Monothioamidophosphoric Acids

Monothioamidophosphoric Acids are derivatives of SP(OH)₃ in which the hydroxyl groups are successively replaced by -NH₂.

The monamide, SP(NH₂)(OH)₂, was prepared from aqueous ammonia and PSCl₃. The solution, which contained NH₄Cl, gave precipitates with salts of cadmium and lead. The salts of the alkaline earth metals were soluble.

The diamide, SP(NH₂)₂OH, was obtained by the action of gaseous ammonia on PSCl₃. It was also prepared by the action of ammonia on PSF₃. In both cases the product was digested with water. Hydrolysis proceeded according to the equation

SP(NH₂)₂F + H₂O = SP(NH₂)₂OH + HF

The solution contained a new acid radical, which gave precipitates with salts of mercury, copper, silver and lead. The product derived from PSCl₃, but not that derived from PSF₃, gave precipitates also with salts of zinc and cadmium. No precipitates were obtained with salts of barium and calcium.

The triamide, SP(NH₂)₃, was prepared by saturating PSCl₃ with ammonia. It was a white solid of density 1.7. When heated it dissociated into ammonium sulphide and sulphur, leaving phosphorus in the residue, probably as "phospham," and was decomposed by warm water giving H₂S and ammonium thiophosphate. It was only slightly soluble in alcohol or carbon disulphide.