亨克尔反应制备2,6-萘二甲酸

以1,8-萘二酸酐为原料与氢氧化钾溶液反应制备1,8-萘二甲酸二钾盐,后在萘为传热介质下异构化合成2,6-萘二甲酸。通过高效液相色谱分析产物,确定反应的收率以及酸值;用核磁、质谱和红外光谱鉴定反应产物,并探讨了催化剂选择与浓度、萘的用量、反应温度、反应时间等对亨克尔反应的影响。结果表明:虽然碘化锌催化剂的催化效果比碳酸锌好,但其在反应过程中会转化为碳酸锌;在萘添加量为反应原料的3倍,碳酸锌摩尔分数为10%,碘化钾摩尔分数为20%,反应温度450℃,反应时间90 min条件下,2,6-萘二甲酸的收率可以达到44.1%。

Synthesis of 2,6-Naphthalenedicarboxylic Acid in Hencel Reaction

The Henkel reaction of dipotassium 1,8-naphthalenedicarboxylate, which was prepared by 1,8-naphthalenedicarboanhydride dissolved in the KOH solution, gave dipotassium 2,6-naphthalenedicarboxyl-ate in naphthalene as dispersion medium. The yield of the reaction was confirmed by HPLC, and the reac-tion product was verified by NMR, LC-MS, IR spectra and acid value. The five technology parameters inHenkel reaction, which contained the activity of catalyst, catalyst concentration, the amount of naphthalene,reaction temperature and reaction time, were analyzed emphatically. The results show that: Although the ac-tivity of the zinc iodide catalyst is more better than that of zinc carbonate in Henkel reaction, it will be con-verted to zinc carbonate finally. Under the optimum technological conditions: the amount of naphthalene is3 times of the reaction raw material, the mole percentage of zinc carbonate is 10%, the mole percentage ofpotassium iodide is 20%, the reaction temperature is 450 ℃ and the reaction time is 90 min, the yield of2,6-naphthalenedicarboxylic acid can reach 44.1%.