Mise en Evidence des Tautomeres Enethioliques des Mercaptopyridines en Spectrometrie de Masse

Equimolar mixtures of HS-Py (Py=pyridine) and DS-Py show primary isotope effects upon metastable ions for the CS loss. This is valid for the 3- and 4- isomers and this observation implies that thiol forms exist in the gaz phase. This result is also confirmed by the analogy in isotope effects between molecular ions of H(D)S-Py and the daughter ones, generated by a four centered elimination of C2H4 and C2D4 respectively from Py-S-C2H5 and Py-S-C2D5. The insensibility of the CS loss following deuteriation of the 2-isomer does not exclude the presence of the thiol tautomer: this phenomenon is explained by and ortho effect exerted by the pyridinic nitrogen.

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