Preparation method of L-cystine with high light transmittance

Abstract

The invention relates to the technical field of pharmaceutical chemical preparation, in particular to a preparation method of high-light-transmittance L-cystine. The preparation method comprises the following specific steps: adding L-cysteine hydrochloride monohydrate into purified water, stirring until the L-cysteine hydrochloride monohydrate is dissolved, and stirring with inorganic alkali to adjust the pH value, so as to obtain a solution A; adding an oxidizing agent into the solution A, and reacting to obtain a solution B; cooling, stirring and crystallizing the solution B, and filtering to obtain an L-cystine crude product; and washing the L-cystine crude product with purified water, and carrying out forced air drying on a filter cake to obtain an L-cystine finished product. The reaction and crystallization are carried out in a standing state, large-crystal cystine is easily and stably prepared, and the problem that the light transmittance of cystine is reduced due to the fact that the crystal is fine and is not easy to dissolve in hydrochloric acid and the fine crystal is easy to adsorb impurities is effectively avoided. No catalyst is used, high-temperature and high-pressure reaction is avoided, reaction conditions are mild, required equipment is simple, and the method is suitable for large-scale industrial production. The method has the advantages of cheap and easily available raw materials, simple operation and few three wastes.

Description

technical field [0001] The invention relates to the technical field of pharmaceutical chemical preparation, and more particularly, to a preparation method of L-cystine with high light transmittance. Background technique [0002] L-cystine has chemical name: L-3,3'-dithiobis(2-aminopropionic acid), molecular formula: C 6 H 12 N 2 O 4 S 2， Molecular weight: 240.30, white flaky crystal or crystalline powder, very slightly soluble in water, insoluble in ethanol and other organic solvents, easily soluble in dilute acid and alkaline solution, easily decomposed in hot alkaline solution [0003] Structural formula: [0004] [0005] L-cystine was discovered in 1810 by Wollaston from bladder stones. In 1832, Berzelius named it cystine, which is a sulfur-containing amino acid, which exists in a small amount in protein and is mostly contained in keratin such as hair, fingers and claws, and can also be obtained by synthetic methods. As an important pharmaceutical intermediate,...

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Problems solved by technology

[0007] The Chinese patent literature publication number is CN1081917221A, and the patent name is " method for purifying L-cysteine ​​" and comprises the following steps: (1) hydrolysis (2) neutralization (3) decolorization (4) refining, the method prepares L-cysteine The raw material of amino acid is hair extract, which is cheap and easy to obtain, but the disadvantages of this method are: long reaction time, cumbersome post-treatment, many wastes, and low extraction efficiency; therefore, it cannot meet the needs of industrial production

The preparation of this method can obtain L-cysteine ​​with high purity and high yield, but the disadvantages of this method are: the need to use ion exchangers, and the post-treatment of a large amount of hydrochloric acid is cumbersome, and there are many wastes

The disadvantage of this method is that it uses high temperature and high pressure technology and ultrasonic equipment, which requires high equipment, poor safety, and is not suitable for industrial production.

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