β-水芹烯异构制备α-松油烯的研究

Preparation ofα-Terpinene by Isomerization ofβ-Phellandrene

对β-水芹烯酸催化异构制备α-松油烯的工艺进行了研究,结果表明:三甲基溴硅烷(TMSBr)因酸性适中对β-水芹烯表现出良好催化效果,但其对α-蒎烯、β-蒎烯、3-蒈烯、苧烯和异松油烯等单萜烯催化效果不佳;助剂30%(质量分数)H_(2)O_(2)因其所含的水可使TMSBr转化为H+从而催化异构反应进行,并通过对H+的扩散作用减少副反应发生,此外H_(2)O_(2)自身酸性对反应起到辅助催化效应,这3方面特性极大提升了反应效率。β-水芹烯异构制备α-松油烯的较佳工艺条件为:β-水芹烯0.1 mol、TMSBr 0.002 mol、30%H_(2)O_(2)0.1 mol、反应温度100℃、反应时间6 h,此条件下原料转化率为88.4%,产物选择性为94.0%。

Acid-catalyzed isomerization ofβ-phellandrene for the preparation ofα-terpinene and relative reaction process were investigated.The results indicated that trimethylsilyl bromide(TMSBr)showed excellent catalytic activity on the isomerizationβ-phellandrene owing to its moderate acidity.However,its catalytic effects on other monoterpenes such asα-pinene,β-pinene,3-carene,limonene and terpinene were limited.The auxiliary agent of 30%(mass fraction)H_(2)O_(2)greatly improved the reaction efficiency owing to its three characteristics including converting TMSBr to H+to catalyze the isomerization reaction due to the existence of water,dispersing H+to reduce the occurrence of side reactions,and assisting the reaction by its own acidity.The optimal conditions for the preparation ofα-terpinene from the isomerization ofβ-phellandrene wereβ-phellandrene of 0.1 mol,TMSBr of 0.002 mol,30%H_(2)O_(2)of 0.1 mol,temperature of 100℃,time of 6 h,and the raw material conversion and product selectivity were 88.4%and 94.0%,respectively.