Tuning Product Selectivity in Catalytic Hydroformylation Reactions with Carbon Dioxide Expanded Liquids

Abstract

An improved hydroformylation process is provided, which comprises reacting an olefin with CO and H2 in the presence of a hydroformylation catalyst in a liquid that has been volumetrically expanded with a compressed gas, such as supercritical carbon dioxide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the chemical structures of the rhodium catalysts and ligands investigated in the examples.

FIG. 2 shows the apparatus schematic for catalyst screening studies discussed in the examples.

FIG. 3 shows the volumetric expansion of acetone by CO₂ at various temperatures.

FIG. 4 shows the volumetric expansion of 1-octene by CO₂ at various temperatures.

FIG. 5 shows the catalyst solubility in representative hydroformylation reaction mixtures expanded with compressed CO₂.

FIG. 6 shows the effect of temperature on activity and product selectivity.

FIG. 7 shows the effects of CO₂ addition on TOF and n/i ratio without added solvent.

FIG. 8 shows the solubility of H₂ in neat and CO₂-expanded 1-octene at 60° C.

FIG. 9 shows the pressure effects on TOF and n/i ratio. The solvents used are liquid CO₂ in run a and n-hexane in runs b-d.

Claims

1. A method for obtaining a target regioselectivity of linear aldehydes over branched aldehydes during hydroformylation of an olefin comprising reacting an olefin substrate with CO and H2 in the presence of a hydroformylation catalyst in a liquid that has been volumetrically expanded with a compressed gas, andvarying the content of the compressed gas in the liquid in order to obtain said desired target regioselectivity.

2. The method of claim 1 comprising the steps of: forming a reaction mixture comprising said olefin substrate and said hydroformylation catalyst in a liquid phase;introducing said compressed gas and into said reaction mixture in order to volumetrically expand the reaction mixture; andintroducing a H2/CO syngas into the reaction mixture;whereby said regioselectivity of linear aldehydes is greater than that without said introduction of said compressed gas into said reaction mixture.

3. The method of claim 1 wherein the said olefin substrate is a higher olefin having more than 5 carbons.

4. The method of claim 1 wherein said olefin substrate is a linear olefin.

5. The method of claim 1 wherein said olefin substrate is a branched olefin.

6. The method of claim 1 wherein said olefin substrate has a terminal double bond.

7. The method of claim 1 wherein said olefin substrate has an internal double bond.

8. The method of claim 1 wherein said olefin substrate has more than one double bond.

9. The method of claim 1 wherein said hydroformylation catalyst is a rhodium catalyst.

10. The method of claim 9 wherein said rhodium catalyst is selected from the group consisting of Rh(acac)(CO)2; Rh(acac)[P(OPh)3]2; Rh(acac)(CO)[P(OAr)3]; and a complex formed of Rh(acac)(CO)2 and a phosphorous-containing ligand.

11. The method of claim 10 wherein said rhodium catalyst comprises a complex of rhodium (“Rh”) and ligand (“L”) with a molar L/Rh ratio ranging between 1 and 270.

12. The method of claim 11 wherein said molar L/Rh ratio ranges between 103 and 270.

13. The method of claim 1 wherein the reaction mixture further comprises an organic solvent.

14. The method of claim 13 wherein said organic solvent is acetone.

15. The method of claim 13 wherein said organic solvent is also said olefin substrate.

16. The method of claim 1 wherein said compressed gas has a volume fraction in the liquid phase between 10% and 90%.

17. The method of claim 1 wherein said compressed gas is dense carbon dioxide.

18. The method of claim 1 wherein said target regioselectivity is greater than about 10.

19. The method of claim 1 wherein said reaction mixture is maintained at a temperature between 30° C. and 90° C.

20. The method of claim 1 wherein said reaction mixture is maintained at a pressure less than 12 MPa.

21. The method of claim 20 wherein said pressure is between about 4 to 6 MPa.

22. A method for obtaining a target chemoselectivity of aldehydes during hydroformylation of an olefin comprising reacting an olefin substrate with CO and H2 in the presence of a hydroformylation catalyst in a liquid that has been volumetrically expanded with a compressed gas, andvarying the content of the compressed gas in the liquid in order to obtain said desired target chemoselectivity.

23. The method of claim 22 wherein the said olefin substrate is a higher olefin having more than 5 carbons.

24. The method of claim 22 wherein said olefin substrate is a linear olefin.

25. The method of claim 22 wherein said olefin substrate is a branched olefin.

26. The method of claim 22 wherein said olefin substrate has a terminal double bond.

27. The method of claim 22 wherein said olefin substrate has an internal double bond.

28. The method of claim 22 wherein said olefin substrate has more than one double bond.

29. The method of claim 22 wherein said hydroformylation catalyst is a rhodium catalyst.

30. The method of claim 29 wherein said rhodium catalyst is selected from the group consisting of Rh(acac)(CO)2; Rh(acac)[P(OPh)3]2; Rh(acac)(CO)[P(OAr)3]; and a complex formed of Rh(acac)(CO)2 and a phosphorous-containing ligand.

31. The method of claim 30 wherein said rhodium catalyst comprises a complex of rhodium (“Rh”) and ligand (“L”) with a molar L/Rh ratio ranging between 1 and 270.

32. The method of claim 31 wherein said molar L/Rh ratio ranges between 103 and 270.

33. The method of claim 22 wherein the reaction mixture further comprises an organic solvent.

34. The method of claim 33 wherein said organic solvent is acetone.

35. The method of claim 33 wherein said organic solvent is also said olefin substrate.

36. The method of claim 22 wherein said compressed gas has a volume fraction in the liquid phase between 10% and 90%.

37. The method of claim 22 wherein said compressed gas is dense carbon dioxide.

38. The method of claim 22 wherein said regioselectivity is greater than about 10.

39. The method of claim 22 wherein said reaction mixture is maintained at a temperature between 30° C. and 90° C.

40. The method of claim 22 wherein said reaction mixture is maintained at a pressure less than 12 MPa.