Alkylaluminum–Lewis base complexes as initiators of vinyl polymerization

Abstract

Abstract Complexes of aluminum alkyls with Lewis bases catalyze the polymerization of vinyl chloride. Triethylaluminum is most effective, but other compounds of type R 3 Al, R 2 AlCl, R 2 AlH, and LiAIR 4 are operable. Dialkylmagnesiums are active, but Grignard reagents, as well as a number of other metal alkyls are inactive. Among Lewis bases, tetrahydrofuran (THF) and tetrahydropyran give the best yields of poly(vinyl chloride). Oxygen bases, such as ethers and esters, are more effective than nitrogen bases, e.g., tertiary amines. Cyclic compounds are better than acyclic ones. The polymerization occurs in a variety of hydrocarbon, chlorinated hydrocarbon, or ether solvents, but especially well in CCl 4 . Radical polymerization is probably initiated through the reaction R 3 Al:Base + CCl 4 → R 2 AlCl: Base + R + Cl 3 C., to form trichloromethyl radical.