Production process of DL-cystein

Details Production process of DL-cystein Production process of DL-cystein

1983-01-14

1984-06-05

Shippen, Michael L.

Organic compounds -- part of the class 532-570 series

Organic compounds

Carboxylic acids and salts thereof

260455B, C07C149247

Patent

active

044530080

DESCRIPTION:

BRIEF SUMMARY
DESCRIPTION

1. Technical Field
This invention relates to a novel process for producing cystein. More specifically, it relates to a process for producing DL-cystein by reacting a .beta.-halogenoanaline with a trithiocarbonate and then decomposing the resulting mono(aminocarboxyethyl) ester of the trithiocarbonate with an acid.
2. Background Art
Cystein is a sulfur-containing amino acid and has found utility as a food additive and for the production of pharmaceutical products, cosmetic products and the like. Conventionally, it has been industrially produced by the electrolytic reduction of cystine extracted from naturally-occurring sources such as human hair.
A wide variety of processes have heretofore been proposed to achieve a chemical synthesis of cystein. Under the circumstances, they are generally accompanied by such drawbacks that they require long reaction steps and complex operations. In addition, they are not fully satisfactory with respect to their production yields. Among such processes, there have been known, as processes for producing cystein from a .beta.-halogenoalanine, (1) to react .beta.-chloroalanine with barium hydrosulfide [Ber., 41, 893 (1908)]; (2) to react .beta.-chloroalanine with mercaptobenzyl to obtain .beta.-benzylthioalanine and then reducing the resultant compound with sodium in liquid ammonium [J. Biol. Chem., 179, 529 (1949)]; and (3) to block the amino group and carboxyl group of .beta.-chloroalanine with protecting groups and react the thusprotected compound with thioacetic acid, followed by its hydrolysis [Nippon Kagaku Zasshi, 89, 716 (1968)]. However, the above process (1) is liable to induce the by-production of sulfides, disulfides and the like which are difficult to remove and is thus accompanied by a shortcoming of poor yield. On the other hand, the above processes (2) and (3) each requires lengthy reaction steps and their operations are complex and cumbersome. Thus, their overall yields are considerably low and they have little industrial value. It has recently been proposed to first react .beta.-chloroalanine with a thiosulfate to obtain S-sulfocystein and then subject it to hydrolysis under acidic conditions to produce cystein (Japanese Patent Laid-open No. 164669/1980). It seems to be difficult to expect high yield for cystein because the preparation step of S-sulfocystein is carried out under heated, refluxing conditions despite of the poor thermal stability of .beta.-chloroalanine in the form of a solution.


INVENTION DISCLOSURE

An object of this invention is to provide a process for producing cystein with high yield.
Another object of this invention is to provide a process for producing cystein under mild reaction conditions through simple reaction operations.
According to this invention, there is thus provided a process for producing DL-cystein, which process comprises reacting a .beta.-halogenoalanine with a trithiocarbonate and then subjecting the resulting mono(aminocarboxyethyl) ester of trithiocarbonate to acid decomposition.


BEST MODE FOR CARRYING OUT THE INVENTION

The process according to this invention comprises reacting a .beta.-halogenoalanine with a trithiocarbonate to obtain the mono(aminocarboxyethyl) ester of the trithiocarbonate and then decomposing the resultant mono(aminocarboxyethyl) ester of the trithiocarbonate with an acid into cystein.
The starting material used in the process according to this invention, i.e., a .beta.-halogenoalanine is an alanine derivative whose carbon atom at the .beta.-position is substituted by a halogen atom. As such a .beta.-halogenoalanine, may be metioned for example .beta.-chloroalanine or .beta.-bromoalanine. It may be readily produced by subjecting an azilidine-2-carboxylate to a ring-opening reaction with a hydrohalogenic acid such as hydrochloric acid or hydrobromic acid in an aqueous reaction medium or by converting its corresponding halogenoacetoaldehyde into its sulfite-addition product, then reacting it first with ammonia and then with hydrocyanic acid to obtain an .alpha.-amino-.beta.-halogenop

REFERENCES:
patent: 2710304 (1955-06-01), Opfermann
patent: 3646094 (1972-02-01), Brooks
patent: 3897480 (1975-07-01), Mita

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