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首页> 外文期刊>Catalysis science & technology >Heterogeneously catalyzed self-condensation of primary amines to secondary amines by supported copper catalysts
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Heterogeneously catalyzed self-condensation of primary amines to secondary amines by supported copper catalysts

机译：通过支撑的铜催化剂的副胺对次级胺的异质催化催化剂的自调降低

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摘要

Self-condensation of primary amines to symmetrically substituted secondary amines could efficiently be promoted by an inexpensive supported copper catalyst, Cu/Al2O3, easily prepared by the reduction of the hydroxide precursor, Cu(OH)_x/AI2O3. Various kinds of structurally diverse primary amines including benzylamine, picolylamine, and aliphatic amine derivatives could selectively be converted into the corresponding secondary amines in moderate to excellent yields without any cocatalysts such as bases and stabilizing llgands in 1 atm of Ar or H2. The reactions in H2 showed higher selectivities to desired secondary amines than those in Ar. The roles of H2 are the promotion of hydrogenation of N-alkylimines and the stabilization of active Cu(0) species. In addition, in the presence of Cu/Al2O3, unsymmetrically substituted secondary amines could efficiently be synthesized by N-alkylation of primary amines with alcohols and reductive amination of aldehydes. The observed catalysis was truly heterogeneous, and the retrieved Cu/Al2O3 catalyst could be reused for self-condensation without a significant loss of its catalytic performance. The reaction mechanism involving dehydrogenation of primary amines and condensation to N-alkylimines followed by hydrogenation, the so-called "borrowing hydrogen pathway", has been proposed.
机译：原代胺对对称取代的次级胺的自调可以通过廉价的铜催化剂CU/AL2O3有效地促进，Cu/Al2O3很容易通过还原氢氧化物前体Cu（OH）_X/AI2O3来制备。各种结构多样的原代胺在内，包括苄胺，果仁胺和脂肪族胺衍生物可以选择性地转换为相应的二级胺，中度至优异的产率，而没有任何cocatalys，而没有任何cocatalys，例如巴斯巴巴和稳定在AR或H2的1个atm中。与AR相比，H2中的反应对所需的二胺的选择性更高。 H2的作用是促进N-烷基亚胺的氢化和活性Cu（0）物种的稳定。另外，在存在Cu/Al2O3的情况下，可以通过醇和醇和还原性醛的胺化促胺通过N-烷基化来有效地合成未取代的次级胺。观察到的催化是真正的异质性，并且可以将检索到的Cu/Al2O3催化剂重新用于自键合，而不会显着丧失其催化性能。已经提出了涉及催化胺的脱氢作用的反应机制，并与N-烷基胺凝结，然后氢化，氢化，即所谓的“借用氢途径”。

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