Used primarily as an intermediate in organic synthesis, especially in the production of pharmaceuticals and agrochemicals. It participates in ring-opening and substitution reactions due to its activated carbonyl groups and reactive chlorine atom. Commonly employed in the preparation of gamma-lactam derivatives and other heterocyclic compounds with biological activity. Also utilized in the synthesis of specialty polymers and resins where functional reactivity and ring structure are required. Its electrophilic nature makes it suitable for use in Friedel-Crafts acylation and other catalytic coupling reactions.