Organotin(IV) Compounds as Intramolecular Transesterification Catalysts in Thermal Depolymerization of Poly(L-Lactic Acid) Oligomer to form LL-Lactide

Abstract

Mono-, di-, and tetraalkyl tin(IV) compounds were evaluated for the intramolecular transesterification reaction of the thermal depolymerization of poly(L-lactic acid) oligomer forming lactide by gas chromatography using a β-cyclodextrin stationary phase capillary column. The most active catalyst was found to be monobutyltin trichloride (BuSnC1₃) (8), which contains tinhalogen bonds, and the least effective was the coordinatively saturated monoorganotin derivative, monobutyltin tris(2-ethylhexanoate) (7). Cordination of the carbonyl group in the oligomer to the tin catalysts is an important factor influencing its activity.