面向单萜烯醇高选择性酯化的双酸位离子液体催化体系的构建及性能研究

The highly selective esterification of monoterpene alcohols (e.g. geraniol, linalool, dihydromyrcenol) to monoterpene esters is one of the most important topics in the field of turpentine oil. Traditional acidic catalysts usually bring about some serious problems, such as many isomerization reactions, and low reactive selectivity. Therefore, there remains a strong need to develop novel environmentally friendly catalyst materials with high efficiency and selectivity for the synthesis of monoterpene esters. In view of this situation, and on the basis of the results obtained from the pre-research in our group, it is proposed in this project to design Bronsted-Lewis acidic ionic liquids and use them as novel catalysts for the highly selective esterification of monoterpene alcohols. Keeping this idea in mind, it is suggested to investigate the design and preparation of Bronsted-Lewis acidic ionic liquids, the highly selective synthesis of monoterpene esters, the kinetic of esterification of monoterpene alcohols, the synergistic catalysis of Bronsted-Lewis acidic ionic liquids, and also the production process of monoterpene esters in a large scale. Several innovative achievements, including the design rule and preparation method of Bronsted-Lewis acidic ionic liquids catalysts and the preliminary clean production technology of monoterpene esters, will be obtained after successful implementation. It is believed that this project may push the application and development of ionic liquids in the field of forestry chemical industry.

将香叶醇、芳樟醇、二氢月桂烯醇等单萜烯醇高选择性酯化为单萜烯酯是松节油深加工行业的研究热点和难点。传统酸催化剂存在单萜烯醇异构化副反应严重、目标酯产物选择性差等缺点，迫切需要研发活性高、选择性好及可重复使用的新型环境友好的催化体系。本项目在前期工作的基础上，创新性提出采用具有Bronsted-Lewis双酸位点的离子液体催化体系来实现单萜烯醇高选择性酯化为单萜烯酯的研究思路。围绕该思路，开展双酸位离子液体的结构设计和合成制备、单萜烯酯的高选择性合成及酯化反应动力学测定、双酸位离子液体的Bronsted-Lewis酸协同催化机制、单萜烯醇选择性酯化反应制备单萜烯酯放大过程等研究，最终获得高性能双酸位离子液体催化剂的设计规律和制备方法，初步建立具有潜在工业应用前景的单萜烯酯的清洁生产新工艺。本项目的实施将有助于促进离子液体在林产化学领域的应用和发展。

松油酯、香叶酯、芳樟酯、二氢月桂烯酯等单萜烯酯是一类高附加值的高级香料。传统酸催化剂催化合成这些单萜烯酯存在异构化副反应严重、目标酯产物选择性差等缺点。为此，本项目利用离子液体可设计性的特点，在阴阳离子上分别设计Bronsted酸位点和Lewis酸位点，成功研制出一系列具有Bronsted-Lewis双酸位点的离子液体催化剂，并精确调控这类离子液体的酸值，实现了松油醇、香叶醇、芳樟醇、二氢月桂烯醇等单萜烯醇与乙酸酐高效高选择性反应制备目标产物松油酯、香叶酯、芳樟酯、二氢月桂烯酯，产率达到90%以上，同时利用反应诱导自分离特性成功回收离子液体催化剂。其次，我们详细研究了香叶酯、松油酯的酯化反应动力学，构建了反应动力学模型并回归得到动力学参数，考察了松油酯等单萜烯酯的反应放大过程，并进一步阐明了离子液体的Bronsted-Lewis双酸位点协同催化酯化反应机理，初步建立了具有潜在工业应用前景的清洁生产单萜烯酯的新工艺。项目共发表SCI论文16篇，获得授权发明专利2项，培养硕士研究生毕业9名，较为圆满地完成了项目合同规定的任务。本项目的顺利完成为实现离子液体催化制备单萜烯酯的工业化应用提供了重要的理论和实践基础。