Chantler, Thomas published the artcileProximity effects in the electron impact mass spectra of 2-substituted benzazoles, SDS of cas: 51656-68-9, the publication is International Journal of Mass Spectrometry (2004), 236(1-3), 65-80, database is CAplus.
The 70 eV electron impact mass spectra of a wide range of 2-substituted benzazoles are reported and discussed. Particular attention is paid to the mechanistic significance and anal. utility of [M-H]+ and [M-X]+ signals in the spectra of benzazoles in which the 2-substituent contains a terminal aryl group with one or more substituents, X. Loss of H• or X• occurs preferentially from an ortho-position from ionized 2-benzylbenzimidazoles, 2-phenethylbenzimidazoles, 2-styrylbenzimidazoles, 2-styrylbenzoxazoles and 2-styrylbenzothiazoles. In the three styrylbenzazole series, the [M-H]+ and/or [M-X]+ signals dominate the spectra. This unusually facile loss of H• or X• may be attributed to a proximity effect, in which cyclization of the ionized mol. is followed by elimination of an ortho-substituent to give an exceptionally stable polycyclic ion. Formation of a new five- or six-membered ring by the proximity effect occurs rapidly; cyclization to a seven-membered ring takes place rather less readily; but formation of a ring with only four atoms or more than seven atoms is not observed to a significant extent. The proximity effect competes effectively with loss of a Me radical by simple cleavage of an Et, iso-Pr and even a t-Bu group in the pendant aromatic ring of ionized 2-(4-alkylstyryl)benzazoles.
International Journal of Mass Spectrometry published new progress about 51656-68-9. 51656-68-9 belongs to chlorides-buliding-blocks, auxiliary class Chloride,Carboxylic acid,Benzene, name is 3-(2,6-Dichlorophenyl)propanoic acid, and the molecular formula is C9H8Cl2O2, SDS of cas: 51656-68-9.
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