Unsymmetric disulfides undergo solution phase reduction with atomic hydrogen regioselectively by displacement at the least hindered sulfur atom. The cleavage of the sulfur- sulfur bond forms mixtures of two thiol and two thiyl radicals. At the temperature at which the reactions are carried out, the thiyl radicals form symmetric disulfides by thiyl-thiyl radical coupling and not by thiyl radical displacement on the starting material. The reaction of ...