Synthesis of caprolactamates of group II metals

Caproiactamates of alkaline-earth metals and magnesium of the general formula\({\text{M[}}{\text{O}}]_2 \), where M = Mg, Ca, Sr, and Ba, were synthesized from alkoxides, hydrides, and organometallic compounds of these metals and ɛ-caprolactam. The catalytic activities of caprolactamates obtained under conditions of anionic polymerization of ɛ-caprolactam were compared. It was demonstrated that the purest caprolactamates and, hence, the most effective catalysts of anionic polymerization of lactams can be obtained from organometallic and hydride compounds of these metals. The reactivities of alkoxides of the alkaline-earth metals and magnesium increase in metallation reactions of ɛ-caprolactam in the order Mg < Ca < Sr < Ba.