Method for preparing 2-keto-l-gulonic acid

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to the improved method for preparing 2-keto-L-gulonic acid. This compound is an intermediate substance in synthesis of vitamin C. Method involves oxidation of L-sorbose in the presence of platinum-containing polymeric catalyst applied on Al2O3 in medium with the equimolar content of NaHCO3 under atmosphere pressure, at the rate stirring 870-1 000 rev/min and bubbling pure oxygen as an oxidizing agent. Reaction is carried out in medium water : ethyl alcohol 7-10 vol. %, in the concentration of L-sorbose 0.29-0.6 mole/l, on spherical microparticles of catalyst in the amount 20-40 g/l with ultra-thin layer of polydiallyldimethylammonium chloride as cationic polyelectrolyte with platinum nanoparticles formed on it. The content of platinum in catalyst is 1-2%. The feeding rate of oxidizing agent is 400-450 ml/min. The end product is obtained with high yield 97-99%.

EFFECT: improved preparing method, enhanced yield of product.

7 cl, 1 tbl, 1 sch, 7 ex

 

The invention relates to organic chemistry, and in particular to methods of oxidation of 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:

There is a method of oxidation of L-sorbose 10% Pd/C oxygen in aqueous alkaline medium with the following content components: sorbose - 5 g, Panso3- 3.5 g Pd/C (10%) - 1 g, water to 50 ml, the Rate of sparging 3 l/min. the Reaction is carried out at a temperature of 70° and 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 the high palladium content in 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.

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 NaHCO3- equimolar quantity, catalyst 5% Pt, % PdCO 3/C - 25 g/l With the speed of bubbling an oxidizing agent (air) 200 ml/min, with vigorous stirring at 500 rpm At a temperature of 40° and atmospheric pressure. The processing time of 2.5 hours. The yield of 2-keto-L-gulonovoy acid was 87%. (U.S. patent No. 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 with a significant content of platinum in the catalyst that leads to its appreciation.

The closest in technical essence is a method of obtaining 2-keto-L-gulonovoy acid, which comprises carrying out the process in an aqueous-alkaline medium with equimolar content of NaHCO3with 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 N2tl6·6N2O (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 55-80° when the oxidizing agent is used pure oxygen, the rate of bubbling which the CSO is 440-460 ml/min (RF Patent No. 2185369, IPC607 With 51/235, C 07 C 59/125, C 07 C 59/105, 2001).

The disadvantage of this method is the high cost of the target product due to the high content of platinum in the catalyst.

The objective of the invention is the development of conditions for the process of obtaining 2-keto-L-gulonovoy acid by the oxidation of L-sorbose, allowing to obtain a high yield of the intermediate product for the synthesis of vitamin C, as well as reduce the cost of the used catalyst by reducing the content of platinum.

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 the oxidation of L-sorbose in the presence of platinum source of polymeric catalyst deposited on Al2About3in an environment with equimolar content of Nano3at atmospheric pressure, with stirring intensity 870-1000 rpm, bubbling an oxidizing agent pure oxygen, according to the invention the oxidation reaction is carried out in the environment water : ethanol in a ratio of 7:10 vol.% when the concentration of L-sorbose 0.29-0.6 mol/l, the spherical particles of the catalyst with ultra-thin layer of cationic polyelectrolyte, polydiallyldimethyl chloride with formed therein nanoparticles of platinum in the amount of 20-40 g/L. the Reaction is carried out at a temperature of 5-70° C. Platinochloride polymer catalyst was prepared by deposition of cationic polyelectrolyte on Al2About3when the polymer concentration of 5-10 g/l followed by the introduction of H2tCl6·6H2About 0,5-1· 10-4mole Pt per 1 g of Al2About3. The content of platinum in the polymer platinum source, the catalyst is 1-2%. The rate of bubbling an oxidizing agent is 400-450 ml/min

As catalyst, use of polymer platinochloride contact, obtained in the following way. The aluminum oxide is applied ultrathin layers of cationic polyelectrolyte, polydiallyldimethyl chloride (polymer concentration of 5-10 g/l). Then enter H2tl6·6N2O (0.5 to 1· 10-4mole Pt per 1 g of Al2About3) on spherical microparticles Al2About3with ultra-thin layer of cationic polyelectrolyte, polydiallyldimethyl chloride, which is due to electrostatic interaction forms a layer of a certain thickness on the surface of the carrier and controls the formation in it of nanoparticles of platinum.

With decreasing temperature oxidation below 50° is slowing the oxidation process, while the opposite change in temperature increases the amount of side products. The change in the ratio of concentration of the catalyst and L-sorbose as in most, and in the smaller side of the agreed intervals leads to a decrease in the yield of 2-keto-L-gulonovoy acid. Upon decrease of the concentration of ethanol in the solvent reduces the solubility of the polyelectrolyte polydiallyldimethyl chloride, catalytic active centers become unavailable and the process slows down. Otherwise decreases the solubility of L-sorbose, which also leads to a decrease in the rate process. The application process for other catalytic systems with different Pt content is possible (for example: PT/Al2About3Pt/SiO2and others), but if their use cannot be very high given the speed of the process without increasing the Pt content. The use of spherical particles of Al2About3due to the fact that they, because of its shape have a large surface area and is not dissolved under stirring. The use of an ultra thin layer of cationic polyelectrolyte, polydiallyldimethyl chloride provides the formation on the surface of the platinum nanoparticles. Platinochloride polymer contact remains stable during 40-50 reaction cycles. Using as oxidizing agent pure oxygen can significantly intensify the chemical reaction that is impossible when using oxygen. Snizeni the content of Pt in the catalyst leads to a significant slowing down of the oxidation process, and the excess content of more than 1-2% of calls pereokislenie L-sorbose and the occurrence of side products.

Polymer platinochloride catalyst synthesized through a series of sequential operations. The linkage Al2About3(1 g), pre-calcined at 300° C for 3 hours, add 5 ml of water and 0.2 ml of NaOH (obtained pH≈ 12), followed by stirring for 10 minutes at high speed stirrer. Then add 5 ml of a solution of cationic polyelectrolyte, polydiallyldimethyl chloride (polymer concentration of 5-10 g/l), followed by stirring for 1-24 hours Received Al2About3coated with ultra-thin layers of polyelectrolyte filtered, washed with water on the filter (not more than 2 times) and dried under vacuum. In an aqueous solution of H2PtCl6(0.5 to 1· 10-4mole Pt per 1 g of Al2O3) add dried Al2About3coated with the polymer and stirred for 1-24 h, followed by filtration, washing and drying. Next is the process of recovering excess NaBH4before the termination of allocation of gas bubbles (1 h) followed by filtration, washing and drying.

The method of obtaining 2-keto-L-gulonovoy acid comprises conducting the process in the environment water : ethanol at a ratio of 7:10 vol.% with equimolar content Panso3when continuous PE is emisiuni intensity 870-1000 rpm on heterogeneous polymeric platinum catalyst (1-2% Pt) in an amount of 20-40 g/l, deposited on Al2About3and put ultrathin layers of cationic polyelectrolyte, polydiallyldimethyl chloride (polymer concentration of 5-10 g/l), then enter H2tl6·6N2O (0.5 to 1· 10-4mole Pt per 1 g of Al2O3) on spherical microparticles Al2About3with ultra-thin layer of cationic polyelectrolyte, polydiallyldimethyl chloride, remaining stable for 40-50 reaction cycles, when the concentration of L-sorbose 0.29-0.6 mol/l, a temperature of 50-70° when the oxidizing agent used pure oxygen, the rate of bubbling is 400-450 ml/min, is new compared to the prototype.

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. the La introduction into the reaction mass alkalizing agent in the unit consists of a block of an automatic titration 11, which by the pH meter 12, provided 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 is as follows: the reactor 1 thermostatic to a temperature of from 50 to 70° C. Then through the nozzle 6 into it load reagents and required amount of water. 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. 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 reactor 1 thermostatic to a temperature of 50-70° and through the nozzle 6 download 0.29-0.6 mol/l L-sorbose and 20-40 g/l of catalyst, 10 ml of ethanol and 7 ml of water. Then separately dissolved equimolar amount of alkalizing agent NaHCO3in 12 ml of water through the fitting 6 is poured 0.6 ml of this solution. Further, through every the e 10 min for 3 hours and 20 minutes poured 0.6 ml NaHCO 3. 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 400-450 ml/min, the Yield of 2-keto-L-gulonovoy acid was 97-99%.

Example 1 to obtain 2-keto-L-gulonovoy acid

The reactor 1 thermostatic to a temperature of 60° and through the nozzle 6 download 0.45 mol/l L-sorbose and 30 g/l of catalyst, 7 ml of water and 10 ml ethanol in a ratio of 7:10 vol%). Then separately dissolved equimolar amount of alkalizing agent NaHCO3in 12 ml of water through the fitting 6 is poured 0.6 ml of this solution. Further, 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 2 with the number of revolutions of 1,000 rpm and then supplied oxygen through the nozzle 7 from the gas cylinder 8, using rotameter 9 set the speed of 425 ml/min, the Yield of 2-keto-L-gulonovoy acid was 99%.

Example 2 obtain 2-keto-L-gulonovoy acid

The reactor 1 thermostatic to temperature is 70° With and through the nozzle 6 load 0.6 mol/l L-sorbose and 40 g/l of catalyst, 7 ml of water and 10 ml ethanol in a ratio of 7:10 vol%). Then separately dissolved equimolar amount of alkalizing agent NaHCO3in 12 ml of water through the fitting 6 is poured 0.6 ml of this solution. Further, 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 with 2 speed 900 rpm then supplied oxygen through the nozzle 7 from the gas cylinder 8, using rotameter 9 set the rate of 400 ml/min, the Yield of 2-keto-L-gulonovoy acid amounted to 98.2%.

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

The reactor 1 thermostatic to a temperature of 50° and through the nozzle 6 download 0.29 mol/l L-sorbose and 20 g/l of catalyst, 7 ml of water and 10 ml ethanol. Then separately dissolved equimolar amount of alkalizing agent NaHCO3in 12 ml of water through the fitting 6 is poured 0.6 ml of this solution. Further, 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 the magician is itnow mixer 2 speed 1000 rpm After that supplied 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 97.4%.

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

The proposed method can be widely applied in the production of vitamins and medications, when he enters the stage of oxidation of L-sorbose to 2-keto-L-gulonovoy acid with a high yield of the final product.

Table 1

The results obtain 2-keto-L-gulonovoy acid by the oxidation reaction of L-sorbose
Conditions reactionThe yield of 2-keto-L-gulonovoy acid, %
t=60°

With0=0.45 mol/l*

Ck=30 g/l**

The rate of bubbling oxygen 425 ml/min

The intensity of mixing 1000 rpm
99
t=50°

With0=0.29 mol/l*

Withk=20 g/l**

The rate of bubbling oxygen 450 ml/min

The intensity of mixing 1000 rpm
97.4
t=70°

With0=0.60 mol/l*

Withk=40 g/l**

The rate of bubbling oxygen at 400 ml/min

The intensity of mixing 900 rpm
98.2
t=50°

With0=0.45 mol/l*

Ck=30 g/l**

The rate of bubbling oxygen 425 ml/min

The intensity of mixing 1000 rpm
96.4
t=60°

With0=0.35 mol/l*

Ck=30 g/l**

The rate of bubbling oxygen 430 ml/min

The intensity of mixing 1000 rpm
97.8
t=60°

With0=0.35 mol/l*

Ck=40 g/l**

The rate of bubbling oxygen 450 ml/min

The intensity of mixing 900 rpm
98.1
t=60° C

With0=0.30 mol/l*

Ck=25 g/l**

The rate of bubbling oxygen 420 ml/min

The intensity of mixing 870 rpm
97.4
* 0the concentration of L-sorbose in the reaction mixture;

** Ckthe concentration of catalyst in the reaction mixture.

1. The method of obtaining 2-keto-L-gulonovoy acid by the oxidation of L-sorbose in the presence of platinum source of polymeric catalyst deposited on Al2O3in an environment with equimolar content of NaHCO3at atmospheric pressure, with stirring intensity 870-1000 rpm, bubbling an oxidizing agent pure oxygen, characterized in that the oxidation reaction of p is avodat in the environment water : ethanol 7-10% vol. when the concentration of L-sorbose 0.29 to 0.6 mol/l, the spherical particles of the catalyst in the amount of 20-40 g/l with an ultra thin layer of cationic polyelectrolyte, polydiallyldimethyl chloride with formed therein nanoparticles of platinum.

2. The method according to claim 1, characterized in that the reaction is carried out at a temperature of 50-70° C.

3. The method according to claim 1, characterized in that platinochloride polymer catalyst was prepared by deposition of cationic polyelectrolyte on Al2O3when the polymer concentration of 5-10 g/L.

4. The method according to claim 1 or 3, characterized in that platinochloride polymer catalyst obtained by the introduction of H2PtCl6×6H2O 0,5-1· 10-4mole Pt per 1 g of Al2About3.

5. The method according to any one of claims 1, 3, 4, characterized in that the content of platinum in the polymer platinum source, the catalyst is 1-2%.

6. The method according to claim 1, characterized in that the rate of bubbling an oxidizing agent is 400-450 ml/min



 

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The invention relates to the field of organic synthesis and concerns a method for obtaining-,-alkalicarbonate acids

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to the improved method for preparing 2-keto-L-gulonic acid. This compound is an intermediate substance in synthesis of vitamin C. Method involves oxidation of L-sorbose in the presence of platinum-containing polymeric catalyst applied on Al2O3 in medium with the equimolar content of NaHCO3 under atmosphere pressure, at the rate stirring 870-1 000 rev/min and bubbling pure oxygen as an oxidizing agent. Reaction is carried out in medium water : ethyl alcohol 7-10 vol. %, in the concentration of L-sorbose 0.29-0.6 mole/l, on spherical microparticles of catalyst in the amount 20-40 g/l with ultra-thin layer of polydiallyldimethylammonium chloride as cationic polyelectrolyte with platinum nanoparticles formed on it. The content of platinum in catalyst is 1-2%. The feeding rate of oxidizing agent is 400-450 ml/min. The end product is obtained with high yield 97-99%.

EFFECT: improved preparing method, enhanced yield of product.

7 cl, 1 tbl, 1 sch, 7 ex

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for preparing 2-ethylhexanoic acid. Method involves catalytic hydrogenation of fraction isolating from the manufacturing waste in the presence of hydrogen by rectification method followed by oxidation of prepared hydrogenation product with air oxygen at temperature 30-80°C and under pressure 0.1-1.0 MPa. Vat residue from rectification of butyl alcohols in oxo-synthesis is used as raw for the process. Fraction with the total content of unsaturated and saturated C8-alcohols 65-95 wt.-% is isolated from vat residue by rectification and in residual pressure on column top 100-300 mm of mercury column. This fraction is subjected for hydrogenation in vapor phase under atmosphere pressure, temperature 220-270°C, volume rate of raw feeding 0.5 h-1, volume ratio raw : hydrogen = 1:1 on copper-containing catalyst and the following isolation 2-ethylhexanal from catalyzate by rectification on two columns working at residual pressure on top of the first column 60-100 mm of mercury column and on top of the second column 20-80 mm of mercury column, and 2-ethylhexanal is oxidized with air oxygen. The end 2-ethylhexanoic acid is isolated from the prepared oxidized product by rectification on two columns working at residual pressure on top of column 20-70 and 10-60 mm of mercury column, respectively. Method provides enhancing the yield of 2-ethylhexanoic acid.

EFFECT: improved method for preparing.

2 cl, 16 ex

FIELD: organic synthesis.

SUBSTANCE: synthesis involves oxidation of substrate with chlorine dioxide in organic solvent at 40-50°C, said selected from myrtenal or myrtenol and said organic solvent from acetone, benzene, and alcohol at molar ratio of myrtenal or myrtenol to chlorine dioxide 1:(0.5-3.5). Thus formed myrtenic acid is isolated in the form of its water-soluble salt and, when alcohol is used as solvent, in the form of ester.

EFFECT: increased yield of product to 66%, reduced expenses, and shortened reaction time.

3 cl, 1 tbl, 2 ex

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