Electron impact induced ortho effects in 2‐nitro‐substituted aromatic sulphides containing 2‐pyridyl, 2‐(5‐methylthio‐1,3,4‐thiadiazolyl) and/or 2‐(4‐methyl‐1,3,4‐thiadiazolinyl‐5‐thione) moieties

Abstract

The most significant mass spectral features of 14 title compounds are discnssed with the aid of deuterinm labelling experiments. The decomposition patterns of these compounds are strongly &ected by several competing ortho effects, due to the interaction of the nitro fnnction(s) with neighbouring electron-poor N-heterocycles. Very intense polycyclic ions are produced via addition-elimination reactions by loss of simple radicals (H, OH, NO2') from the molecular ion, followed by the ejection of neutral molecules (HN02, CHaCN or CHJVCS). In addition, primary or secondary intramolecular oxygen transfers, preceded or not by hydrogen migration, from the nitro group to the imino carbon via spirocyclic intermediates, are generally observed. Minor skeletal rearrangements, triggered by single or multiple intramolecular oxygen transfer to the bridgehead sulphur atom, followed by SO or SO2 ejection, are also noticed.

Mass spectrometry of 1,3,4‐thiadiazolo thiacrown ethers

“…Both ions dd and ee constitute another homologous series ( m / z 222 (13%) and 178 (20%) from dd, and m / z 208 (6%) and 164 (25%) from ee) separated by C2H40 units. Besides, the molecularion may rearrange (by the four-centre y-methylene H migration to the p-methylene) to an open-chain structure fl, having ethylthio and formyl end groups, which could account for the formation of [M-CHO]+, m / z 279 ( 5 % ) , and [M-C2H5S]+, m / z 247 (11'/0), ions.Thiacrown ethers containing two 1,3,44hiadiazole units: compounds[9][10][11] …”