“…Other compounds that are reducible to mercaptans are sulfonic acids (165, 121a), thiosulfonic acids and their esters (165, 161c), and sulfochlorides derived from sulfonic acids (166,157b,119c,115,114c,102c,100,lOOc,98e,98h,97,97e,85c,85d,858,67,59i,57j,57k,34,32,11) either under acid conditions with metals or by electrolysis (167, 117, 115c, 114a). Sulfonamides may be reduced by hydrogen iodide and phosphorus (168).…”