One-electron photooxidation of carbazole in the presence of carbon tetrachloride. Part II. Carbon tetrachloride as a reaction medium. Use of ammonia after irradiation and during irradiation

Abstract

In part I of this series of papers we proposed the mechanism of electron transfer as the primary photochemical reaction in the carbazole – carbon tetrachloride system along with a secondary photochemical reaction initiated by transformations of the radical cation of carbazole in the solvent cage resulting in intermediates:[Formula: see text]In this paper we discuss the influence of ammonia, used after and during irradiation, on the mechanism of secondary transformation and the formation of thermodynamically stable products in the system studied. Such compounds as N-cyanocarbazole, 1-cyanocarbazole, and 3-cyanocarbazole have been formed as the main products during neutralization of the photolyte solution by ammonia gas. The mechanism of formation of these compounds has been explained by the chemical reaction of ammonia with cations α and γi. If ammonia is present in the solution of carbazole in CCl4 during irradiation, such products as N,N′-dicarbazyl and N-cyanocarbazole are mainly formed along with 3-(N-carbazyl)carbazole, 3,9-di-(N-carbazyl)carbazole, and N-cyano-3-(N-carbazyl)carbazole. In such a case, reactions of radicals β are the determining factors in the secondary photochemical transformations. Radicals β are formed by the reaction involving ammonia with radical cations of carbazole. All the results in this paper have been discussed taking under consideration the influence of the reaction media on the mechanism of photochemical transformation of carbazole.