Process for the preparation of phosphinic acid esters

A process for preparing a phosphinic acid ester of formula (I)

• (CnF2n+1−yHy)2P(O)OR (I),
• where
• n in each case, independently of one another, denotes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12,
• y in each case, independently of one another, denotes 0, 1, 2, 3 or 4,
• R denotes unsubstituted or substituted phenyl, a straight-chain or branched, unfluorinated or partially fluorinated or deuterated alkyl group having 1 to 30 C atoms or a straight-chain or branched, unfluorinated or partially fluorinated alkenyl or alkynyl group having 3 to 30 C atoms, where R may be partially substituted by halogen and/or partially substituted by —OH, —C(O)OH, N(CH3)2 and —CN and where one or two carbon atoms of the alkyl, alkenyl or alkynyl group which are not adjacent and are not in the α-position to the oxygen atom or to carbon atoms of the double bond or triple bond may be replaced by atoms and/or atom groups selected from the group consisting of —O, S, S(O)—, —SO2—, —C(O)—, —C(O)O— and —N(R′)— and
• R′ in each case, independently of one another, denotes H, a straight-chain or branched, unfluorinated or partially fluorinated alkyl group having 1 to 18 C atoms, saturated C3- to C7-cycloalkyl, unsubstituted or substituted phenyl,
• comprising reacting a phosphine oxide of formula (II)
• (CnF2n+1−yHy)3P(O) (II),
• where n and y have a meanings indicated for formula (I), with an alcohol or phenol R—OH in the presence of alkali-metal fluoride or tetraalkylammonium fluoride, where R has a meaning indicated for formula (I), where the water content in the reaction is in total a maximum of 1000 ppm and where alkyl in tetraalkylammonium in each case, independently of one another, denotes a straight-chain or branched alkyl group having 1 to 10 C atoms.