Study On Preparation Of Anisaldehyde And Solid Glyoxylic Acid By Ozonolysis Process

Anisaldehyde is an important perfume as well as a fine chemical intermediate, it iswidely utilized as intermediate of drugs and ingredient of pesticides etc. In this paper,the process for preparation of anisaldehyde by ozonolysis method using anethole asraw material were studied. The obtained optimum conditions were using the mixture ofacetic acid and cyclohexane as solvent, m(anethole):m(solvent)=1:3, m(acetic acid):m(cyclohexane)=1:4, ozonolysis temperature 15～20℃, ozonolysis time 140min; usingNaHSO₃ as reductant, n(anethole):n(reductant)=1:1.1, reduction time 60min, reductiontemperature 80℃. The obtained crude anisaldehyde was distalled under 1.6kPa and134～137℃. Under above conditions, the yield of crude anisaldehyde was≥95.0%and the final yield of anisaldehyde was≥84.6% with the purity over 98.2%.Moreover, the using rate of ozone was 50% and reaction order for anethole was first inozonolysis process. The structure of obtained product was characterized by FT-IR.Glyoxylic acid is an important fine chemical intermediate and biochemicalreagent. It is of both the property of aldehyde and the property of carboxyl acid, so it iswidely used in many fields. In this paper, the synthesis of solid glyoxylic acid wasstudied in lab scale using maleic anhydride as raw material, water as solvent and ozoneas oxidant. The obtained optimum conditions were hydrolysis temperature 70℃,hydrolysis time 2.0h, reactant concentration 30%, ozonolysis temperature 20～25℃,ozonolysis time 8h, vacuum distillation temperature 50～55℃at 1.6kPa. And theobtained optimum crystallization conditions were temperature 12℃, crystallizing time12h. Under above conditions, the yield of product was up to 95.6% with the purity97.7%. Moreover, a method for measuring the purity of crystalline glyoxylic acid bychemicai titration was studied and obtained with good verification result. This method has not been reported in literature. The structure of obtained product was characterizedby FT-IR.Based on the results obtained in lab test, the pilot test for the synthesis of solidglyoxylic acid was studied. The obtained optimum conditions of pilot test werehydrolysis temperature 70℃, hydrolysis time 2.0h, ozone air current 40m³/h,ozone contentration 78.29mg/L, ozone distribution board aperture 50μm,ozonolysis temperature 20～25℃, ozonolysis time 41h. Under above conditions, theconversion of maleic anhydride was nears to 100%, the yield of product was up to95.2% with the purity 97.7%. The effects of ozone distribution board aperturesize, ozone air current on the reaction results and ozone using ratio were emphasisexamined in this paper. The results were better and ozone using ratio≥76.2%when ozone distribution board aperture 50μm, ozone air current 40m³/h. Theresults obtained in pilot test was almost the same as that obtained in lab test. To ourknowledgd, there is no report in literature about the study on pilot test for synthesis ofsolid glyoxylic acid using maleic anhydride as raw material, water as solvent andozone as oxidant.