摘要:
A process for the preparation of aqueous sodium methioninate solutions having a low sodium carbonate content from the crude hydrolysis mixtures obtained in the hydrolysis of 5-(.beta.-methylmercaptoethyl)-hydantoin with from 1.1 to 6 equivalents of sodium hydroxide and/or sodium carbonate, by separating off sodium carbonate monohydrate while heating, and granulates subsequently prepared from those solutions by various processes.
摘要:
The invention relates to a process for the preparation of D,L-methionine, in which carbon dioxide is fed to an aqueous potassium methioninate solution obtained by hydrolysis of 5-(2-methylmercaptoethyl)hydantoin, in order to precipitate out crude methionine, which is separated off and purified, where, for the purposes of purification, an aqueous solution of the separated-off crude methionine is prepared and subjected to a recrystallization, characterized in that the solution from which the recrystallization takes place contains potassium ions and also a crystallization additive, where the crystallization additive is a nonionic or anionic surfactant, or a mixture of different nonionic or anionic surfactants, and that the recrystallization takes place by introducing a 60 to 110° C.-hot methionine solution into a 35 to 80° C.-warm methionine suspension, the temperature of which is lower than that of the introduced solution, the temperature of the methionine suspension being maintained between 35 and 80° C. during the addition.
摘要:
Aliphatic alkanals with a water content of greater than 300 ppm which are stable in storage, and a method of improving the storage stability of these aliphatic alkanals, especially of substituted, sulfur-containing alkanals. The formation of oligomers, polymers and condensation products from elimination reactions and oxidation and the subsequent reactions of the products formed results in undesired impurities that are largely prevented by the addition of an organic acid that forms metal complexes and, optionally, alkanolamines or trialkanolamines.
摘要:
The invention relates to a process for the preparation of D,L-methionine, in which carbon dioxide is fed to an aqueous potassium methioninate solution obtained by hydrolysis of 5-(2-methylmercaptoethyl)hydantoin, in order to precipitate out crude methionine, which is separated off and purified, where, for the purposes of purification, an aqueous solution of the separated-off crude methionine is prepared and subjected to a recrystallization, characterized in that the solution from which the recrystallization takes place contains potassium ions and also a crystallization additive, where the crystallization additive is a nonionic or anionic surfactant, or a mixture of different nonionic or anionic surfactants, and that the recrystallization takes place by introducing a 60 to 110° C.-hot methionine solution into a 35 to 80° C.-warm methionine suspension, the temperature of which is lower than that of the introduced solution, the temperature of the methionine suspension being maintained between 35 and 80° C. during the addition.
摘要:
The invention relates to a process for the preparation of methionine of high bulk density, in which a mixture which comprises a compound which has a foaming action and a compound which influences the crystallization is added to the hydrolysis solution, and to the mixture itself.
摘要:
A process for the preparation of &agr;-amino acids by hydrolysis of hydantoins in the presence of water and at least one metallic oxide under conditions such that all the starting materials are completely dissolved in the water as a result of high pressure and high temperature and only one further phase is present in the reactor in addition to the metallic oxide phase.
摘要:
A process for preparing esterified chroman compounds from 2,6,6-trimethylcylohex-2-ene-1,4-dione, wherein the esterified intermediates are reacted directly to give the desired chroman derivatives without an additional purification step.
摘要:
A process is provided for the recovery of sulfuric acid from NH.sub.4 HSO.sub.4 and (NH.sub.4).sub.2 SO.sub.4 salts produced from the sulfuric acid hydrolysis of methylmercaptopropionaldehyde (MMP) cyanohydrin to produce 2-hydroxy-4-methylthiobutyric acid (MHA), which can be used as an additive in animal feed. The sulfate salts are combusted in a furnace to produce sulfur dioxide; the sulfur dioxide is contacted with an aqueous solution containing sulfuric acid and hydrogen peroxide, where the sulfur dioxide is converted into sulfuric acid. The product sulfuric acid is recovered.
摘要:
This disclosure relates to a process for preparing D,L-methionine by feeding carbon dioxide to an aqueous potassium methioninate solution obtained by hydrolysis of 5-(2-methylmercaptoethyl)hydantoin, in order to precipitate out crude methionine, which is separated off and purified. In this process an aqueous solution of the separated-off crude methionine is purified by recrystallization from a solution containing potassium ions and also a crystallization additive. The crystallization additive is a nonionic or anionic surfactant, or a mixture of different nonionic or anionic surfactants. The recrystallization occurs by introducing a 60 to 110° C.-hot methionine solution into a 35 to 80° C.-warm methionine suspension, a temperature of which is lower than that of the introduced solution, such that the temperature of the methionine suspension being maintained between 35 and 80° C. during the addition. The crystallization additive is a sorbitan fatty acid ester or a mixture of different sorbitan fatty acid esters.
摘要:
A method for the isolation of 2-hydroxy-4-methylthiobutyric acid (MHA), wherein MHA is isolated from a reaction mixture obtained by addition of hydrogen cyanide (HCN) to methylmercaptopropionaldehyde (MMP) and hydrolysis by sulphuric acid of the methylmercaptopropionaldehyde cyanohydrin (MMP-CH) thus obtained. The reaction mixture is brought into contact in a liquid/liquid extraction system with an organic solvent substantially immiscible with water, in order to form an extraction solution which contains the solvent and the MHA transferred out of the reaction mixture. By bringing the salt content of the reaction mixture, prior to the liquid/liquid extraction, to a concentration of about >50 wt. % (wt./wt.), preferably >55 wt. %, referred to the sum of the inorganic constituents of the reaction mixture, the coordinated use of energy in the total system is improved, the evaporation of strongly corrosive solutions is avoided, the efficiency of the hydrolysis step is increased and the distribution coefficients during the extraction are improved. The MHA is isolated as the extract from this extraction solution by evaporation, and may be used as animal feed supplement.