Synthesis of Organohalosilane Monomers Via Enhanced Cleavage of Direct Process Residue

A catalytic process for producing an organohalosilane monomer composition from a high-boiling residue resulting from the Direct Reaction of an organohalide with silicon, said process comprising

• (A) heating the high-boiling residue in the presence of a catalyst comprising (1) one or more heterocyclic amines and/or one or more heterocyclic ammonium halides, and (2) one or more quaternary Group 15 onium compounds,
• optionally in the presence of an organohalide and/or a hydrogen halide and/or an inert gas,
• at a temperature within the range of about 75° C. to about 300° C. under atmospheric pressure or superatmospheric pressure
• to convert the high-boiling residue to an organohalosilane monomer composition containing at least one organohalosilane monomer having a general formula selected from the group consisting of R1SiHX2, R12SiHX, R12SiX2 and R13SiX, R1 being an aromatic, aliphatic, alkaryl or cycloaliphatic univalent hydrocarbyl group, X being a halogen atom selected from the group consisting of fluorine, chlorine, bromine, and iodine, and
• (B) optionally recovering the catalyst,
• wherein the high-boiling residue comprises (1) a cleavable component containing at least one of diorganotetrahalodisilanes and triorganotrihalodisilanes and (2) optionally an uncleavable component containing at least one of carbosilanes, polysilanes, hexaorganodisilanes, pentaorganohalodisilanes and tetraorganodihalodisilanes, with the proviso that if present, the uncleavable component has a concentration no greater than that of the cleavable component;
• and
• wherein the quaternary Group 15 onium compound is of the general formula, R4Q+X−, wherein each R is independently an alkyl, cycloalkyl, aryl or alkaryl group of from 1 to 30 carbon atoms, Q is phosphorus, arsenic, antimony or bismuth, and X is a halide selected from the group consisting of F, Cl, Br and I.