Catalyst system for aerobic oxidation of primary and secondary alcohols
The present invention relates to a process of oxidation of alcohols selectively to aldehydes or ketones with molecular oxygen using a TEMPO based catalyst, Fe-bipyridyl or Fe-phenantroline co-catalyst and N-bromosuccinimide promoter in acetic acid solvent. The oxidation takes places at high rates and high aldehyde selectivity at temperatures in the range 45-50° C. and oxygen or air pressures of 0-15 psi. The alcohol conversion of 95-100% and aldehyde selectivity higher than 95% are achieved over 3-4 hours reaction time. Aldehydes such as 3,3-dimethyl-1-butanal can be produced efficiently using the present invention.
1. A process for oxidizing alcohols selected from the group consisting of primary and secondary alcohols to aldehydes or ketones, said process comprising the steps of (a) forming a solution including said alcohol with (i) a first catalyst selected from the group consisting of 2,2,6,6,-tetramethylpiperidinyloxy catalysts, (ii) a second catalyst selected from the group consisting of a Fe-2,2′-bipyridyl complex and a Fe-1,10-phenanthroline complex, and (iii) a bromine promoter selected from the group of N-bromo imides, organic bromides and inorganic bromides, said alcohol acting as the substrate of said solution (b) reacting said alcohol in said solution with an oxidant to produce said aldehyde or ketone.
2. The process of claim 1 wherein the second catalyst is a Fe-2,2′-bipyridyl complex.
3. The process of claim 1 wherein the second catalyst is a Fe-1,10-phenanthroline complex.
4. The process of claim 1 , wherein the second catalyst concentration is 0.01-20% mol based on the substrate.
5. The process of claim 2 where the Fe-2,2′-bipyridyl complex is immobilized on ion exchange resin.
6. The process of claim 5 , where the ion exchange resin is Dowex MSC-1.
7. The process of claim 2 where the Fe-2,2′-bipyridyl is immobilized on clay material.
8. The process of claim 7 , where the clay material is Montmorilonite K.
9. The process of claim 1 wherein the bromine promoter is N-bromosuccinimide.
10. The process of claim 9 where the concentration of said bromine promoter is 0.01-20% mol based on the mol % of the substrate alcohol.
11. The process of claim 1 , wherein the oxidant is selected from the group consisting of molecular oxygen, air, hydrogen peroxide, chlorite, chlorate, bromate, hypochlorite, hypobromite, organic hydroperoxides, and percarboxylic acids.
12. The process of claim 1 , further comprising the addition of one or more solvents to the alcohol solution.
13. The process of claim 12 wherein said solvents are selected from the group consisting of: acetic acid, ethyl acetate, butyl acetate, acetonitrile, tetrahydrofuran, methylene chloride, chloroform, toluene, acetone, diethyl ether, methyl tert-butyl ether and mixture of solvents from the group above.
14. The process of claim 13 wherein said solvent is present in an amount of from 0% to about 80% based on the volume of the substrate used.
15. The process of claim 1 , wherein the oxidation is carried out in absence of a solvent.
16. The process of claim 1 , wherein the reaction temperature is maintained in the range of −10° C. to 100° C.
17. The process of claim 1 , wherein the reaction pressure is maintained in the range of 0 psi-500 psi.
18. The process of claim 1 comprising the additional step of purification of said aldehyde or ketone by use of purification methods selected from the group consisting of distillation, fractional distillation, either batch or continuous or a thin-film evaporator.
19. A process for the production of 3,3-dimethyl-1-butanal, consisting of the step of reacting 3,3-dimethylbutanol with an oxidant wherein said 3,3-dimethylbutanol is in a solution including a catalyst selected from the group consisting of 2,2,6,6,-tetramethylpiperidinyloxy, a co-catalyst selected from the group of Fe 2+ or Fe 3+ nitrates chelated with ligands selected from the group consisting of 2,2′-dipyridyl and 1,10-phenanthroline, a bromine promoter selected from the group of N-bromo imides or inorganic bromide.
20. The process of claim 19 wherein said oxidant selected from the group consisting of molecular oxygen, air, hydrogen peroxide, chlorite, chlorate, bromate, hypochlorite, hypobromite, organic hydroperoxides, and percarboxylic acids.
21. The process of claim 19 wherein said oxidant is selected from the group consisting of molecular oxygen and air.
22. The process of claim 19 wherein said oxidant is present in an amount of from about 10 mol % to about 200 mol % based on the substrate used.
23. The process of claim 19 further comprising the addition of one or more additional solvents to the alcohol solution.
24. The process of claim 23 wherein said solvent is selected from the group consisting of: acetic acid, ethyl acetate, butyl acetate, acetonitrile, tetrahydrofuran, methylene chloride, chloroform, toluene, acetone, diethyl ether, methyl tert-butyl ether and mixture of solvents from the group above.
25. The process of claim 19 wherein said process is carried out in the absence of a solvent.
26. The process of claim 19 , wherein the reaction temperature is maintained in the range of −10° C. to 100° C.
27. The process of claim 19 , wherein the reaction pressure is maintained in the range of 0 psi-500 psi.
28. The method of claim 19 comprising the additional step of purification of the crude aldehyde or ketone via distillation, fractional distillation, either batch or continuous or a thin-film evaporator.