Electron impact studies. XXXI. Skeletal-rearrangement fragments in the mass spectra of anils

Abstract

Skeletal-rearrangement fragments are observed in the mass spectra of all anils derived from aromatic aldehydes. The rearrangement processes have been studied by high-resolution mass spectrometry and in certain cases by deuterium labelling. All processes are of the general type [ABC]+ → [AC]+ +B.

Differentiation of isomeric methylanilines by imidization and gas chromatography/mass spectrometry analysis

“…EI‐MS analysis of the imidization derivatives has been reported previously . Herein, further EI‐MS analysis of the three derivatives was carried out for the isomeric differentiation.…”

“…EI-MS analysis of the imidization derivatives has been reported previously. 22,23 Herein, further EI-MS analysis of the three derivatives was carried out for the isomeric differentiation. As shown in Figure 3, there are several abundant peaks at m/z 195, 194, 118, 91 and 65 observed in the mass spectra.…”

An electron impact study of the two isomeric tricarbonylchromium complexes of N-benzylideneaniline

“…In addition to the fragment ion peaks discussed in the foregoing, which are derived from chromium-containing species, the spectrum in the lower mass-number range extending up to mle 181 shows the typical fragmentation pattern of benzylideneaniline (22,25) as verified by comparison with the mass spectrum of this compound recorded separately under identical conditions. Additionally, the characteristic [C,H,lf peak at mle 51 (through expulsion of acetylene from phenyl cation) should be mentioned, as should the low-intensity peaks at mle 63, 64, 78, and 89.…”

“…In the previous papers (22,25) the generation of mle 77 in the fragmentation of benzylideneaniline was accounted for in terms of loss of C,H6N' from mle 181 (m* reported at mle 32.8). However, we find the metastable peak more accurately at mle 32.9, reflecting the transition mle 180 + mle 77, and this step in fact appears more plausible than mle 181 -t mle 77 on energetic grounds.…”

o‐nitroaniline derivatives. IV—The mass spectra of o‐nitroanils

“…Ref. 7), however, an ortho-effect of type (i) comes into play; the ion (a) is insignificant, and both the molecular ion and the fragment (b) are reduced in intensity. The main fragmentation pathways involve loss of OH from the molecular ion followed either by loss of CN,O or successive loss of NO and HCN,' and the [M -17]+ ion has been formulated2 as (e) (Scheme 2).…”