Synthesis and acid-base properties of α-aminophosphoryl compounds

alpha-Aminophosphoryl compounds of the phosphonate, phosphine oxide, and alpha,omega-bis(phosphine oxide) series and some of their thiophosphoryl analogs were synthesized. Potentiometric measurements of the pK(a) of the conjugate acids revealed an insignificant effect of variation of substituents on the phosphorus, nitrogen, and alpha-carbon atoms on the basicity of the phosphorylated amines. The latter are weak bases. Organophosphorus groups decrease the basicity of the amines by almost 5 pK(a) units. The role of the hydrophobic effect and intramolecular H-bonding in the obtained substances was discussed.