a process is disclosed for one - step preparation of substituted tetrathiafulvalenes by reaction of carbon disulfide with acetylenic compounds under pressures of at least about 1 , 000 atmospheres . substituted tetrathiafulvalenes made by this process are particularly useful as precursors to very pure tetrathiafulvalene , a compound which can complex with tetracyano - p - quinodimethane to form a charge - transfer salt having very high electrical conductivity .