A novel photo-initiated approach for preparing aluminum diethylphosphinate under atmospheric pressure

A novel preparation of aluminum diethylphosphinate (AlPi) was carried out with free-radical addition reaction by means of UV-irradiation under atmospheric pressure. A solution of sodium hypophosphite was treated with ethylene and irradiated with ultraviolet light in the presence of an amount of photoinitiator effective to initiate the free-radical reaction between the hypophosphite anion and the double bond of the ethylene molecule. The ethylene was micro-bubbled into the reaction mixture with the addition of the photoinitiator, and the gas–liquid contact surface and the photoinitiator concentration in the gas–liquid interface were increased largely. The yield of the final product could be improved to about 96%. The contents of P, Al in samples were detected by ICP, and the molecular structure of the samples was confirmed by 31P NMR, 1H NMR and FTIR spectroscopic analysis. Thermal stability of the final products was investigated in detail by TG–DTA.