Synthesis of thiocarbamate salts from amines, sulfur, and carbon monoxide

Sulfur reacts with carbon monoxide and amines without a catalyst at 100-160{degrees}C and 10-100 atm for 1-4 h. The reaction products of primary amines are symmetric ureas. Under the same conditions, secondary amines form thiocarbamic acid salts, which are not converted to tetrasubstituted ureas. In the presence of primary amines at 100-160{degrees}C, they afford trisubstituted ureas, some of whose representatives are pesticides. The same products are formed directly in the carbonylation of a mixture of primary and secondary amines without isolation of intermediate thiocarbamic acid salts. In the presence of catalytic amounts of selenium, the reaction of sulfur with carbon monoxide and amines occurs at atmospheric pressure and affords N-substituted thiocarbamic acid salts from both secondary and primary amines. In the current work the authors present some of the characteristics of these processes. 10 refs., 5 figs., 2 tabs.