Photolysis of triphenylmethyl and related cations in sulphuric acid

Abstract

Photolysis of triphenylmethyl cation in 99% sulphuric acid in the absence of oxygen gives 9-phenylfluorenyl cation. When oxygen is present an additional product, 9-hydroxyfluoren-9-yl cation is formed. The effect of oxygen on the rate of reaction and on the distribution of products is described. As the sulphuric acid concentration is reduced to 88% the rate of reaction is increased. Futher reduction is accompanied by the appearance of a new product, 4-hydroxyphenyldiphenylmethyl cation, which at 78% sulphuric acid becomes predominant. The effect of introducing a methyl or chloro-substituent into one or all of the para-positions of Ph₃C⁺ is described.