The method of obtaining 2-keto-l-gulonovoy acid

 

(57) Abstract:

The invention relates to a method for producing 2-keto-L-gulonovoy acid, which is an intermediate for the synthesis of vitamin C, the oxidation of L-sorbose in the presence of platinum source of catalyst in aqueous-alkaline medium with equimolar content of NaHCO3at atmospheric pressure, intensive stirring and bubbling an oxidizing agent - pure oxygen - speed 440-460 ml/min Putinobamamania the catalyst was prepared by the introduction of H2PtCl66N2In the amount of 0.005 mol/l aqueous solution of block copolymer, polyethylene oxide-poly-2(4)-vinylpyridine) - derivatives containing 0,017-0,0175 mol 2(4)-vinylpyridine groups per liter and 0.06-0,065 mol polietilenoksidnoy groups per liter, and the restoration of NaBH4taken in a five-fold molar excess with obtaining metal nanoparticles stabilized in a solution of polyethylene oxide-poly-2(4)-vinylpyridine) - derivatives, with the subsequent drawing on Al2ABOUT3. The catalyst is used mainly in the number of 25-45 g/l, the content of platinum in the catalyst is 2-3%. The method allows to increase the yield of 2-keto-L-gulonovoy acid to 99%, and also reduce the cost of the used catalyst due to the possibility of his cyclical oxidation ketosis. The resulting product is an intermediate in the synthesis of vitamin C. 2-keto-L-golosovoy acid is obtained by liquid-phase oxidation of L-sorbose:

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There is a method of oxidation of L-sorbose 10% Pd/C oxygen in aqueous alkaline medium, with the following content components: sorbose - 5g, Panso3- 3.5 g Pd/C (10%) - 1G, water - 50 ml the Rate of sparging 3 l/min. the Reaction is carried out at a temperature of 70oAnd atmospheric pressure. The process duration is 5-6 hours, and the output of ketogulonic acid - 53% (Lengyel-Meszaros , A., Losonczi Century, Petro J. et al. The Catalytic Oxidation of Sorbose// Acta Chimica Academiae Scientiarum Hungaricae.-1978, V. 97. - P. 213-220).

The disadvantage of this method is the low selectivity with long-term management of the process, as well as high content Paladiy, the catalyst is Pd/C. in Addition, no data on the stability of the used catalyst. All this points to limited use of this method of oxidation in practice.

Also known is a method of obtaining alkoxyalkanols acid oxidation by oxygen of the corresponding alcohol at atmospheric pressure and a temperature of 60-100oWith pre-preparation of heterogeneous platinumplaybingo catalyst, for example by the introduction of H3tl6m number of platinum varies from 1% to 20% and the method allows efficient use of platinum (U.S. Patent 4348509, IPC607 With 51/235, 1982).

The disadvantages of this method are the long duration of the process is about 7.5 hours and the lack of information about the selectivity of the process. In addition, the use as catalyst of platinum on macrostate supersewn polymer resin is not possible to produce industrially applicable catalysts on carriers with guaranteed technological properties.

The closest in technical essence is a method of obtaining 2-keto-L-gulonovoy acid prepared by impregnation of a heterogeneous platinum source, the catalyst 5% Pt, 3% b3/S in aqueous-alkaline - pH 7-8, with the following content components: sorbose - 0.33 mol/l, Panso3- equimolar quantity of catalyst 5% Pt, 3% PdCO3/C - 25 g/l, with a speed of bubbling an oxidizing agent (air) 200 ml/min, with vigorous stirring speed 500 rpm, at a temperature of 40oAnd atmospheric pressure. The processing time of 2.5 hours. The yield of 2-keto-L-gulonovoy acid was 87% (U.S. Patent 4599446, IPC607 With 51/235, C 07 C 59/125, 1986).

The disadvantage of this method is not a high yield of 2-keto-L-gulonovoy acid at znachitelnaya development of conditions for the process of obtaining 2-keto-L-gulonovoy acid by the oxidation of L-sorbose, allows to increase the output of the intermediate for the synthesis of vitamin C, as well as reduce the cost of the used catalyst due to the possibility of its cyclic application.

The technical result of the invention is obtaining 2-keto-L-gulonovoy acid with high yield.

This object is achieved in that in a method of producing 2-keto-L-gulonovoy acid by preliminary preparation of heterogeneous catalyst with platinum source subsequent vedanam process of oxidation of L - sorbose in aqueous-alkaline medium with equimolar content Panso3at atmospheric pressure, intensive stirring and bubbling an oxidizing agent according to the invention in use as a catalyst deposited on Al2ABOUT3putinobamamania the catalyst as an oxidizing agent use pure oxygen, and the oxidation reaction is carried out at concentrations of L-sorbose 0.3 to 0.55 mol/l and a temperature of 55-80oC. in Addition, platinochloride the catalyst was prepared by introduction of N2tCl66N2About in an aqueous solution of the block copolymer, while platinochloride the catalyst is used in quantities of 25 to 45 g/l And an aqueous solution of the polymer should contain 0.017-0.0175 mol 2(4)-vinylpyridin the Oia N2tCl66N2About (0.005 mol/l) restore NaBH4taken in a five-fold molar excess, to obtain metal nanoparticles stabilized in a solution of polyethylene oxide-poly-2(4)-vinylpyridine) - derivatives. The obtained metal nanoparticles stabilized in a solution of polyethylene oxide-poly-2(4)-vinylpyridine) - derivatives, mainly applied on Al2ABOUT3. In addition, the content of platinum in the polymer platinum source, the catalyst is 2-3%, the rate of bubbling an oxidizing agent is 440-460 ml/min, and the intensity of mixing - 870-1000 rpm

With decreasing temperature oxidation below 55oWith is slowing the oxidation process, while the opposite change in temperature increases the amount of side products. The change in the ratio of the concentration of the catalyst and L-sorbose both in big, and in the smaller side of the agreed intervals leads to a decrease in the yield of 2-keto-L-gulonovoy acid. The application process for other catalytic systems with different Pt content is possible (for example: PT/Al2ABOUT3Pt/SiO2but if they cannot reach a high enough given the speed of the process. Platinochloride polymer contacts the addition of oxygen can significantly intensify the chemical reaction, that is impossible when using oxygen. At lower mixing intensity below 870 rpm also slowed the oxidation process, and increase by more than 1000 rpm does not give any positive effect. The decrease in the content of Pt in the catalyst leads to a significant slowing down of the oxidation process, and the excess content of more than 2-3% raises pereokislenie L-sorbose and the occurrence of side products.

Polymer platinochloride catalyst synthesized by introducing H3PtCl66H2O (0.005 mol) in an aqueous solution of the block copolymer, polyethylene oxide-poly(2(4)-vinylpyridine) - derivatives containing 0.017-0.0175 mol 2(4)-vinylpyridine groups per liter and 0.06-0.065 mol polietilenoksidnoy groups per liter, with the subsequent recovery of the metal nanoparticles by adding a five-fold molar excess NaBH4and drawing on Al2ABOUT3. For this purpose the tube Slinka, fitted with a rubber septum, placed aqueous solution of block copolymer (polyethylene oxide-pyridine). The content of polymer in the solution is 5.6 g/L. Under vigorous stirring in a solution is injected H2tCl66N2About in such quantity that the concentration was 3 g/L. Solution of polyethylene which means balance. The restoration of the obtained solution is performed NaBH4taken in a five-fold molar excess with respect to PT (10.9 g/l). To do this, NaBH4sprinkled to the solution under vigorous stirring and the mixture is left on the stirrer until complete cessation allocation of gas bubbles. Cleaning solution from the decomposition products NaBH4(borates of sodium and NaCl) solution is subjected to dialysis. For applying the solution on Al2ABOUT3use the Pt concentration is 30 g/l, in the end, after dialysis solution volume is reduced 25 times.

To explain the method of producing 2-keto-L-gulonovoy acid shown the drawing, which shows a plant for carrying out the oxidation of L-sorbose to 2-keto-L-gulonovoy acid (General view).

Installation oxidation consists of the reactor 1 equipped with a magnetic stir bar 2 and is attached to a laboratory transformer 3. The reflux condenser 4 is attached to the fitting 5 of the reactor 1 through the fitting 6 of the reactor 1 load reagents and through the nozzle 7 provide a supply of oxygen from the gas cylinder 8. Measuring the amount of oxygen carried out by the flowmeter 9, the reactor 1 thermostatic water supplied from thermostat 10. To put is that by means of a pH meter 12, fitted with electrodes 13, controls and through the burette 14 and fixed thereto electromagnetic valve 15 enters the alkalizing agent in the reactor 1 through the nozzle 16.

The method of obtaining 2-keto-L-gulonovoy acid comprises conducting the process in an aqueous-alkaline medium with equimolar content Panso3with continuous mixing intensity 870-1000 rpm on heterogeneous polymeric platinum catalyst (2-3% Pt) deposited on Al2ABOUT3in the amount of 25-45 g/l, is obtained by introducing the N2PtCl66N2About (0.005 mol/l) in an aqueous solution of the block polymer containing 0.017-0.0175 mol 2(4)-vinylpyridine groups per liter and 0.06-0.065 mol polietilenoksidnoy groups per liter and restored NaBH4remaining stable for 30-50 reaction cycles, when the concentration of L-sorbose 0.30-0.55 mol/l, a temperature of 55-80oWith, when the oxidizing agent is used pure oxygen, the rate of bubbling is 440-460 ml/min, is new compared to the prototype.

The method is as follows: the reactor 1 thermostatic to a temperature of from 55 to 80oC. Then through the nozzle 6 into it load reagents and required amount of water. Temperaturecontrol mass connecting magnetic stirrer 2. Then fed oxygen through the nozzle 7 from the gas cylinder 8, the rate of bubbling oxygen is controlled by the flowmeter 9. Intensive mixing of the contents of the reactor allows the process in the kinetic region.

A process for the catalytic oxidation of L-sorbose under the described conditions provides a selective process and high yield of 2-keto-L-gulonovoy acid.

The best variant implementation of the method

The process is carried out at atmospheric pressure. The reactor 1 thermostatic to a temperature of 55-80oWith and through the nozzle 6 download 0.30-0.55 mol/l L-sorbose and 25-45 g/l of catalyst, 13 ml of water. Then separately dissolved equimolar amount of alkalizing agent Panso3in 12 ml of water through the fitting 6 is poured 0.6 ml of this solution. In the future, every 10 min for 3 hours and 20 minutes poured 0.6 ml NaHCO3. The temperature of the reaction mixture to support the supply of the heating fluid in the jacket of the reactor 1 of thermostat 10. Set the stirring of the reaction mass connecting magnetic stirrer 2 with the number of revolutions 900-1000 rpm and then supplied oxygen through the nozzle 7 from the gas cylinder 8, using rotameter 9 set the speed 440-460 ml/min. Output Process is carried out at atmospheric pressure. The reactor 1 thermostatic to a temperature of 70oWith and through the nozzle 6 download 0.36 mol/l L-sorbose and 30 g/l of catalyst, 13 ml of water. Then separately dissolved in 12 ml of water, 0.36 mol/l alkalizing agent Panso3through the fitting 6 is poured 0.6 ml of this solution. In the future, every 10 min for 3 hours and 20 minutes poured 0.6 ml Panso3. The temperature of the reaction mixture to support the supply of the heating fluid in the jacket of the reactor 1 of thermostat 10. Set the stirring of the reaction mass connecting magnetic stirrer with 2 speed 1000 rpm then deliver oxygen through the nozzle 7 from the gas cylinder 8, using rotameter 9 set the rate of 450 ml/min, the Yield of 2-keto-L-gulonovoy acid was 99.0%.

Example 2 obtain 2-keto-L-gulonovoy acid.

The process is carried out at atmospheric pressure. The reactor 1 thermostatic to a temperature of 65oWith and through the nozzle 6 download 0.36 mol/l L-sorbose and 30 g/l of catalyst, 13 ml of water. Then separately dissolved in 12 ml of water, 0.36 mol/l alkalizing agent Panso3through the fitting 6 is poured 0.6 ml of this solution. In the future, every 10 min for 3 hours and 20 minutes poured 0.6 ml Panso3. The temperature of reaction the e reaction mass connecting magnetic stirrer with 2 speed 1000 rpm Then deliver oxygen through the nozzle 7 from the gas cylinder 8, using rotameter 9 set the speed of 440 ml/min, the Yield of 2-keto-L-gulonovoy acid was 97%.

Example 3 to obtain 2-keto-L-gulonovoy acid.

The process is carried out at atmospheric pressure. The reactor 1 thermostatic to a temperature of 75oWith and through the nozzle 6 download 0.36 mol/l L-sorbose and 30 g/l of catalyst, 13 ml of water. Then separately dissolved in 12 ml of water, 0.36 mol/l alkalizing agent Panso3through the fitting 6 is poured 0.6 ml of this solution. In the future, every 10 min for 3 hours and 20 minutes poured 0.6 ml Panso3. The temperature of the reaction mixture to support the supply of the heating fluid in the jacket of the reactor 1 of thermostat 10. Set the stirring of the reaction mass connecting magnetic stirrer with 2 speed 900 rpm then deliver oxygen through the nozzle 7 from the gas cylinder 8, using rotameter 9 set the speed of 460 ml/min, the Yield of 2-keto-L-gulonovoy acid was 98%.

The results obtain 2-keto-L-gulonovoy acid by the oxidation reaction of L-sorbose are given in table.1.

The proposed method can be widely applied in the production of vitamins and lekarstvennogo product.

1. The method of obtaining 2-keto-L-gulonovoy acid by the oxidation of L - sorbose in the presence of platinum source of catalyst in aqueous-alkaline medium with equimolar content of NaHCO3at atmospheric pressure, intensive stirring and bubbling an oxidizing agent, wherein as the catalyst use pre-prepared printed at Al2O3putinobamamania the catalyst as an oxidizing agent use pure oxygen, the rate of bubbling is 440-460 ml/min, and the oxidation reaction is carried out at concentrations of L-sorbose 0.3 to 0.55 mol/l and a temperature of 55-80oC.

2. The method according to p. 1, characterized in that platinochloride the catalyst was prepared by the introduction of H2PtCl66H2O in an aqueous solution of the block copolymer.

3. The method according to p. 1, characterized in that platinochloride the catalyst is used in quantities of 25 to 45 g/L.

4. The method according to PP. 1 and 2, characterized in that the aqueous solution of the polymer contains 0,017-0,0175 mol 2(4)-vinylpyridine groups per liter and 0.06-0,065 mol polietilenoksidnoy groups per liter.

5. The method according to PP. 1-4, characterized in that the obtained polymer solution after the introduction of the H2PtCl66H< the nanoparticles of metal, stable in solution, the polyethylene oxide-poly-2(4)-vinylpyridine) - derivatives.

6. The method according to PP. 1 and 5, characterized in that the metal nanoparticles stabilized in a solution of polyethylene oxide-poly-2(4)-vinylpyridine) - derivatives, put on Al2O3.

7. The method according to p. 1, characterized in that the content of platinum in the polymer platanistidae the catalyst is 2-3%.

8. The method according to p. 1, characterized in that the intensity of mixing is 870-1000 rpm

 

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