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

The homogeneous depolymerization of polycaprolactone (PCL) with excess iodotrimethylsilane (Me 3 SiI) proceeds without catalysts and selectively afforded I(CH 2 ) 5 CO 2 SiMe 3 or a mixture of I(CH 2 ) 5 CO 2 SiMe 3 and I(CH 2 ) 5 CO 2 I depending on the solvent (CH 2 Cl 2 , MeCN). The latter mixture can undergo methanolysis or hydrolysis into the valuable ester I(CH 2 ) 5 CO 2 Me or the acid I(CH 2 ) 5 CO 2 H. In contrast, SiH 2 I 2 depolymerized PCL into the fully deoxygenated species I(CH 2 ) 6 I and n -hexane.