The mass spectra of some chlorinated pesticidal compounds

The mass spectra of nine bridged polycyclic chlorinated pesticidal compounds have been investigated, and fragmentation modes to account for the more abundant ions are postulated. The principal features of the spectra are ions corresponding to a set of retro-Diels-Alder decompositions, ions resulting from successive losses of Cl, HCl, or both, ions produced by combinations of a retro-Diels-Alder process with a preliminary or subsequent loss of Cl or HCl, and ions whose processes of formation more specifically involve the epoxide group.     

The mass spectra of some chlorinated aromatic pesticidal compounds

Mass 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 Work are chlorinated aromatic pesticidal compounds which consist of a diphenylemthane, a diphenylethylene, or a diphenylmethanol structure. The compounds p,?-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 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.     

The mass spectra of some pyridazines,pyrido-pyridazines and related compounds

The mass spectral fragmentation behaviour of substituted sulphur containing pyridazines, pyrido (2,3-d) pyridazines and pyrido-thiazolo-pyridazines has been investigated and fragmentation patterns proposed.     

On the mass spectra of some alkyl digermanium compounds

This paper reports the monoisotopic mass spectra of the compounds (CH₃)Ge? Ge(CH₃)₃,(C₂H₅)₃Ge? Ge(C₂H₅)₃ and (CH₃)₃Ge? Ge(C₂H₅)₃. With the aid of metastable ion transitons and appearance potentials the fragmentation patterns can be given. The dominant reactions are explained in terms of the valence of the metal atom. According to the valence rule the possibility of forming an ion in which two germanium atoms are bonded to five other groups (alkyl or hydrogen) determines greatly the spectra, while successive elimination of the methyl groups appears to be difficult and elimination of the ethyl groups is a predominant process.     

The mass spectra of reissert compounds

A series of Reissert compounds containing the quinoline, isoquinoline and phthalazine nuclei show the common feature in their mass spectra of the initial loss of the N-substituent and either of the substituents attached to the adjacent carbon atom.     

The mass spectra of some guanidines

The mass spectra of guanidine and ten of its derivatives have been studied under both high and low resolution conditions. Evidence was detected for the migration of methyl groups, the formation of intermediate three-membered ring structures and decompositions involving expulsion of N^. with release of kinetic energy.     

The mass spectra of some chromans

The mass spectra of 4-p-hydroxyphenyl-2,2,4-trimethylchroman and of its thia, selena and sulphonyl analogues are reported and discussed. Formal charge localization on the oxygen atom of the oxo compound is reflected in the production of an abundant [M - 15]⁺ ion. Lack of charge location on the heteroatom of the seleno compound leads to a retro-Diels-Alder reaction. The thio compound exhibits intermediate behaviour, but charge localization on the oxygen atoms is preferred in the sulphone.     

Electron impact mass spectra of some tertiary aliphatic nitro compounds. Nitrocarbonyl compounds and some analogues

The mass spectra of some tertiary aliphatic nitroaldehydes, nitroketones, nitroesters, nitronitriles and related nitrocarbonyl compounds are discussed and compared with those of some analogous nitro compounds lacking the carbonyl function. The M⁺˙ ? NO₂˙ and in several cases M⁺˙ ? HNO₂ fragmentation seem to be the most characteristic features of all tertiary aliphatic nitro compounds. In the presence of the primary nitro group, the loss of NHO₂ is always observed.     

The mass spectra of some naphthoquinones. Lapachol,isolapachol and related compounds

Several alkylhydroxynaphthoquinones and chemically related cyclic compounds were subjected to mass spectrometric investigation. Fragmentation pathways were elucidated by use of metastable ions, relative intensities of normal ions and accurate mass measurement. In these series, differences in the spectra of 1,2- and 1,4-naphthoquinones are slight. Evidence for ring expansion in ions from furans is suggested.     

Characteristics of the mass spectra of acetonides of some natural compounds

Summary The acetonides of alkaloids and coumarins can be identified by their mass-spectrometric properties. The intensity of the fragments characteristic for the dioxolane ring largely depends on the structure of the chain attached to it.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 336–340, May–June, 1972.     

Energetic consideration applied to the mass spectra of some aromatic compounds

It is shown that the ‘metastable’ mass spectra of a series of monosubstituted benzenes are consistent with reaction over the lowest available energy surfaces. The non-occurrence of some qualitatively possible decomposition pathways may therefore be used to place lower limits on the heats of formation of gaseous cations. Conversely, where characterized reactions are preempted by new reactions upon introduction of additional substituents, upper limits may be placed upon the heats of formation of the ionic products of the new reactions. The concepts are employed to deduce that C₃H₆ elimination from n-butylbenzence subsequent to ionization leads to ionized toluene rather than ionized methyleneclohexadience.     

Fluorinated tropylium ions in the mass spectra of some polyfluoroaromatic compounds

The most prominent ion in the mass spectra of C₆F₅CH₂X (X ? H, Br, CH:CH₂, COCl, and CH₂C₆F₅) is C₇F₅H₂⁺, formulated as the pentafluorotropylium cation. This ion is also found, in an amount comparable to the parent ion, in the spectrum of (C₆F₅)₂CH₂. The heptafluorotropylium cation is found similarly in the spectrum of C₆F₅CF₃. The mass spectra of (C₆F₅)₂CHBr and [(C₆H₅)₂CH]₂ exhibit an ion C₁₃F₁₀H⁺ as the base peak, which is probably a pentafluorophenylpentafluorotropylium cation. The alcohol (C₆F₅)₂CHOH shows loss of C₆F₅, followed by 2H, as a major breakdown pathway. The mode of formation, and the subsequent fragmentation, of the major ions in these spectra, are discussed.     

The mass spectra of some aromatic polyketones

The behaviour of some aromatic tri- and tetraoxo compounds and of their p-substituted derivatives under electron-impact has been investigated by means of high and low resolution mass spectrometry, metastable refocusing and deuterium labelling. Some characteristic fragmentation processes observed with these compounds indicate that their molecular ions exist in the enol form. The formation of principal fragment ions is discussed.     

The mass spectra of some cyclic ethers

The mass spectral fragmentations of the saturated five-, six- and seven-membered ring ethers have been determined by studying their site-specifically deuterated analogues by both high and low-resolution mass spectrometry. The initial processes, governing the fragmentations of the cyclic ethers are shown to be identical with the well-known processes of linear nonbranched ethers, i.e. predominant α-fisson in the lower members and predominant carbon-oxygen fisson with charge retention on the carbon atom in the higher members.     

The mass spectra of some 3,5-diarylisoxazoles

The mass spectra of several 3,5-diarylisoxazoles are reported. The fragmentation patterns of 3-aryl-5-phenyl- and 5-aryl-3-phenylisoxazoles are very significantly different.