以(-)-β-蒎烯为原料,经选择性氧化合成(+)-诺蒎酮,分析了在不同氧化剂及溶剂体系下β-蒎烯的氧化行为。研究了β-蒎烯与高锰酸钾摩尔比、硫酸与高锰酸钾摩尔比、溶剂类型、反应温度、反应时间等因素对β-蒎烯氧化转化率和诺蒎酮产物选择性的影响。结果表明,左旋β-蒎烯选择性氧化合成右旋诺蒎酮适宜的氧化工艺条件:β-蒎烯与高锰酸钾摩尔比为1∶3,硫酸与高锰酸钾摩尔比0.054∶1,以丙酮为溶剂,反应温度为15~25℃,反应时间为5h。此条件下β-蒎烯转化率为94.15%,诺蒎酮选择性为89.19%,诺蒎酮得率为83.97%,纯度为95.29%,比旋光度为[α]D18+33.86°(c1.01,CHCl3)。另外,采用IR、GC-MS、1HNMR和13CNMR等对诺蒎酮结构进行了表征。
(+)-nopinone was synthesized through selective oxidation of (-)-β-pinene, and the oxidation behavior of β-pinene under different oxidants and solvents system were examined. Effects of the molar ratios of β-pinene/KMnO4 and H2SO4/KMnO4, types of solvents, reaction temperature and time on the conversion of β-pinene and selectivity of (+)-nopinone were investigated. The results showed that the suitable oxidation conditions of (-)-β-pinene into (+)-nopinone were as follows: β-pinene/KMnO4 molar ratio 1∶3, H2SO4/KMnO4 molar ratio 0.054∶1, acetone was used as the solvent, reaction temperature 15—25 ℃, and reaction time 5 h. The conversion of β-pinene, selectivity of oxidation, yield of (+)-nopinone, specific rotation and purity of obtained product were 94.15 %, 89.19 %, 83.97 %, [α]18D+33.86°(c 1.01, CHCl3), and 95.29 %, respectively. The structure of (+)-nopinone was determined by IR, 1H NMR, 13C NMR and GC-MS spectra.