JPS5842855B2 - Isolation method for pyruvate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention describes a method for isolating pyruvate in solid form from an aqueous solution containing pyruvate, more particularly from an aqueous pyruvate solution prepared by catalytic oxidation of lactate. ,
The present invention relates to a method for isolating pyruvate.

Pyruvate has poor thermal stability, and simply evaporating an aqueous solution containing pyruvate to dryness will result in decarboxylation due to thermal decomposition, etc., resulting in acetate by-products or polymers. Therefore, it is difficult to obtain highly pure pyruvate.

Conventionally, to obtain a high-purity product, water was removed at low temperature under reduced pressure, or methods such as freeze-drying were used, which resulted in high costs for isolation. It was difficult to obtain salt solids.

An object of the present invention is to provide a method for obtaining solid pyruvate from an aqueous pyruvate-containing solution, in particular a pyruvate-containing aqueous solution obtained by catalytic oxidation of lactate.

As a result of various studies on methods for isolating solid pyruvate from an aqueous solution containing pyruvate, the present inventor discovered that a method for isolating solid pyruvate from an aqueous solution containing pyruvate and isopropyl alcohol (hereinafter abbreviated as isopropanol) It was discovered that solid pyruvate precipitates when mixed, leading to the completion of the present invention.

That is, the gist of the present invention is to mix isofuropanol and a pyruvate-containing aqueous solution, precipitate pyruvate solids, and then filter and separate the solids.

According to the method of the present invention, solid pyruvate can be easily and industrially advantageously obtained from an aqueous solution containing pyruvate.

The aqueous solution containing pyruvate to which the method of the present invention is applied is usually produced by the following method.

Air is blown into an aqueous solution containing lactate in the presence of a catalyst to oxidize and dehydrogenate the lactate to form pyruvate.

After separating the catalyst from the aqueous solution of pyruvate produced by this method, isopropanol is added to precipitate the pyruvate.

The solvent that is mixed with the pyruvate-containing aqueous solution to precipitate pyruvate is Impropatool, which is mixed with the pyruvate-containing aqueous solution using a lower alcohol other than Impropatool, such as methanol, ethanol, or butanol, from the pyruvate-containing aqueous solution. Precipitating pyruvate as a precipitate has an extremely low yield and is not practical.

A pyruvate-containing aqueous solution produced by catalytic oxidative dehydrogenation in an aqueous lactate solution usually contains trace amounts of acetate and unreacted lactate as byproducts.

It has been difficult to economically obtain only pyruvate by separating pyruvate from acetate and unreacted lactate from such a pyruvate-containing aqueous solution.

That is, according to the method of the present invention, which is a precipitation method using Improper Tool, acetate and lactate can be separated from pyruvate because acetate and lactate dissolve relatively well in Improper Tool. One of the excellent features of the method of the present invention is that it can be carried out simultaneously.

Therefore, by applying the method of the present invention to a pyruvate-containing aqueous solution produced by catalytic oxidative dehydrogenation of an aqueous lactate solution, acetate, which is a byproduct, and unreacted lactate can be simultaneously separated and solidified. It has the excellent characteristics that pyruvate can be isolated and obtained.

As described above, the pyruvate-containing aqueous solution to which the method of the present invention is applied can be obtained by separating the catalyst from the reaction solution after the oxidation reaction has been completed, but if the aqueous solution is significantly colored, It is preferable to subject the aqueous solution to an appropriate decolorization treatment, such as activated carbon treatment.

When Improper Tool is added without decolorization,
The deposited precipitate is colored, and it is often difficult to decolorize the colored precipitate.

The concentration of the pyruvate aqueous solution to which the method of the present invention is applied is:
Usually, it is in the range of 20 to 70 wt%, but especially 30 to 70 wt%.
A range of 50 wt% is preferred.

The isopropanol used in the method of the present invention does not need to be a highly pure alcohol, and can be used even if it has a water content.

The water content may be 20 to 30%.

Therefore, the mixed waste solution of isopropanol and water used in the method of the present invention is subjected to a simple distillation operation to recover an azeotropic mixture of 88% isopropanol and 12% water.
It can be used repeatedly, and the isopropanol does not require special extractive distillation for recovery and reuse.

The amount of Impropatool to be used is preferably 2 to 10 volumes, particularly 4 to 6 volumes, per 1 volume of the pyruvate-containing aqueous solution.

When isopropanol and a pyruvate-containing aqueous solution are mixed in the above ratio and stirred, a white pyruvate precipitate is precipitated.

This precipitate is left to ripen for several hours or more and then separated into sawasetsu.

The precipitate separated by Sawabetsu is air-dried at room temperature to 70°C, or
The product is obtained by drying under reduced pressure.

The present invention will be explained below with reference to Examples.

Example 1 200 g of 10% aqueous solution of sodium lactate, 2 wt of platinum
% and activated carbon powder catalyst supporting 3 wt% of lead carbonate 4
The mixture was charged into a bubble column type reactor, and normal pressure air was blown into the reactor at a reaction temperature of 70° C., and the reaction was carried out for 1 hour and 30 minutes.

After the reaction was completed, the reaction solution from which the catalyst had been removed was analyzed by high performance liquid chromatography, and the conversion rate of sodium lactate was 90%, the selectivity of sodium pyruvate was 85%, and the selectivity of sodium acetate was 5%.

This reaction solution was concentrated to 5Of under reduced pressure, and 10Of of isopropanol was added and stirred to precipitate a white precipitate.

The white precipitate was separated and dried at 45°C under reduced pressure to obtain a white powder of sodium pyruvate 13.7? obtained.

When the obtained powder was dissolved in a heavy water solvent and the NMR spectrum was measured, the content of sodium lactate and sodium acetate was minute, and highly pure sodium pyruvate was obtained.

Claims (1)

[Claims] 1. When isolating pyruvic acid from a pyruvate-containing aqueous solution obtained by oxidizing lactate in an aqueous solution with an oxygen-containing gas, the pyruvate-containing aqueous solution and isopropyl alcohol are mixed to separate the solid pyruvate. A method for isolating pyruvate, the method comprising precipitation.