Introduction of Purification Process of Guanidine Hydrochloride Solution Using Modified Coconut Shell Activated Carbon

Pharmaceutical grade guanidine hydrochloride is mainly used in the fields of protein and cell biology. It can be used to synthesize 2-aminopyrimidine, 2-amino-6-methylpyrimidine and 2-amino-4,6-dimethylpyrimidine. It is a pharmaceutical intermediate for the manufacture of sulfadiazine, sulfamethazine, sulfamethazine and other sulfa drugs, and can be used as a strong denaturant in the experiment of extracting RNA from cells. Due to the special requirements of its application field, the product has very high requirements for impurities. In addition to the conventional technical parameters such as content, melting point, pH, insoluble matter, moisture, etc., it also requires lower heavy metal content and pigment technical indicators in order to obtain High-purity pharmaceutical grade guanidine hydrochloride.

The purification of guanidine hydrochloride generally adopts the process of dissolving crude guanidine hydrochloride into an aqueous solution, and utilizing the solubility difference between impurities and products in the aqueous solution, crystallization and precipitation of solid impurities, and the process of separating guanidine hydrochloride. There are many kinds of impurities in this process, and there are also cyanamide polymers generated by side reactions. This paper introduces a process for purifying guanidine hydrochloride solution with activated carbon as adsorbent.

Specific steps are as follows:

1. Provide coconut shell raw materials, pulverize, sieve and dry the coconut shell to obtain pretreated powder.

2. Mix the coconut shell powder with the phosphoric acid solution mixed with 27-hydroxyisomango alkyd, the ratio of phosphoric acid and coconut shell powder is 0.1-0.3mol:8-10g, and the addition amount of 27-hydroxyisomango alkyd is 1:1 to 6. The above solution is impregnated for 10 to 14 hours to obtain an impregnated mixture. The impregnated mixture is placed in a muffle furnace for activation, cooling, washing, drying and grinding, the activation temperature is 480-550℃, and the activation time is 1-3 hours, and then the modified coconut shell activated carbon is obtained. The average particle size of the modified coconut shell activated carbon is 18-30 mesh.

3. A centrifugal pump is used to transport the guanidine hydrochloride solution into the activated carbon adsorption cylinder, and the flow rate and pressure are adjusted to ensure the adsorption process conditions. The operating pressure of the guanidine hydrochloride solution in the activated carbon adsorption cylinder is 0.4-0.5Mpa, and the control flow per unit cross-sectional area is 500ml/min· cm². When the modified coconut shell activated carbon in the adsorption cylinder is saturated with adsorption, the expired modified coconut shell activated carbon is renewed and disposed of harmlessly.

The appearance of the pharmaceutical grade guanidine hydrochloride product produced by the above technology is pure white, and the content of heavy metal elements in the product is less than or equal to 10ppm.

References

CN113086981A  Modified coconut shell activated carbon and its use in the preparation of pharmaceutical grade guanidine hydrochloride