Catalyst-free depolymerization of polycaprolactone to silylated monoesters and iodide derivatives using iodosilanes

Abstract

The homogeneous depolymerization of polycaprolactone (PCL) with excess iodotrimethylsilane (Me₃SiI) proceeds without catalysts and selectively afforded I(CH₂)₅CO₂SiMe₃ or a mixture of I(CH₂)₅CO₂SiMe₃ and I(CH₂)₅CO₂I depending on the solvent (CH₂Cl₂, MeCN). The latter mixture can undergo methanolysis or hydrolysis into the valuable ester I(CH₂)₅CO₂Me or the acid I(CH₂)₅CO₂H. In contrast, SiH₂I₂ depolymerized PCL into the fully deoxygenated species I(CH₂)₆I and n-hexane.