JPS5925361A - Separation of amino acid and mandelic acid form compounded substance of amino acid and mandelic acid - Google Patents

Abstract

PURPOSE:To separate an amino acid from mandelic acid by a simple operation in high yield in high purity, by extracting mandelic acid directly from an aqueous solution of compounded substance of an amino acid and mandelic acid using an ether-based organic solvent without using a mineral acid or an alkali. CONSTITUTION:An aqoueous solution of compounded substance of an amino acid (e.g., alanine, cysteine, phenylalanine, etc.) and mandelic acid is treated with an ether-based organic solvent (e.g., especially preferably diisopropyl ether), mandelic acid is directly extracted and separated, so that the amino acid is separated from mandelic acid. Noncontinuous extration method, continous counter or parallel flow extraction method can be applied arbitrarily. Attention is especially required when a relatively unstable amino acid such as cysteine, etc. is used, and the extraction temperature is preferably 10-30 deg.C in this case.

Description

Detailed Description of the Invention The present invention involves directly extracting mandelic acid from an amino acid/mandelic acid complex by liquid-liquid extraction using an ether organic solvent, and extracting the amino acid and mandelic acid from the amino acid/mandelic acid complex. It concerns a method of separating .

As a method for optically resolving some DL-amino acids,
A method using optically active mandelic acid has been reported (Japanese Patent Application Laid-Open No. 53-119844, Japanese Patent Application No. 56-75686).
. The amino acid/mandelic acid complex produced during the splitting is decomposed with a mineral acid and then separated into the amino acid and mandelic acid using an organic solvent or a strongly acidic ion exchange resin. In any case, in order to obtain both amino acids and manganic acid, mineral acids and alkalis are required, salt by-products are produced by neutralizing them, the operation takes several steps, and there are several problems such as increasing the capacity. There are problems.

Based on the above-mentioned points, the present inventors have developed a direct separation method that does not involve salt by-products, and simplified the operation, regarding the separation of amino acids and mandelic acid from the amino acid-mandelic acid complex. As a result of intensive studies to overcome these problems, we succeeded in extracting mandelic acid directly from an aqueous solution of the amino acid/mandelic acid complex using an ether-based organic solvent and concentrating the aqueous and organic solvent layers. The present invention was completed by discovering scales that can separate amino acids and mandelic acid with high purity and high yield.

That is, according to the present invention, both components can be obtained with a much simpler operation and in a better yield than when decomposing an amino acid/mandelic acid complex with a mineral acid or an alkali.

The types of amino acids constituting the complex to which the present invention can be applied are not particularly limited, but examples include haalanine, cysteine, phenylalanine, methionine, and 2-aminobutyric acid.

The extraction operation itself is not particularly defined, and any method that can be employed in this type of technique can be applied. Therefore, a discontinuous extraction method in which new extractants are successively added to the amino acid/mandelic acid complex aqueous solution and the treatment is repeated, a method in which countercurrent or cocurrent extraction is performed continuously in an extraction column, etc. can be used.

Regarding the extraction temperature, it is necessary to consider the stability of the liberated amino acids, and it is important to pay particular attention to the temperature when handling relatively unstable amino acids such as cysteine. In the case of cis gain, the range is preferably 10 to 30°C.

Suitable oils for use in the present invention include solvents that dissolve mandelic acid but do not dissolve amino acids, are immiscible with water, which is the solvent for the extracted liquid, and are inert to water, including ether-based organic solvents. Especially considering industrial safety, neuisopropyl ether is preferable.

The concentration during extraction varies depending on the type of amino acid, but it is preferable to use a saturated aqueous solution of each complex at the extraction temperature.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example I D-cysteine/D-mandelic acid complex ([α]14-
91.8° (c 1.00, 2N-Hα)) 69.5
0 g (255 mmol) was dissolved in 330 mm water, and an extraction operation was performed for 25 hours using noisopropyl ether using a continuous extraction device for liquids. After separating into an aqueous layer and an organic layer, the aqueous layer was concentrated under reduced pressure, and 50ml of methanol was added.
In addition, the precipitated crystals are filtered. Furthermore, the crystals were washed three times with 507 methanol and dried to yield 28.80 g of D-
(-)-cystine was obtained. Free yield 93.5tI) [
α] −6,7° (C■, 02.2N-HCl,) The organic layer was further concentrated to dryness, 37.44,! 7 D-
(−)-mandelic acid was obtained. Free yield 96.7% [L]
-153,3° (c 1. OO, H2O) Example 2 Compound ([α)” -87,9° (c 2.3'98, 2o
)) 4.34 g (17 mrnol) was dissolved in 30-mL water, and extraction operation was performed for 20 hours using noisopropyl ether using a continuous extraction device for liquids. After separating the aqueous layer and the organic layer, the aqueous layer was concentrated under reduced pressure, and methanol was added to
0- was added, the precipitated crystals were filtered, and the crystals were added to 5 m
Wash twice with 1 liter of methanol and dry to give 1.449 liters.
-(+)-Alanine was served. Free yield 93.2 mm, [α
l”+15.00(c 10.0 6N-HC7riD
=c mp, 275-288 dec,) The organic layer was further concentrated to dryness to obtain 2.40 g of D-(-)-mandelic acid.

Free yield 90.9%, [α115-153.4° (c
l, oo, H2O) Example 3 DL-cysteine 4.24. F (35 mmol),
aDL-mandelic acid 5.325' (35 mmol)
30m/! The mixture was dissolved in water and subjected to extraction operation for 24 hours using noisopropyl ether using a continuous extraction device for liquids. After separating into an aqueous layer and an organic layer, the aqueous layer is concentrated under reduced pressure, 30% of methanol is added, and the precipitated crystals are filtered.

Furthermore, the crystals were washed twice with 30-methanol and dried to obtain 4.05 g of DL-cisgain. Free yield 95
．． The organic layer was further concentrated to dryness to obtain 5.19.9 DL-Mandel ff.

Yield: 97.6% Example 4 L-phenylalanine/L-mandelic acid complex ([α]
28+ 53.9° (c 1.00, H2O))
3.65 g (11.5 rnmol) of D was dissolved in 150 ml of water, and extracted using diethyl ether using a continuous extraction device for liquids for 20 hours. After separating into an aqueous layer and an organic layer, the aqueous layer was concentrated under reduced pressure, and methanol was
Add ml and filter out the crystals. The crystals were further washed twice with 30 ml of methanol and dried to give 1.66 g of crystals (
-)-phenylalanine was obtained. Free yield: 87.4;
[α,:l”-32,9° (c2.00, H2O)

Claims (1)

[Claims] A method for separating amino acids and mandelic acid from an amino acid/mandelic acid complex, which is characterized by extracting and separating mandelic acid by applying an ether-based organic solvent to an aqueous solution of the amino acid/mandelic acid complex.