Production of hydroxyalkylphosphine oxides

Production of tertiary hydroxyalkylphosphine oxides of general formula (I) (I) in which R1 and R2 each stand for organic groups having from 1 to 18 carbon atoms, where R1 may be identical with R2 and R2 may be identical with R which stands for a radical of general formula (II) (II) in which R3 and R4 equally stand for organic groups having from 1 to 18 carbon atoms and/or more preferably for hydrogen. The compounds are made from phosphines of general formula (III) (III) in which R3 and R4 have the meanings given above, which are reacted in a single step operation with carbonyl compounds of general formula (IV) (IV) in which R3 and R4 equally have the meanings given above. The reaction is effected while adding at least one substance yielding hydroxyl ions and in the presence of water, and the resulting hydroxyalkylphosphine oxides are separated from the reaction product.