DE1668959A1 - Production of alpha-aminocarboxylic acids - Google Patents

Description

β. mb H. CHEMICAL FACTORY

DARMSTADT

Pat. Dr.B / RS / 10

Production of oc-aminocarboxylic acids

It is known to produce ^ aminocarboxylic acids in such a way that one or an aldehyde or ketone cyanohydrin, an equimolar Mixture of a carbonyl compound and hydrocyanic acid in aqueous solution with ammonia and carbonic acid at a Reacts temperature above 100 ° C under pressure and isolates the α-aminocarboxylic acid formed «In this process is the Decomposition of the cyanohydrins into carbonyl compounds and hydrocyanic acid or »the decomposition of the aminonitrile formed as an intermediate product into ammonia, carbonyl compounds and hydrocyanic acid, the in turn z, T, is hydrolyzed to ammonium formate, cannot be avoided, - Furthermore, it is known a-aminocarboxylic acids to produce by hydrolysis of hydantoins. It is well known that hydantoins are obtained in a simple manner by reacting Cyanohydrins and ammonium carbonate or with the help of a number other method, about the E, Ware in "! Marriage Chemistry of the Hydantoins ", Chem. Rev, 46, p. 441 ff. (1950) in detail has reported »E. Ware also describes the possibilities of saponifying hydantoins to ot-aminocarboxylic acids * as suitable Hydrolyzing agents are barium hydroxide, aqueous ammonium sulfide and acids such as sulfuric acid and hydrochloric acid and called hydriodic acid, - In the same work with reference to Gränacher and Landolt (HeIv * Chim » Acta 10, S, 799-815 C1927]) stated that upon implementation of hydantoins with aqueous ammonia, the corresponding hydantoic acid or whose ammonium salt is formed.

The subject of the United States Patent 2,527,366 discloses a process for the production of "amino carboxylic acids by reacting

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of a hydantoin with aqueous barium hydroxide in an autoclave at temperatures above I50 ⁰ C and at the autogenous pressure that results, through subsequent precipitation of the barium as a water-insoluble salt, separation of the barium salt, crystallization of the amino acid formed and washing out of the contaminating by-products with a monohydric aliphatic alcohol » In this patent it is pointed out that the hydrolysis with ammonium hydroxide under otherwise identical conditions leads to completely unsatisfactory results, since considerable amounts of by-products are formed. When 0.04 moles of 5- (β-mercaptoethyl) hydantoin were reacted with 0.9 moles of ammonium hydroxide and 200 g of water, the inventors obtained only one yield over a reaction time of 60 minutes in an autoclave at a temperature of 155-160 ° C of 42.8 % methionine, while the reaction with 0.12 moles of barium hydroxide after a reaction time of 15 minutes produced a methionine yield of 92.8 % »- In summary, it can be stated that only the hydrolysis of hydantoins with barium hydroxide is known as a technically useful process was, whereby the laborious isolation of the aminocarboxylic acid from its barium salt had to be accepted »

It has been found that hydantoins saponify with aqueous ammonia in this way to give the corresponding amino acids let them in a pressure vessel with aqueous ammonia at temperatures between 120 and 220 ° C and the resulting autogenous pressure for more than an hour be heated. When the method according to the invention is carried out, the free amino acid is obtained in one go high degree of purity, which allows their use directly for practically all technical purposes in question.

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Particularly advantageous must be the possibility of returning the mother liquor, which remains in most cases in crystalline form and in which the by-products of the reaction, primarily amino acid amides and linear dipeptides, are dissolved, to the process and the above-mentioned Conversion of byproducts into amino acid in a second hydrolysis process · - The above-mentioned procedure of reducing the mother liquor containing byproducts and hydrolyzing them together with the aqueous solution of hydantoin and ammonia in the pressure vessel already indicates the most expedient embodiment of the new process; The reaction mixture consisting of hydantoin, ammonia and V / ater ^ vird into a reactor, _e B _e z in a print queue, is introduced and flows through the latter during a period of more than an hour "From the expanded and cooled solution deposits the formed a -Aminocarboxylic acid usually in crystallized or crystalline form and is separated from the mother liquor in the usual way. The mother liquor is fed into the pressure vessel with a fresh aqueous hydantoin-ammonia solution Ammonia can be injected in gaseous form into the aqueous hydantoin solution.

The molar ratio between hydantoin, ammonia and water to be converted can vary within wide limits. take place at temperatures between 120 - 7: 20 ° 0 . The temperature range between 14o and 180 ° C has proven to be favorable. 'The duration of the

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Implementation also depends on the hydantoin to be hydrolyzed naturally on the reaction temperature. With which as preferred The specified range of 140-180 ° C. is left in the usually about 30% aqueous ammonia for a period of 4-10 hours act on the hydantoin to be hydrolyzed.

In the following examples, a number of hydantoins are mentioned, which according to the present invention in the corresponding amino acids are transferred. The scope of the protection sought is not limited to the compounds listed as examples,

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- 5 - Example 1;

12.5 g hydantoin, 38.5 S 33- # ige ΝΗ, solution and 154.0 g water (molar ratio 1: 6: 80) are heated to 160 ° G for 6 hours in a 0.3 liter autoclave After cooling, it is filtered, evaporated to dryness in vacuo, taken up with a little water and precipitated with alcohol * After suction and drying, 7.6 g of glycine (89.0%) corresponding to 72.2 % d _# Th *

Example 2i

23.8 g of 5-methyl-5-phenylhydantoin, 61.8 g of 33% ammonia solution and 137 * 0 g of water (molar ratio 1:10:80) are heated to ΙβΟ C for 14 hours in a 0.5 l autoclave . After cooling, it is filtered, evaporated to dryness in vacuo, the residue is washed with alcohol and dried in a drying cabinet at 70 ° C. to constant weight. 14.8 g of ″ -phenyl-a-alanine (99> 6- # ig) £ 71.8 % of theory are obtained .

example

10.5 g 5 * 5- (spiro-pentamethylene) -hydantoin, 38.5 g 33- / 6ige Ammonia solution and 199.0 g of water (molar ratio 1: 12/200) are heated to 160 ° G for 6 hours in a 0.5 liter autoclave » The work-up is carried out as in Example 2.

Yield of l-amino-cyelohexanecarboxylic acid-l (99.7% Product) 4 78.4 jTd, Th.

Example 4;

14.25 g of 5-methylhydantoin, 77.0 g of 33- ^ ammonia solution and 308.0 g of water (molar ratio of 1 t 12: I60) are in accordance

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Example 2 reacted for 6 hours at 160 ° C., yield of α-alanine (96.2 % ) = 86.5% d, Hi,

Example 5 «

10.9 g of 5- (β-methylniercapto-ethyl) hydantoin, 77.0 g 33% ammonia solution and 308 g water (molar ratio 1: 24: 320) are in an autoclave for 10 hours 140 ° C heated »Work up is carried out according to the example

Yield of methionine (98.0 % ) - 72.7% d »Th,

Example 6;

16.0 g of 5,5-dimethylhydantoin, 77.0 g of ammonia solution and 508 g of water (molar ratio 1:12: 160) are heated in an autoclave at 160 ° C. for 10 hours. After working up according to Example 2, 11.4 g of α-aminoisobutyric acid (100 %) = 88.6% of theory are obtained . Th.

- 7th

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Claims (1)

Claims 1 ») Verfaliren for the production of α-Aniinocarbonsäuren by Hydrolysis of hydantoins, characterized, that on a hydantoin in a pressure vessel aqueous ammonia is brought into action at temperatures between 120 and 22i hours " at temperatures between 120 and 220 ° G longer than one 2 * ) Method according to claim 1, characterized in that the molar ratio of hydantoin: ammonia: V / water was 1: 5- ^ 0: 50-400 3o) Method according to claims 1 and 2, characterized in that that the hydrolysis takes place at a temperature of l40 - l80 ° C took place 4 ») ancestors according to claims 1 to 3, characterized in that the aqueous ammoniacal solution is one Hydantoin is forced through a coil of pipes at such a rate that hydrolysis occurs on exit of the reaction material from the reactor has practically ended, then the formed a ^ amino carboxylic acid from the cooled Solution abfic separates and the mother liquor along with fresh Implementation.sgerniseh is passed through the reactor again » 109829/1718