The mass spectra of some chlorinated aromatic pesticidal compounds

Abstract

AbstractMass spectral studies of some chlorinated aromatic pesticidal compounds are reported. The compounds studied include substituted diphenyl derivatives of methane, ethene and methanol.The diphenylmethanes are characterized by a relatively intense peak at m/e 165. Comparison of their low voltage spectra with 9‐dichloromethylfluorene indicates that this ion has a fluorenyl ion structure.The structure of the base peak (m/e 246) of the diphenylethenes was investigated by comparing competitive metastable transitions with 9‐dichloromethylenefluorene and utilizing defocusing metastables. Additional studies of model compounds suggest that the m/e 246 ion is very complex and is probably comprised of a number of structures.The mass spectra of the diphenylmethanols are significantly different from the other two groups. The hydroxyl group markedly affects the fragmentation process for these compounds; the characteristic peak is presumably the chlorobenzoyl ion and is probably precursor for other fragment ions.Mass spectral correlations of pesticidal compounds of similar structure are needed to obtain enough background to facilitate interpretation of the mass spectra of their metabolites. Furthermore, such studies make feasible the identification of characteristic product ions formed by rearrangement processes during ionization of organic molecules in the gas phase. This information can be a nucleus for correlating the other significant mass spectral data of an unknown compound. Intensive studies of carbamates,1 organophosphorus2 and bridged polycyclic chlorinated pesticidal3 compounds were invaluable in identifying metabolites of the aforementioned pesticides.4,5,6 The compounds in this magnified image magnified image Work are chlorinated aromatic pesticidal compounds which consist of a diphenylemthane, a diphenylethylene, or a diphenylmethanol structure. The compounds p,ṕ‐DDE were briefly discussed by Jorg, Houriet and Spiteller.7 The compounds examined are listed in Table 1.Treatment of data. The mass spectra of the pesticides are presented as bar graphs in Figs 1 to 12 magnified image magnified image magnified image magnified image magnified image magnified image It a metastable peak is observed, the metastable transition is indicated by m* on the figures and also by (m*) when confirmed or identified using the defocusing technique.8 Since the relative abundances of the metastable peaks for these compounds are very small (<0.1%) on special effort was made to establish their presence unless they wre pertinent.