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In this study,in situformed ruthenium hydride species that were generated from Grubbs type catalysts are used as efficient catalysts for dehydrogenative alcohol coupling and sequential cross-metathesis/dehydrogenative coupling reactions. The selectivity of Grubbs first generation catalysts (G1) in dehydrogenative alcohol coupling reactions can be tuned for the ester formation in the presence of weak bases, while the selectivity can be switched to the β-alkylated alcohol formation using strong bases. The performance of Hoveyda-Grubbs 2nd generation catalyst (HG2) was improved in the presence of tricyclohexylphosphine for the selective synthesis of ester derivatives with weak and strong bases in quantitative yields. Allyl alcohol was used as self and cross-metathesis substrate for the HG2 catalyzed sequential cross-metathesis/dehydrogenative alcohol coupling reactions to obtain γ-butyrolactone and long-chain ester derivatives in quantitative yields.

The ABNO@PMO-IL-Br material obtained by anchoring 9-azabicyclo[3.3.1]nonane-3-oneN-oxyl (keto-ABNO) within the mesopores of periodic mesoporous organosilica with bridged imidazolium groups is a robust bifunctional catalyst for the metal-free aerobic oxidation of numerous primary and secondary alcohols under oxygen balloon reaction conditions. The catalyst, furthermore, can be successfully employed in the first metal-free self-esterification of primary aliphatic alcohols affording valued esters.

Aerobic self-esterification of primary alcohols catalyzed by mesoporous metal oxides (manganese and cobalt oxides) is reported under base and solvent free conditions. For a range of aliphatic alcohols, up to 90 % conversions to esters was achieved. The catalytic reaction is likewise applicable to neat aldehydes as substrates with yields of up to 86 %. High pressure batch reaction for ethanol to ethyl acetate led to 22 % yield. Isotope labeling studies indicated decarboxylation on the catalyst surface. Mechanistic and kinetic experiments implicate oxygen rebound and α-carbon removal as intermediate steps. Mesoporous cobalt oxide showed about 20 % higher catalytic activity compared to mesoporous manganese oxide.

Oxidative esterification of aliphatic primary alcohols with bromide and bromate couple in aqueous acidic medium at room temperature is reported with a wide range of substrate scope for both aliphatic and cyclic alcohols and obtained excellent yields of products.

A novel catalytic system with a tripodal cobalt complex is developed for efficiently converting primary alcohols to esters. KOtBu is found essential to the transformation. A preliminary mechanistic study suggests a plausible reaction route that involves an initial Co-catalyzed dehydrogenation of alcohol to aldehyde, followed by a Tishchenko-type pathway to ester mediated by KOtBu.

One-pot indirect electrochemical oxidation of alcohols in the methylene chloride–aqueous solution of sodium hydrocarbonate two-phase system in the presence of potassium iodide, 4-acetylamino-2,2,6,6-tetramethylpiperidin-1-oxyl, and 2,6-lutidine results in

An efficient method for the oxidation of alcohols to aldehydes or ketones in a two-phase CH2Cl2/NaHCO3 (aq.) system, using iodine and catalytic amounts of 4-acetylamino-2,2,6,6-tetramethylpiperidine-1-oxyl and 2,4,6-trimethylpyridine, was developed. The performance of the method was demonstrated by the selective oxidation of 37 variously substituted alcohols in ≥90% yield, including the gram-scale synthesis of the important chemical 2,5-diformylfuran from biomass-derived 5-hydroxylmethylfurfural.

Nanoparticles (NPs) of Pd and Pt were used for the selective oxidation of aliphatic alcohols with molecular oxygen as an oxidant at near ambient temperatures under visible light irradiation. Distinct final products were obtained under identical reaction conditions, aliphatic esters formed over the Pd NPs while aldehydes formed over the Pt NPs. The reason for this different product selectivity is proven to be due to the much stronger interaction of Pd NPs with alcohol and aldehyde compared to Pt NPs. The photocatalytic activity is tuneable by light intensity or a moderate change in the reaction temperature.

Long aliphatic esters were prepared by the one-step catalytic self-esterification of primary alcohols using molecular oxygen as a green oxidant and supported gold nanoparticles (Au NPs) as catalyst. This heterogeneous catalyst achieved high activity and selectivity in a wide range of less reactive straight-chain alcohols (C4-C12) at atmospheric pressure O2 and near ambient temperature (45?°C). Under optimised conditions, the catalyst with Au loading of 3?wt% achieved the highest catalytic activity and selectivity. The AuNP catalysts are efficient and readily recyclable. The finding of this study may inspire further studies on new efficient catalytic systems for a wide range of organic syntheses using supported AuNP catalysts.

Pyridine catalyzes oxidation of alcohols with 4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxyl–iodine catalytic system at room temperature. Symmetric esters are formed in good yields.

Selective oxidation of aliphatic alcohols under mild and base-free conditions is a challenging process for organic synthesis. Herein, we report a one-pot process for the direct oxidative esterification of aliphatic alcohols that is significantly enhanced by visible-light irradiation at ambient temperatures. The new methodology uses heterogenerous photocatalysts of gold-palladium alloy nanoparticles on a phosphate-modified hydrotalcite support and molecular oxygen as a benign oxidant. The alloy photocatalysts can absorb incident light, and the light-excited metal electrons on the surface of metal nanoparticles can activate the adsorbed reactant molecules. Tuning the light intensity and wavelength of the irradiation can remarkably change the reaction activity. Shorter wavelength light (550 nm) drives the reaction more efficiently than light of longer wavelength (e.g., 620 nm), especially at low temperatures. The phosphate-exchanged hydrotalcite support provides sufficient basicity (and buffer) for the catalytic reactions; thus, the addition of base is not required. The photocatalysts are efficient and readily recyclable. The findings reveal the first example of using "green" oxidants and light energy to drive direct oxidative esterification of aliphatic alcohols under base-free, mild conditions.

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.

PROBLEM TO BE SOLVED: To provide a method for obtaining alcohol by hydrogenation of carboxylic acid compound efficiently by using a homogeneous system catalyst, especially a method for obtaining alcohol by hydrogenation of various carboxylic acid compound by the homogeneous system catalyst efficiently even under alleviation condition. SOLUTION: There is provided a method of manufacturing alcohol by hydrogenation of a carboxylic acid compound in a presence of a ruthenium complex represented by RumXnYpZq and a specific alkali metal salt. COPYRIGHT: (C)2015,JPOandINPIT

Oxoammonium salt oxidations (using 4-acetylamino-2,2,6,6- tetramethylpiperidine-1-oxoammonium tetrafluoroborate) of alcohols containing a β-oxygen atom in the presence of pyridine yield dimeric esters, while in the presence of 2,6-lutidine the product is a simple aldehyde. The formation of a betaine between pyridine and an aldehyde is presented to explain this disparity in reactivity. The betaine is oxidized by the oxoammonium salt to give an N-acylpyridinium ion that serves as an acylating agent for ester formation. Steric effects deter the formation of such a betaine with 2,6-disubstituted pyridines. A series of alcohols containing a β-oxygen substituent were oxidized to aldehydes in the presence of 2,6-lutidine, and a short study of the relative reactivity of various alcohols is given. An overall mechanism for oxoammonium cation oxidations is suggested, premised on nucleophilic additions to the oxygen atom of the positively charged nitrogen-oxygen double bond. Possible mechanisms for both dimeric oxidations and simple oxidations are given.

In this Letter we outline the synthesis of a variety of dibromoolefins (DBOs) from a series of alkenes by coupling an oxidative cleavage and a reaction with a phosphorous ylide. This approach strategically avoids isolation of reactive aldehyde intermediates and presents one of the few examples coupling carbon-carbon bond formation with ozonolysis.

The homogeneous catalyzed dehydrogenation of methanol in a synthetically valuable cross-coupling reaction was achieved. By the use of a simple ruthenium-N-heterocyclic carbene complex, MeOH and primary or secondary amines can be converted into formamides.

Oxidation of linear or branched primary alkanols with H2O 2-MBr (M = Li, Na, K)-HCl system in water affords the corresponding "symmetrical" esters in almost quantitative yield.

Action of a novel oxidation system, Ce(NO3)3? 6H2O (cat.)-LiBr (cat.)-H2O2 (stoichiometric oxidant) on primary aliphatic C6-C9 alcohols gives selectively esters, whereas secondary aliphatic C5-C9 alcohols are converted into ketones. Selectivity of these transformations is provided by slow addition of H2O2 to the other reactants.

A method for the synthesis of "symmetric" esters based on the oxidation of primary straight-and iso-chain aliphatic alcohols C6 -C11 with the system Ce(SO4)2-LiBr in water has been suggested.

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Esters are formed during the solvent-free oxidation of primary aliphatic C5-C9 alcohols with Ce(NH4)2(NO 3)6-LiBr, whereas secondary octan-2-ol gives a mixture of isomeric 1-and 3-bromooctan-2-ones.

Oxidative dimerization of primary alcohols with 2-butanone in the presence of an amino alcohol-based Ir bifunctional catalyst was accomplished for the first time. The reaction proceeds with 1-2 mol% of the catalyst and 0.3 mol equivalents of K2CO3 in 2-butanone at room temperature to give the corresponding dimeric esters in 30-93% yield. Georg Thieme Verlag Stuttgart.

Alkyl hypochlorites under UV irraduation at room temperature are selectively transformed into the corresponding esters. The reaction can be applied to preparation of higher esters. Free radical chain mechanism of products formation was presumed including intermediate aldehydes and acyl radicals. Under the same conditions aldehydes readily react with alkyl hypochlorites to yield esters.