- Method for preparing L-asparaginic acid disodium
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The invention discloses a method for preparing L-asparaginic acid disodium. The method comprises the following steps of performing a reaction at the temperature of 70-80 DEG C by using sodium carbonate or sodium hydroxide, and L-asparaginic acid as raw materials, and by using water as a solvent, after the reaction is finished, adjusting the pH value of reaction liquid to 9.0-12.0, decoloring the reaction liquid, performing filtration, performing concentration until the Baume degree of a solution is 40-45 degree Be, and reducing temperature; transferring the solution after temperature reduction is completed to a vacuum freeze drier, maintaining the pressure of the vacuum freeze drier to be 20-40Pa, performing pre-freezing at the temperature of minus 30 to minus 20 DEG C for 2-4h, and then maintaining the temperature to be at minus 25 to minus 15 DEG C for 3-5h; and drying materials after vacuum freeze-drying at the temperature of 70-80 DEG C for 3-6 hours, so as to obtain L-asparaginic acid disodium products. According to the method disclosed by the invention, an organic solvent is not used, so that the safety coefficient of production environment is increased; and the products are free from solvent residues, so that the quality of the products is improved, and the water content is easy to control.
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Paragraph 0019; 0020; 0021; 0022; 0023; 0024
(2017/01/19)
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- METHODS FOR PRODUCING POLYASPARTIC ACID PRECURSOR POLYMER AND POLYASPARTIC ACID SALT
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Disclosed are a method for producing a polyaspartic acid precursor polymer by polymerization using at least one kind selected from a product obtained from maleic anhydride and ammonia and, maleamic acid as a monomer, wherein at least part of carboxyl groups in the monomers are a tertiary amine salt; and an industrially inexpensive and simple method for producing a polyaspartic acid salt by treating the polyaspartic acid precursor polymer obtained by this method with a basic aqueous solution.
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- COMPOSITIONS AND METHODS OF MAKING A PHOTOACTIVE AGENT
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An improved two stage reaction process for production of mono-L-aspartyl chlorin e6. In a first stage, the activation reaction between chlorin e6 and a carbodiimide produces a previously unknown anhydride in an activation reaction product. This reaction product is purified to remove a significant proportion of the precursors of di-L-aspartyl chlorin e6. The purified activation reaction product contains a higher concentration of the previously unknown anhydride. This purified reaction product is used in a second stage: a coupling reaction of the purified activation reaction product with aspartate. The coupling reaction produces a coupling reaction product that has significantly reduced di-L-aspartyl chlorin e6 concentration. This reduced di-L-aspartyl chlorin e6 concentration facilitates purification of mono-L-aspartyl chlorin e6 from the coupling reaction mixture.
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Page/Page column 34
(2008/06/13)
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