六芳基二咪唑的合成研究

为开发六芳基二咪唑类光致变色材料 ,以联苯甲酰、对甲氧基苯甲醛及乙酸铵为原料 ,经过环合、氧化合成了光致变色化合物 2 ,2′-二对甲氧苯基 - 4,4′,5 ,5′-四苯基 - 1 ,2′-二咪唑。研究了多种因素对反应收率的影响 ,得到最佳工艺条件 :在冰乙酸中 ,联苯甲酰、对甲氧基苯甲醛及醋酸铵物质的量之比为 1∶ 1∶ 8,回流 3 h后生成 2 -对甲氧苯基 - 4,5 -二苯基咪唑 ,收率为 93 .6 % ;以乙二醇 -乙醚为溶剂 ,2 -对甲氧苯基 - 4,5 -二苯基咪唑与氧化剂 K3 Fe(CN) 6]的物质的量之比为 1∶ 2 ,在 0～1 5°C下反应 5 h,得到产品 2 ,2′-二对甲氧苯基 - 4,4′,5 ,5′-四苯基 - 1 ,2′-二咪唑 ,收率为 87.5 %。

Study on Synthesis of Hexaarylbisimidazole as Phototropic Material

Bis(p-methoxyphenyl)-4,4′-5,5′-tetraphenyl-1,2′-biimidazole (2) was prepared from benzil, p-methoxybenzaldehyde and ammonium acetate. Experiments were done under different reaction conditions, and the optimal conditions were determined. In acetic acid, as mole ratio of benzil, p-methoxybenzaldehyde and ammonium acetate was 1∶1∶8, 93.6% of 2-(p-methoxyphenyl)-4,5-diphenylimidazole (1) was obtained after refluxing for 3 h. When reaction temperature was 0～15 °C, 1 was dissolved in HOCH_2CH_2OCH_2CH_3 and mole ratio of 1 to K_3Fe(CN)_6] was 1∶2, the yield of 2 was 87.5% after reacting for 5 h.