Study On The Preparation Of The Verbenone From α-Pinene By Catalyzed Oxidation

Verbenone was the product of allylic oxidation of a-pinene, because of its distinct four-member ring and six-member ring structure and the double band, which was broadly applied in flavors and fragrances, pharmaceuticals, pesticide industry and so on. Especially, the material to synthesis verbenone which was natural renewable resource could provide abundant source for study. However, the yield using the generic oxidized methods was relatively low and the selectivity was not high. With the people’s awareness growth of environmental protection, therefore, it was essential for investigators to search for some new, more efficient, high activity and environment-benign catalysts or adopt the new experimental technology and methods to make the reaction conditions more moderate, more efficient and bring the reaction along with the environmental protection and accord with the development of green chemistry which was the aim and the highlight of the investigators.This article adopted Gif system (Fe2(SO4)3-H2O2) catalyzed oxidation methods for the first time used for a-pinene compound study which could synthesis the verbenone and brought into the detail research for the every influencing factors by means of ultrasonic method. In addition, a new mechanism of copper chloride tert-butyl peroxide oxidation system was proposed which was a higher conversion and better selective method in the reaction.1、Gif system (Fe2(SO4)3-H2O2) oxidation reactions was very mild condition, which could obtain very good conversion rate, but relatively poor selectivity. Orthogonal experimental research was applied to study the major influencing factors under the ultrasonic experimental condition. The order of influencing factors was:the amount of H2O2> the amount of catalyst> ultrasonic time> pyridine volume. Took the pyridine volume was the minimal influencing factor and the displeased odor also the toxicity into account we attempted to replace the pyridine for the acetonitrile and gained some progress. The optimized reaction conditions as follows:2.0 ml a-pinene in the 5.0ml pyridine-3.0ml acetic acid, 0.1g ferric for the catalyst,2.0ml H2O2 as the oxidant, ultrasound time 3h, the yield of the verbenone was 2.3%.2、Copper chloride tert-butyl hydroperoxide system catalyzed oxidation methods expressed excellent result which could gain extraordinary high conversion (100%) and selectivity (83.7%). Influencing factors such as temperature, catalyst, oxidant, oxygen as well as the solvents in the reaction were investigated. The experiment confirmed the oxidant addition volume was the maximal influencing factor, the next was catalyst addition; the catalyst exhibited the catalyze activity when the temperature between 60 and 80℃; the oxygen was able to accelerate the a-pinene transformation and increased the selectivity; acetonitrile was the best solvent for the reaction, meanwhile n-hexane and acohol was also able to gain the good result. The optimized reaction conditions as follows:2.0 ml a-pinene,4.0ml acetonitrile,6.0ml TBHP,1%(mol) catalyst, the oxygen flow controlled at 25～35ml/min, reaction time 6h under 70℃. Due to the problems emerged from the results which could not explain depending on the literatures, the new transition metal Insert-Removal of reaction mechanism was proposed. The mechanism confirmed entirely feasible based on the results of the reaction.3、After the reaction, purified the mixed products with column chromatogragh method, and chose the petroleum ether and ethyl acetate (Vpetroleum ether:Vethyl acetate=1:10) system as the extended solvent to separate and purify the crude products, finally obtained high purified verbenone. The verbenone of IR, MS and HNMR were detected, furthermore, the data was analyzed and confirmed the structure of the compounds according with standard chromatograph.