Ester hydrolysis

Ester hydrolysis is the cleavage of an ester by water, producing a carboxylic acid or carboxylate and an alcohol. Acid or base catalysis can accelerate the reaction.

Nucleophilic acyl substitution: A reaction in which a nucleophile replaces a group attached to an acyl carbon through an addition–elimination sequence. Ester hydrolysis follows this general pattern: water or hydroxide adds, then an alcohol-derived group leaves.
Ester: An organic compound containing a carbonyl group bonded to an oxygen that is bonded to another carbon group. Its acyl–oxygen framework supplies the bond broken during ester hydrolysis.
Lipase: An enzyme that catalyzes the hydrolysis of fats and other ester bonds. Lipases perform selective ester cleavage in digestion and biotechnology.
Esterification: A reaction that forms an ester, commonly from a carboxylic acid and an alcohol. It is the reverse transformation of ester hydrolysis under suitable conditions.
Acid-catalyzed ester hydrolysis: Ester cleavage in acidic water, proceeding through carbonyl protonation and nucleophilic addition by water. Protonation activates the ester carbonyl and ultimately allows the alcohol group to leave.
Carbonyl group: A functional group consisting of a carbon atom double-bonded to oxygen. The electrophilic carbonyl carbon is the site attacked by water or hydroxide.
Lipid digestion: The enzymatic breakdown of dietary fats into absorbable molecules in the digestive tract. Hydrolysis of triglyceride ester bonds releases fatty acids and monoacylglycerols.
Transesterification: A reaction that exchanges an ester’s alcohol-derived group for one from another alcohol. Unlike hydrolysis, it replaces one alcohol-derived group without requiring water as the reactant.
Saponification: Base-promoted ester hydrolysis that yields a carboxylate salt and an alcohol. Its carboxylate product is poorly electrophilic, making the base-driven cleavage effectively irreversible.
Nucleophile: A species that donates an electron pair to form a chemical bond. Water or hydroxide acts as the nucleophile that initiates acyl substitution.

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