2,3,5-三甲基-5,6-二氢吡嗪脱氢芳构化研究

Studies on Dehydroaromatization of 2,3,5-Trimethyl-5,6-Dihydropyrazine

介绍以丁二酮和1，2-丙二胺为原料，经缩合、脱氢芳构化反应合成2，3，5-三甲基毗嗪的新方法．重点考察了脱氢剂组成、脱氢剂用量、溶剂用量等对反应的影响．确定了合成2，3，5-三甲基吡嗪的优化条件为：以元水乙醇为溶剂，投料比为丁二酮：丙二胺：脱氢剂：无水乙醇=1：0．67：1．4：1．31（质量比）；缩合反应温度为20～25℃；回流脱氢4h,2，3，5-三甲基吡嗪的含量达98％以上．

A novel method introduce to synthesis 2,3,5-trimethylpyrazine by consendation of biacetyl and 1,2-diaminopropane followed by dehydroarmatization was studied. The composition of dehydrogenation oxidizer, the amount of dehydrogenation oxidizer and solvent were investigated emphatically. The optimum conditions were established as follow： anhydrous ethyl alcohol as solvent, the ratio of biacetyl, 1,2-diaminopropane, dehydrogenation oxidizer and solvent is 1：0.67： 1.4：1.31 （ by weight）, condensation at 20 - 25 ℃, and dehydrogenation at refluxing temperature of ethyl alcohol for 4 h, 2,3,5-trimethylpyrazine can be obtained with 98% purity.