关键词: β-蒎烯, 诺蒎酮, 羟醛缩合, 甲醛, 3-亚甲基诺蒎酮

Abstract: Synthesis of the 3-methylenenopinone was carried out using β-pinene as the starting material. Nopinone was prepared by selective oxidation with acidic potassium permanganate in acetone. The influences of oxidants, solvents, reaction temperature and reaction time on the oxidation selectivity of β-pinene and the yield of nopinone were investigated. 3-Methylenenopinone was further synthesized by aldol condensation of nopinone and formaldehyde catalyzed by potassium hydroxide. The influences of the molar ratio of nopinone to formaldehyde, types and dosages of catalysts, solvents, reaction temperature and reaction time on the aldol condensation were examined in detail. The optimum reaction conditions were determined according to the results of orthogonal experiments as follows: n(formaldehyde)∶n(nopinone) molar ratio 21∶1; potassium hydroxide used as the catalyst for aldol condensation, and n(KOH)∶n(nopinone) molar ratio 1.5∶1; the reaction conducted at 65℃ for 2h without solvent. The yield of 3-methylenenopinone was over 92% under the aforesaid conditions, and its chemical structure was analyzed GC-MS, FT-IR, ¹HNMR and ¹³CNMR spectra.

Key words: β-pinene, nopinone, aldol condensation, formaldehyde, 3-methylene-nopinone