Study On Esterification Reaction Of Aromatic α-Keto Acid

Aromatic a-keto acid and its ester is an important intermediate in organic synthesis. It’s widely used in pharmaceutical synthesis, pesticide, functional skin care products, biological metabolism and functional materials. In this paper, the esterification of benzoylformic acid and methanol is the typical reaction. The comparison of Hβ、HY、HZSM-5、SAPO-34、MCM-41 on the catalytic synthesis of methyl benzoylformate was studied, and SO₄^2-/SnO₂-HY was also used as catalyst for the synthesis of methyl benzoylformate.It is found that molecular sieve have a better catalytic activity on esterification. The yield of esterification was improved, and the catalytic activity of HY was the highest. The synthesis condition had been optimized and discussed by the yield of esterification catalyst by HY. The best condition were as following:cyclohexane used as water carrying agent, reaction for 5 h in the temperature of 78℃, molar ratio of benzoylformic acid and methanol is 1:2.5, HY catalyst 0.08 g. Under this condition, the yield can reach 97.4%. And the catalyst have a better stability, it can be reused more than 5 times.SO₄^2-/SnO₂-HY was used to catalyze the synthesis of methyl benzoylformate. The preparation condition were optimized and discussed by the yield of esterification. The best condition were as following:pH=8, hydrolysis time equal to 2 h, the concentration of H2SO4 was 3 mol/L, burning temperature equal to 500℃, activation time equal to 4 h. Under this condition, the catalyst was used in the synthesis of methyl benzoylformate and the synthesis process was optimized, the life of the catalyst was investigated. The best condition were as following:reaction for 5 h in the temperature of 78℃, molar ratio of benzoylformic acid and methanol is 1:1.5, the content of catalyst 6%. The best yield was 98.1%. The catalyst can be reused for 4 times. At last, the production of esterification was analyzed by HPLC,IR and 1HNMR and the result showed it was methyl benzoylformate.