KR820000822B1 - Process for producing salts of pyruvic acid - Google Patents

Abstract

Title salts were produced by oxidizing salts of lactic acid with an O2-contg. gas in a H2O-contg. solvent in the presence of a catalyst optionally supported on Al2O3 or C and comprising >=1 of Pt or Pd together with >=1 of Pb, Sn, Te, In, Bi, and compds. of these elements. Thus, Na pyruvate was prepd. by blowing air through a mixt. of aq. Na lactate and a catalyst comprising activated C powder supporting 3 wt. % Pt and 5 wt. % Pb (NO3)2 at 45≰ for w h.

Description

Method for preparing pyruvate

The present invention relates to a novel process for producing pyruvate salts by oxidizing lactates with an oxygen containing gas.

Pyrubinic acid or a salt thereof is an important intermediate in the metabolic pathway in vivo and is also an important raw material for producing L-tryptophan by a fermentation method in which tryptopanase is applied to indole, pyruvate and ammonia. In addition, it is a useful compound having an important use as a raw material for the production of L-cystine by fermentation method using pyruvate ammonia and hydrogen sulfide as raw materials, or as a raw material for the production of L-DOPA by fermentation method from caticool, pyruvate and ammonia.

Conventionally, for the production of pyruvic acid or pyruvate, for example,

(1) a method of synthesizing and hydrolyzing acetyl cyanide by reacting soda cyanide with acetyl chloride;

(2) distilling tartaric acid in the presence of potassium hydrogen sulfate;

(3) a method of producing by fermentation method using lactic acid as a raw material,

(4) a method of oxidizing lactic acid ester with potassium permanganate,

(5) a method of oxidizing propylene glycol,

Various methods, such as these, are proposed.

However, in the method of (1), the raw material is expensive, the yield is low, and the by-products are difficult to separate and purify, and in the method of (2), the tartaric acid of the raw material is expensive and the secondary raw material is potassium hydrogen sulfate in large quantities. In the method of (3), by-producing α-ketoglutaric acid and oxidizing the lactic acid ester with a reagent, for example, a large amount or more of potassium permanganate is produced. It is extremely cumbersome to consume and further recover and reclaim manganese. Further, the propylene glycol alcohol oxidation method of (5) is not suitable for the purpose of obtaining pyruvate as a main product by producing a large amount of lactic acid salt or the like as well as pyruvate. Thus, the manufacturing method of pyruvic acid by the conventional method has various drawbacks.

It is an object of the present invention to provide a novel and improved method for producing pyruvate which does not have the drawbacks of the prior art.

It is another object of the present invention to provide a process for the preparation of pyruvate salts by oxidation of lactate in a water-containing solvent in the presence of a novel catalyst.

Another object of the present invention is to provide a novel method for isolating pyruvate from the reaction solution obtained.

The object of the present invention is achieved by oxidizing lactate to an oxygen containing gas in the presence of a catalyst in a water containing solvent. Wherein (a) at least one element selected from the group consisting of platinum and palladium, and (b) at least one element selected from the group consisting of zinc, tin, tellurium, indium and bismuth or compounds of this element Containing catalyst is used.

The pyruvate solution thus obtained is concentrated as necessary and isopropyl alcohol is then added thereto to isolate the solid pyruvate.

The catalyst in the process of the invention comprises at least one element or compound of platinum or (and) palladium selected from the group consisting of zinc, tin, tellurium, indium and bismuth as the second and third components. Containing is used.

As the second and third components, in the case of using a catalyst containing only a noble metal containing no element or compound of the above group, the production of pyruvate is little or substantially zero, yielding pyruvic acid. In order to obtain good, addition of the 2nd, 3rd component selected from the said group becomes a requirement.

As a catalyst used by adding a base metal as a 2nd and 3rd component to a normal raw material and a noble metal catalyst, a rindra catalyst is famous, for example. Rindra catalyst poisons paradium with acetate, hydrogenates acetylene bonds to olefin bonds, and decreases catalytic activity by poisoning by soft compounds so that olefin bonds are not hydrogenated to paraffins. It is an improvement.

By the way, a catalyst in which, for example, a soft compound is added to platinum or (and) palladium as a second or third component by the method of the present invention is different from a rindra catalyst, and thus the catalytic activity increases to zinc and the oxidation reaction is increased. Absorption rate of oxygen increases significantly.

That is, the catalyst according to the method of the present invention does not improve the selectivity due to poisoning of the noble metal by the nonmetallic compound, but improves the activity of the noble metal catalyst by addition of the nonmetal. Thus, by using the catalyst according to the method of the present invention, pyruvate is produced in lactic acid salt with a good yield that is not previously conceivable.

It is essential that the catalyst used in the present invention contain the above-mentioned second and third components in addition to the platinum and / or palladium components, and the platinum, or (and) paradium or the like supported on a carrier When a catalyst is used the production of pyruvic acid is near or substantially zero.

Although these catalyst components may be used alone, it is usually industrially advantageous to use the catalyst components described above on a carrier.

As the carrier, activated carbon, alumina, diatom, pumice or magnesia and the like are used, but usually activated carbon or alumina is used.

The amount of the catalyst component supported on the carrier is in the range of 0.1 to 20% by weight, preferably 0.5 to 10% by weight, particularly in the range of 1 to 5% by weight, when supporting platinum or (and) palladium. do.

Support amount when at least one of the elements selected from the group consisting of zinc, tin, tellurium, indium and bismuth, or a compound of the elements is added to and supported as the second and third components on the platinum or (and) paradium The total of 0.1 to 20% by weight, preferably in the range of 0.5 to 10% by weight is used. The use form of a platinum group element is usually elemental, and can be used as a form of compounds, such as an oxide.

The second and third components are in the form of elements or compounds, and the compound is an oxide, hydroxide, nitrate, sulfate, halide, carbonate or organic acid salt.

The catalyst used in the method of the present invention is prepared by a conventional method, for example, by mixing a predetermined amount of an aqueous solution of chloroplatinic acid and an aqueous solution of siloxane, and immersing it in a carrier and reducing the product with promalin or the like.

Commercially available noble metal catalysts can also be used in the process of the present invention. That is, the second and third components can be supported on a commercially supported noble metal supported catalyst by a method such as immersion treatment and used for the catalyst. For example, a catalyst is prepared by immersing a lead acetate or lead nitrate aqueous solution in a commercially available palladium activated carbon powder catalyst.

Alternatively, the catalyst can be prepared by adding a water-soluble compound of the second and third components to the reaction solution while the platinum catalyst supported on the activated carbon powder is stirred, for example, in the reaction solution during the oxidation reaction operation.

The amount of the catalyst to be used is not particularly limited. For example, in the case of the suspended phase, a range of 5 to 100 g of a supported catalyst is used per 1 L of the reaction solution. There is a number.

Lactic acid salt, which is a raw material of the method of the present invention, is industrially produced in large quantities using acetaldehyde and cyanide as a raw material, and is supplied at safety. As a kind of lactic acid salt, alkali metal salts of lactic acid, such as sodium lactate and potassium lactate, alkaline earth salts of lactic acid, such as calcium lactate, or ammonium sulfate, etc. are used, Usually, sodium lactate is used a lot.

Although water is suitable as a water-containing solvent used in the method of the present invention, water and other solvents, for example, water such as dimethylform acid, ethers of diethylene glycol, dioxane or tert-butyl butyl alcohol A mixed solvent with a solvent to be mixed with can also be used.

The concentration of the lactic acid salt in the water-containing solvent is preferably 2 to 30% by weight, particularly preferably 5 to 20% by weight.

If the concentration of the lactic acid salt is too lean, it is not preferable because the reaction for concentrating the reaction product becomes large, and energy consumption such as stirring of the reaction liquid and blowing of air increases. On the other hand, if the concentration of lactate is higher than the above range, the reaction rate is lowered and the side reactions are also increased, resulting in poor results. The oxygen-containing gas used in the method of the present invention is one obtained by diluting oxygen, air or oxygen with an inert gas such as air or nitrogen, or by diluting air with an inert gas such as nitrogen. Of these, it is particularly good to use air.

In this invention, reaction temperature has good room temperature 100 degreeC, and the range of 35-70 degreeC is especially preferable. If the reaction temperature is lower than the above range, the reaction rate is slow and not practical.

In addition, if the temperature is higher than the above-mentioned range, the number of side reaction products increases and the yield decreases, which is not preferable.

The reaction pressure is preferably from normal pressure to 10 kg / cm 2, particularly preferably from atmospheric pressure to 5 kg / cm 2, but it is usually advantageous to use atmospheric pressure. The oxygen partial pressure is preferably 0.2 to 2 kg / cm 2, particularly 0.2 to 1 kg / cm 2, but the reaction may be performed at 0.2 kg / cm 2 or less. Increasing the reaction pressure (oxygen partial pressure) increases the reaction rate, but if the reaction operation is carried out under a condition where the oxygen partial pressure is too high when the catalyst is used repeatedly for a long time, it accelerates the decrease of the catalytic activity, thereby using a pressure higher than the above range. It is not desirable.

The time required for the reaction is determined by the amount of the catalyst used, the reaction temperature, and the like, and is usually in the range of 0.5 to 5 hours in the case of a batch reaction.

The method of the present invention can be carried out by any of batch or continuous methods. The reactor type is agitated or bubble column type, the catalyst phase is used a lot of suspension phase, it can be carried out in a fixed manner.

An aqueous solution of pyruvate can be obtained by filtering the catalyst from the reaction aqueous solution after the reaction and concentrating it. The aqueous solution of the pyruvate salt can be used as it is as a raw material for producing an amino acid using an enzyme. In order to obtain free pyrvinic acid, conventional methods such as neutralizing with an acid or treating with an ion exchange resin are used.

In order to isolate pyruvate, for example, soda pyruvate, from the solution which is separated from the catalyst in the reaction product, it is preferable to use the following method. In other words, pyruvate is poor in thermal stability, and only by evaporating and drying an aqueous solution containing the pyruvate, polymer is produced or decarbonated to produce acetate by-products, etc. It is difficult to obtain acid salts in high purity.

However, the above difficulty was eliminated by mixing the pyruvate-containing aqueous solution with isopropyl alcohol. When isopropyl alcohol and an aqueous solution containing pyruvate are mixed, pyruvate precipitates as a solid, and pyruvate is isolated by filtration and washing.

The solvent which precipitates pyruvate by precipitation by mixing with an aqueous solution of pyruvate must be isopropyl alcohol. Lower alcohols other than isopropyl alcohol, such as methanol, ethanol or butanol, may not precipitate pyruvate from the pyruvate-containing aqueous solution as a precipitate or even if some precipitate is precipitated. The yield is extremely low, making it impractical.

The pyruvate-containing aqueous solution obtained by the method of the present invention usually contains a trace amount of acetate and an unreacted lactate as a by-product. It was difficult to economically obtain only pyruvate by separating pyruvate from acetate and unreacted lactate. However, according to the precipitation precipitation method using isopropyl alcohol, since acetate and lactate are relatively well dissolved in isopropyl alcohol, separation of acetate and lactate from pyruvate can also be performed at the same time.

In carrying out the precipitation method using isopropyl alcohol, when the pyruvate aqueous solution is remarkably colored, it is preferable that the aqueous solution is subjected to a suitable decolorization treatment such as activated carbon treatment. If isopropyl alcohol is added without decolorizing, the precipitated precipitate may be colored. The concentration of the pyruvate aqueous solution when adding isopropyl alcohol is usually in the range of 20 to 70% by weight, particularly 30 to 50% by weight. The isopropyl alcohol used does not need to be a high purity alcohol, and can also use water-containing products. Therefore, a simple distillation operation is performed on the mixed solution of isopropyl alcohol and water used in the method of the present invention to recover an azeotropic mixture of 88% isopropyl alcohol and 12% water and can be repeatedly used. For this reason, it is not necessary to perform extraction distillation.

The amount of isopropyl alcohol is preferably used for 2 to 10, especially for 4 to 6, relative to 1 for the pyruvate-containing aqueous solution. When isopropyl alcohol is stirred and a pyruvate-containing aqueous solution is added thereto and stirred, a precipitate of white pyruvate precipitates. The precipitate is stirred for some time and the precipitate is aged and then separated by filtration. The precipitates separated by filtration are washed with anhydrous isopropyl alcohol or acetone and the like, and air-dried or mixed-dried at room temperature to 60 ° C.

Hereinafter, the present invention will be described by way of examples.

Example 1

A reactor with a staple plate, a turbine-stirred stirrer and an air blower pipe was used as a reactor in a 1 L stainless steel cylinder.

An aqueous solution of 11.2 g of sodium lactate dissolved in 150 g of water and 2.5 g of activated carbon powder loaded with 3 wt% platinum and 5 wt% lead nitrate were injected into the reactor, and maintained at 45 ° C. with air at 150 ml / min. Blow and react with stirring at 600 revolutions / minute.

As a result of analysis by high performance liquid chromatography, it was confirmed that sodium lactate was substantially lost in 2 hours after the start of the reaction, and thus the reaction operation was stopped, and the catalyst was separated from the reaction solution. The reaction solution is colorless and clarified, and coloration is not recognized at all. As a result of high-performance liquid chromatography quantification, it was recognized that 10 g of sodium pyruvate was produced. The reaction solution was ion exchanged to free pyruvic acid, concentrated, and then a condensate with orthoferrenediamine was precipitated to confirm that the compound obtained by the NMR spectrum was pyruvic acid.

Example 2

4 g of activated carbon powder catalyst carrying 200 g of 10% by weight aqueous solution of sodium lactate, 2% by weight of platinum and 3% by weight of lead carbonate was injected into a bubble column reactor, and the reaction mixture was blown with atmospheric air at a reaction temperature of 65 ° C for 1 hour and 30 minutes. Was performed.

After completion of the reaction, the reaction mixture was filtered and analyzed by high performance liquid chromatography. The conversion rate of sodium lactate was 90%, the selectivity of sodium pyruvate 85%, and the selectivity of sodium acetate 5%.

The reaction solution was concentrated to 50 g under reduced pressure, 100 g of isopropanol was added thereto, followed by stirring to precipitate a white precipitate. The white precipitate was filtered off and dried at 45 ° C. under reduced pressure to obtain 13.7 g of a white powder of sodium pyruvate. The obtained powder was dissolved in a heavy aqueous solution and the NMR spectrum was measured. As a result, high purity sodium pyruvate with a slight content of sodium lactate and sodium acetate was obtained.

Example 3

A reactor with a staple plate, a turbine-stirred stirrer, and an air blower pipe was used as a reactor in a 1 liter stainless steel cylindrical container.

240 g of an aqueous solution in which 24.0 g of sodium lactate was dissolved in distilled water, and 5 g of activated carbon powder loaded with 2 wt% Pt and 5 wt% Bi (OH) ₃ were injected into the reactor and heated with a bath in the outside to maintain the reaction temperature at 64 ° C. It was.

The air was blown at a rate of 250 ml / min of the air blown tube and reacted with stirring at 700 revolutions / min.

Since it was recognized by analysis of high-performance liquid chromatography that more than 90% of sodium lactate was lost 2 hours and 30 minutes after the start of the reaction, the reaction was stopped at this point and the catalyst was filtered out from the reaction solution. The reaction solution was colorless and clear, and coloration was not recognized.

When the reaction solution was quantified by high performance liquid chromatography, 20 g of sodium pyrubinate was produced, 1 g of condensate of pyruvic acid and 2 g of unreacted sodium lactate remained, and 0.2 g of sodium acetate was produced. The reaction solution was concentrated to half, and the NMR spectrum was measured to confirm the production of pyruvate at the absorption of methylproton of pyruvate.

Example 4

Only the catalyst used in the same apparatus and reaction conditions as in Example 1 was reacted with 2 wt% Pd and 5 wt% Bi (OH) ₃ / alumina powder. When the reaction solution was quantified by high performance liquid chromatography, it was confirmed that 1g of sodium pyrubinate, 6g of unreacted sodium lactate and 2g of condensate of pyruvic acid were produced.

Example 5

Into the same reaction vessel as in Example 1, an aqueous solution of 11.2 g of sodium lactate dissolved in 150 g of water and 2.0 g of activated carbon powder carrying 0.5 wt% platinum, 2.0 wt% palladium, and 3 wt% carbonate were added and maintained at 60 ° C. Air was blown at 250 ml / min and reacted with stirring at 650 revolutions / min.

Two hours after the start of the reaction, more than 90% of sodium lactate was lost and the production of 9.5 g of sodium pyruvate was confirmed.

Example 6-9

The reaction was carried out by changing various catalysts used at the reaction temperature of 60 ° C. under the same apparatus and reaction conditions as in Example 1. The results are shown below. The catalyst is obtained by carrying a compound described in the remarks column in 1.5 g of a commercially available 2% by weight Pt carbon powder.

Example 10

200 g of 7% by weight aqueous sodium lactate solution was injected into a bubble column reactor, and 3.0 g of activated carbon powder carrying 3% by weight platinum and 3% by weight carbonate was added thereto, and the reaction was carried out while blowing air at 65 ° C. 70 minutes after the start of the reaction, the conversion rate of sodium lactate was 90%, and the selectivity of sodium pyruvate 89%.

An air inlet of the sintered metal plate is attached to the bottom of the bubble column so that the reaction solution after the completion of the reaction can be taken out from the sintered metal plate and the catalyst powder can be retained in the reactor without loss.

After the reaction termination liquid was taken out, 200 g of 7% by weight aqueous sodium lactate solution was injected again, and the reaction was repeated. When the reaction was carried out using a catalyst after repeating the reaction 24 times, the conversion rate of soda lactate was 84%, the selectivity of soda pyruvate soda was 84% in a reaction of 2 hours.

Claims (1)

In the presence of a catalyst containing lactate in a water-containing solvent, at least one component selected from the group consisting of platinum and palladium and at least one component selected from the group consisting of zinc, tin, tellurium, indium, bismuth and these compounds A method for producing pyruvate by oxidation of lactic acid salt, which is oxidized as an oxygen-containing gas.