The Synthesis Of Vanillin And Its Derivative Of Eugenol

Vanillin, as a broad spectrum type of high-grade perfumes is widely used in food, tabacco and cosmetics industry. Vanillin can be synthetized. The aroma of vanillin which were synthesized from eugenol smell best and have high value. The most important chemical reactions involved in the synthetic process were isomerization of double bond and oxidation of double bond.Traditional isomerization process is using KOH as catalyst, oxidation reaction use potassium dichromate as oxidant.However,the process will produce a large number of waste. In this thesis,triiron dodecarbonyl was used to replace the traditional catalyst to synthesize isoeugenol. The RuCl2(PPh3)3 were used as catalyst for the isomerization of isoeugenol which can improve the selectivity of trans-isomer, and the synthesis route of vanillin propylene glycol acetal was studied.The isoeugenol was synthesized from eugenol. Based on screening of different types of catalysts,triiron dodecarbonyl was determined as the best one. Better conditions were determind by the experiments of different reaction time, different reaction temperature and the different amount of triiron dodecarbonyl. Through orthogonal experiment, we get the optimal conditions as follows: reaction temperature 100 ℃, reaction time 4 h, the amount of triiron dodecarbonyl1 % and the yield was 91.8 %.Structure of isoeugenol was characterized by GC-MS,FI-IR and NMR.The RuCl2(PPh3)3 complex catalyst was prepared from RuCl3·3H2O and triphenylphosphine which were studied for the isomerization of eugenol in different solvents.The polar protic solvents such as alcohol worked better in which the conversion of the isoeugenol was 98.3% with 94.1% selectivity of the trans-isomer. Effects of different factors,including reaction time, the amount of catalyst and solvent were studied in ethanol. The results show that the highest yield of isoeugenol was achieved when 0.015 mol eugenol was extracted under conditions of reaction time 3 h, catalyst 0.5 % and ethanol 300 %, the conversion of isoeugenol was 98.8 % with 94.8 % selectivity of trans-isomer.Compared with the traditional metheod, the temperature droped about 100 ℃, the reaction time was shorted and the selectivity of trans-isomer is improved. And its fragrance has improved greatly. Structure of RuCl2(PPh3)3was characterized by FI-IR, XRD and SEM.Using isoeugenol as the raw material, ozone as the oxidant to synthetic vanillin. Firstly, the amount of Na2S2O5, hydrolysis time and hydrolysis temperature effects were studied. The results show the best technological conditions :the amount of Na2S2O5 was 20 %, hydrolysis time was 1 h, the hydrolysis temperature was 90 ℃ and the yield was 85.6%.Keep other conditions maintain invariably, effect of reaction temperature, reaction time, ozone flow and substrate concentration on vanillin yield was studied, and ensure the best technological conditions through the orthogonal experiment. Using benzyl acetate as solvent,the best conditions get as follows:reaction temperature 15 ℃, reaction time 2 h,the ozone flow 3 LPM and the substrate concentration 20 %,and the yield of vanillin is 91.5%. Structure of vanillinwas characterized by GC-MS,FI-IR and NMR.Using vanillin and propylene glycol as the raw materiat to synthetic vanillin propylene glycol acetal.Through the screening of catalysts, we choose D72 solid resin as catalyst.Time,mole ratio of materials, the amount of catalyst, volume of dehydrating agent effects on acetal yield were studied. The experiment results showed the best conditions: the molar ratio of1,2-propylene glycol to vanillin is 2:1,the catalyst was 3.5 %, benzene was 20 mL and reaction time was 3 h, and the yield was 90.1%.Structure of vanillin propylene glycol acetal was characterized by GC-MS,FI-IR and NMR.