Efficient ring-opening polymerization of ɛ-caprolactone using anilido-imine-aluminum complexes in the presence of benzyl alcohol

A number of new anilido-imine-Al complexes ortho-C6H4(CHNAr1)(NAr2)AlMe2 [Ar1 = C6H5, Ar2 = C6H5 (2a); Ar1 = 2,6-Me2C6H3, Ar2 = 2,6-Me2C6H3 (2b); Ar1 = 2,6-Et2C6H3, Ar2 = 2,6-Et2C6H3 (2c); Ar1 = 2,6-iPr2C6H3, Ar2 = 2,6-Me2C6H3 (2d); Ar1 = 2,6-iPr2C6H3, Ar2 = 2,6-Et2C6H3 (2e)] were synthesized, characterized and used as initiators for the ring-opening polymerization of ɛ-caprolactone in the presence of benzyl alcohol. The effect of initiator structure and reaction conditions, such as benzyl alcohol/Al molar ratio and reaction temperature on the reactivity, and polymer molecular weight were investigated. The polymerization of ɛ-caprolactone initiated by these complexes was found to take place in an immortal fashion.