5599-71-3Relevant academic research and scientific papers
N,N-di(4-halophenyl)nitrenium ions: Nucleophilic trapping, aromatic substitution, and hydrogen atom transfer
Thomas, Selina I.,Falvey, Daniel E.
, p. 4626 - 4634 (2008/02/07)
(Figure Presented) The reactive intermediates N,N-di(4-chlorophenyl) nitrenium ion and N,N-di(4-bromophenyl)nitrenium ion were generated through photolysis of the corresponding N-amino(2,4,6,-collidinium) ions. The behavior of these diarylnitrenium ions was characterized by laser flash photolysis, analysis of the stable photoproducts, and ab initio calculations with density functional theory. The latter predict these species to have singlet ground states. The halogenated diarylnitrenium ions are significantly longer lived than the unsubstituted diphenylnitrenium ion. Specifically, cyclization to form carbazole derivatives occurs negligibly, if at all, with the halogenated derivatives. They do, however, carry out most of the characteristic reactions of singlet arylnitrenium ions, including combining with nucleophiles on the aryl rings, adding to arenes, and accepting electrons from readily oxidized traps. Interestingly these species also abstract H atoms from 1,4-cyclohexadiene and various phenol derivatives. The implication of the latter process in relation to the computed singlet-triplet energy gaps of ca. -12.5 kcal/mol is discussed.
On the Synthesis and Isolation of Chlorocarbazoles Obtained by Chlorination of Carbazoles
Bonesi, Sergio M.,Erra-Balsells, Rosa
, p. 877 - 889 (2007/10/03)
Carbazole (1) undergoes electrophilic aromatic substitution with various chlorinating reagents. Although 3-chlorocarbazole (1b), 3,6-dichlorocarbazole (1d) and 1,3,6,8-tetrachlorocarbazole (1f) obtained by chlorination of carbazole were isolated and characterized sometime ago, 1-chlorocarbazole (1a), 1,6-dichlorocarbazole (1c) and 1,3,6-trichlorocarbazole (1e) had never been isolated from the reaction mixtures. The preparation and subsequent isolation and characterization of 1a, 1b, 1e, 1d, 1e and 1f are reported (mp, tF, Rf, 1H- and 13C-nmr, ms). Physical and spectroscopic properties of le are compared with those of 1b and 1d in order to show that the former is the major product obtained in several chlorinating processes. As chlorinating reagents, chlorine in glacial acetic acid, sulfuryl chloride, N-chlorosuccinimide, N-chlorosuccinimide-silica gel, N-chlorobenzotriazole, and N-chlorobenzotriazole-silica gel in dichloromethane and in chloroform have been used and their uses have been compared. The chlorination reaction of different carbazole derivatives such as 2-hydroxycarbazole (2), 2-acetoxycarbazole (3), 3-bromocarbazole (4) and 3-nitrocarbazole (5) was also studied and the corresponding chloro derivatives 2a, 2b, 2c, 2d, 3a, 3b, 3c, 3d, 3e, 3f, 4a, 4b, 4c, 4d, 5a and 5b are described for the first time. Semiempirical PM3 calculations have been performed in order to predict reactivity of carbazole (1), substituted carbazoles 2-5 and chlorocarbazoles (Scheme 1). Theoretical and experimental results are discussed briefly.
Acid-Catalyzed Intermolecular Rearrangement of N-Chlorocarbazole
Rosa, Michael De,Quesada, Andres P.,Dodsworth, David J.
, p. 173 - 175 (2007/10/02)
The chlorination of carbazole with sodium hypochlorite in CH2Cl2, CHCl3, or CCl4 gave N-chlorocarbazole in 63-95percent yield.It rearranged in refluxing methanol to give carbazole, 3-chlorocarbazole, 1-chlorocarbazole, 3,6-dichlorocarbazole, and 1,6-dichlorocarbazole.These chlorocarbazoles were formed in an acid-catalyzed intermolecular reaction.In the presence of potassium carbonate dechlorination of N-chlorocarbazole was observed.No evidence for an intramolecular rearrangement was found.
