Mondal John, Salam Noor, Bhaumik Asim
Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur 700032, India.
J Nanosci Nanotechnol. 2013 Jul;13(7):4883-95. doi: 10.1166/jnn.2013.7574.
Furfural-imine functionalized mesoporous organosilica material has been synthesized by post-synthesis surface functionalization of 2D-hexagnoal mesoporous SBA-15 with organosilane precursor 3-aminopropyltriethoxy-silane (APTES) followed by Schiff-base condensation with furfural. On the other hand, furfural-imine functionalized MCM-41 has been synthesized by Schiff-base condensation of furfural and 3-aminopropyltriethoxy-silane (APTES) followed by its hydrothermal co-condensation with tetraethylorthosilicate (TEOS) in the presence of a cationic surfactant CTAB. Subsequent reaction of the imine-functionalized mesoporous organosilicas with Cu(OAc)2 in absolute ethanol produced Cu(II)-grafted mesoporous nanocatalysts 1 and 2, respectively. Powder XRD, HR TEM, FE SEM, N2 sorption and EPR experimental tolls are employed to characterize these Cu-grafted furfural-imine functionalized nanocatalysts. Cu-grafted MCM-41 (1) showed very good catalytic efficiency for the coupling of aryl bromides and thiophenol under aerobic conditions to produce different thioethers. On the other hand, Cu-anchored mesoporous SBA-15 nanocatalyst (2) exhibited high catalytic activity for one-pot three component coupling of different aryl halides with thiourea and benzyl bromide in aqueous medium to produce different aryl alkyl thioethers in very good yields. Both Cu-grafted mesoporous nanocatalysts can be efficiently reused for several reaction cycles.
糠醛亚胺功能化介孔有机硅材料是通过二维六方介孔SBA - 15与有机硅烷前驱体3 - 氨丙基三乙氧基硅烷（APTES）进行后合成表面功能化，随后与糠醛进行席夫碱缩合反应合成的。另一方面，糠醛亚胺功能化MCM - 41是通过糠醛与3 - 氨丙基三乙氧基硅烷（APTES）进行席夫碱缩合反应，然后在阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）存在下与正硅酸乙酯（TEOS）进行水热共缩合反应合成的。将亚胺功能化介孔有机硅与醋酸铜（Cu(OAc)₂）在无水乙醇中进行后续反应，分别制备了Cu(II)接枝的介孔纳米催化剂1和2。采用粉末X射线衍射（XRD）、高分辨透射电子显微镜（HR TEM）、场发射扫描电子显微镜（FE SEM）、N₂吸附和电子顺磁共振（EPR）实验手段对这些Cu接枝的糠醛亚胺功能化纳米催化剂进行表征。Cu接枝的MCM - 41（1）在有氧条件下对芳基溴化物与苯硫酚的偶联反应表现出非常好的催化效率，可生成不同的硫醚。另一方面，Cu锚定的介孔SBA - 15纳米催化剂（2）在水相中对不同芳基卤化物与硫脲和苄基溴的一锅三组分偶联反应表现出高催化活性，能以非常好的产率生成不同的芳基烷基硫醚。两种Cu接枝的介孔纳米催化剂都可以高效地重复用于多个反应循环。
