Catalyst-free Depolymerization of Polycaprolactone to Silylated Monoesters and Iodide Derivatives Using Iodosilanes

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 later 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.