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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.
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 ...
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 ...
In the case of esterification with acetic anhydrides the currently accepted mechanism involves three steps. First, DMAP and acetic anhydride react in a pre-equilibrium reaction to form an ion pair of acetate and the acetylpyridinium ion.
In the Steglich esterification, alcohols, including even some tertiary alcohols, can be esterified using a carboxylic acid in the presence of DCC and a catalytic amount of DMAP. [7] In protein synthesis (such as Fmoc solid-state synthesizers), the N-terminus is often used as the attachment site on which the amino acid monomers are added.
The reaction mechanism is described as follows: . With amines, the reaction proceeds without problems to the corresponding amides because amines are more nucleophilic.If the esterification is slow, a side-reaction occurs, diminishing the final yield or complicating purification of the product.
The esterification reaction of p-Chlorocresol with acetic anhydride to obtain 4-chloro-3-methylphenyl acetate. [11] Step 1: Protonation of the phenol group Acetic anhydride is a source of acetyl cation (CH 3 CO +). In the presence of a Lewis acid catalyst like sulfuric acid, the acetyl cation can react with the lone pair of electrons on the ...