水相中金纳米颗粒催化的醛基选择性氧化

本文开发了一种新型的用生物质淀粉保护的金纳米颗粒作为催化剂，选择性氧化醛基得到羧酸的方法. 在4-羟甲基苯甲醛的催化氧化中，金纳米颗粒对醛基表现出了压倒性的选择性，而醇羟基则保持不变. 该非均相催化体系由可溶解的催化剂和不溶解的底物构成. 金催化剂的制备、储存、和使用都在水相中. 反应条件优化之后，双氧水被证明是最佳的氧化剂，可以得到100%转化率. 此外，在不同官能团取代的醛衍生物中，金纳米颗粒也表现出了很好的普适性. 反应结束之后，有机组分被有机溶剂萃取，而金颗粒被保留在水中通过分液分离以回收使用.

Selective Oxidation of Aldehyde over Hydroxymethyl Group Catalyzed by Gold Nanoparticles in Aqueous Phase

A protocol for selectively oxidizing aldehyde over hydroxymethyl group is developed, using biomass starch protected gold nanoparticles (NPs) as catalyst. The Au NPs show high selectivity that aldehyde is oxidized into carboxylic acid while alcoholic hydroxyl group stays intact in selective oxidation of 4-(hydroxymethyl)-benzaldehyde. The heterogeneous catalysis system is composed of soluble catalysts and insoluble substrate. The gold catalyst is prepared, preserved and applied for catalytic oxidation all in water. After reaction conditions are optimized, H₂O₂ is found to be the best oxidizing agent with complete conversion. Besides, the gold catalyst displays good versitility for aldehyde derivatives. After reaction completes, organic components are extracted by organic solvent and gold NPs in water are separated and recycled.