SPONTANEOUS COPOLYMERIZATION OF 1,3-CYCLOHEPTADIENE WITH ACRYLONITRILE IN THE PRESENCE OF ZINC-CHLORIDE

Results of an experimental study are presented which demonstrate that the reaction of 1,3-cycloheptadiene (1,3-CHpD) with acrylonitrile (AN) in the presence of ZnCl//2 leads spontaneously to the simultaneous formation of an alternating copolymer and a small amount of cycloadduct. The copolymer has a predominantly cis-1,4-structure. The formation of the charge-transfer complex between 1,3-CHpD and (AN)c (AN coordinated to ZnCl//2) in AN was detected by ultraviolet (UV) spectroscopy. The activation energies for the cycloaddition and for the copolymerization under the conditions used were determined to be 17. 6 (in the presence of 1,1-diphenyl-2-picrylhydrazyl) and 16. 3 kcal/mole, respectively. The rate of copolymerization in AN was found to depend on the 1. 5th power of the concentrations of (AN)c and of 1,3-CHpD. Oxygen and UV irradiation causes an acceleration of the copolymerization only. The mechanism of the spontaneous copolymerization is discussed and its relation to the cycloaddition in systems of 1,3-cyclodienes and AN in the presence of ZnCl//2 is mentioned.