Abstract: D,L-Homocystine is obtained by treating an aqueous solution of the disodium salt of D,L-homocysteine having a concentration between 0.4 and 1.6 moles/l and an initial pH between 7.0 and 8.0 under vigorous stirring with at least the equivalent amount of an aqueous solution of hydrogen peroxide and after the end of the oxidation adjusting the pH to about 5.3. The hydrogen peroxide solution can be employed with a concentration between 20 and 60 weight percent.

Abstract: D,L-Homocystine is obtained by introducing molecular oxygen into an aqueous solution of the disodium salt of D,L-homocysteine having a concentration between 0.8 and 1.2 moles/l and an initial pH between 7.0 and 8.0 in the presence of a catalytic amount of iron(III) ions until there is no longer an increase in pH and subsequently adjusting the pH to about 5.3 with stirring.

Abstract: 5-Arylidene hydantoins are produced by condensation of an aromatic aldehyde with hydantoin in the presence of at least one ammonium salt of an aliphatic or aromatic carboxylic acid. The desired 5-arylidene hydantoins are obtained in high yields.

Abstract: Methionine and potassium are recovered from the recycling solution of the potassium carbonate-methionine process by concentrating the mother liquor after the methionine precipitation and with cooling carbonating the mother liquor.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Malononitrile is prepared by the short time high temperature reaction of gaseous acetonitrile and cyanogen chloride in the molar ratio of acetonitrile to cyanogen halide of above 1 characterized in that the well mixed reaction components are reacted at an average temperature below 800.degree. C. and the reaction is quenched to condense acetonitrile and malononitrile by introducing a cooling medium into the reaction system.

Abstract: 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.

Abstract: Finely divided solid cyanuric chloride is produced by feeding a jet of liquid cyanuric chloride into a separatory container, cooling the liquid cyanuric chloride with recycling inert gases to such an extent that the cyanuric chloride is separated in crystalline form, washing the thereby warmed cyanuric chloride vapor or dust containing gases free of cyanuric chloride in countercurrent flow with an inert liquid that is a good solvent for cyanuric chloride in a washing column connected to the outlet side of the separatory column, thus simultaneously cooling the gases, and subsequently again returning the gases to the separatory container, while the temperature of the cyanuric chloride containing washing liquid which has increased in the washing process is again brought to the original temperature by leading it in the cycle over a heat exchanger and spraying the inside of the pipe connected to the separatory container and leading to the washing column constantly with the washing liquid while dividing a partial s

Abstract: Cyanogen is prepared by passing hydrogen cyanide together with hydrogen peroxide into a solution of copper(II) bromide, chloride, cyanide, nitrate, or sulfate containing ferric ions that is maintained at a temperature between 0.degree. and 100.degree. C.

Abstract: Methionine is stabilized by adjusting the pH to the range from 3 to <5. The source of the hydantoin is preferably 5-(beta-methylmercaptoethyl)-hydantoin.