α-蒎烯合成樟脑酸酐的研究

Synthesis of Camphoric Anhydride from α-Pinene

α-蒎烯与干燥HCl加成、异构得到2-氯莰烷,再经消除反应得到冰片烯,以乙酸酐-水混合溶剂为反应介质、高锰酸钾作氧化剂氧化冰片烯,得到樟脑酸酐。探讨了溶剂种类、乙酸酐-水的体积比、KMnO4用量、反应温度、反应时间等对冰片烯氧化反应的影响,确定了适宜的氧化工艺条件:以高锰酸钾为氧化剂,高锰酸钾与冰片烯的物质的量比为2.5∶1;以乙酸酐-水混合溶剂作为氧化反应介质,乙酸酐-水的体积比为3∶1,溶剂与冰片烯的比为20∶1(mL∶g),反应温度为40℃,反应时间4 h。在此工艺条件下,樟脑酸酐得率达94%以上。采用GC-MS、FT-IR、1H NMR、13C NMR等分析手段对合成所得产物的化学结构进行了分析测定。

Synthesis of eamphoric anhydride was carried out using a-pinene as the starting material. 2-chlorocamphane was prepared by addition and isomerization of a-pinene and dry hydrogen chloride, and it was further eliminated HCI in alkaline condition to obtain bornylene. Camphoric anhydride was finally obtained by oxidation of bornylene with KMnO4 in mixed acetic anhydride-water solvent. Influences of solvent systems, volume ratio of acetic anhydride and water, the amount of KMnO4, reaction temperature and reaction time on the oxidation of bornylene were examined in detail. The suitable oxidation conditions were determined as follows： KMnO4 used as the oxidant for oxidizing bomylene into camphoric anhydride, KMnOJbornylene molar ratio 2.5： 1, acetic anhydride/H20 mixture with a volume ratio of 3：1 used as the solvent, solvent/bornylene ratio 20：1 （ mL： g） , reaction temperature 40 ℃ and reaction time 4 h. The yield of camphoric anhydride was over 94 % under the aforesaid conditions. Its chemical structure was determined with GC-MS, FT-IR, JH NMR, and t3C NMR spectra.