By reacting primary and secondaryamines with 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide, 1A, at 25° ammonium 4-methoxyphenylphosphonamidodithioates, 2, are formed. Upon heating to 140° 2 eliminates hydrogen sulfide in a new type of reaction yielding 4-methoxyphenylphosphonothioic diamides, 3, which also are formed directly fromprimaryamines and 1A at 140°. For dibenzylamine