Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2000-05-10
2003-11-11
Richter, Johann (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C560S179000, C568S880000
Reexamination Certificate
active
06646135
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a continuous process for the enantioselective hydrogenation of alpha ketocarbonyl compounds. In particular, the invention relates to a continuous process for the enantioselective hydrogenation of alpha-ketoesters and alpha-ketolactones.
BACKGROUND OF THE INVENTION
Orito, et al., U.S. Pat. No. 4,329,487 (“Orito '487”) describes a method for the asymmetric hydrogenation of alpha-ketoesters which includes subjecting an alpha-ketoester to asymmetric hydrogenation in the presence of a platinum-alumina catalyst modified with a solution of a cinchona-alkaloid selected from at least one member of the group of quinine, quinidine, cinchonidine and cinchonine.
According to Orito '487, alpha-ketoesters are reacted by a batch reaction accomplished in a pressure container such as an autoclave.
The hydrogenation of ketopantolactone over a cinchonidine modified Pt-alumina catalyst in a batch process has been investigated and described by A. Baiker et al. in Journal of Catalysis, 176, 569-571, (1998).
Japanese patent publication JP 62158268 describes the asymmetric hydrogenation of alpha ketolactones in a batch process in the presence of a platinum-carbon catalyst modified with a solution of a cinchona-alkaloid selected from at least one of quinine, cinchonine or cinchonidine. The preparation of the catalyst includes mixing 0.5 g 5% Pt/C with 40 ml 1% cinchonidine/ethanol and refluxing the mixture for 3 hours. The catalyst is separated with a centrifuge. A mixture of the catalyst and e.g. ketopantolactone in benzene is autoclaved to give D-pantolactone. The reaction temperature is about 10 to about 100° C. (e.g., room temperature). The hydrogen pressure is normal pressure to about 100 kg/cm
2
, preferably about 60 kg/cm
2
.
The drawback of the batch process is the huge reactor volume needed for reaction and solid-liquid separation. Another drawback of the batch process is the need for a stirrer which leads to mechanical abrasion of catalyst particles (M. Garland, H. P. Jalett and H. U. Blaser,
Stud. Surf. Sci. Catal
. 59 (1991) 177).
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a process that overcomes the aforesaid drawbacks, and still preserves the high enantioselectivity characteristic of the batch process.
It has now been found that it is possible to carry out the hydrogenation of alpha-ketocarbonyl compounds continuously.
Thus, the present invention includes a continuous process for catalytic hydrogenation of a substrate containing or consisting of an alpha ketocarbonyl compound which process includes the steps of:
(i) contacting in a reactor a substrate and hydrogen in the presence of a modified platinum catalyst, optionally in the presence of a solvent and, for example, a supercritical co-solvent, at a temperature of from about −20° C. to about 100° C. and at pressures ranging from about 2 bar to about 150 bar to convert the alpha ketocarbonyl compound to the corresponding alpha hydroxy carbonyl compound;
(ii) continuously feeding the substrate which optionally contains a modifier to the reactor;
(iii) continuously feeding hydrogen to the reactor;
(iv) continuously discharging the reaction product from the reactor; and
(v) recovering the alpha hydroxy carbonyl compound from the reaction product.
Another embodiment of the invention is a process for making alpha hydroxy carbonyl from alpha ketocarbonyl which includes:
(i) continuously feeding a substrate solution and a modified platinum catalyst into an apparatus wherein the substrate solution includes an alpha ketocarbonyl/compound;
(ii) continuously feeding hydrogen into the apparatus;
(iii) continuously discharging a reaction product from the reactor, wherein the temperature in the apparatus is from about −20° C. to about 100° C. and the pressure in the apparatus is about 2 to about 150 bar.
REFERENCES:
patent: 4329487 (1982-05-01), Orito et al.
patent: WO-9738955 (1997-10-01), None
Minder et al, Enantioselective Hydrogenation of Ethyl Pyruvate in Supercritical Fluids, 1995, Catalysis Letters, 34(12), pp. 1-9. Complete Document.*
Minder et al Catalysis Letters 1995, 34(12). pp. 1-9, Abstract Only.*
Schürch, et al., “Enantioselective Hydrogenation of Ketopantolactone: Effect of Stereospecific Product Crystallization During Reaction,”Journal of Catalysis, vol. 176, pp. 569-571 (1998).
Schürch, et al., “Enantioselective Hydrogenation of Ketopantolactone,”Journal of Catalysis, vol. 169, pp. 275-286 (1997).
Derwent English language abstract of JP 62158268 (1987).
Patent Abstracts of Japan, vol. 011, No. 398, of JP 62158268 (1987).
Patent Abstracts of Japan, vol. 004, No. 069, of JP 55035060 (1980).
Baiker Alfons
Künzle Niklaus
Mallat Tamas
Bryan Cave LLP
Richter Johann
Roche Vitamins Inc.
Zucker Paul A.
LandOfFree
Continuous process for the enantioselective hydrogenation of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Continuous process for the enantioselective hydrogenation of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Continuous process for the enantioselective hydrogenation of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3164860