Claims
- 1. A process for improving the yield and purity of fluoro-alkyl substituted cyclic siloxane compounds, comprising:
- (a) adding to a silicone fluorohydrolyzate, an effective amount of an alkali metal carbonate cracking catalyst; and
- (b) reacting said fluorohydrolyzate in the presence of said catalyst to produce the fluoro-alkyl substituted cyclic siloxane compounds, wherein the heating temperature varies from about 120.degree. C. to about 275.degree. C., the vacuum varies from about 5 to about 100 mm Hg, and the reflux ratios from about 1:5 to 15:1.
- 2. The process of claim 1, wherein the silicone fluorohydrolyzate contains a trifluoropropyl group.
- 3. The process of claim 1, wherein the silicone fluorohydrolyzate has the empirical formula
- R(R.sup.3 CH.sub.2 CH.sub.2)SiO
- where R is alkyl, preferably C.sub.1 to C.sub.6, most preferably methyl, and R.sup.3 is perfluoroalkyl group.
- 4. The process of claim 2, wherein the silicone fluorohydrolyzate is methyltrifluoropropylsiloxane.
- 5. The process of claim 1, wherein the catalyst is selected from the group consisting of: Potassium carbonate, Cesium carbonate and Rubidium carbonate.
- 6. The process of claim 5, wherein the catalyst is selected from the group consisting of: Potassium carbonate and Cesium carbonate.
- 7. The process of claim 5, wherein the catalyst is Potassium carbonate.
- 8. The process of claim 5, wherein the catalyst is present at a concentration of from about 0.01 to about 10% by weight of the fluorohydrolyzate siloxane composition.
- 9. The process of claim 8, wherein the catalyst is present at a concentration of from about 0.1 to about 5% by weight of the fluorohydrolyzate siloxane composition.
- 10. The process of claim 9, wherein the catalyst is present at a concentration of from about 0.25 to about 2.5% by weight of the fluorohydrolyzate siloxane composition.
- 11. The process of claim 1, wherein the heating temperature varies from about 150.degree. C. to about 260.degree. C.
- 12. The process of claim 1, wherein the vacuum varies from about 20 to about 80 mm Hg.
- 13. The process of claim 12, wherein the vacuum varies from about 35 to about 50 mm Hg.
- 14. The process of claim 1, wherein the reflux ratio is from about 1:5 to 10:1.
- 15. The process of claim 1, wherein the fluoro-alkyl substituted cyclic siloxane compound is 1,3,5-tris(3,3,3-trifluoropropyl)-1,3,5-trimethylcyclotrisiloxane.
- 16. The process of claim 1, wherein the fluoro-alkyl substituted cyclic siloxane compound is 1,3,5-tris(perfluoroalkyl-ethyleneyl)-1,3,5-trimethylcyclotrisiloxane.
- 17. The process of claim 1, wherein the fluoro-alkyl substituted cyclic siloxane trimer compounds are recovered by distillation.
Parent Case Info
This application claims rights of priority from U.S. Provisional Patent Application Ser. No. 60/067,727, filed Dec. 8, 1997, which is hereby incorporated by reference.
US Referenced Citations (11)