finally the invention also relates to the use of metal dialkylphosphinate salts prepared by the process according to the invention as additives in polymeric molding compounds the invention is described in more detail by the examples below 1000 g 12 5 mol of methylphosphonous acid were introduced into an autoclave together with 50 g 0 18 mol 1 5 mol of 2 2 u2032 azobis 2 amidinopropane dihydrochloride and the mixture was first heated to 60 u00b0 c with stirring thereafter ethylene was introduced into the reactor up to saturation at a pressure of 20 bar after a reaction time of 17 h at a maximum of 81 u00b0 c the reactor was depressurized and cooled the yield was 1 35 kg 1100 g of the mixture obtained according to a predominantly comprising methylethylphosphinic acid and methylbutylphosphinic acid were dissolved in 2800 ml of acetic acid and 270 g 3 4 mol of aluminum hydroxide were added the mixture was heated for 5 hours under reflux then cooled filtered off by suction and dried in a vacuum drying cabinet at 135 u00b0 c in total 1172 g of product were obtained corresponding to a yield of 97 the content of aluminum methylethylphosphinate was 93 2 mol and of aluminum methylbutylphosphinate was 6 1 mol 2 2.