Mass spectrometric studies of sulfur compounds. Some 1-(5-ethyl-2-thienyl)-1-thiaalkanes

Abstract

Fragmentation studies of the mass spectra of 15 high purity compounds of the 1-(5-ethyl-2-thienyI)-l-thiaalkane series are presented. The molecular weight range covered is from 158 to 284. These substances are of importance to those utilizing fossil fuels which contain them and also to those studying natural products. The molecular ion intensities are moderately strong and easy to verify due to the presence of two sulfur atoms in the molecule. Prominent ions occur in all spectra at m/z 144 and 129. A total of six different ion species are base peaks for the compounds reported, including alkyl and alkenyl ions. The methyl and ethyl compounds are exceptions to the correlations developed in this work and are discussed in detail. Metastable and low ionization voltage data are presented in support of the suggested mechanisms of fragmentation. Those using only three to four peaks in selected ion monitoring should anticipate experiencing difficulties with positive identification of these types of molecules due to the plethora of alkyl ions. An integration of the correlations developed with those of other sulfur containing moieties is presented.An earlier publication' has reported mass spectral data for 24 members of the thienylthiaalkanes and the variety of reasons for interest in such materials in petroleum fractions, coal and other natural products. To assist further in identification of such compounds, this work presents the mass spectra and correlations with structure for 15 additional members of the thienylthiaalkanes in the molecular weight range of 158-284. These molecules differ from those studied in the earlier series in that the thienyl group also has an ethyl group substituted in the 5-position of the thiophenic ring. Correlations for these compounds indicate much more diversity than those reported in the earlier work. Some do present minor problems of interference, requiring an integration of correlations from the 39 thienylthiaalkanes examined so far.