11-氰基十一酸的甲酯化研究

Study on the methy1 esterification of 11-cyanoundecanoic acid

11-氰基十一酸甲酯(MCU)可由11-氰基十一酸(CUA)与甲醇酯化合成.CUA的氰基酯化时易水解,需选择合适的催化剂并控制好酯化条件.通过实验确定98%H2SO4是酯化反应合适的催化剂(兼具吸水作用).用正交试验考察酯化条件,优化条件为:将0.03mol的CUA和3.0g硅胶(吸水剂)加入到0.225mol甲醇与0.015mol的浓H2SO4混合液中,回流3h,反应的产品收率可达65.8%,酸醇比对收率影响最大.合成产物用正己烷结晶精制后经质谱测得其相对分子量为225,红外光谱、质谱、核磁共振(1HNMR及13CNMR)结构表征证明酯化产物确为MCU;其熔点27.3～28.4℃,40℃时折光率1.4403.

Methyl 11-cyanoundecanoate （MCU） can be synthesized by methyl esterifying 11-cyanoundecanoic acid （CUA） with methanol in the presence of catalyst. During the esterification process, to choose a kind of catalyst and control the synthesis conditions to prevent the cyanogens group attached to CUA from being fiydrolyzed is very important On the basis of experiments, 98% H2SO4 was selected as the suitable catalyst （also as water absorbent） to catalyze this reaction. The optimized methylation parameters were obtained through a designed orthogonal test as follows： putting 0.03 mol CUA and 3.0 g silica gel （water absorbent） into 0.225 mol solution of methanol： 0.015 mol 98% H2SO4, then refluxing 3 hours. Under these conditions, the product yield rate could reach 65.8%. Orthogonal test results indicated that the ratio of CUA with methanol was the premier factor effecting the product yield rate. Relative molecular mass of the synthesized product having been refined by recrystallization it in n-hexane is 225 determined by MS. And the methyl esterification product is structurally confirmed MCU itself through analyzing its MS, IR, 1HNMR and 13CNMR. Melting point and refractive index of MCU were 27.3-28.4℃ and 1.4403 （at 40℃） respectively.