The pyrolysis of dimethyl and diethyl disulphides and ''disulphide oil
'' (a waste product of oil refining) was carried out at 580-610 degree
s C. On the basis of the gas-phase reaction of ''disulphide oil'' with
the chlorobenzene-acetylene system or 2-chlorothiophene-acetylene sys
tem, new methods have been developed for the simultaneous production o
f thiophene and benzothiophene or thiophene and thienothiophene in hig
h yields. The mechanism of the reactions studied are discussed.