Mass spectral fragmentation pattern of 2,2′‐Bipyridyls. Part X. trans‐1,2‐Di‐(2‐pyridyl)ethylene

Abstract

The base peak in the mass spectrum of trans‐1,2‐di‐(2‐pyridyl)ethylene is due to the M‐1 ion. A major fragmentation route involves loss of HCN from the M‐1 ion. Another important pathway involves rupture of one of the bonds linking a pyridine ring with the central CHCH group.

Electron‐ionization‐induced mass spectral study of isomeric (E)‐N‐ethyl‐1,2‐bispyridylethylene iodides

“…This type of fragmentation has been observed previously for the molecular ion of (E)-1,2-bis-(2,2 0 -pyridyl)ethylene. 10 As can be seen from Scheme 1 and the data in Table 1 ) bonds of the ethyl substituent. As follows from Table 1, the position of the nitrogen atom, especially the quaternary nitrogen atom, in the pyridine ring can be deduced in three ways: (1) …”

“…8 The mass spectral behaviour of isomeric (E)-N-ethyl-1,2-bispyridylethylene has been widely studied. [9][10][11] However, the mass spectral study of isomeric (E)-N-ethyl-1,2-bispyridylethylene iodides 1-6 ( Fig. 1) has not, to my knowledge, been reported.…”

The electron impact fragmentation of 3‐ and 4‐styrylpyridazine

“…Compared to stilbene, which has been the subject of numerous investigations (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14), the reported fragmentation of its monoaza (6) and diaza-analogs (6,15) upon electron impact is governed essentially by two competitive factors: i) the influence of nitrogen incorporation on a stabilizing cyclisation of the molecular structure; and ii) the driving force of nitrogen expulsion via elimination of N,andlor N2-containing fragments. A comparison of isomeric styrylpyridines (6), however, shows that the mass spectrometric behaviour resulting from these effects, depends additionally on the position of the nitrogen atom; the orthoisomer, i.e., with -N= in the 2-position, exhibits little and well explicable fragmentation, whereas otherwise rather complex spectra are obtained.…”

“…Intensities of the M*', [M-l]*, [M-2]' and [M-15]' Ions of Stilbene(6,14) and Various Mono-(6) and Diaza-Stilbenes(6,15) with Electron Impact (70 eV) Ionisation % t.i.i. = % of total ion intensity for mlz t 50.…”