Electron impact mass spectrometry of phenyl thiophosphoroorganic amides

Rapid Commun. Mass Spectrom.

Moldovan

et al. 1998

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The electron impact ionization mass spectra of the p-carboxyphenylsulfonylamide (1), p-carbomethoxyphenylsulfonylamide (2), p-methoxyphenylsulfonylamide (3) and p-fluorophenylsulfonylamide (4), of O,Odiphenyl-thiophosphoric acid, are discussed and interpreted, based on accurate mass measurements and metastable ion analysis. The fragmentation pattern shows common features for all compounds. Some cleavage processes specific to the radicals bonded to the aryl site are observed in each spectrum. # 1998 John Wiley & Sons, Ltd. Received 20 June 1998; Revised 7 September 1998; Accepted 9 September 1998 Due to their biological activity, organic thiophosophonic compounds have been extensively studied lately.1-3 Mass spectrometry is an important tool in the molecular structure analysis of these substances. [4][5][6][7] The aim of this work is to study the electron impact mass spectra and to propose a fragmentation pattern for the new p-arylsulfonamides synthesized at the Chemistry Institute "Raluca Ripan". The compounds are expected to have biological activity, due to their structure and elemental composition: RESULTS AND DISCUSSIONFigures 1-4. present the 70 eV EI mass spectra of compounds 1-4, and in Table 1 are listed the mass-tocharge ratios and their relative abundances for the main fragment ions from the fragmentation pattern exhibited in Scheme 1. The molecular ion M Á , m/z (404 Y), has low abundance (3) or is even missing altogether (1 and 2), due to a higher degree of fragmentation. A fairly abundant (18 %) molecular ion is observed in the mass spectrum of 4, with a fluorine atom bonded to the aryl group. The ion a, m/z (294 Y), probably results from the cleavage of the thiolic isomer [M']Á of the molecular ion (Scheme 1), by the elimination of a neutral C 6 H 5 SH molecule. Similar eliminations, subsequent to a thionethiol isomerization, were observed in other O,O-diphenylthiophosphonic derivatives analysed in the same laboratory. 8 Metastable ion detection in the mass analysed kinetic energy (MIKES) mode confirmed that ion a further decomposes into ion b, m/z (76 Y), and ion e, m/z (139 Y), respectively, by losing the neutral group C 6 H 4 O 3 P. The kinetic energy released was estimated in the MIKE scanning mode, 9,10 from the width at half height of the Gaussian shaped peaks. The a → b transition appears to be different from a simple bond fission. It probably takes place by the cleavage of the S-C bond, involving electrons withdrawn by the SO 2 group with the positive charge left on the aryl group. The value found for the kinetic energy release for this reaction, T 50 = (30.3 AE 2.1) meV, is slightly greater than that usually found for usual simple fission and is consistent with the process described.During the a → e decomposition, sulphur changes its valence state from 6 to 4, as one O atom from the SO 2 group migrates to the neutral fragment eliminated through a fivemembered transition state. The value found for the kinetic energy release, T 50 = (25.3 AE 1.8) meV corresponds to the range previously foun...

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Mass spectral study of the fragmentation pathways for some new thiophosphororganic molecules

Rapid Commun. Mass Spectrom.

Moldovan

et al. 1998

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Mass spectral study of some new arylsulphonylamido‐thiophosphonamides

Nicoarã

Rapid Comm Mass Spectrometry

et al. 1995

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Fragmentation of organophosphorus compounds under electron impact I

Moldovan

Science of The Total Environment

et al. 1993