Photoreaction of 9-vinylcarbazole in acetonitrile in the presence of titanium dioxide and a catalytic amount of magnesium perchlorate gave 3, 6-di (9-carbazolyl)-1, 2-dioxane as a photooxygenated product via photodimerization of 9-vinylcarbazole. The photoreaction proceeds via an electron transfer mechanism, where magnesium perchlorate accelerated formation of the photooxygenated product.
