Formation of thiophenethiols by flash vacuum pyrolysis of1,6,6aλ4-trithiapentalenes

The thermal behaviour of 1,6,6aλ4-trithiapentalene 3 and some methyl-substituted derivatives 5–7 has been investigated using a combination of flash vacuum pyrolysis (FVP), tandem mass spectrometry (MS–MS) and matrix isolation IR spectroscopy. The main products of the fragmentation (losses of CS and/or CH2CS) are shown to be thiophene-3-thiones (or the thiol tautomers) which are also shown to be readily available by direct sulfuration of thiophenes in chemical ionization (CS2 reagent gas) conditions.