Efficient synthesis of esters through oxone-catalyzed dehydrogenation of carboxylic acids and alcohols

Abstract

An environmentally friendly oxone (20 mol%) catalyzed esterification of carboxylic acids with alcohols has been developed, providing an attractive alternative to the construction of valuable carbonyl esters.

Applications of Oxone® in Organic Synthesis: An Emerging Green Reagent of Modern Era

“…reported an efficient synthesis of esters 713 a – x through oxone‐mediated esterification of carboxylic acids 712 with alcohols under mild reaction condition (Scheme 216). [486] The reaction was found to be compatible with both electron‐rich as well as electron‐poor groups and the gram‐scale synthesis was also fruitfully accomplished by the authors. A plausible mechanism for this reaction involving path A and path B is detailed in the Scheme 217.…”

Electrochemical strategies for NaX-mediated hydrolysis and alcoholysis of hydrosilanes under mild conditions

“…Employing methanol ( 2a ), ethanol ( 2b ) or n -propanol ( 2c ) as both a nucleophilic coupling partner and solvent, the alcoholysis transformation furnished the desired products in satisfactory outcomes under electrochemical conditions. Although moderate to good yields were obtained for other alcohols in this electrochemical alcoholysis transformation, there were three principal changes that should be noted: firstly, the gradually decreased yields for the conversion reflected the decay of nucleophilicity caused by the increased steric hindrance of the alcohol substrates, 20 especially for the relatively high steric hindrance of alcohol substrates ( 2d–j ), and therefore electrochemical alcoholysis transformation needed to be carried out under inert nitrogen conditions to suppress possible side reactions including homocoupling of alkoxysilanes or hydrolysis of silane with H 2 O in air; secondly, the increased carbon chain length of alcohol substrates ( 2e–j ) resulted in diminished solubility for the reaction mixtures; hence anhydrous CH 3 CN/ROH (5 : 0.1) mixed solvents were employed as solvents instead of alcohols alone to promote the solubility and conductivity of the reaction system; thirdly, the generation of the disiloxane byproduct hexaphenyldisiloxane rather than the desired alcoholysis product was observed for NaBr-mediated alcoholysis of triphenylsilane in anhydrous CH 3 CN/ t -amyl alcohol ( 2j ) mixed solvents under inert nitrogen conditions. Considering that TBAB is a good redox mediator for some electrochemical conversion, 18 TBAB was used instead of NaBr as the mediator and electrolyte for the electrochemical alcoholysis transformation between triphenylsilane and t -amyl alcohol ( 2j ).…”

Zn Promoted Mg-Al Mixed Oxides-Supported Gold Nanoclusters for Direct Oxidative Esterification of Aldehyde to Ester

“…Ester compounds are one of the most important raw materials in chemical industry and organic synthesis and constitute numerous artificial fragrances, flavoring agents, solvent extractants and chemical intermediates [1]. The traditional synthetic method for preparation of esters involves a two-step procedure, including the oxidation of aldehyde and/or alcohol and the subsequent esterification between carboxylic acid and its activated derivatives with alcohols [2][3][4]. The multistep process involves the production of large amounts of toxic wastes and irremovable byproducts, which is not conducive to the development of green chemistry.…”