Green Synthesis Of Phenol Ethers Spices

Phenol ethers spices, a large class of synthetic spices, are widely used in perfumeindustry and medicine industry with strong and pleasant aroma and stable chemicalproperties. The most important chemical reactions involved in the synthetic process aremethylation of phenolic hydroxyl and isomerization of double bond. In this thesis,dimethyl carbonate （DMC） was used to replace the traditional methylation reagent andreact with phenols to synthesize methyleugenol and p-methylanisole. Poly（ethylene glycol）-400（PEG-400） was used as phase transfer catalyst for the isomerization ofmethyleugenol, and the one-step synthesis of isoeugenol methyl ether was studied.Using DMC as a methylating agent, reactive distillation was applied to synthesizemethyleugenol. Through screening, K₂CO₃was chosen as the catalyst of the reaction andcentral composite design process was used to optimize the synthesis of methyleugenol.The optimum reaction conditions for the preparation of the targeted product were found:reaction temperature was155°C, the amount of K₂CO₃was6.12%, the molar ratio ofDMC and eugenol was4.3:1and reaction time was6hours. Under these conditions, theyield of the product was96.16%. With the support of activated carbon （AC）, preparedK₂CO₃/AC was used as the catalyst for the methylation reaction of eugenol. Thepreparation method of K₂CO₃/AC catalyst was conformed: soaking concentration was20%, soaking temperature was60°C, soaking time was10hours. Through the orthogonaltest, the optimal reaction conditions of the synthesis of methyleugenol were found:reaction temperature was165°C, the molar ratio of DMC and eugenol was5:1, theamount of K₂CO₃/AC was10%and reaction time was5.5hours. Under these conditions,the yield of the product was95.19%.Phase transfer catalyst and KOH was used for isomerization of methyleugenol tosynthesize isoeugenol methyl ether. The activity of PEG-400and supported PEG-400asphase transfer catalyst for isomerization of methyleugenol were investigated. The optimalreaction conditions, via using PEG-400as phase transfer catalyst, were found: the amountof KOH was10%, the amount of PEG-400was0.8%, reaction temperature was80°C,reaction time was4hours. Under these conditions, the yield of the product was96.28%.The optimal reaction conditions, via using supported PEG-400as phase transfer catalyst,were found: reaction temperature was100°C, the amount of supported PEG-400was2.5g, the amount of KOH was9%, reaction time was5.5hours. Under these conditions,the yield of the product was93.86%. After6cycles of supported PEG-400, the yield ofisoeugenol methyl ether remained at around92%.It was found that K₂CO₃/PEG-400had good catalytic activity on the one-stepsynthesis of isoeugenol methyl ether while using eugenol and DMC as the raw material.Through the orthogonal test, the optimum reaction conditions were found: reactiontemperature was170°C, the amount of K₂CO₃was6%, the amount of PEG-400was6%, the molar ratio of DMC and eugenol was4:1and reaction time was4.5hours. Under theseconditions, the yield of the product was96.01%.In the case of high pressure, the methylation reaction between DMC and p-cresol tosynthesize p-methylanisole was studied. Through screening, K₂CO₃was chosen as thecatalyst of the reaction. Under the condition of0.8Mpa, through the orthogonal test, theoptimum reaction conditions were found: reaction temperature was200°C, the amount ofK₂CO₃was7%, the molar ratio of DMC and p-cresol was2:1and reaction time was4hours. Under these conditions, the yield of the product was91.15%.The products were analyzed by gas chromatography-mass spectrometry （GC-MS）and FTIR. The supported catalysts were analyzed by X-ray diffraction （XRD）, scanningelectron microscopy （SEM）, thermogravimetric analysis （TG） and FTIR.