The invention relates to a process for synthesizing
trigonelline hydrochloride from
dimethyl carbonate and nicotinic acid. The process comprises the following steps of: reacting the nicotinic acid and the
dimethyl carbonate in the presence of a catalyst K2CO3, after completely reacting, filtering and removing the K2CO3 and other undissolved substances, and decompressing, concentrating and removing the
solvent, namely the
dimethyl carbonate; dissolving the remained
solid by using 4 mol / L of
hydrochloric acid, adjusting pH to 2-3, and decompressing and removing the
solvent; dissolving the remained
solid by using proper absolute
methanol, and filtering and removing the undissolved substances after standing; concentrating and crystallizing the filtrate, filtering to obtain
solid, re-crystallizing the solid by using
ethanol with a certain concentration, and obtaining the product. According to the process disclosed by the invention, the green methylated
reagent, namely the dimethyl
carbonate, for substituting the methylated reagents, such as dimethyl sulphate,
halomethane and the like, which are poisonous on human bodies and risky on the environment, is reacted with the nicotinic acid; the green
trigonelline hydrochloride is synthesized; the process condition is simple; the conversion rate of the nicotinic acid is high; the average substitution degree of the product is high; and the method is environment-friendly.