Synthesis Of 2-methylpyrazine-5-carboxylic Acid And Process Optimization

2-Methylpyrazine-5-carboxylic acid is a kind of important medicinal intermediate, mainly used for synthesizing the second generation sulphonylureas hypoglycemic agent, new generation long effect blood-lipid lowering drug and the medicine used to efficiently treat bacillary phthisis.The process to synthesize 2-methylpyrazine-5-carboxylic acid using 2,5-dimethylpyrazine as raw material and potassium permanganate as oxidant was studied in this thesis. First on the base of the previous work, the optimal reaction temperature, reaction time, feeding time and the optimal feeding ratio were obtained by the method of liquid feeding. The yield of the product was 43.15%. And the purity was 96.12%. To solve the problem that the potassium permanganate has bad solubility in water, the method of solid feeding was studied and optimized. The yield reached 41.72%. And the purity was 97.75%. By comparing with once acidification method, twice acidification method gave higher purity product. To save the cost, the unreacted 2, 5-dimethylpyrazine was recycled and the yield of the product in total increased nearly 30%. And the optimal reaction temperature was 70℃, optimal reaction time was 2h and feeding molar ratio of potassium permanganate to 2, 5-dimethylpyrazine was 2. The yield of the product was above 75%. The overall yield of 2-methylpyrazine-5-carboxylic acid was 61% and the purity reached 99% after recrystallization, which was in accord with the standard of medicine intermediate and had great potential for industrial production.