76334-12-8Relevant articles and documents
One-electron photooxidation of N-ethylcarbazole in the presence of carbon tetrachloride. Products and mechanism of the photochemical reaction
Zelent, Bogumil,Durocher, Gilles
, p. 1654 - 1665 (2007/10/02)
The mechanism of the photodecomposition of N-ethylcarbazole (NEC) in the presence of carbon tetrachloride has been discussed on the basis of the photoproducts identified.The photodissociation of the N-ethyl bond and the electron transfer in the transiently formed ex-CT complex, 1(NEC?+...CCl4?-)*, have been proposed as the primary photochemical processes involved in the singlet excited NEC molecule.The latter, treated as the main process, leads to the radical cation of NEC, chloride ion, and trichloromethyl radical in the solvent cage, +.Cl-.CCl3>.The other reactions in the system studied are analysed following the decomposition of NEC+. in the presence of Cl- and .CCl3, which can occur by the N-ethyl group and (or) by the aromatic ring.The formation of intermediate products such as αr, αk, and γ'i(i=1,2,3, or 4) in the solvent cage gives rise to secondary photochemical reactions in the system studied.The polarity and chemical activity of the reaction media used strongly influence the nature of the secondary photochemical transformations both in and outside the solvent cage.The formation mechanism of the photochemical reaction products in CCl4 when ammonia was used, after and during irradiation, has been explained mainly by the transformations of the radical αr and cation αk as well as by the carbazyl radical β, which is also formed in the reaction medium.On the other hand, reaction of the cation γ'i explains the formation of the photoproducts in the irradiated solution of NEC with CCl4 in ethanol.These photochemical results have been compared to the photochemical reactions involved in the carbazole-CCl4 system.
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
Zelent, Bogumil,Durocher, Gilles
, p. 2442 - 2450 (2007/10/02)
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: .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.
