Patent EA-001709-B1 (EA)
Title: Improved method for obtaining organosilanes implementing a redistribution reaction
Inventor: CATHALA MAX
IPC: C07F7/20
Filed: 1997-06-11
Abstract: 1. A process for the preparation of organosilanes comprising the steps of: 1) carrying out a redistribution reaction between a chlorinated organohydrosilane of formula (1): (R)a(H)bSiCl4-a-b and an organosubstituted and optionally chlorinated silane of formula (2): (R')cSiCl4-c, wherein: a=1 or 2; b=1 or 2; a+b=2 or 3; c=1, 2, 3 or 4; and the symbols R and R' are alike or different and each represent a linear or branched C1-C6 alkyl or a C6-C12 aryl; said redistribution reaction taking place in the presence of an effective amount of a catalyst consisting of a Lewis acid of formula (3) M(X)d, wherein: M represents a metal selected from the group consisting of Ti, Fe, Cu, Ag, Zn, Cd, Hg, Al, Ga, In, B, Sn, Pb, Sb and Bi; X represents a halogen atom; and d represents the valency of the metal M; 2) carrying out a separation by distillation of the chlorinated organohydrosilane produced by redistribution characterised in that after the redistribution at least one compound which inhibits of the redistribution catalyst is added, said inhibitor being a fluid polyorganosiloxane (POS), having a viscosity at 25< degree >C at most equal to 5000 mPaòs; and being used in proportions such that the ratio: r=the mole amount of metal M atoms, given by catalyst / the mole amount of oxygen atoms, given by inhibitor is equal to or less than 0.9. 2. A process according to Claim 1, wherein the inhibitor is organosilicon compound is used in amounts when the ratio r is from 0.6 to 0.9. 3. A process according to Claim 1 or 2, wherein the inhibiting organosilicon compound can represent: (i) a linear or substantially linear POS comprising units of formula (4), terminated at one of the ends of the chains by a unit of formula (5) and at the other end by a unit of formula (6), (2i) a cyclic POS comprising units of formula (4), (3i) a mixture of species (i) and species (2i), or (4i) a mixture of one or more species (i) with one or more species (2i),   wherein: the R<1> symbols are alike or different and each represent a linear or branched C1-C8 alkyl optionally substituted by one or more halogens; a C5-C8 cycloalkyl; or a C6-C12 aryl or aralkyl having a C6-C12 aryl part and a C1-C4 alkyl part, optionally substituted on the aromatic part by one or more halogens, C1-C3 alkyl (alkyls) and/or C1-C3 alkoxy; the Y symbols are alike or different and each represent: either an R<1> radical or an OR<2> radical, where R<2> is a hydrogen atom or a linear or branched C1-C3 alkyl. 4. A process according to Claim 3, wherein the inhibiting organosilicon compound is a fluid of species (i), (2i), (3i) or (4i) having a viscosity at 25< degree >C. of at most equal to 1000 mPaòs and at least 60% by number of the R' symbols represent methyl radicals. 5. A process according any of Claims 1-4, wherein the Lewis acid catalyst is a chloride or a bromide. 6. A process according to Claim 5, wherein the catalyst is TiCl4, FeCl3, CuCl, AgCl, ZnCl2, AlCl3, SnCl2, BiCl3 or their various mixtures. 7. A process according any of Claims 1-6, wherein the quantity of catalyst is from 0.1 to 10% by weight with respect to the total weight of the charged silanes of formulae (1) and (2). 8. A process according any of Claims 1-7, wherein the redistribution reaction is carried out at a temperature of between 50 and 200< degree >C, expediently under autogenous pressure, then the temperature of reacting mixture is lowered at less than 40< degree >C, and then the inhibitor-organosilicon compound is added, and, the targeted chlorinated organohydrosilane, produced by redistribution, is separated by distillation. 9. A process according to any of Claims 1-7, wherein the redistribution reaction is carried out at a temperature of between 50 and 200< degree >C, expediently under autogenous pressure, the inhibitor-organosilicon compound is added, so that the redistribution reaction is interrupted, then the temperature of reacting mixture is lowered at less than 40< degree >C, and, the targeted chlorinated organohydrosilane is separated by distillation. 10. A process according to any of Claims 1-9, wherein the chlorinated organohydrosilane of formula (1) and the organosubstituted and optionally chlorinated silane of formula (2) are used, and wherein the R and R' symbols are alike or different and each represent a linear or branched C1-C3 alkyl or a phenyl. 11. A process according to any of Claims 1-10, wherein the redistribution reaction is carried out between the chlorinated organohydrosilane (1) of formula RHSiCl2 and the organosubstituted and chlorinated silane (2) of formula R'3SiCl wherein a=1, b=1, and c=3.