用于合成油酸甲酯的两类聚环糊精固相催化剂的研究

摘要

Two solid phase catalysts of CroCD-H and CroCD-Cu were prepared through crosslinking ofβ-cyclodextrin with epichloro-hydrin. They were both used for the synthesis of methyl oleate. The esterification kinetics of oleic acid with methanol catalyzed by CroCD-H was investigated. The results indicated that it was corresponded to pseudo-first-order reaction according to oleic acid con-centration,and the sulfonic acid group content directly influenced the reaction rate. The sulfonic acid group content of CroCD-H5 reached to 5. 82%,through whose catalysis the oleic acid conversion was above 90%in 8 h. It also showed excellent catalytic stabil-ity for esterification with many repeats. Another catalyst CroCD-Cu showed dramatic catalytic ability to the ester exchange reaction between glycerol trioleate and methanol. The catalytic mechanism might refer to the structure of the Cu-bridge quaternary-ring in this double-copper( II) complex,and the ester exchange reaction might be occurred according to the action of OH-/O2- base-center and reversible breakage of Cu—O bond. The XRD spectra were introduced to study the structure of CroCD-Cu both before and after the ester exchange reaction. It revealed that the deactivation process was probably due to destruction of the Cu-bridge bond.%以环氧氯丙烷交联β-环糊精,制备了CroCD-H和CroCD-Cu两类固相催化剂,并分别用于油酸甲酯的合成。对CroCD-H催化油酸的酯化反应动力学进行考察,表明此反应符合油酸浓度的准一级反应,催化剂中磺酸基含量直接影响酯化反应速率,其中CroCD-H5磺酸基含量可达5．82%,催化反应8 h,油酸转化率大于90%,且多次重复使用稳定性良好。而在三油酸甘油酯与甲醇的酯交换反应中,CroCD-Cu表现出较强的催化能力,其催化机理可能与双核铜复合物的Cu桥键四元环结构有关,通过其OH-/O2-碱性中心作用和Cu—O键可逆断裂实现酯交换。采用XRD谱对CroCD-Cu催化酯交换反应前后的结构进行研究,揭示了其失活过程可能与Cu桥键被破坏有关。