ZnTPP-sensitized photoreaction of α-methylstyrene in the presence of Et 3N and CCl 4

Abstract

The photolysis (greater than 400 nm) of α-methylstyrene ( 1), sensitized by zinc 5,10,15,20-tetraphenylporphine (ZnTPP) in the presence of Et 3N and CCl 4, was studied. The main products were the two stereoisomers of 3,4-dimethyl-3,4-diphenyl-1,1,1,6,6,6-hexachlorohexane ( 2 and 3), which probably resulted from the addition of a trichloromethyl radical to 1, followed by radical coupling. Yields of approximately 11 000% were obtained on the basis of ZnTPP. 2-Phenyl-4,4,4-trichloro-1-butene ( 4), one of the previously reported main products from the reaction of 1 and CCl 3 was only obtained in very low yields. In addition to the trichloromethylation of 1, chloroform was produced in very high yields (up to 130 000% on the basis of ZnTPP).