Thioacylthioketenes by pyrolysis of 1,3-dithiethanes and 1,2-dithiole derivatives

Abstract

Thioacylthioketenes are formed by flash vacuum pyrolysis (FVP) of 1,3-dithiethanes 6, 1,2-dithiole-3-thiones 11, 14, 15, 3-iodo-1,2-dithiolylium iodide 9, 3-methylthio-1,2-dithiolylium iodides 16, 17 and 1,2-dithiol-3-one tosylhydrazone sodium salt 10. They show IR absorption in the region 1754–1700 cm^–1 due to the CCS grouping. It is proposed based on the results obtained that 1,2-dithiol-3-ylidenes (1,2-dithiole carbenes) rearrange to give thioacylthioketenes which further rearrange forming thiete-2-thiones. The latter finally fragment into carbon disulfide and alkynes. Formation of C₃S₂ has been observed in the pyrolysis of the dithiethanes and 1,2-dithiole-3-thione.