Thioester hydrolysis and C-C bond formation by carboxymethylproline synthase from the crotonase superfamily

Hydrolysis of esters under acidic conditions proceeds through a nucleophilic acyl substitution. In the presence of excess water, the reaction proceeds in a reversible manner, forming carboxylic acids and alcohols.
During hydrolysis, the ester is first activated towards nucleophilic attack through the protonation of the carboxyl oxygen atom by the acid catalyst. The protonation makes the ester carbonyl carbon more electrophilic. In the next step, water acts as a nucleophile and adds to the...

Nitriles undergo acid-catalyzed hydrolysis or base-catalyzed hydrolysis to form a carboxylic acid. These reactions proceed via an amide intermediate.

Regular Claisen condensation involves the synthesis of β-ketoesters by combining identical ester molecules bearing two α hydrogens in the presence of an alkoxide base. The reaction commences with the deprotonation of the acidic α hydrogen by the base to form a resonance stabilized ester enolate. This nucleophilic ion then attacks the carbonyl center of another ester molecule to generate a tetrahedral alkoxide intermediate. Next, the expulsion of the alkoxide group from the intermediate restores...

Esters can be hydrolyzed to carboxylic acids under acidic or basic conditions. Base-promoted hydrolysis of esters is a nucleophilic acyl substitution reaction in which esters react with an aqueous base, followed by an acid to give carboxylic acids. This reaction is also known as saponification because it forms the basis for making soaps from fats.
The reaction requires a base in stoichiometric amounts, which participates in the reaction and is not regenerated later. So, the base acts as a...

Hydrolysis of acid halides is a nucleophilic acyl substitution reaction in which acid halides react with water to give carboxylic acids. The reaction occurs readily and does not require acid or a base catalyst.
As shown below, the mechanism involves a nucleophilic attack by water at the carbonyl carbon to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen π bond along with the departure of a halide ion. A final proton transfer step yields carboxylic acid...

Nitriles (R–CN) can be converted into carboxylic acids (R–COOH) upon treatment with aqueous acids, i.e., upon hydrolysis of nitriles. Under base-catalyzed conditions, carboxylate anions (R–COO−) are formed.