Loading patent…
AssigneeDegussa AG
InventorsHans-Albrecht Hasseberg, Klaus Huthmacher, Stephan Rautenberg, Heinrich Petsch, Horst Weigel
Estimating the term…
The direct saponification of methionine nitrile obtained from methylmercaptopropionaldehyde, prussic acid and ammonia gives low yields, catalyst and educt losses and unwanted side-products. The aim of the invention is therefore to provide a method which can be carried out without isolating the intermediate products, in particular continuously, and with low losses. The ketone used is recovered in high yields after amide saponification since this liberates the ketone from side-products. In order to recover the ammonia, it is necessary for the ammonia to be substantially freed of ketone, the mixture of ammonia, ketone and water obtained being separated under pressure in a separation column. When the amide is saponified at .gtoreq.160.degree. C., amide concentrations of less than 25% by wt. are preferred. Methionine nitrile is produced by treatment with at least 4 equivalents of .gtoreq.50% by wt. ammonia at between 40.degree. and 80.degree. C./or between 5 and 60 min. Cyanide residues are destroyed by heating to over 150.degree. C. Methionine is of particular use as a feedstuff, in particular in aqueous solution.
In process for the production of methionine or a salt thereof by hydrolysis of methionine nitrile to methionine amide in the presence of a ketone, followed by saponification with a base to form a crude methionine product mixture wherein the improvement comprises simultaneously drawing off ammonia, ketone and water at a temperature of .gtoreq.85.degree. C. by application of a vacuum or vacuum or by distillation either during and/or after saponification of the amide.
In process for the production of methionine amide, methionine or a salt thereof by the reaction of methylmercaptopropionaldehyde (MMP) with hydrocyanic acid and ammonia or of the corresponding cyanohydrin (CH) with ammonia or a mixture of MMP, CH, hydrocyanic acid and ammonia to form methionine nitrile, followed by hydrolysis of the nitrile in the presence of a ketone to the amide, optionally followed by saponification of the amide, separation of the excess ammonia and at least partial return of the separated excess ammonia to the nitrile synthesis stage, wherein the improvement comprises substantially removing the ketone from the ammonia before recycling separated ammonia to the nitrile synthesis stage.
In process for the separation of ammonia from an ammonia/ketone/water mixture wherein the improvement comprises feeding the mixture into a central region or a lower half of a column, maintaining the column at a pressure of 1 to 20 bar above atmospheric and the bottom temperature at 100.degree. to 200.degree. C. and drawing off the ketone, water and optionally small quantities of ammonia from the sump.
In process for the production of methionine amide, methionine or a salt thereof by the hydrolysis of methionine nitrile to methionine amide in the presence of a ketone, optionally followed by saponification with a base, wherein the improvement comprises hydrolyzing the nitrile in the presence of 15 to 50 eq of H.sub.2 O, 0.2 to 2 eq of ketone, 0.1 to 1.1 eq of hydroxide and 1 to 7 eq of NH.sub.3, in each case relative to the nitrile, and at a temperature of 10.degree. to 30.degree. C. and a reaction time of 10 to 90 minutes.
In a process for the production of an amino acid or a salt thereof by the reaction of an appropriate aldehyde with hydrocyanic acid and ammonia or by the reaction of a corresponding aldehyde with hydrocyanic acid followed by a reaction with ammonia to the nitrile of the amino acid, hydrolysis of the nitrile of the amino acid to the amide of the amino acid and subsequent saponification with a base, wherein the improvement comprises saponifying at a temperature of above 150.degree. C. for up to 40 minutes until the cyanide content of the solution has been reduced to below 10 ppm, relative to a 40 wt. % amino acid solution.
Dependencies are inferred from the claim text.