Process for preparation of 3-methacryloxypropyldimethylchlorosilane in continuous flow reactor

1. A process for the preparation of 3-methacryloxypropyldimethylchlorosilane by reaction of allylmethacrylate with dimethylchlorosilane in the presence of a hydrosilylation catalyst, wherein the reaction is carried out in the absence of a peroxide by the process comprising:

i) providing a first stream containing allylmethacrylate;

ii) providing a second stream containing dimethylchlorosilane;

iii) contacting said streams in a single pass continuous flow reactor in the presence of said hydrosilylation catalyst, thereby producing 3-methacryloxypropyldimethylchlorosilane; and

iv) continuously removing a product stream from said single pass continuous flow reactor.

2. The process as claimed in claim 1 , wherein the surface area/volume ratio of the single pass continuous flow reactor is in the range of from 4:1 to 400:1.

3. The process as claimed in claim 1 wherein, the ratio of the cross sectional area of the single pass continuous flow reactor to the path length of the reagents in the single pass continuous flow reactor is in the range of from 0.01:10,000 to 100:10,000.

4. The process as claimed in claim 1 , wherein the process is carried out in the absence or substantial absence of solvent.

5. The process as claimed in claim 1 , wherein in-line analysis of the product stream produced in step (iii) is carried out.

6. The process as claimed in claim 5 , in which the in-line analysis is carried out by HPLC, GC-FID, GC-MS or IR.

7. The process as claimed in claim 5 , further comprising determining the purity and/or yield of 3-methacryloxypropyldimethylchlorosilane present in the product stream and, where the purity and/or yield of 3-methacryloxypropyldimethylchlorosilane is equal to or greater than a pre-defined value, passing the product stream to a first vessel; or, where the purity and/or yield of 3-methacryloxypropyldimethylchlorosilane is less than said predefined value, passing the crude product stream to a second waste vessel.

8. The process as claimed in claim 1 , wherein the first and second streams are provided to the single pass continuous flow reactor at a flow rate such that they are contacted in the single pass continuous flow reactor at a pressure in the range of from 100 to 10,000 kilopascals.

9. The process as claimed in claim 1 , wherein step (iii) as carried out at temperature in the range of from 30 to 120° C.

10. The process as claimed in claim 1 , wherein the hydrosilation catalyst contains rhodium or platinum.

11. The process as claimed in claim 10 , wherein the catalyst is the reaction product of H 2 PtCl 6 and divinyltetramethyldisiloxane.

12. The process as claimed in claim 1 , wherein step (iii) is carried out in the presence of an inhibitor.

13. The process as claimed in claim 12 , wherein the inhibitor is phenothiazine and/or bis(tert butyl)-4-methylphenol.

14. A process as claimed in claim 1 , further comprising an additional step v) which comprises subjecting the product stream from step iv) to batch distillation.

15. The process as claimed in claim 1 , further comprising converting 3-methacryloxypropyldimethylchlorosilane to a compound of the general formula:

in which n is 0 to 100, and each R independently is a C 1-4 alkyl group.

16. The process as claimed in claim 15 , wherein converting comprises reacting 3-methacryloxypropyldimethylchlorosilane with a (poly)siloxane of the formula:

in which M+ is a cation, to form a compound of formula (I); or dimerising two molecules of 3-methacryloxypropyldimethylchlorosilane in the presence of water to form a compound of formula (II); or reacting two molecules of 3-methacryloxypropyldimethylchlorosilane with a compound of formula:

in which M + is a cation, to form a compound of the formula III.

17. The process as claimed in claim 2 , wherein the ratio of the cross sectional area of the single pass continuous flow reactor to the path length of the reagents in the single pass continuous flow reactor is in the range of from 0.01:10,000 to 100:10,000.

18. The process as claimed in claim 6 , further comprising determining the purity and/or yield of 3-methacryloxypropyldimethylchlorosilane present in the product stream and, where the purity and/or yield of 3-methacryloxypropyldimethylchlorosilane is equal to or greater than a pre-defined value, passing the product stream to a first vessel; or, where the purity and/or yield of 3-methacryloxypropyldimethylchlorosilane is less than said pre-defined value, passing the crude product stream to a second waste vessel.