Synthesis of phosphinic acids

Two types of phosphinic acids were prepared: N,N-bis(carboxymethyl)aminomethyl phosphinic acid and carboxyethylphosphinic acid. Afterwards they were used to synthesize bisphosphinic acids: 1-hydroxy-ethan-1,1-bis[N,N-bis(carboxymethyl)aminomethyl phosphinic] acid and 1-hydroxy-ethan-1,1-bis(carboxyethyl)phosphinic acid. All compounds were characterized by NMR and mass spectroscopy. N,N-bis(carboxymethyl)aminomethylphosphinic acid was synthesized by Mannich type reaction. Carboxyethylphosphinic acid was prepared by alkylation of bis(trimethylsilyloxy)phosphine. Both bisphosphinic acids were prepared by reaction of silylesters of phosphinic acids with acetylchloride. All compounds were prepared in moderate or good yields. Keywords: Organophosphorus synthesis, phosphinic acids, bisphosphinic acid