Synthetical applications of activated metal catalysts. XXII. The desulphurization of 2,5-Diphenyl-1,4-dithiin

Abstract

The desulphurization of 2,5-diphenyl-1,4-dithiin (II) with a hydrogen-poor Raney nickel (W-7J Raney nickel) has been shown to give 2,4-diphenylthiophen together with three hydrocarbons, viz. cis- and trans-1,3-diphenylbuta-1,3-diene, and 1,3-diphenylcyclobut-1-ene. In another experiment with a Raney nickel having a higher hydrogen content, the hydrocarbon fraction was found to be 1,3-diphenylbut-2- ene. It has been concluded that chemisorption via one sulphur atom leads to 2,4-diphenylthiophen, but that chemisorption via both sulphur atoms leads to the intermediate diradicals (VI) which subsequently react further to give the observed hydrocarbon products.