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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 ...
First, the Lewis acid catalyst activates the TFBA, and then a carboxyl group in seco acid reacts with the activated TFBA to produce mixed anhydride (MA) once. Then, a carbonyl group derived from the seco acid in MA is selectively activated and is attacked by a hydroxyl group in the seco acid through intramolecular nucleophilic substitution.
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 ...
An ester of a carboxylic acid.R stands for any group (typically hydrogen or organyl) and R ′ stands for any organyl group.. In chemistry, an ester is a compound derived from an acid (organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group (−OH) of that acid is replaced by an organyl group (R ′). [1]
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 ]
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.
The classic example of a dehydration reaction is the Fischer esterification, which involves treating a carboxylic acid with an alcohol to give an ester RCO 2 H + R′OH ⇌ RCO 2 R′ + H 2 O. Often such reactions require the presence of a dehydrating agent, i.e. a substance that reacts with water.