Synthesis of hydrofluoroalkanols and hydrofluoroalkenes
View Patent ↗Described herein is a process for the manufacture of hydrofluoroalkanols of the structure R f CFClCHROH, comprising reacting a halofluorocarbon of the structure R f CFX 2 , wherein each X is independently selected from Cl, Br, and I, with an aldehyde and a reactive metal in a reaction solvent to generate a reaction product comprising a metal hydrofluoroalkoxide, neutralizing said metal hydrofluoroalkoxide to produce a hydrofluoroalkanol, and recovering the hydrofluoroalkanol. Also described herein are methods of manufacturing hydrofluoroalkenes of the structure R f CF═CHR from halofluorocarbons of the structure R f CFX 2 , wherein each X is independently selected from Cl, Br, and I, comprising (1) reacting halofluorocarbons of the structure R f CFX 2 , wherein each X is independently selected from Cl, Br, and I, with an aldehyde and a reactive metal to generate a reaction product comprising a metal hydrofluoroalkoxide, and reductively dehydroxyhalogenating said metal hydrofluoroalkoxide to produce a hydrofluoroalkene or (2) reacting a hydrofluoroalkanol of the structure R f CFXCHROH or a hydrofluoroalkoxide of the structure R f CFXCHROMX, wherein M is a reactive metal in the +2 oxidation state, with a carboxylic acid anhydride and a reactive metal in a reaction solvent to form a hydrofluoroalkene and isolating the hydrofluoroalkene. In particular, 2,3,3,3,-tetrafluoro-1-propene may be manufactured with this process. Also described are compounds of the formula R f CFClCHROC(═O)R′.
1. A process for the manufacture of hydrofluoroalkenes of the structure R f CF═CHR, comprising reacting a halofluorocarbon of the structure R f CFX 2 , wherein each X is independently selected from Cl, Br, and I, with an aldehyde and a reactive metal in a reaction solvent to generate a reaction product comprising a metal hydrofluoroalkoxide, and reductively dehydroxyhalogenting said metal hydrofluoroalkoxide in a second step to produce a hydrofluoroalkene, wherein the reactive metal is selected from the group consisting of magnesium turnings, activated zinc powder, aluminum, and a powder of any of the following metals: magnesium, calcium, cobalt, nickel, zinc, and combinations thereof.
2. The process of claim 1 , further comprising isolating said hydrofluoroalkene product.
3. The process of claim 1 wherein the aldehyde is selected from the group consisting of formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde and isobutyraldehyde.
4. The process of claim 1 further comprising adding a zinc salt in addition to said reactive metal.
5. The process of claim 4 wherein the zinc salt is zinc acetate.
6. The process of claim 3 , when the aldehyde is formaldehyde, further comprising adding a quaternary ammonium salt in the reaction of a halofluorocarbon with an aldehyde and a reactive metal.
7. The process of step 1 wherein the reductive dehydroxyhalogenation comprises reacting the metal hydrofluoroalkoxide, with a carboxylic acid anhydride and a reactive metal, said reactive metal being the same as the reactive metal in claim 1 , or different.
8. The process of claim 7 wherein the reactive metal is selected from the group consisting of magnesium turnings, activated zinc powder, aluminum, and a powder of any of the following metals: magnesium, calcium, titanium, iron, cobalt, nickel, copper, zinc indium, and combinations thereof.
9. The process of claim 7 wherein the carboxylic acid anhydride is selected from the group consisting of acetic anhydride, propionic anhydride, butyric anhydride, succinic anhydride, glutaric anhydride, adipic anhydride, and formic anhydride.
10. The process of claim 1 wherein the R group of the hydrofluoroalkene is selected from the group consisting of H, CH 3 and C 2 H 5 .
11. The process of claim 1 wherein R f is a perfluoroalkyl group having from one to four carbon atoms.
12. The process of claim 11 wherein R f is CF 3 .
13. The process of claim 1 wherein R f is CF 3 and R is H.
14. The process of claim 1 wherein the said halofluorocarbon is prepared by halogenating the corresponding hydrofluorocarbon R f CFH 2 .
15. The process of claim 1 wherein the reductive dehydroxyhalogenation comprises neutralizing the metal hydrofluoroalkoxide, to produce a hydrofluoroalkanol; mixing a dehydrating agent with the said hydrofluoroalkanol, thereby forming a gaseous mixture; and contacting a catalyst with said gaseous mixture, thereby forming the hydrofluoroalkene.
16. The process of claim 15 wherein said dehydrating agent is at least one gas selected from the group consisting of methane, ethane, propane, butane, natural gas, alcohols, aldehydes and carbon monoxide.
17. The process of claim 15 wherein said catalyst is a transition metal.
18. The process of claim 17 wherein said transition metal is at least one metal selected from the group consisting of nickel, palladium and platinum.
19. The process of claim 15 wherein said catalyst is a supported catalyst.
20. The process of claim 19 wherein said supported catalyst comprises a transition metal and a support material.
21. The process of claim 20 wherein said support material is at least one selected from the group consisting of activated carbon and γ-alumina.