Sulfuric Acid → ethylphosphonous acid aluminum(III) salt

Participants

Reaction Conditions

Reaction Steps

1500 g (14 mol) of sodium hypophosphite monohydrate and 14 g of concentrated sulfuric acid are dissolved in 7.5 kg of water and initially charged in a 16 l steel-enamel jacketed pressure reactor. After heating the reaction mixture to 100° C., a reducing valve set to 6 bar is used to introduce ethylene into the reactor up to saturation. While stirring constantly at an ethylene pressure of 6 bar and a temperature of 100-110° C., a solution of 22 g (1 mol %) of sodium percarbonate in 300 g of water is metered in homogeneously. At a conversion of ethylene of 83.5%, the metered addition of sodium percarbonate is stopped and the reactor is decompressed. After cooling to about 90° C., 3000 g (4.67 mol of aluminum) of a 46% aqueous solution of Al2(SO4)3.14H2O were added within 60 minutes. Subsequently, the resulting solid is filtered off, washed with 2 l of hot water and dried at 130° C. under reduced pressure. The resulting mixture comprises diethylphosphinic acid aluminum(III) salt and ethylphosphonous acid aluminum(III) salt in a ratio of 76.4% by weight of diethylphosphinic acid aluminum(III) salt and 23.6% by weight of ethylphosphonous acid aluminum(III) salt (95.0% yield).

Provenance & Evidence