均三乙苯的Blanc溴甲基化反应研究

The Blanc Bromomethylation of 1,3,5-Triethylbenzene

以苯为起始原料,通过傅克烷基化反应生成热力学稳定的均三乙苯.通过改变Blanc溴甲基化反应条件,均三乙苯可以单一地生成单溴甲基化、二溴甲基化和三溴甲基化产物,摩尔产率分别是86%、83%和72%.这些溴甲基化产物经核磁确认结构正确.重点考察Lewis酸、温度、反应物配比对二溴甲基化反应的影响,优选反应条件为:n(均三乙苯)∶n(多聚甲醛)∶n(锌粉)=1∶4∶1,温度为85℃,反应时间为4~8h.

The Friedel-Crafts alkylation of benzene afforded a thermodynamically favored 1,3,5-triethylbenzene,which could be further transferred to pure mono-,di-and tri-bromomethylated products by altering the Blanc bromomethylation conditions with the molar yields of 86 %,83 % and 72 %,respectively.The structures of these bromomethylated products were characterized by NMR.The effects of Lewis acid,temperature,and mole ratio of reagents on di-bromomethylation were studied,and the optimal conditions were as follows∶ n (1,3,5-triethylbenzene)∶ n (paraformaldehyde)∶ n (Zn powder)=1∶4∶1,the temperature as 85 ℃,and the reaction time was 4~8 h.