Carboxylic acids ester hydrolysis

Carboxylic acid ester hydrolysis is frequently observed as the initial reaction for pesticides with ester bonds, such as 2,4-D esters, pyrethroids, and DCPA (dacthal) (8) (eq. 11) (16). 

Quinoline, 2-cyano-8-hydroxy-hydro lysis metal catalysis, 452 Quinoline, 8-hydroxy-carboxylic acid esters hydrolysis, metal-catalyzed, 438 metal complexes... 

Figure 2.8. Examples of carboxylic acid ester hydrolysis.

The action of esterases consists essentially in the hydrolysis (or synthesis) of carboxylic acid esters according to the equation ... 

Inspired by the many hydrolytically-active metallo enzymes encountered in nature, extensive studies have been performed on so-called metallo micelles. These investigations usually focus on mixed micelles of a common surfactant together with a special chelating surfactant that exhibits a high affinity for transition-metal ions. These aggregates can have remarkable catalytic effects on the hydrolysis of activated carboxylic acid esters, phosphate esters and amides. In these reactions the exact role of the metal ion is not clear and may vary from one system to another. However, there are strong indications that the major function of the metal ion is the coordination of hydroxide anion in the Stem region of the micelle where it is in the proximity of the micelle-bound substrate. The first report of catalysis of a hydrolysis reaction by me tall omi cell es stems from 1978. In the years that... 

Carboxylic acid derivative (Section 20 1) Compound that yields a carboxylic acid on hydrolysis Carboxylic acid de nvatives include acyl chlondes acid anhydndes esters and amides... 

Mineral surfaces may accelerate the rate of ester hydrolysis (Stone, 1989 Hoffmann, 1990 Torrents and Stone, 1991). One plausible scheme for this heterogeneous catalysis assumes a nucleophilic addition of the ester to the surface functional group, e.g., in case of a carboxylic acid ester... 

Before discussmg the mechanism of cleavage of carboxylic acid esters and amides by hydrolases, some chemical principles are worth recalling. The chemical hydrolysis of carboxylic acid derivatives can be catalyzed by acid or base, and, in both cases, the mechanisms involve addition-elimination via a tetrahedral intermediate. A general scheme of ester and amide hydrolysis is presented in Fig. 3. / the chemical mechanisms of ester hydrolysis will be... 

Fig. 3.1. General scheme for chemical hydrolysis of carboxylic acid esters and amides. Pathway a Proton (general acid) catalyzed hydrolysis. Pathway b HO (general base) catalyzed...

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