蒜头果油催化关环选择性合成环十五内酯的研究

Malania oleifera Chun et S. Lee is the secondary protection plant in China. It is one of characteristic forest products in Guangxi. Usually, as woody oil plant, its seed is extracted oil to make soap. Thus, its utilization is low. There is 40% - 60% cis-15-tetracosenic acid in the Malania oleifera seed oil by saponification. It is one of the ideal raw materials to synthesize cyclopentadecanolide as high-grade flavor. In this project, ω-hydroxyfatty acids, ω-hydroxyfatty acid esters, and ω-hydroxyfatty acid triglyceride are obtain by double bonds of unsaturated fatty acid chains of fatty acid triglyceride in Malania oleifera oil which are cut off selectively by ozonation. Cyclopentadecanolide is synthesized selectively through the cyclization of ω-hydroxyfatty acids, ω-hydroxyfatty acid esters, and ω-hydroxyfatty acid triglyceride catalyzed by solid catalyst. Intermolecular polymerization to generate polymers is blocked to improve the selectivity of synthesis of cyclopentadecanolide from Malania oleifera oil. the structure – reactivity relationship of solid catalyst and intramolecular cyclization of reactants is discussed. The catalytic mechanism of cyclopentadecanolide from Malania oleifera oil is further studied in detail. Therefore, a new method of highly efficient, highly selective synthesis of cyclopentadecanolide from Malania oleifera oil can be put forward. Our works can not only provide a theoretical basis for seeking new method of efficient synthesis of the macrocyclic lactones, but also contribute significantly to plant, protection and deep-processing utility of Malania oleifera.

蒜头果是我国二级保护植物，是广西特色林产品之一。作为木本油料植物，蒜头果种仁通常榨油制皂，利用率低。蒜头果种仁油脂皂化后含有40%-60% 的二十四碳-15-烯酸，是合成高档香料环十五内酯的理想原料之一。本项目研究蒜头果种仁油脂中脂肪酸甘油酯的不饱和脂肪酸链选择性臭氧化切断双键得到ω-羟基脂肪酸、ω-羟基脂肪酸酯、ω-羟基脂肪酸甘油酯，固体催化剂催化关环选择性合成环十五内酯。阻断分子间聚合生成多聚体，提高蒜头果油合成环十五内酯的选择性，探讨催化剂结构与反应物分子内关环的构效关系，研究相应的催化关环机理。从而提出蒜头果油高效、高选择性合成环十五内酯的新方法。本项目的开展为探索大环内酯的高效合成新方法提供理论基础，对促进蒜头果的种植和保护，及其深加工利用具有重要意义。

蒜头果是广西特色林产资源之一，项目开展固体酸催化蒜头果油选择性关环合成环十五内酯研究。蒜头果油通过臭氧化、还原、酸化和酯化反应得到ω-羟基脂肪酸、ω-羟基脂肪酸酯，选用了浸渍法负载Mo的Mo/HZSM-5和Mo/HY固体酸催化ω-羟基脂肪酸、ω-羟基脂肪酸酯合成环十五内酯，通过对催化剂进行NH3-TPD、BET、XRD的结构表征，探究了催化剂表面酸强、酸量、比表面积、孔径和Mo形态与环化反应的构效关系，发现催化剂弱酸酸位点、平均孔径3.5~4nm孔道在环化反应里起主要贡献。负载的Mo以MoO3形式存在，通过调变催化剂表面酸强酸量来影响环化反应。负载Mo后，使催化剂表面积下降，扩大了孔径，使得ω-羟基脂肪酸、ω-羟基脂肪酸酯可以进入孔道内，提高了反应的选择性。另外，发现即使在温和反应条件下（90 ℃回流），ω-羟基脂肪酸和ω-羟基脂肪酸酯环化反应后大部分产物是多聚物，利用固体超强酸TiO2/SO42-进行解聚，环十五内酯产率达到48.74%。项目的研究成果为固体酸催化合成大环内酯提供了理论基础，并对开发蒜头果的深加工具有重要的指导意义。