- Disproportionation of aliphatic and aromatic aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions
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Disproportionation of aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions often requires the application of high temperatures, equimolar or excess quantities of strong bases, and is mostly limited to the aldehydes with no CH2 or CH3 adjacent to the carbonyl group. Herein, we developed an efficient, mild, and multifunctional catalytic system consisting AlCl3/Et3N in CH2Cl2, that can selectively convert a wide range of not only aliphatic, but also aromatic aldehydes to the corresponding alcohols, acids, and dimerized esters at room temperature, and in high yields, without formation of the side products that are generally observed. We have also shown that higher AlCl3 content favors the reaction towards Cannizzaro reaction, yet lower content favors Tishchenko reaction. Moreover, the presence of hydride donor alcohols in the reaction mixture completely directs the reaction towards the Meerwein–Ponndorf–Verley reaction. Graphic abstract: [Figure not available: see fulltext.].
- Sharifi, Sina,Sharifi, Hannah,Koza, Darrell,Aminkhani, Ali
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p. 803 - 808
(2021/07/20)
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- Metal complex catalysts and method for catalytically reducing carboxylic acids
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The invention relates to a metal complex catalyst, which contains at least one of metal complexes with a chemical formula comprising a structural unit represented by a formula I. According to the invention, the center metal of the metal complex catalyst is iridium, and the metal complex catalyst is composed of pentamethylcyclopentadienyl, a bitetrahydropyrimidine ligand and proper coordination anions; the metal complex catalyst has activity on a carboxylic acid reduction reaction, and a carboxylic acid compound is reduced into an alcohol compound in the presence of hydrogen; and the method ismild in reaction condition, can be carried out at room temperature, and is good in catalytic performance and high in reduction product yield.
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Paragraph 0085-0144; 0149; 0150; 0167-0168; 0178-0179
(2020/06/20)
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- Preparation method of long-chain ester
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The invention relates to the field of organic synthesis and provides a preparation method of long-chain ester, which comprises the following steps: carrying out esterification reaction of the carboxylic acid and the alcohol through a catalyst and obtaining a long-chain ester phase and a water phase post the standing and layering of the reaction liquid; the catalyst comprises ionic liquid or eutectic solvent; purifying and separating the long-chain ester phase to obtain high-purity long-chain ester; introducing the residual substance again into the esterification reaction system for reaction after the water in the water phase is removed. The yield and the purity of the long-chain ester prepared by the invented method are as high as 99.8% and 99% respectively as indicated by the embodiment of the preparation method.
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Paragraph 0072; 0073; 0074; 0075; 0076; 0077-0093
(2019/03/23)
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- Synthesis, characterization and catalytic performances of benzimidazolin-2-iminato actinide (IV) complexes in the Tishchenko reactions for symmetrical and unsymmetrical esters
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A new family of benzimdazolin-2-iminato actinide?(IV) complexes [(Bim7-MeDipp/MeN)An(N(SiMe3)2)3] (An = U (3), Th (4)) and [(Bim4-MeDipp/MeN)An(N(SiMe3)2)3] (An = U (5), Th (6)) were synthesized and their solid state structures were established by single-crystal X-ray diffraction analysis. The catalytic performances of complexes 3–6 towards the homo- and cross-coupling of aldehydes (Tishchenko reaction) were studied and the thorium complexes 4 and 6 displayed moderate to high activities for the production of the corresponding symmetric and unsymmetrical esters. Coupling of aldehyde and alcohols, known as the tandem proton-transfer esterification, and the intermolecular coupling reaction between aldehyde and trifluoromethylketones were also investigated by these thorium complexes, indicating a complementary method to obtain unsymmetrical esters selectively. Plausible mechanisms for these reactions are proposed based on stoichiometric studies.
- Liu, Heng,Khononov, Maxim,Fridman, Natalia,Tamm, Matthias,Eisen, Moris S.
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p. 123 - 137
(2017/10/25)
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- Manganese Pincer Complexes for the Base-Free, Acceptorless Dehydrogenative Coupling of Alcohols to Esters: Development, Scope, and Understanding
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Aliphatic PNP pincer-supported earth-abundant manganese(I) dicarbonyl complexes behave as effective catalysts for the acceptorless dehydrogenative coupling of a wide range of alcohols to esters under base-free conditions. The reaction proceeds under neat conditions, with modest catalyst loading and releasing only H2 as byproduct. Mechanistic aspects were addressed by synthesizing key species related to the catalytic cycle (characterized by X-ray structure determination, multinuclear (1H, 13C, 31P, 15N, 55Mn) NMR, infrared spectroscopy, inter alia), by studying elementary steps connected to the postulated mechanism, and by resorting to DFT calculations. As in the case of related ruthenium and iron PNP catalysts, the dehydrogenation results from cycling between the amido and amino-hydride forms of the PNP-Mn(CO)2 scaffold. For the dehydrogenation of alcohols into aldehydes, our results suggest that the highest energy barrier corresponds to the hydrogen release from the amino-hydride form, although its value is close to that of the outer-sphere dehydrogenation of the alcohol into aldehyde. This contrasts with the ruthenium and iron catalytic systems, where dehydrogenation of the substrate into aldehyde is less energy-demanding compared to hydrogen release from the cooperative metal-ligand framework.
- Nguyen, Duc Hanh,Trivelli, Xavier,Capet, Frédéric,Paul, Jean-Fran?ois,Dumeignil, Franck,Gauvin, Régis M.
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p. 2022 - 2032
(2017/08/14)
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- Rethinking the Claisen–Tishchenko Reaction
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Pincer-type complexes [OsH2(CO){PyCH2NHCH2CH2NHPtBu2}] and [OsH2(CO){HN(CH2CH2PiPr2)2}] catalyze the disproportionation reaction of aldehydes via an outer-sphere bifunctional mechanism achieving turnover frequencies up to 14 000 h?1. The N?H group of the catalysts is a key player in this process, elucidated with the help of DFT calculations.
- Morris, Stacey A.,Gusev, Dmitry G.
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supporting information
p. 6228 - 6231
(2017/05/19)
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- Thorium complexes possessing expanded ring N-heterocyclic iminato ligands: Synthesis and applications
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Six and seven membered N-heterocyclic iminato ligands (L) are introduced allowing access a new class of Th(iv) complexes of the type Cp?2Th(L)(CH3). These complexes were studied in the Tishchenko reaction. Stoichiometric reactions together with kinetic and thermodynamic studies permit us to propose a plausible mechanism.
- Ghatak, Tapas,Drucker, Shani,Fridman, Natalia,Eisen, Moris S.
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supporting information
p. 12005 - 12009
(2017/09/25)
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- Method for treating isobutyrate-containing wastewater by alcohol etherification
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The invention discloses a method for treating isobutyrate-containing wastewater by alcohol etherification, comprising the following steps: 1), acidifying isobutyrate-containing wastewater with concentrated sulfuric acid, adding alcohol, subjecting a reaction system to etherification under reflux condition so as to generate isobutyrate, and stopping reacting until no water is generated in the reaction system; 2), cooling reaction liquid obtained in step 1) to room temperature, re-adding water separated from the reaction system and obtained in step 1), into the cooled reaction liquid, and stirring and standing to obtain oil phase and water phase; subjecting the water phase to solid-liquid separation to obtain low-COD wastewater and sulfate; 3), rectifying the oil phase obtained in step 2); collecting an alcohol fraction and an isobutyrate fraction. The wastewater treated by the method has low COD value.
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-
Paragraph 0033; 0034; 0035; 0036; 0037; 0041; 0042
(2016/12/26)
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- Synthesis and crystal structures of three amidinatoaluminum compounds and their catalytic behavior in the Tishchenko reaction
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Three amidinatoaluminum compounds, [{MeC(NCy)2}AlMe(μ-OMe)]2 (1), [{(PhN)MeC(NCy)}AlMe(μ-OMe)]2 (2) and [{(PhN)MeC(NtBu)}AlMe(μ-OMe)]2 (3), were prepared by the insertion reaction of oxygen with the corresponding aluminum amidinate in high yield and characterized by 1H and 13C NMR spectra and single crystal X-ray diffraction analysis. 1-3 were used as pre-catalysts to catalyze the Tishchenko reaction and both 2 and 3 exhibited good to excellent catalytic activity under mild conditions.
- Zhang, Shaofeng,Han, Hongfei,Guo, Zhiqiang,Tong, Hongbo,Wei, Xuehong
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p. 118 - 122
(2015/04/27)
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- CATALYST CAPABLE OF FORMING 2,5-DIMETHYLHEXENES
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A process of making a catalyst and the catalyst composition made by that process comprising a multinuclear metal compound of the formula Ma(PCy3)b(H)c(CO)d(OR)e(H2O)f with molar ratios a:b:c:d:e:f, wherein a is in the range from 2 to 2000, b is in the range from 0 to 4000, c is in the range from 0 to 6000 and d is in the range from 0 to 2000, e is in the range from 1 to 2000, and f is in the range from 0 to 100; wherein PCy3 indicates tricyclohexylphosphine, H indicates hydride, R is an alkyl group determined by the alcohol utilized and H2O is water from the reaction; and a is at least twice w. A method of making one or more 2,5-dimethylhexenes is described. A method of making p-xylene using one or more 2,5-dimethylhexenes is also described.
- -
-
Paragraph 0052
(2015/09/23)
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- Mixed Imidazolin-2-iminato-Cp? Thorium(IV) Complexes: Synthesis and Reactivity Toward Oxygen-Containing Substrates
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The mixed pentamethylcyclopentadienyl thorium(IV) imidazolin-2-iminato complexes Cp?2Th(ImDippN)(Me) (2) and Cp?2Th(ImMesN)(Me) (3) were synthesized in quantitative yields via rapid protonolysis of Cp?2Th(Me)2 (1) with the respective neutral imidazolin-2-iminato ligand ImRNH. Cp?2Th(ImDippN)(Me) (2) and Cp?2Th(ImMesN)(Me) (3) display short Th-N bond lengths and large Th-N-C angles. The reactivity of complex 2 and 3 toward oxygen-containing substrates was studied, and the catalytic activity of 2 was compared to the dimethyl (bispentamethyl-cyclopentadienyl) thorium complex 1. Complex 2 was applied in the catalytic Tishchenko reaction with aromatic, heteroaromatic, and branched aliphatic aldehydes, displaying a higher catalytic activity than Cp?2Th(Me)2 and Cp?2Th(ImMesN)(Me). Furthermore, 2 was applied as a catalyst in the crossed Tishchenko reaction and in the oligomerization of bis(aldehydes), as well as in the ring-opening polymerization of ε-caprolactone. In all reactions, the activity of Cp?2Th(ImDippN)(Me) (2) and Cp?2Th(ImMesN)(Me) (3) was higher than that observed for Cp?2Th(Me)2 (1), which can be attributed to the increased electron density introduced by the coordination of the imidazolin-2-iminato ligand. (Chemical Equation Presented).
- Karmel, Isabell S. R.,Fridman, Natalia,Tamm, Matthias,Eisen, Moris S.
-
supporting information
p. 2933 - 2942
(2015/06/30)
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- Mono(imidazolin-2-iminato) actinide complexes: Synthesis and application in the catalytic dimerization of aldehydes
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The synthesis of the mono(imidazolin-2-iminato) actinide(IV) complexes [(ImRN)An(N{SiMe3)2}3] (3-8) was accomplished by the protonolysis reaction between the respective imidazolin-2-imine (ImRNH, R = tBu, Mes, Dipp) and the actinide metallacycles [{(Me3Si)N}2An{κ2C,N-CH2SiMe2N(SiMe3)}] (1, An = U; 2, M = Th). The thorium and uranium complexes were obtained in high yields, and their structures were established by single-crystal X-ray diffraction analysis. The mono(imidazolin-2-iminato) actinide complexes 3-8 display short An-N bonds together with large An-N-C angles, indicating strong electron donation from the imidazolin-2-iminato moiety to the metal, corroborating a substantial π-character to the An-N bond. The reactivity of complexes 3-8 toward benzaldehyde was studied in the catalytic dimerization of aldehydes (Tishchenko reaction), displaying low to moderate catalytic activities for the uranium complexes 3-5 and moderate to high catalytic activities for the thorium analogues 6-8, among which 8 exhibited the highest catalytic activity. In addition, actinide coordination compounds showed unprecedented reactivity toward cyclic and branched aliphatic aldehydes in the catalytic Tishchenko reaction mediated by the thorium complex [(ImDippN)Th{N(SiMe3)2}3] (8), exhibiting high activity even at room temperature. Moreover, complex 8 was successfully applied in the crossed Tishchenko reaction between an aromatic or polyaromatic and an aliphatic cyclic and branched aldehyde, yielding selectively the asymmetrically substituted ester in high yields (80-100%).
- Karmel, Isabell S. R.,Fridman, Natalia,Tamm, Matthias,Eisen, Moris S.
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p. 17180 - 17192
(2015/02/02)
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- Nematicidal activity of natural ester compounds and their analogues against pine wood nematode, bursaphelenchus xylophilus
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In this study, we evaluated the nematicidal activity of natural ester compounds against the pine wood nematode, Bursaphelenchus xylophilus, to identify candidates for the development of novel, safe nematicides. We also tested the nematicidal activity of synthesized analogues of these ester compounds to determine the structure-activity relationship. Among 28 ester compounds tested, isobutyl 2-methylbutanoate, 3-methylbutyl 2-methylbutanoate, 3-methylbutyl tiglate, 3-methyl-2-butenyl 2- methylbutanoate, and pentyl 2-methylbutanoate showed strong nematicidal activity against the pine wood nematode at a 1 mg/ mL concentration. The other ester compounds showed weak nematicidal activity. The LC50 values of 3-methylbutyl tiglate, isobutyl 2-methylbutanoate, 3-methylbutyl 2-methylbutanoate, 3-methyl-2-butenyl 2-methylbutanoate, and pentyl 2- methylbutanoate were 0.0218, 0.0284, 0.0326, 0.0402, and 0.0480 mg/mL, respectively. The ester compounds described herein merit further study as potential nematicides for pine wood nematode control.
- Seo, Seon-Mi,Kim, Junheon,Koh, Sang-Hyun,Ahn, Young-Joon,Park, Il-Kwon
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p. 9103 - 9108
(2015/03/14)
-
- Expanding ester biosynthesis in Escherichia coli
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To expand the capabilities of whole-cell biocatalysis, we have engineered Escherichia coli to produce various esters. The alcohol O-acyltransferase (ATF) class of enzyme uses acyl-CoA units for ester formation. The release of free CoA upon esterification with an alcohol provides the free energy to facilitate ester formation. The diversity of CoA molecules found in nature in combination with various alcohol biosynthetic pathways allows for the biosynthesis of a multitude of esters. Small to medium volatile esters have extensive applications in the flavor, fragrance, cosmetic, solvent, paint and coating industries. The present work enables the production of these compounds by designing several ester pathways in E. coli. The engineered pathways generated acetate esters of ethyl, propyl, isobutyl, 2-methyl-1-butyl, 3-methyl-1-butyl and 2-phenylethyl alcohols. In particular, we achieved high-level production of isobutyl acetate from glucose (17.2 g l -1). This strategy was expanded to realize pathways for tetradecyl acetate and several isobutyrate esters.
- Rodriguez, Gabriel M,Tashiro, Yohei,Atsumi, Shota
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p. 259 - 265
(2014/04/03)
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- VARIATIONS ON PRINS-LIKE CHEMISTRY TO PRODUCE 2,5-DIMETHYLHEXADIENE FROM ISOBUTANOL
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The method of the present invention provides a high yield pathway to 2,5-dimethylhexadiene from renewable isobutanol, which enables economic production of renewable p-xylene (and subsequently, terephthalic acid, a key monomer in the production of PET) from isobutanol. In addition, the present invention provides methods for producing 2,5-dimethylhexadiene from a variety of feed stocks that can act as “equivalents” of isobutylene and/or isobutyraldehyde including isobutanol, isobutylene oxide, and isobutyl ethers and acetals. Catalysts employed in the present methods that produce 2,5-dimethylhexadiene can also catalyze alcohol dehydration, alcohol oxidation, epoxide rearrangement, and ether and acetal cleavage.
- -
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Page/Page column 6
(2012/11/07)
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- Rhodium(III)-catalyzed dimerization of aldehydes to esters
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No sooner said than done: A rhodi- um(III) hydride complex is an outstandingly effective and selective catalyst for the dimerization of aldehydes to the corresponding esters (see scheme). Evidence for an unusual mechanism in catalysis by rhodium is given.
- Tejel, Cristina,Ciriano, Miguel A.,Passarelli, Vincenzo
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experimental part
p. 91 - 95
(2011/03/21)
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- Tishchenko reactions of aldehydes promoted by diisobutylaluminum hydride and its application to the macrocyclic lactone formation
-
Aliphatic aldehydes react with catalytic amount of Dibal-H in n-pentane to give the corresponding Tishchenko products in good to excellent yields. On contrary, α-silyloxy aldehydes give α-silyloxy ketones via Oppenauer oxidation under similar condition. Tishchenko reaction of ω-alkene aldehydes followed by RCM and hydrogenation affords a convenient method to prepare the 11-37 membered macrocyclic lactones.
- Hon, Yung-Son,Wong, Ying-Chieh,Chang, Chun-Ping,Hsieh, Cheng-Han
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p. 11325 - 11340
(2008/03/12)
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- Mechanistic studies on reaction of [ReH4(η2- H2)(Cyttp)]+ with ketones to give the hydrido-oxo complex [ReH2(O)(Cyttp)]+ (Cyttp = PhP(CH2CH 2CH2PCy2)2)
-
Mechanistic studies were conducted on reaction of [ReH4(η 2-H2)(Cyttp)]OTf (1(OTf); Cyttp = PhP(CH 2CH2CH2PCy2)2, OTf = O3SCF3) with ketones, both neat and in solution. Treatment of 1(OTf) with excess acetone at 60-65°C affords [ReH2(O)(Cyttp) ]OTf (2(OTf)) in high yield, nearly 1 equiv. of H2, 2 equiv. of 2-propanol, 1 equiv. of each of 4-hydroxy-4-methyl-2-pentanone (B) and 4-methylpent-3-en-2-one (C), and smaller amounts of other organic products derived by condensation or related reactions of acetone. The presence of C, apparently arising by dehydration of B, points to the formation of 1 equiv. of H2O in the reaction system. Use of acetone-d6 in conjunction with 1(OTf) gives 2(OTf) containing no deuterium, as well as 1 equiv. of each of (CD3)2CHOH/OD and (CD3) 2CDOD/OH. Reactions of 1(OTf) with cyclohexanone, including cyclohexanone-2,2,6,6-d4, under comparable conditions, give analogous results. The ketones cyclopentanone, 2-butanone, and 3-pentanone also convert 1(OTf) to 2(OTf) upon heating, as does isobutyraldehyde, but only in the presence of the stabilizer BHT. In contrast, the more robust ketones 2,4-dimethyl-3-pentanone, 2,6-dimethylcyclohexanone, and 2-adamantanone, which do not undergo condensation, failed to effect this transformation. Other organooxygen compounds, i.e., methanol, cyclohexanol, 1,2-butene oxide, cyclohexene oxide, DMSO, and Me3NO, also are ineffective. A mechanism is proposed which begins with loss of H2 by 2 to give a 16-electron [ReH4(Cyttp)]+ which, depending on the experimental conditions, binds a solvent or ligand molecule. A [ReH 4(R2CO)(Cyttp)]+ intermediate generated in this manner reacts spontaneously by elimination of R2CHOH (containing methine hydrogen even when deuteriated ketone is used), which results from transfer of two hydride ligands to coordinated ketone. Continued reaction leads to the formation of 2 and another molecule of R2CHOH (containing methine deuterium when deuteriated ketone is employed), with the added hydrogens coming from H2O, which derives from solvent/reactant ketone.
- Rende, Dean E.,Wojcicki, Andrew
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p. 862 - 873
(2007/10/03)
-
- Remarkable reactivity of pyridinium chlorochromate adsorbed on neutral alumina under solvent-free conditions
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Pyridinium chlorochromate adsorbed on neutral alumina (PCC-Al2O3) under solvent-free conditions has been found to oxidize primary aliphatic alcohols to alkyl alkanoates whereas primary benzylic and primary allylic alcohols produce the corresponding aldehydes. Secondary aliphatic and aromatic alcohols produce ketones without isomerization and polymerization of double bonds, overoxidation and other side-reactions.
- Bhar, Sanjay,Chaudhuri, Subrata Kumar
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p. 3493 - 3498
(2007/10/03)
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- Generation of alkyl hypochlorites in oxidation of alcohols with carbon tetrachloride catalyzed by vanadium and manganese compounds
-
Primary alcohols and diols with various structures were subjected to transformations into esters, aldehydes, ketones, and lactones under the action of carbon tetrachloride in the presence of manganese compounds (MnCl 2, MnO2, Mn(OAc)2, Mn(acac)3) and vanadium compounds (VCl5, V2O5, VO(acac) 2) as catalysts. These transformation proceeded with the involvement of alkyl hypochlorites, which were generated in the course of oxidation of alcohols with carbon tetrachloride catalyzed by manganese or vanadium compounds. The optimum molar ratios between the catalyst and reagents were determined, and the reaction conditions for the highly selective synthesis of esters, aldehydes, ketones, and lactones from alcohols were found.
- Khusnutdinov,Shchadneva,Baiguzina,Lavrentieva,Dzhemilev
-
p. 2074 - 2079
(2007/10/03)
-
- Homoleptic lanthanide amides as homogeneous catalysts for alkyne hydroamination and the Tishchenko reaction
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The homoleptic bis(trimethylsilyl)amides of Group 3 metals and lanthanides of the general type [Ln{N(SiMe3)2}3] (1) (Ln = Y, lanthanide) represent a new class of Tishchenko precatalysts and, to a limited extent, precatalysts for the hydroamination/cyclization of aminoalkynes. It is shown that 1 is the most active catalyst for the Tishchenko reaction. This contribution presents investigations on the scope of the reaction, substrate selectivity, lanthanide-ion size-effect, and kinetic/ mechanistic aspects of the Tishchenko reaction catalyzed by 1. The turnover frequency is increased by the use of large-center metals and electron-with-drawing substrates. The reaction rate is second order with respect to the substrate. While donor atoms, such as nitrogen, oxygen, or sulfur, on the substrate decrease the turnover frequency, 1 shows a tolerance for a large number of functional groups. For the hydroamination/cyclization of aminoalkynes, 1 is less active than the well-known metallocene catalysts. On the other hand, 1 is much more readily accessible (one-step synthesis or commercially available), than the metallocenes and might therefore be an attractive alternative catalyst.
- Buergstein, Markus R.,Berberich, Helga,Roesky, Peter W.
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p. 3078 - 3085
(2007/10/03)
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- Simple Syntheses, Structural Diversity, and Tishchenko Reaction Catalysis of Neutral Homoleptic Rare Earth(II or III) 3,5-Di-tert-butylpyrazolates - The Structures of [Sc(tBu2pz)3], [Ln2(tBu2pz)6] (Ln = La, Nd, Yb, Lu), and [Eu4(tB2pz)8]
-
The homoleptic rare-earth pyrazolate complexes [Sc(tBu2pz)3], [Ln2(tBu2pz)6] (Ln = La, Nd, Sm, Lu), [Eu4(tBu2pz)8] and the mixed oxidation state species [Yb2(tBu2pz)5] (tBu2pz = 3,5-di-tert-butylpyrazolate) have been prepared by a simple reaction between the corresponding rare-earth metal and 3,5-di-tert-butylpyrazole, in the presence of mercury, at elevated temperatures. In addition, [Yb2(tBu2pz)6] was prepared by redox transmetallation/ligand exchange between ytterbium, diphenylmercury(II) and tBu2pzH in toluene, whilst the same reactants in toluene under different conditions or in diethyl ether gave [Yb2(tBu2pz)5]. The complexes of the trivalent lanthanoids display dimeric structures [Ln2(tBu2pz)6] (Ln = La, Nd, Yb, Lu) with chelating η-terminal and η2:η2-bridging pyrazolate coordination. The considerably smaller Sc(3+) ion forms monomeric [Sc(tBu2pz)3] of putative D3h molecular symmetry, with pyrazolate ligands solely η2-bonded. [Eu4(tBu2pz)8] is a structurally remarkable tetranuclear Eu(II) complex with two types of europium centres in a linear array. The outer two are bonded to one terminal and two bridging pyrazolates, and the inner two are coordinated by four bridging ligands. Unprecedented μ-η5:η2 pyrazolate ligation is observed, with each outer Eu(2+) sandwiched between two η5-bonded pyrazolate groups, which are also η2-linked to an inner Eu(2+). The two inner Eu(2+) ions are linked together by two equally occupied components of each of two symmetry related, disordered pyrazolate groups with one component η4:η2 bridging and one η3:η2 bridging. [La2(tBu2pz)6] has also been shown to be a Tishchenko reaction catalyst with several organic substrates.
- Deacon, Glen B.,Gitlits, Alex,Roesky, Peter W.,Buergstein, Markus R.,Lim, Kevin C.,Skelton, Brian W.,White, Allan H.
-
p. 127 - 138
(2007/10/03)
-
- Oxidative Esterification of Primary Alcohols by NaBrO3/NaHSO3 Reagent in Aqueous Medium
-
NaBrO3 combined with NaHSO3 was found to be an efficent reagent for the oxidative esterification of primary alcohols.Thus, a variety of esters was prepared from primary alcohols, aldehydes, and acetals in aqueous medium under mild conditions.Treatment of α,ω-diols with NaBrO3/NaHSO3 reagent afforded the corresponding lactones and/or dicarboxylic acids in fair yields.
- Takase, Kiyoshi,Masuda, Haruyoshi,Kai, Osamu,Nishiyama, Yutaka,Sakaguchi, Satoshi,Ishii, Yasutaka
-
p. 871 - 872
(2007/10/03)
-
- Oxidation Using Quaternary Ammonium Polyhalides. III. An Effective Oxidation of Alcohols and Ethers by the Use of Benzyltrimethylammonium Tribromide
-
The reaction of primary alcohols or simple ethers and α,ω-diols or cyclic ethers with a stoichiometric amount of benzyltrimethylammonium tribromide (BTMA) Br3) in carbon tetrachloride in the presence of Na2HPO4 aq or in acetic acid in the presence of CH3CO2Na aq at 60-70 deg C gave dimeric esters and lactones respectively in good yields.The reaction of secondary alcohols with 1 equiv of BTMA Br3 in the presence of a buffer at 60 deg C gave ketones.
- Kajigaeshi, Shoji,Kawamukai, Hiroshi,Fujisaki, Shizuo
-
p. 2585 - 2588
(2007/10/02)
-
- CATALYSED LIQUID PHASE OXIDATION OF ACETALS BY MOLECULAR OXYGEN
-
Nine different acetals have been oxidized in the presence of Co(OOCCH3)2*4H2O under isobaric conditions (0.1 - 0.2 MPa O2) while following the uptake of molecular oxygen.The reactivity of acetals was expressed by the rate constants of the autocatalytic model of oxidation.The main product of the oxidation are alcohols, esters and acids.The distribution of products and the total reactivity of acetals are controlled by the structure of both parts of acetal molecule.The dominant effects of the course of the reaction exerts the type of carbon atoms on which radicals are formed.The oxidation is accompanied by consecutive and co-oxidation reactions, by deactivation of the catalysts and by decarbonylation of intermediate products.The effect of oxygen pressure is reported and the more detailed radical mechanism of the oxidation is proposed.
- Vcelak, Jaroslav,Klimova, Miroslava,Chvalovsky, Vaclav
-
p. 847 - 866
(2007/10/02)
-
- Selective Dimerization of Aldehydes to Esters Catalyzed by Hydridoruthenium Complexes
-
RuH2(PPh3)4 and other hydridoruthenium complexes catalyze selective conversion of aldehydes into esters in high yields.The method is applicable to most aliphatic aldehydes as well as to aromatic aldehydes.The purity of aldehydes is critical for achieving high conversions, since the presence of carboxylic acid completely inhibits the reaction and alcohol and triphenylphosphine reduce the yields of esters.RuH2(PPh3)4 is converted into Ru(CO)3(PPh3)2 through the reaction indicating the occurrence of decarbonylation of aldehyde.A mechanism involving the acyl-H cleavageof aldehyde is proposed to account for the catalysis and formation of compounds accompanying the reaction.The mechanism is compared with an alternative one which comprises of consecutive insertions of two aldehyde molecules into Ru-H bond followed by β-hydrogen abstraction from an alkoxo intermediate formed.Addition of water changes the reaction course togive carboxylato carbonyl complexes Ru(OCOR)2(CO)m(PPh3)2 (m = 1 and 2).Cross esterification studies showed the reactivity order of RCHO as R = Et > Me > n-Pr > i-Pr >> Ph.
- Ito, Takashi,Horino, Hiroshi,Koshiro, Yoshitaka,Yamamoto, Akio
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p. 504 - 512
(2007/10/02)
-
- H-TRANSFER CATALYSIS WITH Ru3(CO)12
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Ru3(CO)12 , in the presence of tolane, catalyses the formation of esters from the following three systems: alcohol + aldehyde, alcohol and aldehyde.
- Blum, Y.,Reshef, D.,Shvo, Y.
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p. 1541 - 1544
(2007/10/02)
-
