硒催化水合肼还原芳香族硝基化合物制芳胺

在温和条件下,研究了硒对水合肼还原芳香族硝基化合物制芳胺的催化性能。邻位或对位有取代基的芳香族硝基化合物被还原为相应芳胺的收率较低;硝基苯或间位有取代基的芳香族硝基化合物被还原为相应芳胺的收率较高。以硝基苯为底物,考察了溶剂、硒粉用量和NaOH用量等因素对反应的影响。得到的适宜条件为:以5 mL乙醇和1 mL水为溶剂,2 mmol芳香族硝基化合物,4 mmol水合肼,O.04 g NaOH和0.02 g硒粉,反应温度为75℃,反应时间为2～5 h,硝基苯或间位有取代基的芳香族硝基化合物被还原为芳胺的收率为87%～99%。催化剂重复使用4次活性没有降低。

SELENIUM-CATALYZED REDUCTION OF AROMATIC NITRO COMPOUNDS TO ANILINES WITH HYDRAZINE HYDRATE

Under mild conditions,the catalytic performance of selenium in the reduction of aromatic ni- tro compounds with hydrazine hydrate to the corresponding anilines was studied.When the substitu- ent was at ortho or para position to the nitro group,the aromatic nitro compounds were reduced in poor yields to the corresponding anilines.In contrast,nitrobenzene or the aromatic nitro compounds with meta substituent were reduced in good yields to the corresponding anilines.The effects of sol- vent,selenium amount and NaOH amount on the yield of aniline were investigated with nitrobenzene as the substrate.Under the conditions of 2.0 mmol aromatic nitro compound,4.0 mmol hydrazine hy- drate,0.04 g NaOH,0.02 g selenium,5 mL ethanol and 1 mL water as solvent,reaction temperature 75℃,and reaction time 2.0-5.0 h,anilines with meta substituent were prepared in 87%-99% yields.No deactivation was observed after four times recycling of the catalyst.