Method for synthesizing 2-acetyl pyrazine

Abstract

The invention relates to the field of chemical organic synthesis, in particular to a method for synthesizing 2-acetyl pyrazine. The method comprises the following steps: (1) preparation of a Grignardreagent: adding metallic magnesium, an anhydrous polar solvent, elemental iodine and methyl chloride into a pressure vessel, and stirring to prepare the Grignard reagent; (2) adding reaction: adding 2-cyanopyrazine, tetrahydrofuran, a catalyst and the Grignard reagent into a reactor, and refluxing and condensing to obtain an intermediate product; (3) hydrolyzing: adding water into the intermediateproduct, adjusting the pH value by using dilute acid, stirring and refluxing, and then adjusting to be neutral; and finally, extracting with toluene; and (4) aftertreatment: desolventizing a tolueneextracting solution, dissolving desolventized solid with ethanol, adding activated carbon, filtering, and cooling to obtain a white solid P1; and recrystallizing with the ethanol to obtain the 2-acetylpyrazine. According to the method, a monovalent copper salt is adopted as a catalyst, the yield of 2-acetylpyrazine is increased to be 69%, meanwhile, the reaction speed is increased, and the synthesis reaction temperature is also reduced.

Description

technical field [0001] The invention relates to the field of chemical organic synthesis, in particular to a method for synthesizing 2-acetylpyrazine. Background technique [0002] In 1928, compounds such as methylpyrazine were only detected from coffee. So far, pyridine compounds can be detected in natural foods and foods in the process of boiling, frying and fermenting. 2-Acetylpyrazine is a colorless to slightly yellow solid crystal, easy to absorb moisture, and needs to be sealed and stored in a cool place. It is almost insoluble in water, soluble in ethanol and other organic solvents, and has a melting point of 76-78°C. Acetyl pyrazines have the smell of popcorn and were later detected from sesame oil, peanuts, hazelnuts, almonds, coffee, and have been used as spices in many fast foods. [0003] There are mainly three methods for the synthesis of 2-acetylpyrazine: oxidation method, metal reagent method and multi-step method. [0004] (1) Oxidation method. As early as ...

AI Technical Summary

Problems solved by technology

The main disadvantage of the organolithium reagent method is that the organolithium reagent is expensive, flammable and explosive, and the reaction needs to be carried out at low temperature

The multi-step method usually requires more than 4 steps of reaction to be synthesized, the steps are cumbersome and the operability is poor

[0007] Although the Grignard reagent method is safer to operate, it also needs to be carried out at low temperature, and the yield is difficult to improve