Stability of Salts of N-Carboxy-, N-Thiocarboxy-, and N-Dithiocarboxyglycine1

Salts of N-carboxy-, N-thiocarboxy-, and N-dithiocarboxyglycine (1–3) have been prepared and their stability in aqueous solution investigated by NMR spectroscopy. Salts of N-carboxyglycine (1) undergo partial hydrolysis in aqueous solution, giving the same equilibrium mixtures as those formed in the reaction of glycine with carbonate. Salts of N-dithiocarboxyglycine (2) are stable in aqueous solution. even at 100°C. The disodium salt 2d, which has often been employed as a reaction intermediate but never adequately characterized, has been synthesized by several independent methods. Salts of N-thiocarboxyglycine (3) are stable in aqueous solution at 25°C but not at 100°C.