Process for the manufacture of phosphinic and phosphonic acid anhydrides

Process for the manufacture of phosphinic and phosphonic acid anhydrides of the formula ##STR8## in which A stands for alkylene, aralkylene or arylene with 1 to 10 carbon atoms each,

• R is C.sub.1 -C.sub.8 -alkyl,
• R.sup.1 is C.sub.1 -C.sub.18 -alkyl or alkenyl which may be substituted by fluorine, chlorine or bromine and may be interrupted by ether oxygen atoms;
• cycloalkyl or alkylcycloalkyl of a total of 1 to 10 carbon atoms each;
• aryl or alkylaryl optionally being substituted in the ring by chlorine and/or bromine;
• f is 0 ot 1, preferably 0, and always 0 if h is 1;
• g is 1, if h is 1 and f is 0 at the same time, or if h is 0, f is 1 and A is C.sub.3 H.sub.6 ;
• g is 3 to formally infinite, if h and f are 0, and
• g is 2 to formally infinite, if h is 0, f is 1 and A is other than C.sub.3 H.sub.6, and
• h is 0 or 1, preferably 0, which comprises reacting at 30.degree.-160.degree. C. one mol of a compound of the formula ##STR9## in which X is chlorine or bromine, preferably chlorine, Y is defined as R and is additionally defined as X, and R, R.sup.1, A and f are defined as in the above formula I, with at least b/2 mol(s) of an aliphatic carboxylic acid anhydride of the formula
• (R.sup.2 --CO--).sub.2 --O (III),
• b being the number of the halogen atoms in the compound of the formula I and R.sup.2 being C.sub.1 -C.sub.3 -alkyl, chloromethyl, dichloromethyl or trichloromethyl, preferably CH.sub.3 and C.sub.2 H.sub.5, and removing the carboxylic acid halides being formed as by-products by distillation.