxylic acids can be transformed to their corresponding methyl esters with high conversion and selectivity (17 aliphatic and 18 aromatic examples). On the basis of a series of experiments, a mechanism has been proposed to account for the various steps involved in the catalytic pathway. More importantly, this approach provides a promising route for using CO2 as a C1 source for the production of biofuels, fine chemicals and methanol.
- Li, Yong,Liu, Qingbin,Ma, Yanping,Solan, Gregory A.,Sun, Wen-Hua,Wang, Zheng,Zhang, Qiuyue,Zhao, Ziwei,Zhong, Yanxia
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p. 6766 - 6774
(2020/08/25)
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- Hydrodealkenylative C(sp3)–C(sp2) bond fragmentation
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Chemical synthesis typically relies on reactions that generate complexity through elaboration of simple starting materials. Less common are deconstructive strategies toward complexity—particularly those involving carbon-carbon bond scission. Here, we introduce one such transformation: the hydrodealkenylative cleavage of C(sp3)–C(sp2) bonds, conducted below room temperature, using ozone, an iron salt, and a hydrogen atom donor. These reactions are performed in nonanhydrous solvents and open to the air; reach completion within 30 minutes; and deliver their products in high yields, even on decagram scales. We have used this broadly functionality tolerant transformation to produce desirable synthetic intermediates, many of which are optically active, from abundantly available terpenes and terpenoid-derived precursors. We have also applied it in the formal total syntheses of complex molecules.
- Smaligo, Andrew J.,Swain, Manisha,Quintana, Jason C.,Tan, Mikayla F.,Kim, Danielle A.,Kwon, Ohyun
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p. 681 - 685
(2019/06/11)
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- Aldehyde effect and ligand discovery in Ru-catalyzed dehydrogenative cross-coupling of alcohols to esters
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The presence of different aldehydes is found to have a significant influence on the catalytic performance when using PN(H)P type ligands for dehydrogenation of alcohols. Accordingly, hybrid multi-dentate ligands were discovered based on an oxygen-transfer alkylation of PNP ligands by aldehydes. The relevant Ru-PNN(PO) system provided the desired unsymmetrical esters in good yields via acceptorless dehydrogenation of alcohols. Hydrogen bonding interactions between the phosphine oxide moieties and alcohol substrates likely assisted the observed high chemoselectivity.
- Jiang, Xiaolin,Zhang, Jiahui,Zhao, Dongmei,Li, Yuehui
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p. 2797 - 2800
(2019/03/27)
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- Dehydrogenative cross-coupling of primary alcohols to form cross-esters catalyzed by a manganese pincer complex
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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)
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- 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.
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Paragraph 0072; 0073
(2019/06/30)
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- Aldehydes as potential acylating reagents for oxidative esterification by inorganic ligand-supported iron catalysis
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The oxidative esterification of various aldehydes with alcohols could be achieved by a heterogeneous iron(iii) catalyst supported on a ring-like POM inorganic ligand under mild conditions, affording the corresponding esters, including several drug molecules and natural products, in high yields. ESI-MS and control experiments demonstrated that POM-FeV(O) was the active catalytic species and the plausible mechanism was presented. More importantly, the 6th run of the iron catalyst recycles shows only a slight decrease in the yield.
- Yu, Han,Wang, Jingjing,Wu, Zhikang,Zhao, Qixin,Dan, Demin,Han, Sheng,Tang, Jiangjiang,Wei, Yongge
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supporting information
p. 4550 - 4554
(2019/08/21)
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- Exploration of Intrinsic Lipase-Like Activity of Zirconium-Based Metal-Organic Frameworks
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To overcome the disadvantages of natural enzymes, artificial enzyme mimics attracted increasing attention of researchers. Metal-organic frameworks (MOFs) are expected as one of the most appropriate candidates for artificial enzyme mimics. In this work, we demonstrate that the zirconium-based MOF material UiO-66 and its analogues possess intrinsic lipase-like activity and can efficiently catalyze ester hydrolysis, transesterification and esterification reactions. Furthermore, the UiO-66(NH2) exhibits much higher catalytic activity than that of UiO-66, which can be attributed to the synergy effect between the zirconium cluster centres and the amino moieties during the catalytic cycle.
- Liu, Xiao,Qi, Wei,Wang, Yuefei,Su, Rongxin,He, Zhimin
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p. 4579 - 4585
(2018/10/26)
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- A biocatalytic method for the chemoselective aerobic oxidation of aldehydes to carboxylic acids
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Herein, we present a study on the oxidation of aldehydes to carboxylic acids using three recombinant aldehyde dehydrogenases (ALDHs). The ALDHs were used in purified form with a nicotinamide oxidase (NOx), which recycles the catalytic NAD+ at the expense of dioxygen (air at atmospheric pressure). The reaction was studied also with lyophilised whole cell as well as resting cell biocatalysts for more convenient practical application. The optimised biocatalytic oxidation runs in phosphate buffer at pH 8.5 and at 40 °C. From a set of sixty-one aliphatic, aryl-Aliphatic, benzylic, hetero-Aromatic and bicyclic aldehydes, fifty were converted with elevated yield (up to >99%). The exceptions were a few ortho-substituted benzaldehydes, bicyclic heteroaromatic aldehydes and 2-phenylpropanal. In all cases, the expected carboxylic acid was shown to be the only product (>99% chemoselectivity). Other oxidisable functionalities within the same molecule (e.g. hydroxyl, alkene, and heteroaromatic nitrogen or sulphur atoms) remained untouched. The reaction was scaled for the oxidation of 5-(hydroxymethyl)furfural (2 g), a bio-based starting material, to afford 5-(hydroxymethyl)furoic acid in 61% isolated yield. The new biocatalytic method avoids the use of toxic or unsafe oxidants, strong acids or bases, or undesired solvents. It shows applicability across a wide range of substrates, and retains perfect chemoselectivity. Alternative oxidisable groups were not converted, and other classical side-reactions (e.g. halogenation of unsaturated functionalities, Dakin-Type oxidation) did not occur. In comparison to other established enzymatic methods such as the use of oxidases (where the concomitant oxidation of alcohols and aldehydes is common), ALDHs offer greatly improved selectivity.
- Knaus, Tanja,Tseliou, Vasilis,Humphreys, Luke D.,Scrutton, Nigel S.,Mutti, Francesco G.
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supporting information
p. 3931 - 3943
(2018/09/11)
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- A Co2B Mediated NaBH4 Reduction Protocol Applicable to a Selection of Functional Groups in Organic Synthesis
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A high-yielding and high-rate reduction method that operates with alkenes, alkynes, azides, nitriles, and nitroarenes was developed and optimized. The method makes use of sodium borohydride reduction of CoSO4 under release of hydrogen along with the formation of Co2B as a nanoparticle material. The produced Co2B activates the various functional groups for hydride reduction. The protocol was proven to operate with an assortment of functional groups to provide good to excellent yields. Furthermore, the reduction method was successfully adapted, implemented, and developed for a continuous flow approach using the multi-jet oscillating disk (MJOD) flow reactor platform at atmospheric pressure.
- Lundevall, Frida Johanne,Elumalai, Vijayaragavan,Drageset, Audun,Totland, Christian,Bj?rsvik, Hans-René
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supporting information
p. 3416 - 3425
(2018/07/29)
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- Of the trometamol prostaglandin F2 α synthesis method (by machine translation)
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The invention discloses a of the trometamol prostaglandin F2 α synthesis method, as the compound (-) - Corey lactone diol as raw materials, through the oxidation reaction to obtain lactone aldehyde, lactone aldehydechain after the weidiWeidi Greecehuo Naer reaction with - the lower side of the splicing an olefin, the olefin double-carbonyl after reduction to obtain the alcohol, with puncture ylide - wittich reaction the upper side of the obtained prostaglandin F2 α, then the prostaglandin F2 α of the trometamol after crystallization by dissolving of the trometamol prostaglandin F2 α. The synthesis method, without noble metal catalyst, there is little side reaction, high yield, low cost, less pollution, is suitable for industrial production. (by machine translation)
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Paragraph 0023
(2017/08/30)
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- Linear Selective Isomerization/Hydroformylation of Unsaturated Fatty Acid Methyl Esters: A Bimetallic Approach
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Herein, we report about the development of an isomerization/hydroformylation tandem reaction to selectively convert fatty acid methyl esters into asymmetric α,ω-functionalized aldehyde esters. An orthogonal tandem catalytic system consisting of a palladium-based isomerization catalyst and a rhodium-based hydroformylation catalyst was developed, using methyl 3-hexenoate as a model substrate. Using this catalyst, high yields (81% at 99% conversion) and regioselectivities (l/b-ratio of 98/2) toward the desired terminal hydroformylation product are obtained in the conversion of methyl 3-hexenoate under mild conditions. Ethyl 4-decenoate was subsequently applied as a second model substrate to identify challenges associated with the longer chain length of the unsaturated ester. Finally, methyl oleate was converted using the developed catalyst system. High aldehyde yields of 74% (at 99% conversion) with an l/b-ratio of 91/9 are obtained.
- Gaide, Tom,Bianga, Jonas,Schlipk?ter, Kim,Behr, Arno,Vorholt, Andreas J.
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p. 4163 - 4171
(2017/06/19)
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- One-pot oxidative bromination – Esterification of aldehydes to 2-bromoesters using cerium (IV) ammonium nitrate and lithium bromide
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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.
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supporting information
p. 352 - 354
(2017/01/03)
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- Methylation of mono- and dicarboxylic acids with dimethyl carbonate catalyzed with binder-free zeolite NaY
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Synthesis of methyl mono- and dicarboxylates was developed consisting in treating the corresponding acids with dimethyl carbonate in the presence of a heterogenic catalyst, crystalline aluminosilicate whose mechanically strong granules to 90–95% were built of crystal aggregates of zeolite Y with modulus of about 5.0 in the Na-form. Optimum catalyst and reagents ratio and the reaction conditions were found for the preparation in high yields of methyl esters of mono- and dicarboxylic acids.
- Khusnutdinov,Shchadneva,Mayakova, Yu. Yu.,Konovalova, Yu. S.,Khazipova,Kutepov
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p. 163 - 168
(2017/04/24)
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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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- The scope and mechanism of palladium-catalysed Markovnikov alkoxycarbonylation of alkenes
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Hydroesterification reactions represent a fundamental type of carbonylation reaction and constitute one of the most important industrial applications of homogeneous catalysis. Over the past 70 years, numerous catalyst systems have been developed that allow for highly linear-selective (anti-Markovnikov) reactions and are used in industry to produce linear carboxylates starting from olefins. In contrast, a general catalyst system for Markovnikov-selective alkoxycarbonylation of aliphatic olefins remains unknown. In this paper, we show that a specific palladium catalyst system consisting of PdX2/N-phenylpyrrole phosphine (X, halide) catalyses the alkoxycarbonylation of various alkenes to give the branched esters in high selectivity (branched selectivity up to 91%). The observed (and unexpected) selectivity has been rationalized by density functional theory computation that includes a dispersion correction.
- Li, Haoquan,Dong, Kaiwu,Jiao, Haijun,Neumann, Helfried,Jackstell, Ralf,Beller, Matthias
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p. 1159 - 1166
(2016/11/28)
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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.
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Paragraph 0052; 0053
(2017/03/14)
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- Synthesis, characterization and catalytic performance of a novel picolinic acid-12-molybdophosphoric acid hybrid catalyst
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A novel 12-molybdophosphoric acid (HPM)-based complex (H2 PI)2(H 3 O)[PMo12O 40] [Mo2 O5 (H2 O)2 (PI)2 ]?11H2 O (PI-HPM) was prepared by modification with picolinic acid (HPI) and characterized by the methods of Fourier transform infrared (FTIR) spectroscopy, thermogravimetry (TG), X-ray powder and single crystal diffraction. The complex retained the classical Keggin structure of bulk HPM, there were some strong hydrogen bonds existing between the [PMo12 O40 ]3- polyanion, the [Mo2 O5 (H2 O)2 (PI)2 ] coordination moiety, the protonated HPI and the lattice water molecules. Then PI-HPM was employed as heterogeneous catalyst for esterification reaction to evaluate its acid-catalytic activity. The complex exhibited high activity and good durability in reaction mixtures, indicating that it was a promising heterogeneous acid catalyst for esterification that including the conversion of oleic acid to oleates.
- Liu, Lijun,Wang, Honghong,Gong, Shuwen,Lu, Jing,Zhang, Qian
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p. 1007 - 1013
(2016/06/15)
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- Copper-Catalyzed O-Methylation of Carboxylic Acids Using DMSO as a Methyl Source
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A copper-catalyzed O-methylation of carboxylic acids using dimethyl sulfoxide (DMSO) as the methyl source is disclosed. This transformation exhibits a broad substrate scope and excellent functional group tolerance. Mechanistic studies indicate that a methyl radical is generated from dimethyl sulfoxide in the reaction process.
- Jia, Jing,Jiang, Qing,Zhao, An,Xu, Bin,Liu, Qiang,Luo, Wei-Ping,Guo, Can-Cheng
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p. 421 - 428
(2016/01/28)
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- Supported cobalt oxide nanoparticles as efficient catalyst in esterification and amidation reactions
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Co/SBA-15 nanoparticle catalysts (CoNP) were prepared using a commonly adapted synthetic route and then utilised for esterification and amidation reactions using aromatic and linear chain compounds for the production of long chain esters and amides. The study shows that the use of CoNP catalysts favours the use of aromatic reactants with electron donating substituents specifically in the para position. For the amidation reaction, good to excellent yields were obtained demonstrating tolerance towards differently substituted aromatic compounds. Overall, the synthesized catalysts proved to be efficient and highly versatile, and recyclable under the investigated conditions.
- Rajabi, Fatemeh,Raessi, Mojdeh,Arancon, Rick A.D.,Saidi, Mohammad Reza,Luque, Rafael
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p. 122 - 126
(2015/01/09)
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- Sulfonic acid-functionalized periodic mesoporous organosilicas in esterification and selective acylation reactions
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The application of sulfonic acid-functionalized periodic mesoporous organosilicas (PMOs) having either phenyl (1a) or ethyl (1b) bridging groups was investigated in the esterification of a variety of alcohols and fatty acids. It was found that 1b consistently exhibited higher catalytic performance than 1a in the described reaction. In particular, it was proposed that the superior catalytic activity of 1b in esterification of fatty acids with methanol is a result of adequate hydrophobic-hydrophilic surface balance in the ethyl PMO catalyst. In addition, the study of chemoselective acylation of 1,3-butanediol with dodecanoic acid with varied mesoporous silica-supported solid sulfonic acids including both 1a and 1b implies that there is a compromise between the reaction selectivity and the surface physicochemical properties of the employed catalyst. Our results clearly show that the catalyst having high surface hydrophilic nature gives high selectivity toward the formation of mono-acylated products whereas those with relatively high hydrophobic characteristics showed enhanced selectivity toward the formation of di-acylated products.
- Karimi, Babak,Mirzaei, Hamid M.,Mobaraki, Akbar,Vali, Hojatollah
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p. 3624 - 3631
(2015/07/01)
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- Palladium complex immobilized on graphene oxide-magnetic nanoparticle composites for ester synthesis by aerobic oxidative esterification of alcohols
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A well dispersed magnetically separable palladium complex immobilized to magnetite-graphene oxide nanocomposite has been synthesized via solvothermal route. The successfully decorated graphene oxide sheets with the homogeneously dispersed iron nanoparticles and palladium(II) complex were proved by transmission electron microscopy. X-ray diffraction pattern of the synthesized catalyst revealed that palladium(II) complex was successfully immobilized to the support. Further, X-ray photoelectron spectroscopy confirmed that palladium is present in +2 oxidation state. The synthesized heterogeneous material was found to be an efficient catalyst for the oxidative esterification of alcohols with methanol by using molecular oxygen as oxidant. The developed catalyst was found to be more reactive than its homogeneous analog, i.e. PdCl2(CH3CN)2. Similarly, no reaction occurred in the presence of Pd(0)/magnetite-graphene nanocomposite catalyst. These studies confirmed that the palladium(II) ions are the main catalyst and superior reactivity of heterogeneous palladium catalyst is attributed to the promotion role of graphene support in the adsorption of reactant alcohol and oxygen. After the reaction, the catalyst was easily separated by external magnetic effect and reused for several runs with consistent catalytic activity without any detectable leaching.
- Verma, Sanny,Verma, Deepak,Sinha, Anil K.,Jain, Suman L.
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- Ultrasound assisted direct oxidative esterification of aldehydes and alcohols using graphite oxide and Oxone
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A sonochemical procedure for direct oxidative esterification of aldehydes and alcohols using graphite oxide and Oxone in an alcoholic solvent is described. Mild reaction conditions, short reaction times, cost-effectiveness, and facile isolation of the products make the present system as a practical method.
- Mirza-Aghayan, Maryam,Zonoubi, Somayeh,Molaee Tavana, Mahdieh,Boukherroub, Rabah
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p. 359 - 364
(2014/10/16)
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- METHOD OF MANUFACTURE OF OCTANEDIOIC ACID, PRECURSORS, AND DERIVATIVES
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A method for the manufacture of 1,8-octanedioic acid comprises: reacting gamma-valerolactone with an alcohol in the presence of an acid or a base catalyst to provide an alkyl pentenoate, converting the alkyl pentenoate in the presence of a metathesis initiator to provide the dialkyl octenedioate, reacting the dialkyl octenedioate with hydrogen in the presence of a hydrogenation catalyst to provide a dialkyl 1,8-octanedioate and hydrolyzing the dialkyl 1,8-octanedioate to provide the 1,8-octanedioic acid.
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Paragraph 0086; 0087; 0088
(2014/10/04)
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- Silver nanoparticles embedded over mesoporous organic polymer as highly efficient and reusable nanocatalyst for the reduction of nitroarenes and aerobic oxidative esterification of alcohols
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Silver nanoparticles (Ag-NPs) have been finely dispersed at the mesoporous organic polymer via post-synthetic chemical grafting over mesoporous poly-triallylamine (MPTA-1). The resulting Ag-MPTA-1 nanomaterial has been characterized by elemental analysis, powder x-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), UV-vis diffuse reflectance spectroscopy (DRS), thermogravimetric analysis (TGA), EPR spectroscopy and AAS elemental analysis. The Ag-MPTA-1 acts as an efficient heterogeneous nanocatalyst in the reduction of substituted nitrobenzenes via transfer hydrogenation. The material also showed excellent catalytic activity in one-step catalytic oxidative esterification of primary alcohols using molecular oxygen as a green oxidant. The catalyst is air-stable, inexpensive, easy to prepare and reused several times without significant decrease in activity and selectivity.
- Salam, Noor,Banerjee, Biplab,Roy, Anupam Singha,Mondal, Paramita,Roy, Susmita,Bhaumik, Asim,Islam, Sk. Manirul
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p. 184 - 194
(2014/05/06)
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- Conversion of levulinate into succinate through catalytic oxidative carbon-carbon bond cleavage with dioxygen
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Grand Cleft Oxo: Levulinate, available from biomass, is oxidized into succinate through manganese(III)-catalyzed selective cleavage of C-C bonds with molecular oxygen. In addition to levulinate, a wide range of aliphatic methyl ketones also undergo oxidative C-C bond cleavage at the carbonyl group. This procedure offers a route to valuable dicarboxylic acids from biomass resources by nonfermentive approaches. Copyright
- Liu, Junxia,Du, Zhongtian,Lu, Tianliang,Xu, Jie
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p. 2255 - 2258
(2014/01/06)
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- METHOD FOR CONTINUOUSLY PREPARING CARBOXYLIC ACID ESTER
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A method for continuously preparing a carboxylic acid ester is disclosed. In the method of the present invention, a vertical reactor is filled with a solid catalyst, a carboxylic acid and an alcohol are introduced into a lower part of the vertical reactor, esterification is performed to form an esterized mixture, the esterized mixture is output from an upper part of the vertical reactor, and distillation is performed to isolate the carboxylic acid ester. The method of the present invention is simple, easily controlled and environmental friendly, and has significantly high conversion rate and selectivity.
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Paragraph 0024; 0026
(2013/11/19)
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- A unique palladium catalyst for efficient and selective alkoxycarbonylation of olefins with formates
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Forget about CO! Carbonylations are among the most important homogeneously catalyzed reactions in the chemical industry, but typically require carbon monoxide. Instead, straightforward and efficient alkoxycarbonylations of olefins can proceed with alkyl formates in the presence of a specific palladium catalyst. Aromatic, terminal aliphatic, and internal olefins are carbonylated to give industrially important linear esters at low catalyst loadings. Copyright
- Fleischer, Ivana,Jennerjahn, Reiko,Cozzula, Daniela,Jackstell, Ralf,Franke, Robert,Beller, Matthias
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p. 417 - 420
(2013/04/24)
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- Continuous Method For Producing Esters Of Aliphatic Carboxylic Acids
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The invention relates to a continuous method for producing aliphatic carbonic acid esters by reacting at least one aliphatic carboxylic acid of formula (I) R1—COOH (I), wherein R1 represents hydrogen or an optionally substituted aliphatic hydrocarbon group with 1 to 50 carbon atoms, with at least one alcohol of formula (II) R2—(OH)n (II), wherein R2 represents an optionally substituted hydrocarbon group with 1 to 100 C atoms and n is an integer from 1 to 10, in the presence of at least one transesterification catalyst in a reaction tube the longitudinal axis of which extends in the direction of propagation of the microwaves of a monomode microwave applicator, under microwave irradiation to form the ester.
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Page/Page column 9
(2012/05/07)
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