The present invention refers to a process for the preparation of a bis(acyl)phosphinic acid silyl ester of the general formula (I), wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.7, R.sub.8, R.sub.9, R.sub.10 and R.sub.11 are the same or different and are independently selected from H, halogen, linear or branched C.sub.1-C.sub.20-alkyl, linear or branched C.sub.2-C.sub.8-alkenyl, C.sub.1-C.sub.8-alkoxy, C.sub.2-C.sub.8-alkenyloxy, C.sub.3-C.sub.8-cycloalkyl, C.sub.6-C.sub.12-aryl, C.sub.3-C.sub.8-cycloalkoxy, C.sub.7-C.sub.12-arylalkoxy, C.sub.9-C.sub.15-alkenylarylalkoxy, nitro-, C.sub.6-C.sub.12-arylsulfonyl, 4-alkylarylsulfonyl, C.sub.1-C.sub.20-alkylcarboxy, C.sub.1-C.sub.8-alkoxycarbonyl, SR.sub.12, NHR.sub.12 or NR.sub.12R.sub.13 with R.sub.12 and R.sub.13 being independently selected from H, linear or branched C.sub.1-C.sub.20-alkyl, linear or branched C.sub.2-C.sub.8-alkenyl and C.sub.3-C.sub.8-cycloalkyl, and an O-, S- or N-containing 5- or 6-membered heterocyclic ring; R.sub.6 is OSiR.sub.14R.sub.15R.sub.16 with R.sub.14, R.sub.15 and R.sub.16 being independently selected from linear or branched C.sub.1-C.sub.20-alkyl or C.sub.6-C.sub.12-aryl; as well as the bis(acyl)phosphinic acid silyl ester and the bis(acyl)phosphinic acid obtained by the process. ##STR00001##

The present invention refers to a process for the preparation of a bis(acyl)phosphinic acid silyl ester of the general formula (I), wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.7, R.sub.8, R.sub.9, R.sub.10 and R.sub.11 are the same or different and are independently selected from H, halogen, linear or branched C.sub.1-C.sub.20-alkyl, linear or branched C.sub.2-C.sub.8-alkenyl, C.sub.1-C.sub.8-alkoxy, C.sub.2-C.sub.8-alkenyloxy, C.sub.3-C.sub.8-cycloalkyl, C.sub.6-C.sub.12-aryl, C.sub.3-C.sub.8-cycloalkoxy, C.sub.7-C.sub.12-arylalkoxy, C.sub.9-C.sub.15-alkenylarylalkoxy, nitro-, C.sub.6-C.sub.12-arylsulfonyl, 4-alkylarylsulfonyl, C.sub.1-C.sub.20-alkylcarboxy, C.sub.1-C.sub.8-alkoxycarbonyl, SR.sub.12, NHR.sub.12 or NR.sub.12R.sub.13 with R.sub.12 and R.sub.13 being independently selected from H, linear or branched C.sub.1-C.sub.20-alkyl, linear or branched C.sub.2-C.sub.8-alkenyl and C.sub.3-C.sub.8-cycloalkyl, and an O-, S- or N-containing 5- or 6-membered heterocyclic ring; R.sub.6 is OSiR.sub.14R.sub.15R.sub.16 with R.sub.14, R.sub.15 and R.sub.16 being independently selected from linear or branched C.sub.1-C.sub.20-alkyl or C.sub.6-C.sub.12-aryl; as well as the bis(acyl)phosphinic acid silyl ester and the bis(acyl)phosphinic acid obtained by the process.

##STR00001##