Polyacylation

Polyacylation is a term used in organic and polymer chemistry to describe reactions in which two or more acyl groups are introduced into a molecule or polymer. An acyl group is a carbonyl-containing moiety such as R-CO–. In small-molecule substrates, polyacylation can occur at nucleophilic sites such as amines, hydroxyls, or aromatic rings and may proceed stepwise using acyl chlorides, acid anhydrides, or other activated carboxyl derivatives, often with catalysts or protecting groups to control selectivity. In polymer chemistry, polyacylation refers to step-growth or condensation processes that link monomers via acyl linkages, producing polyamides, polyesters, or other polyacylated polymers; common routes include diacyl chlorides with diamines or diols, and esterification of diacids with diols.

Reaction outcomes depend on substrate reactivity, substituent effects, and stoichiometry. Achieving selective polyacylation frequently requires protecting groups to prevent overreaction at alternative sites. Overacylation can lead to crosslinking, insolubility, or loss of functionality, while controlled polyacylation enables tuning of material properties such as hydrophobicity, thermal stability, and mechanical strength.

Applications of polyacylation include synthesis of polyamides and polyesters, modification of peptides or proteins (for example, multiacetylation of lysine residues in biochemical studies), and the preparation of functionalized polymers for coatings, adhesives, and advanced materials. Safety considerations reflect those of general acylating agents: acid chlorides, anhydrides, and related reagents are reactive and corrosive, requiring appropriate handling.