JPS5865257A - Preparation of l-threonine - Google Patents

Abstract

PURPOSE:To prepare the titled compound useful as an essential amino acid, in high yield and purity, by the ring-opening reaction of a specific economically available propylene oxide with NH3 followed by oximation, reduction, nitrilation and hydrolysis of the product. CONSTITUTION:A propylene oxide having l-type optical activity is subjected to the ring-opening reaction with NH3 to obtain beta-aminoisopropanol, which is oximated to 2-hydroxypropyl aldoxime. The product is reduced and nitrilated, and the resultant 1-amino-2-hydroxy-propane carbonitrile is hydrolyzed to obtain the objective L-threonine. The content of the asymmetric carbon atom having R- configuration in the propylene oxide used as the starting material is preferably >=70wt%. The propylene oxide can be obtained easily from propylene, and accordingly, the process is especially advantageous.

Description

[Detailed Description of the Invention] The present invention! The present invention relates to a method for producing L-threonine from propylene oxide having a type of optical activity.

L-threonine is one of the essential amino acids that exhibits biologically effective effects, but threonine KG
In addition to L-threonine, there are isomers of KD-threonine, L-allothreonine, and D-allothreonine.

Currently, as an industrial method for producing threonine, a method is employed in which glycine steel and acetaldehyde are subjected to a condensation reaction in the presence of a base. However, this method produces a mixture of the above four isomers, and has the disadvantage that it is necessary to perform complicated purification operations such as optical resolution and racemization on this mixture in order to obtain pure L-threonine. can be seen.

In addition, in recent years, a method using so-called L-threonine fermentation, which uses microorganisms, has been proposed as a method for producing L-threonine. However, this method uses a relatively expensive substance such as glycine as a fermentation substrate as a raw material. In addition, since fermentation requires a long time, production efficiency is low.

In view of the above-mentioned current situation, the present inventor investigated an efficient method for producing L-threonine, and found that L-threonine could be produced advantageously by a synthetic method using propylene oxide, which has l-type optical activity, as a starting material. The present invention was made based on the knowledge that it can be manufactured.

That is, an object of the present invention is to provide a method capable of synthesizing highly pure L-threonine in high yield using starting materials that are available at relatively low cost.

The present invention will be explained in detail below.

A feature of the present invention is that propylene oxide having l-type optical activity is ring-opened using ammonia to form β-aminoisopropanol, and the β-aminoisopropanol is converted into an oxime to form 2-hydroxypropyl aldoxime. and reducing and nitrifying the 2-hydroxypropyl aldoxime to hydrolyze 1-amino-2-hydroxypropanenitrile pannitrile to produce L-threonine.

11 "Propylene oxide having l-type optical activity" used as a starting material in the present invention refers to the absolute configuration of the asymmetric carbon atom in propylene oxide.
Propylene oxide in which the propylene oxide of the us )-configuration is present in a larger amount than that of the S (5inister)-configuration is preferred, and the propylene oxide in which the R-configuration is present in an amount of at least 70 M% is preferred. Propylene oxide having such l-type optical activity can be obtained, for example, by treating 1-2-chlorpropanol with an alkali, but it is possible to obtain propylene oxide by treating 1-2-chlorpropanol with an alkali. It can also be obtained by culturing epoxide-producing bacteria belonging to the
(see publication). It was later confirmed that propylene oxide obtained by this method using microorganisms has type I optical activity, and since it can be produced from propylene in a simple process, it is particularly advantageous as a starting material in the present invention. It can be said that

In the present invention, first, the above-mentioned propylene oxide is reacted with ammonia to open the ring and convert it into β-aminoisopropanol. At this time, 0.0. Propylene oxide was heated at 0 to 100°C to a concentration of 0.5 to 0.8 molar.
Add with stirring at a temperature of . A peroxide, e.g. hydrogen peroxide, is added to the aqueous solution of β-aminoisopropanol obtained by this operation in the presence of a catalyst, e.g. sodium tungstate or sodium molybdate. The corresponding oxime, 2-hydroxypropyl aldoxime, is obtained by reaction at a temperature below 15°C. In this case, in terms of reaction efficiency, the amount of catalyst added should be 0.1 to 0.5 mol and the amount of peroxide should be about 2 to 2.5 mol per 1 mol of β-aminoisoglopanol. preferable.

The 2-hydroxypropyl aldoxime thus obtained is then reduced and nitrified by reacting with a reducing agent such as sodium bisulfite and a cyanating agent such as hydrogen cyanide, potassium cyanide or sodium cyanide. In this case, the above aldoxime is added together with a cyanating agent to an aqueous solution of a reducing agent such as sodium bisulfite to carry out the reduction and nitrification in one step to produce the corresponding nitrile, 1-amino-2-hydroxypropane nitrile. However, L, which is a target product of higher purity,
-Threonine is preferably obtained in two steps: first reducing the aldoxime and then converting the resulting reduction product into IJ. That is, the above aldoxime is mixed with water and a polar solvent such as methanol or ethanol (water/polar solvent ratio is 1/1 to 10/1).
Sodium bisulfite is then reacted with a reducing agent to separate the resulting white crystalline product.Then, the crystalline product is washed with ethanol, ether, etc., suspended in water, and added with cyanide. A curing agent is added and reacted to obtain 1-amino-2-hydroxypropanenitrile.

In the present invention, the 1-amino-2-
An aqueous solution K of hydroxypropanenitrile, for example, concentrated hydrochloric acid, is added and refluxed at a temperature of about 100° C. for hydrolysis.

Since an aqueous solution of L-threonine is obtained by this hydrolysis, the pH of this aqueous solution is adjusted to 6.0 to 6.7 VCIM using dimethylamine, for example.

When the mixture is adjusted, L-threonine crystals are precipitated.

Since the crystals of this thi-threonine contain D-allothreonine, a recrystallization method is applied to separate and collect L-threonine. When D-allothreonine is racemized, for example, by heating in the presence of an acid or alkali, it easily forms a mixture with KL-threonine, so the above operation of separating L-su1/onine and racemization are repeated. As mentioned above, the present invention has the advantage that L-threonine can be produced with high purity and high yield from inexpensively available starting materials. There is.

EXAMPLES The present invention will be specifically described below with reference to Examples.

Example This example shows an example in which propylene oxide obtained from propylene using microorganisms was used as the starting material.

Production of propylene oxide: In a 500 ml Sakalo flask, add NBG medium (Lab-Remco Bauder (Okinoid) 10.9. Bacteriological Peptone (Oxoid) 1011, NaC
A! 5 g of glucose and 10 g of glucose to a total volume of 1000 ml by adding deionized water to make a total volume of 1000 ml, a liquid medium (100 m) obtained by heating and sterilizing the mixture was inoculated with Nocardia coralina B, 30
'C for 17 hours with shaking.

The bacterial cells produced by the above culture were washed twice with 20 ml each of 100 molar phosphoric acid solution, and then incubated with reaction medium (K2I (Po, 1.74, !9, MgS).
O3・7H, 01, 5y, FθSO, ◆7H20501
119 was dissolved in 1000 bar of deionized water and the pH was adjusted to 8.
OK-adjusted solution) K the bacterial cells to a bacterial concentration of 9.5 jj/l
A bacterial suspension was prepared.

The bacterial suspension Loom/ prepared as described above and the antifoaming agent Disform CC-222■, 2at manufactured by NOF were placed in a glass reaction tank with an inner diameter of 28N and a height of 400mm, and the mixture was poured from the bottom of the reaction tank. A mixed gas consisting of 20% propylene and 80% air is passed through the glass sintered body at 3001 nI per minute!
Adjust the pH to IN H2SO, or l
120 hours 30 while adjusting to 7.2 from NNa0HK
The reaction was carried out at ℃. Propylene oxide produced by the reaction was continuously taken out of the system.

The content of R-configuration in the propylene oxide thus obtained was measured by applying an optical rotation measuring method and was found to be 89.5% by weight.

Synthesis of L-threonine: 51-volume three-loaf flask equipped with a stirrer (with 500 ml dropping funnel and cooling tube) K29 Hgt% ammonia water 4
.

After the above dropwise addition was completed, the temperature of the contents of the flask was raised to room temperature (approximately 20°C) while stirring to complete the reaction. After the reaction was completed, the reaction mixture was distilled to obtain β-aminoisoprobanol 3409 as a fraction with a boiling point in the range of 159 to 161°C.

β-Aminoisopropatool 7 thus obtained
5g (1 mol) and sodium tungstate (Na2W
An aqueous solution of O4) s 9 y (0.2 mol) dissolved in 100 - water was placed in a flask, and a 2'8% hydrogen peroxide aqueous solution 243I+It (2 mol) was added dropwise to this with stirring, during which time the reaction occurred. The flask was cooled so that the temperature did not exceed 15°C.

After continuing stirring for 30 minutes after the above dropwise addition, 3001d of ethanol was added to the reaction product in the flask, and then 230g (2.2 mol) of sodium bisulfite was further dissolved in a mixed solvent of 400ml of water and 300ml of ethanol. The resulting solution was added and left at room temperature for 2 days.

The crystals precipitated by the above-mentioned standing were separated, washed with water, ethanol and ether in this order, and then dried to obtain a crystalline product of 253I.

Next, an aqueous solution of 149 g (0.5 mol) of sodium cyanide (NaCN) dissolved in 1,004 mol of water was added to the crystalline product, and after standing overnight, the mixture was heated to 100°C. 650 g of concentrated hydrochloric acid was added to the reaction solution and allowed to flow for 2 hours. Next, barium chloride (BaCl24
H20) An aqueous solution of 29311 (1.2 mol) dissolved in hot water was added, and the resulting precipitate was filtered off. The slurry was decolorized with activated carbon and dried. This was extracted with 21 g of methanol, dried and then extracted with 1 g of absolute ethanol. Dimethylamine was gradually added to the extract while stirring, and white crystals were precipitated. The crystals were filtered, washed with ethanol, then with ether, and dried.

The threonine thus obtained consists of a mixture of DL-threonine and D-2L-allothreonine, with a yield of 49. ? Met.

This mixture contains 1 and 4 of L-threonine.
1 mol% Thea Hiro further contains L-threo=y -11
- Agent Yoshio Kawaguchi = 12 - Procedural amendment 1, Indication of case 1982 Japanese Patent Application No. 162391 2, Title of invention Process for producing L-threonine 3, Person making the amendment Relationship to the case Name of patent applicant Name: BioResearch Center Co., Ltd. 7, Subject of amendment: Specification 8, Statement of contents of the amendment is amended as follows.

(The scope of claims 11 will be amended as a separate sheet.

(2) Last line of page 3, lines 1 to 2 of page 4, line 6
Page 11 to 12, page 7, line 5, and 7 to 8, K [1-amino-2-hydroxypropanenitrile] is replaced with "1-amino-2-hydroxypropanecarbonitrile" Correct each.

2-2. Claims (1) Propylene oxide having type No. optical activity is ring-opened by reaction with ammonia to form β-aminoisopropanol, and the β-aminoisopropanol is converted into an oxime. 2-hydroxypropyl aldoxime is obtained, and the 2-human p-xypropyl aldoxime is reduced and nitrified to obtain 1-amino-2-hydroxypropane carbonitrile. - A method for producing monothreonine, which comprises hydrolyzing rubonitrile.

Claims (1)

[Claims] (1) Propylene oxide having type I optical activity is ring-opened by reaction with ammonia to form β-aminoisopropanol, and the β-aminoisopropanol is converted into an oxime to obtain 2-hydroxypropyl aldoxime. ,
L-threosui, characterized in that the 2-hydroxypropyl aldoxime is reduced and nitrified to obtain 1-amino-2-hydroxypropanenitrile, and then the obtained 1-amino-2-hydroxypropanenitrile is hydrolyzed. manufacturing method.