New heterogeneous B(OEt)3-MCM-41 catalyst for preparation of α,β-unsaturated alcohols
作者:Burcu Uysal、Birsen S. Oksal
DOI:10.1007/s11164-013-1498-0
日期:2015.6
Grafting of boron tri-ethoxide on mesoporous MCM-41 resulted in a highly active catalyst for the Meerwein–Ponndorf–Verley (MPV) reduction and the catalyst denoted as B(OEt)3-MCM-41. Chemoselective reduction of α,β-unsaturated aldehydes and ketones to the corresponding α,β-unsaturated alcohols was achieved by MPV reduction reaction using a new B(OEt)3-MCM-41 catalyst. The prepared new heterogeneous catalyst, B(OEt)3-MCM-41, was characterized in detail by using XRD, 29Si NMR-, 11B NMR-, 13C NMR-, and TEM, N2 adsorption, and ICP-OES. The results demonstrated the successful homogenous distribution of the B(OEt)3 on the MCM-41 support. The heterogeneous B(OEt)3-MCM-41 catalyst, in comparison with the homogeneous B(O i Pr)3 and B(OEt)3 catalysts, displayed similiar catalytic activity in the MPV reduction of α,β-unsaturated aldehydes and ketones with alcohols as reductants. Reduced reaction times and very high selectivities for the unsaturated alcohols were obtained with the heterogenous catalyst compared with the homogeneous catalysts. The B(OEt)3-MCM-41 catalyst was found to be encouraging, as is is recyclable up to six cycles without any significant loss in its catalytic activity.
三乙氧基硼(B(OEt)3)在中孔MCM-41上的接枝产生了一种高度活性的催化剂,用于Meerwein–Ponndorf–Verley(MPV)还原,该催化剂称为B(OEt)3-MCM-41。通过使用新型的B(OEt)3-MCM-41催化剂,成功实现了对α,β-不饱和醛和酮的选择性还原,生成相应的α,β-不饱和醇。所制备的新型多相催化剂B(OEt)3-MCM-41通过XRD、29Si NMR、11B NMR、13C NMR、TEM、氮气吸附和ICP-OES进行了详细表征。结果表明B(OEt)3在MCM-41载体上的均匀分布是成功的。在MPV还原反应中,与均相催化剂B(OiPr)3和B(OEt)3催化剂相比,多相催化剂B(OEt)3-MCM-41表现出类似的催化活性,使用醇作为还原剂还原α,β-不饱和醛和酮。与均相催化剂相比,使用多相催化剂显著缩短了反应时间,并获得了非常高的不饱和醇的选择性。B(OEt)3-MCM-41催化剂的表现令人鼓舞,因为它可以循环使用达六个周期,而其催化活性未显著下降。