Fluorination of acrylate esters and derivatives
The present invention generally relates to processes for converting acrylate esters or a derivative thereof to difluoropropionic acid or a derivative thereof. This process is generally performed using fluorine gas in a hydrofluorocarbon solvent.
1. A process for fluorinating a double bond comprising:
forming a reaction mixture comprising a hydrofluorocarbon or fluorocarbon solvent, fluorine gas, and a compound of formula 5
to form a compound of formula 6
2. The process of claim 1 wherein the hydrofluorocarbon solvent has a melting point less than about −20° C.
3. The process of claim 2 wherein the reaction mixture is a liquid at a temperature less than about −40° C.
4. The process of claim 3 wherein the hydrofluorocarbon solvent has a boiling point greater than about 30° C.
5. The process of claim 1 wherein the hydrofluorocarbon or fluorocarbon solvent is 2H,3H-decafluoropentane, eicosafluorononane, tetradecafluorohexane, tetradecafluoro-2-methylpentane, hexafluorobenzene, octadecafluorodecahydronaphthalene, octadecafluorooctane, octafluorocyclopentene, octafluorotoluene, perfluoro(1,3-dimethylcyclohexane), perfluoroheptane, perfluoro(2-butyltetrahydrofuran), perfluorotriethylamine, heptacosafluorotributylamine, tetradecafluoromethylcyclohexane, 1,1,1,3,3-pentafluorobutane, or a combination thereof.
6. The process of claim 5 wherein the hydrofluorocarbon solvent is 2H,3H-decafluoropentane.
7. The process of claim 1 wherein the reaction mixture has a temperature from about −80° C. to about −20° C.
8. The process of claim 7 wherein the reaction mixture has a temperature from about −80° C. to about −60° C.
9. The process of claim 1 wherein the reaction mixture further comprises a fluorination additive.
10. The process of claim 9 wherein the fluorination additive is an alcohol, an acid, or a combination thereof.
11. The process of claim 10 wherein the fluorination additive is the alcohol, and the alcohol comprises ethanol, methanol, trifluoroethanol, or a combination thereof.
12. The process of claim 10 wherein the fluorination additive is the acid, and the acid comprises triflic acid, trifluoroacetic acid, sulfuric acid, formic acid, acetic acid, or a combination thereof.
13. The process of claim 1 wherein the process is a continuous process.
14. The process of claim 13 wherein the infusion rate of the compound of formula 5 is from about 0.2 to about 2 mL/minute.
15. The process of claim 14 wherein the flow rate of the fluorine gas is from about 0.2 to about 2 mmol/minute.
16. The process of claim 15 wherein the residence time is from about 1 second to about 10 seconds.
17. The process of claim 1 further comprising contacting the compound of formula 6 with an alcohol and a catalyst.
18. The process of claim 17 wherein the catalyst is a Brønsted acid or a Lewis acid, and the Brønsted acid comprises toluenesulfonic acid, sulfuric acid, hydrochloric acid, phosphoric acid, acetic acid, formic acid, triflic acid, trifluoroacetic acid, or a combination thereof and the Lewis acid comprises boron tribromide, aluminum oxide, titanium tetraethoxide, or a combination thereof.
19. The process of claim 17 wherein the catalyst is a base and the base comprises dimethylaminopyridine, diethylhydroxyamine, triethylamine, N,N-diisopropylethylamine (Hunig's base), pyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,4-diazabicyclo[2.2.2]octane (DABCO), or a combination thereof.
20. The process of claim 1 wherein the reaction mixture contains at least about 50% formula 6 based on the number of moles of formula 5 added to the reaction mixture.