Study On The Preparation Of Four-membered Ring Female Pheromones From α-pinene

Insect sex pheromone plays an important role in biological control against insect, because of its high activity and strong specificity. In which mealybug female sex pheromone cause more and more concerns. As an big agricultural country, it is necessary for our country to research and develop mealybug sex pheromone which is a new type of pesticides. This paper uses natural chiralα-pinene as the original raw material which is the highest one of the turpentine-content, by continuous three-step reaction, synthetize the four-membered ring compound pinononic acid methyl ester, This compound is the key intermediate for the preparation of two kinds of mealybug female sex pheromone and has important significance in synthesis research of insect sex pheromone. Moreover, synthetic route has the advantages of broad source of raw materials, mild reaction conditions and so on.Firstly, this paper introduce ultrasonic into the allylic oxidation ofα-pinene, copper chloride is the catalyst and tert-butyl hydroperoxide oxidant. In which less catalyst addition can achieve good catalytic effect, and the post treatment is easy. while applying the ultrasonic can reduce the time of reaction. The optimized reaction conditions are as follows: by keeping acetonitrile as 2.0ml, tert-butyl hydroperoxide 3.0ml, catalyst content as 1%, oxygen quantity as 25-35 ml/min, temperature as 50℃, ultrasound power as 100W, continuous ultrasound time as 1.5h, magnetic stirring time as 2h, the conversion ofα-pinene could reach 100% and the yield of verbenone could reach 68.8%。Secondly, when studying on the ring-opening reaction of verbenone, we used potassium permanganate as oxidant and various factors that effect the reaction had been discussed. The results showed that using potassium permanganate as the only oxidant would lead to the difficulties in post processing. Therefore, we prepare supported potassium permanganates which were supported on seven different kinds of carrier and their structures were characterized by XRD. At last we took the silica gel-supporting KMnO₄ as the heterogeneous oxidant for the oxidation of verbenone to pinononic acid. The optimal conditions were determined: under the room temperature, reaction time as 2h, 10.32g KMnO₄-SiO₂ as oxidant, the ratio of acetic acid to water as 10:1, the conversion of verbenone could reach 100% and the yield of pinononic acid could reach 81.04%. By comparison, using KMnO₄-SiO₂ as oxidant could simplify the post processing, reduce the post treatment time and increase the yield of the target product.Thirdly, this paper also investigate the effects of different water entrainers and catalysts on catalyzing methyl esterification of pinononic acid. The results showed that cyclohexane was the best water entrainer, using sulfuric acid as catalyst the reaction could reach the highest yield 71.3%, but the impossible to recycle and emissions lots of waste water would result in the severe environment contamination. Therefore it is not a good methord from the point of view of environment protection. And that of appling sol-gel method to prepare supported phosphotungstic acid as catalyst, the yield was 63.7%. Its catalytic effect is slightly lower than that of sulfuric acid, but the post treatment is easy and the supported phosphotungstic acid could recycle. It is a green methord and its research has a great future.Fourthly, we analyze and identify the target products of the various steps by IR, 1HNMR, MS.Fifthly, at last this paper choose to useα-pinene which has natural four-membered ring structure as the original raw material, by catalytic allylic oxidation, ring-opening reaction and methyl esterification to synthetize the key intermediate pinononic acid methyl ester of insect sex pheromone. The total yield is 35.5%。...