纳米磁性固体酸SO42-/Zr（OH）4-Fe3O4催化水相不对称Aldol反应

摘要

Magnetic solid acid catalysts SO42−/Zr(OH)4–Fe3O4 were prepared using magnetic Fe3O4 nanoparti‐cles, ZrOCl2·8H2O, and sulfuric acid as starting materials in the calcination temperature range 110–650 °C. The properties of the magnetic solid acid, such as loaded SO42−content, acid distribu‐tion, surface morphology, and porous structure, were characterized. In the aqueous asymmetric aldol reaction of various benzaldehydes with strong electron‐withdrawing groups (R=NO2 and CN), good to excellent catalytic performance (83%–100%yield, 86.0%–95.6%ee anti, and anti/syn=88–96/12–4) was achieved. These nanomagnetic solid acids can be quantitatively recycled from the reaction mixture using an external magnet and reused five times without significant loss of catalytic activity.%以纳米磁性材料Fe3O4, ZrOCl2·8H2O和硫酸为原料,在不同焙烧温度下制备了纳米磁性固体酸催化剂SO42–/Zr(OH)4-Fe3O4.详细表征了该磁性固体酸的SO42–负载量、酸分布、表面形貌和孔结构等特性.在含有硝基和氰基强吸电子基苯甲醛的不对称水相Aldol反应中, SO42–/Zr(OH)4-Fe3O4表现出优良的催化性能(83%–100%收率,86.0%–95.6% eeanti和anti/syn =88–96/12–4).该类磁性固体酸可在外加磁体作用下定量地从催化反应体系中分离并回收使用,重复使用5次未见显著失活.