N-Benzylidene-2-nitrobenzenesulfenamide and 1-Nitro-2-(phenylthio)benzene: Comparision of Their Behaviour on Flash Vacuum Pyrolysis and Under Electron Impact

Article abstract of DOI:10.1071/CH9901779

The molecular ion of N-benzylidene-2-nitrobenzenesulfenamide (1) loses SO2 and N2 and gives a base peak at m/z 165, C13H9, and another abundant peak at m/z 166, C13H10.Analysis, by gas chromatography/mass spectrometry and by preparative thin-layer chromatography, of the products of flash vacuum pyrolysis at 500-800 deg C of (1) showed no detectable hydrocarbon, but dibenzothiophen (mol. wt 184) was isolated and identified.The abundance of m/z 184 in the positive-ion mass spectrum of (1) is about 1percent.In the mass spectrum of 1-nitro-2-(phenylthio)benzene (2a) the base peak is at m/z 167, C12H9N, and there is a fragment ion at m/z 184, C12H8S (35percent).However, carbazole (3) could not be isolated from the flash vacuum pyrolysis products, but dibenzothiophen (4) was obtained in increasing yield as the pyrolysis temperature was raised from 500 to 800 deg C.It is clear from these results that drawing analogies between electron impact mass spectra and flash vacuum pyrolysis results is somewhat hazardous.