1914-12-1Relevant academic research and scientific papers
Intramolecular Addition of Aryl Radicals to Carbon-Nitrogen Double Bonds
Gioanola, Milena,Leardini, Rino,Nanni, Daniele,Pareschi, Patrizia,Zanardi, Giuseppe
, p. 2039 - 2054 (2007/10/02)
Cyclisation of radicals 6a,b is highly regioselective towards a 5-exo process; 6-endo ring closure is a minor route and their ratio depends on the substituents.No ring expansion of the five-membered radical intermediates 7a,b was observed.Radicals 27a,b give rise to 5-exo cyclisation regiospecifically.A competitive 1,5-hydrogen shift leading to imidoyl radicals was noticed.An analogous behaviour is also exhibited by vinyl radicals when allowed to add to carbon-nitrogen double bonds.
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.
Photocleavage of Diarylnitrosamines in Neutral Media
Crumrine, David S.,Brodbeck, Charles M.,Dombrowski, Paul H.,Haberkamp, Thomas J.,Kekstas, Rita J.,et al.
, p. 4246 - 4249 (2007/10/02)
N-Nitrosodiphenylamine, N-nitroso(2-nitrophenyl)phenylamine, N-nitroso(3-methylphenyl)phenylamine, and N-nitrosocarbazole were irradiated in degassed neutral solution to give the corresponding diarylamine as the initial photoproduct.The effects of changing solvents, concentrations, and substituents and of adding catalysts were examined.Quantum yield studies, sensitization work, and ESR studies were used to study the mechanism of this photolysis.
