Study On Preparation Of Methyl (Ethyl)vanillin By Solid Glyoxylic Acid

Vanillin is a broad spectrum spice,which is mainly two kinds of vanillin and ethyl vanillin.They are widely used in food,chemical,pharmaceutical industries and other fields.From now,we have developed a variety of synthesis about vanillin,but most of processes exist serious pollutions,high costs,backward technology and not high yield.3-Methoxy-4-hydroxylmandelic acid sodium as intermediate product of vanillin was prepared by solid glyoxylic acid,guaiacol and sodium hydroxide.The effects of the factors such as raw material ratio,reaction time,reaction temperature,concentration of NaOH on reaction results were investigated.Results showed that n(solid glyoxylic acid): n(guaiacol): n(NaOH)=1:1.2:2.4,reaction temperature was 35?,reaction time was 6h,n(NaOH)=2mol/L.Under above conditions,the product yield was more than 81%.The structure of the product was characterized by FI-IR and ~1H NMR.Vanillin was synthesized by 3-methoxy-4-hydroxylmandelic acid sodium as raw material,the effects of the factors such as catalyst type,catalyst amount,basicity of the reaction system,reaction time,reaction temperature and the pressure of oxygen on reaction results were investigated.Results showed that copper acetate as catalyst,n(copper acetate): n(3-methoxy-4-hydroxylmandelic acid sodium)= 1: 1.5,reaction system pH =13,the reaction time was 8h,the reaction temperature was 93?,p(O2)= 2.0MPa.Under above conditions,the product yield was 86%.The structure of the product was characterized by FI-IR and ~1H NMR.Vanillin was refined by recrystallization,the effects of the temperature,the solvent type and the mount of activated carbon were investigated.Under the synthesis conditions as follows: ethanol-water mixture of which mass ratio of ethanol to water was 3:1,the amount of activated carbon was 3% and the temperature was 5?-65?.Under above conditions,the yield of product was 87%.The purity of obtained product was characterized by HPLC,the purity was 98.8%.3-Ethoxy-4-hydroxylmandelic acid sodium as intermediate product of ethyl vanillin was prepared by solid glyoxylic acid,ethyl guaiacol and sodium hydroxide.The effects of the factors such as raw material ratio,reaction time,reaction temperature,concentration of NaOH on reaction results were investigated.Results showed that n(solid glyoxylic acid): n(ethyl guaiacol): n(NaOH)=1:1.2:2.4,reaction temperature is 50?,reaction time is 6h,n(NaOH)=2mol/L.Under above conditions,the product yield was 80%.The structure of the product was characterized by FI-IR and ~1H NMR.Ethyl vanillin was synthesized by 3-ethoxy-4-hydroxylmandelic acid sodium as raw material,the effects of the factors such as catalyst type,catalyst amount,basicity of the reaction system,reaction time,reaction temperature and the pressure of oxygen on reaction results were investigated.Results showed that copper acetate as catalyst,n(copper acetate): n(3-ethoxy-4-hydroxylmandelic acid sodium)= 1: 1.5,reaction system pH =13,the reaction time was 8h,the reaction temperature was 85?,,p(O2)= 2.0MPa.Under above conditions,the product yield was 84%.The structure of the product was characterized by FI-IR and ~1H NMR.Ethyl vanillin was refined by recrystallization,the effects of the temperature,the solvent type and the mount of activated carbon were investigated.Under the synthesis conditions as follows: ethanol-water mixture of which mass ratio of ethanol to water was 3:1,the amount of activated carbon was 3% and the temperature was 5?-65?.Under above conditions,the yield of product wasmore than 88%.The purity of obtained product was characterized by HPLC,the purity was 98.7%.