Specific process for preparing silicon compounds bearing fluoroalkyl groups by hydrosilylation

1. A process for preparing a silicon compound bearing at least one fluoroalkyl group by hydrosilylation of a fluoroolefin in the presence of a Pt-containing hydrosilylation catalyst, the process comprising:

initially charging and heating a hydrogenchlorosilane;

metering in the fluoroolefin and reacting the reaction mixture; and

subsequently isolating the hydrosilylation product, and

wherein the Pt-containing hydrosilylation catalyst consists of a hexachloroplatinic acid or a Pt(0) complex;

wherein the fluoroolefin has an iodine content from 6.5 ppm to 170 ppm by weight, a diene content from 1 ppm to less than 100 ppm by weight, and a water content of less than 100 ppm by weight.

2. The process as claimed in claim 1 , wherein,

(i) the hydrogenchlorosilane is initially charged, heated, the hydrosilylation catalyst dissolved in an inert solvent is added and the fluoroolefin is then metered in; or

(ii) the hydrogenchlorosilane is initially charged, heated and a mixture of fluoroolefin, hydrosilylation catalyst and optionally solvent is metered in; or

(iii) a mixture of the hydrogenchlorosilane and the hydrosilylation catalyst dissolved in a solvent are initially charged, heated, and the fluoroolefin is metered in.

3. The process as claimed in claim 1 , wherein the initially charged hydrogen-chlorosilane or the initially charged hydrogenchlorosilane-containing mixture is heated to a temperature in the range from 85 to 120° C.

4. The process as claimed in claim 1 , wherein hydrogenchlorosilane and fluoroolefin are used in a molar ratio of from 3:1 to 0.5:1.

5. The process as claimed in claim 1 , wherein toluene or xylene is used as an inert solvent.

6. The process as claimed in claim 1 , wherein the catalyst is used in a molar ratio of Pt to hydrogenchlorosilane of from 1:100 000 to 1:100.

7. The process as claimed in claim 1 , wherein at least one hydrogenchlorosilane of the formula (I)

H( 4-a−b )SiR a X b   (I),

wherein the groups R are identical or different and R is a linear, branched or cyclic alkyl group having from 1 to 20 carbon atoms or an aryl group,

the X is Cl,

a=0, 1, 2 or 3,

b=0, 1, 2 or 3, and

1≦(a+b)≦3.

8. The process as claimed in claim 1 , wherein at least one fluoro-olefin of the formula II

R 1 Y m CH═CH 2   (II),

wherein R 1 is a monofluorinated, oligofluorinated, or perfluorinated alkyl group having from 1 to 12 carbon atoms or a perfluorinated aryl group, Y is a —CH 2 —, —O—, —O—CH 2 —, or —S—group, and m is 0 or 1.

9. The process as claimed in claim 1 , wherein the fluoroolefin is selected from the group consisting of

3,3,3-trifluoro-1-propene,

3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctene,

3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-tridecafluorooccene,

1,1,2,2-tetrafluoroethyl allyl ether,

3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecene,

3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-hencosafluorooctene, and

3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13,14,14,14-pentacosafluorooctene.

10. The process as claimed in claim 1 , wherein the fluoroolefin is added to the initially charged hydrogenchiorosilane as set forth in (i) or (ii) or (iii) at a pressure of from 1 to 15 bar abs.

11. The process as claimed in claim 1 , wherein the fluoroolefin is metered in at a rate of from 50 to 300 1 /h, based on 1 t of chlorosilane.

12. The process as claimed in claim 1 , wherein the reaction is carried out at a temperature in the range from 85 to 120° C. and a pressure of from 1.5 to 50 bar abs. for a period of from 4 to 20 hours.

13. The process as claimed in claim 1 , wherein the hydrosilylation product is isolated from the product mixture by distillation and is subsequently esterified with an alcohol, wherein the alcohol is used in an excess of from 0.1 to 10% and the alcohol used is denatured with ≦1% by weight of methyl ethyl ketone or petroleum ether.

14. The process as claimed in claim 1 performed batchwise in a stirred tank reactor.