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In acidic Shiina esterification, Lewis acid catalysts are used, while nucleophilic catalysts are used for Shiina esterification under basic conditions. Shiina esterification using Lewis acid catalyst. In the acidic reaction, 4-trifluoromethylbenzoic anhydride (TFBA) is mainly used as a dehydration condensation agent.
All of the processes of Shiina macrolactonization consist of reversible reactions, with the exception of the last cyclization step.At the first stage of the reaction, mixed anhydride (MA) is produced quickly under mild conditions; at the second stage, a faster cyclization of the MA prevents an increase in MA concentration.
The natural esterification that takes place in wines and other alcoholic beverages during the aging process is an example of acid-catalysed esterification. Over time, the acidity of the acetic acid and tannins in an aging wine will catalytically protonate other organic acids (including acetic acid itself), encouraging ethanol to react as a ...
The Yamaguchi esterification is the chemical reaction of an aliphatic carboxylic acid and 2,4,6-trichlorobenzoyl chloride (TCBC, Yamaguchi reagent) to form a mixed anhydride which, upon reaction with an alcohol in the presence of stoichiometric amount of DMAP, produces the desired ester. It was first reported by Masaru Yamaguchi et al. in 1979 ...
2-Methyl-6-nitrobenzoic anhydride is an organic acid anhydride also known as the Shiina reagent, [1] [2] having a structure wherein carboxylic acids undergo intermolecular dehydration condensation. It was developed in 2002 by Prof. Isamu Shiina ( Tokyo University of Science , Japan). [ 3 ]
The reaction mechanism of the Mitsunobu reaction is fairly complex. The identity of intermediates and the roles they play has been the subject of debate. Initially, the triphenyl phosphine (2) makes a nucleophilic attack upon diethyl azodicarboxylate (1) producing a betaine intermediate 3, which deprotonates the carboxylic acid (4) to form the ion pair 5.
Strong acids catalyze the reaction by donating a proton to the carbonyl group, thus making it a more potent electrophile. Bases catalyze the reaction by removing a proton from the alcohol, thus making it more nucleophilic. The reaction can also be accomplished with the help of enzymes, particularly lipases (one example is the lipase E.C.3.1.1.3 ...
Anthranilic acid is an aromatic acid with the formula C 6 H 4 (NH 2)(CO 2 H) and has a sweetish taste. [ 5 ] [ 6 ] [ 7 ] The molecule consists of a benzene ring, ortho -substituted with a carboxylic acid and an amine .