MnO₂/graphene oxide: A highly efficient catalyst for imine synthesis from alcohols and amines

Abstract

α‐MnO2 nanocrystals supported on graphene oxide (α‐MnO2/GO) was prepared through a soft chemical route and evaluated for the first time as a novel, eco‐friendly and efficient catalyst in the coupling reaction of alcohols and amines to imines. The well‐organized α‐MnO2/GO was characterized using various techniques. The results show that MnO2 nanocrystals are highly dispersed on the GO sheets and interconnected with each other, leading to large available surface area, which greatly enhances the catalytic performance of conventional MnO2. Under mild conditions, the catalyst exhibits excellent catalytic activity and selectivity with O2 serving as terminal oxidant. Various imines can be smoothly obtained in good to excellent yield. Importantly, the catalyst is easily recovered and can be reused six times with no significant loss of activity.

Synthesis of isomorphically substituted Ru manganese molecular sieves and their catalytic properties for selective alcohol oxidation

“…For example, chromium-based reagents are toxic, irritants and corrosive; whereas manganese dioxide (MnO 2 ), being more environment-friendly, has been used over the years as a highly efficient and selective catalyst for oxidation of allylic and benzylic alcohols to aldehydes, amines to imines, oxidation of CO, H 2 O 2 decomposition, oxygen reduction, oligomerization of methane… [19,55,[60][61][62][63][64] Table 2 includes the most important results obtained with K-OMS2, [Ru]-K-OMS2 (2 wt%) as well as other related oxides as catalysts for the sele ctive synthesis of benzaldehyde from benzyl alcohol as model reaction.…”

Recent advancements in organic synthesis catalyzed by graphene oxide metal composites as heterogeneous nanocatalysts

“…Cheng et al [ 196 ] reported the synthesis of imines from one‐pot multicomponent condensation reaction of benzyl alcohol, aniline by using α‐MnO 2 /GO (0.010 g) as a catalyst with O 2 balloon, and toluene as a solvent system at 110°C for 6–8 h (Scheme 31). To optimize the reaction conditions, different solvents were tested such as toluene, DMF, EtOH, THF, and MeCN, but the use of toluene at 110°C gave excellent yields (76% to 96%).…”

Cobalt-Based Quasi-Metal–Organic Framework as a Tandem Catalyst for Room-Temperature Open-Air One-Pot Synthesis of Imines

“…1 By having an active CN bond, imines are key intermediates in the synthesis of pharmaceuticals, fine chemicals, and biologically active heterocyclic compounds, such as α-amino acids and α-amino alcohols. 2 Imine reactivity includes reduction, addition, condensation, and multicomponent reactions. 3,4 Several synthetic routes are described in the literature for imine synthesis.…”