Preparation method of metformin hydrochloride

Abstract

The invention discloses a preparation method of metformin hydrochloride. The preparation method is characterized by using dicyandiamide and dimethylamine hydrochloride as raw materials, feeding the materials in a mole ratio of (1:1)-(1:1.2), using N,N-dimethylacetamide or dimethyl sulfoxide 2-4 times dicyandiamide by weight as a solvent, and reacting for 4-8 hours at 140+ / -5 DEG C to prepare a crude metformin hydrochloride product; recrystallizing the crude product with ethanol, regulating the pH value to be 5-6, decoloring the crystal, cooling the crystal to minus 10-0 DEG C while stirring, precipitating the crystal, obtaining a refined metformin hydrochloride product through filtering and drying, and recovering the solvent from filtrate. The qualified product has yield of 80-85% and high purity. The preparation method has the advantages that as the selected reaction solvent has a relatively high boiling point, the recovery rate of the solvent is high; the phenomenon of material surging can be effectively avoided, so that the preparation method has the advantages of mild reaction conditions, simplicity in operation and high safety.

Description

technical field

[0001] The invention belongs to the field of medicine and chemical industry, and in particular relates to a preparation method of metformin hydrochloride. Background technique

[0002] Metformin Hydrochloride is a biguanide antihypertensive drug. More than 50 years of clinical use have proved that Metformin has a good hypoglycemic effect and safety.

[0003] Metformin hydrochloride can effectively control the weight of patients while lowering blood sugar, and reduce cardiovascular complications such as myocardial infarction in patients with type 2 diabetes. In addition, the price of metformin hydrochloride is low; it can be used in combination with sulfonylureas, glitazones and insulins; it is administered orally and is convenient and quick to take.

[0004] At present, the synthetic methods of metformin hydrochloride mainly contain dry method and wet method. The dry method is the melting method, which is widely used. However, the initial and later stages...