Conversion of glucose to sorbose
The present invention is directed to methods for preparing sorbose from glucose, said method comprising: (a) contacting the glucose with a silica-containing structure comprising a zeolite having a topology of a 12 membered-ring or larger, an ordered mesoporous silica material, or an amorphous silica, said structure containing Lewis acidic Ti 4+ or Zr 4+ or both Ti 4+ and Zr 4+ framework centers, said contacting conducted under reaction conditions sufficient to isomerize the glucose to sorbose. The sorbose may be (b) separated or isolated; or (c) converted to ascorbic acid.
1. A process for preparing sorbose from glucose, said process comprising:
(a) contacting the glucose with a silica-containing structure comprising a zeolite having a topology of a 12 membered-ring or larger, an ordered mesoporous silica material, or an amorphous silica, said structure containing Lewis acidic Ti 4+ or Zr 4+ or both Ti 4+ and Zr 4+ framework centers, said contacting conducted under reaction conditions sufficient to isomerize the glucose to sorbose; and
(b) separating the sorbose from the starting materials and co-products.
2. A process for preparing ascorbic acid, said process comprising:
(a) contacting the glucose with a silica-containing structure comprising a zeolite having a topology of a 12 membered-ring or larger, an ordered mesoporous silica material, or an amorphous silica, said structure containing Lewis acidic Ti 4+ or Zr 4+ or both Ti 4+ and Zr 4+ framework centers, said contacting conducted under reaction conditions sufficient to isomerize the glucose to sorbose;
(b) optionally separating the sorbose; and
(c) converting the sorbose to ascorbic acid.
3. The process of claim 2 , wherein the process comprises:
(a) contacting the glucose with the silica zeolite containing the Lewis acidic Ti 4+ or Zr 4+ or both Ti 4+ and Zr 4+ framework centers under reaction conditions sufficient to isomerize the glucose to sorbose.
4. The process of claim 2 , wherein the silica zeolite comprises a Ti-Beta zeolite.
5. The process of claim 2 , wherein the process comprises:
(a) contacting the glucose with the ordered mesoporous silica material containing Lewis acidic Ti 4+ or Zr 4+ or both Ti 4+ and Zr 4+ framework centers under reaction conditions sufficient to isomerize the glucose to sorbose.
6. The process of claim 2 , wherein the process comprises:
(a) contacting the glucose with the amorphous silica containing Lewis acidic Ti 4+ or Zr 4+ or both Ti 4+ and Zr 4+ framework centers under reaction conditions sufficient to isomerize the glucose to sorbose.
7. The process of claim 2 , wherein the silica-containing structure contains Lewis acidic Ti 4+ framework centers.
8. The process of claim 2 , wherein the sorbose is L-(−)-sorbose and the glucose is D-(+)-glucose.
9. The process of claim 2 , wherein the ascorbic acid is L-ascorbic acid.
10. The process of claim 2 , wherein the reaction conditions comprise contacting the glucose with the silica zeolite, ordered mesoporous silica material, or amorphous silica containing the Lewis acidic Ti 4+ or Zr 4+ or both Ti 4+ and Zr 4+ framework in the presence of an aqueous or an alcoholic medium.
11. The process of claim 2 , wherein the reaction conditions comprise contacting the glucose with the zeolite in the presence of an alcohol.
12. The process of claim 10 , wherein the alcohol is methanol.
13. The process of claim 2 , wherein the zeolite has a composition such that the atomic ratio of Si to Ti, Zr, or combination of Ti and Zr is in a range of from about 35 to about 250.
14. The process of claim 13 , wherein the zeolite has a composition such that the atomic ratio of Si to Ti, Zr, or combination of Ti and Zr is in a range of from about 65 to about 120.
15. The process of claim 2 , wherein the molar ratio of glucose to Ti, Zr, or combination of Ti and Zr, is in a range is in a range of from about 5 to about 500.
16. The process of claim 2 , wherein the glucose is present in an aqueous solvent and the glucose concentration in the aqueous solvent is in a range of from about 0.1 w/w to about 45 w/w, relative to the weight of the solvent.
17. The process of claim 2 , wherein the glucose is present in a methanolic solvent and the glucose concentration in the methanol solvent is in a range of from about 0.1 w/w to about 2 w/w, relative to the weight of the solvent.
18. The process of claim 2 , wherein the reaction conditions comprise heating the reaction mixture to a temperature in a range of from about 60° C. to about 200° C.
19. The process of claim 2 , wherein the sorbose is separated or isolated by filtration, crystallization, freeze-thawing, chromatographic separation, solvent removal, or a combination thereof.
20. The process of claim 2 , wherein converting the sorbose to ascorbic acid comprises a sequential oxidation step followed by a step of gamma lactonization with removal of water.
21. The process of claim 18 , wherein the reaction conditions comprise heating the reaction mixture to a temperature in a range of from about 80° C. to about 120° C.
22. The process of claim 1 , wherein the process comprises:
(a) contacting the glucose with the silica zeolite containing the Lewis acidic Ti 4+ or Zr 4+ or both Ti 4+ and Zr 4+ framework centers under reaction conditions sufficient to isomerize the glucose to sorbose.
23. The process of claim 1 , wherein the silica zeolite comprises a Ti-Beta zeolite.
24. The process of claim 1 , wherein the process comprises:
(a) contacting the glucose with the ordered mesoporous silica material containing Lewis acidic Ti 4+ or Zr 4+ or both Ti 4+ and Zr 4+ framework centers under reaction conditions sufficient to isomerize the glucose to sorbose.
25. The process of claim 1 , wherein the process comprises:
(a) contacting the glucose with the amorphous silica containing Lewis acidic Ti 4+ or Zr 4+ or both Ti 4+ and Zr 4+ framework centers under reaction conditions sufficient to isomerize the glucose to sorbose.
26. The process of claim 1 , wherein the silica-containing structure contains Lewis acidic Ti 4+ framework centers.
27. The process of claim 1 , wherein the sorbose is L-(−)-sorbose and the glucose is D-(+)-glucose.
28. The process of claim 1 , wherein the reaction conditions comprise contacting the glucose with the silica zeolite, ordered mesoporous silica material, or amorphous silica containing the Lewis acidic Ti 4+ or Zr 4+ or both Ti 4+ and Zr 4+ framework in the presence of an aqueous or an alcoholic medium.
29. The process of claim 1 , wherein the reaction conditions comprise contacting the glucose with the zeolite in the presence of an alcohol.
30. The process of claim 29 , wherein the alcohol is methanol.
31. The process of claim 1 , wherein the zeolite has a composition such that the atomic ratio of Si to Ti, Zr, or combination of Ti and Zr is in a range of from about 35 to about 250.
32. The process of claim 31 , wherein the zeolite has a composition such that the atomic ratio of Si to Ti, Zr, or combination of Ti and Zr is in a range of from about 65 to about 120.
33. The process of claim 1 , wherein the molar ratio of glucose to Ti, Zr, or combination of Ti and Zr, is in a range is in a range of from about 5 to about 500.
34. The process of claim 1 , wherein the glucose is present in an aqueous solvent and the glucose concentration in the aqueous solvent is in a range of from about 0.1 w/w to about 45 w/w, relative to the weight of the solvent.
35. The process of claim 1 , wherein the glucose is present in a methanolic solvent and the glucose concentration in the methanol solvent is in a range of from about 0.1 w/w to about 2 w/w, relative to the weight of the solvent.
36. The process of claim 1 , wherein the reaction conditions comprise heating the reaction mixture to a temperature in a range of from about 60° C. to about 200° C.
37. The process of claim 36 , wherein the reaction conditions comprise heating the reaction mixture to a temperature in a range of from about 80° C. to about 120° C.
38. The process of claim 1 , wherein the sorbose is separated or isolated by filtration, crystallization, freeze-thawing, chromatographic separation, solvent removal, or a combination thereof.
39. The process of claim 2 , comprising forming 2-keto-L-gulonic acid by (a) acetal protection of ring hydroxyls of the sorbose followed by the chemical oxidation of the protected sorbose by hypochlorite or permanganate; or (b) oxidation of the sorbose using oxygen and a noble metal catalyst, such as platinum; or both (a) and (b).
40. The process of claim 39 , further comprising employing conditions to ring close by gamma-lactonization of the 2-keto-L-gulonic acid, with removal of water.