Synthesis of bis(acyl)phosphines by activation of unreactive metal phosphides

A process for the preparation of a mono(acyl)phosphine of the general formula I and/or a bis(acyl)phosphine of the general formula II,

• wherein R1, R2, R3, R4 and R5 are the same or different and are independently selected from H, halogen, linear or branched C1-C20-alkyl, linear or branched C2-C8-alkenyl, C1-C8-alkoxy, C2-C8-alkenyloxy, C3-C8-cycloalkyl, C6-C12-aryl, C3-C8-cycloalkoxy, C7-C12-arylalkoxy, C9-C15-alkenylarylalkoxy, nitro-, C6-C12-arylsulfonyl, 4-alkylarylsulfonyl, C1-C20-alkylcarboxy, C1-C8-alkoxycarbonyl, SR14, NHR14 or NR14R15 with R14 and R15 being independently selected from H, linear or branched C1-C20-alkyl, linear or branched C2-C8-alkenyl and C3-C8-cycloalkyl, and an O-, S- or N-containing 5- or 6-membered heterocyclic ring;
• R6 is H or R6 is replaced by an alkaline earth metal cation or a mixed alkali metal/alkaline earth metal cation;
• wherein R1, R2, R3, R4, R5, R7, R8, R9, R10 and R11 are the same or different and are independently selected from H, halogen, linear or branched C1-C20-alkyl, linear or branched C2-C8-alkenyl, C1-C8-alkoxy, C2-C8-alkenyloxy, C3-C8-cycloalkyl, C6-C12-aryl, C3-C8-cycloalkoxy, C7-C12-arylalkoxy, C9-C15-alkenylarylalkoxy, nitro-, C6-C12-arylsulfonyl, 4-alkylarylsulfonyl, C1-C20-alkylcarboxy, C1-C8-alkoxycarbonyl, SR14, NHR14 or NR14R15 with R14 and R15 being independently selected from H, linear or branched C1-C20-alkyl, linear or branched C2-C8-alkenyl and C3-C8-cycloalkyl, and an O-, S- or N-containing 5- or 6-membered heterocyclic ring;
• the process comprising the steps of:
• a) contacting a metal phosphide selected from the group comprising Ca3P2, Zn3P2, Mg3P2, AlP, Fe3P, Ni3P2, Sr3P2, Ba3P2, Co3P2, SCP, Ti3P4, Sn3P4, WP2, LaP, Pb3P2, BiP, and mixtures thereof or a mixed metal phosphide comprising two or more metal cations, with a chelating agent,
• b) contacting the mixture obtained in step a) with a compound of the general formula IIIa and/or IIIb,
• wherein R1, R2, R3, R4 and R5 and/or R7, R8, R9, R10 and R11 are as defined above;
• Z is selected from halogen, C1-C20-alkylcarboxy, C6-C12-arylcarboxy, C1-C8-alkoxy and C6-C12-aryloxy;
• and
• c) and acidifying the mixture obtained in step b).