Deutsche Gold- Und Silber-scheideanstalt Vormals Roessler

Alfred Maierhofer

Hans B Wagner

Theodor Lussling

Heribert Offermanns

Herbert Klenk

Paul Scherberich

Tryptophane and tryptophane derivatives are purified by treating them in an inert solvent at a temperature between about 20.degree. C. and the boiling point of the mixture with a salt of dithionous acid. Preferably there is used as solvent a mixture of water and a lower aliphatic carboxylic acid. Normally a single treatment results in a pure, colorless, satisfactory product.

Process for the purification of tryptophane and derivatives of

The process described in Klenk U.S. Pat. No. 4,113,773 is improved by employing alkali metal cyanide in which at least half of the alkali metal cyanide has a particle size below 0.4 mm and the remainder has a particle size below 1.0 mm.

Process for the production of benzoyl cyanide (I)

Benzoyl cyanide is made from benzoyl chloride and an alkali metal cyanide in a two phase system comprising water and an inert organic solvent which has only slight miscibility with water in the presence of a tertiary amine and hydrogen cyanide.

Process for the production of benzoyl cyanide (IV)

Very pure S-carboxymethyl-L-cysteine is prepared by reacting L-cystine in liquid ammonia with metallic sodium to form the disodium salt of L-cysteine, evaporating the ammonia, reacting the disodium salt of L-cysteine with an aqueous solution of chloroacetic acid and precipitating the S-carboxymethyl-L-cysteine formed by acidifying the reaction mixture. There is employed 0.1 to 10 weight percent of a reducing agent based on the chloroacetic acid.

Process for the production of high purity S-carboxymethyl-L-cysteine

2-Hydroxy-4-methyl valeric acid and its salts are useful as sweeteners. The preferred sweeteners are the sodium and potassium salts.

Sweet material

Benzoyl cyanide is made by reacting benzoyl chloride with an alkali cyanide in the presence of a carboxylic acid nitrile and a copper (I) salt at a temperature of about 50.degree. to 160.degree. C.

N-acetyl-L-methionine is prepared by reacting L-methionine with acetic anhydride in the presence of aqueous alkali at a temperature between 20.degree. and 60.degree. C. at a pH between 6.5 and 10. Preferably, there are used 1.05 to 1.70 moles of acetic anhydride per mole of L-methionine.

Process for the production of N-acetyl-L-methionine

3,6-BIS-(2-METHYLMERCAPTOETHYL)-2,5-PIPERAZINEDIONE IS PREPARED FROM 5-(2-METHYLMERCAPTOETHYL)-HYDANTOIN IN THE PRESENCE OF WATER AT 100.degree. TO 200.degree.C. at elevated pressure.

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Allensbach, Germany

Alfred Maierhofer