Abstract: In the methionine synthesis involving a hydantoin reaction in its steps, a process for recovering and reusing the useful components in the waste gas by (1) washing the waste gas generated in the hydantoin synthesis reactor with methylmercaptopropionaldehyde (hereinafter referred to as MA) and returning the washing into the MA synthesis reactor system and/or (2) washing the waste gas with an aqueous solution of a compound substantially constituted of ammonia and carbon dioxide, i.e. the starting material of hydantoin synthesis, or with the liquid reaction mixture of methionine containing hydantoin (hereinafter referred to as MH) and returning the washing into the MH synthesis reactor system.

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: Novel compounds are prepared by reacting essential or semi-essential amino acids with nitrogen-free analogues thereof, particularly alpha-keto and/or alpha-hydroxy analogues. The mixed salt reaction products are precursors of essential and semi-essential amino acids in the body, and mixtures of the salts are useful in the treatment of renal and hepatic disorders characterized by protein intolerance leading to deficiencies of various essential and semi-essential amino acids in the body. They may also be useful in the treatment of nitrogen wasting disorders and protein malnutrition. The novel compounds are generally far more palatable and soluble in aqueous solutions than the individual essential or semi-essential amino acids, nitrogen-free analogues thereof, or simple mixtures of these.

Abstract: 5-(Beta-methylmercaptoethyl)-hydantoin is hydrolyzed at superatmospheric pressure in an autoclave by heating in a mixture of (a) a hydroxide of a monovalent cation such as lithium, sodium, potassium, ammonium or alkyl substituted ammonium and (b) a hydroxide of a divalent cation such as calcium, barium or zinc.

Abstract: Methionine is prepared from 5-(beta-methylmercaptoethyl)-hydantoin at atmospheric pressure by refluxing the hydantoin with a metal hydroxide such as sodium hydroxide, potassium hydroxide, or barium hydroxide and an alkanol having a boiling point of from about 125.degree. C. to about 230.degree. C. at atmospheric pressure, preferably, a water saturated alkanol having a boiling point of from about 125.degree. C. to about 230.degree. C. at atmospheric pressure and thereafter recovering methionine.

Abstract: A process for the chemical catalytic hydrolysis of an .alpha.-aminonitrile or of one of the salts thereof, characterized in that an aqueous solution containing at least one carbonyl derivative is reacted with the said .alpha.-amine nitrile or with one of the salts thereof in the presence of hydroxide ions.

Abstract: Two optically active amino acid-mandelic acid complexes are obtained by reacting in a solvent under pH conditions of 1.0-4.0, an amino acid expressed by a general formula ##STR1## (in which R represents a methyl group, an ethyl group or a methylthioethyl group) and mandelic acid, one of the acids being an optically active substance and the other being a racemic modification, and optically resolving the resulting complexes into two diastereomers by using a solubility difference therebetween. The optically active complexes are each decomposed by means of an acid, a strongly acidic ion-exchange resin, or a weakly basic ion-exchange resin to obtain optically active amino acids or optically active mandelic acid.