Reduced Graphene Oxides as Carbocatalysts in Acceptorless Dehydrogenation of N-Heterocycles

Abstract

The catalytic properties of graphene-derived materials are evaluated in acceptorless dehydrogenation of Nheterocycles. Among them, reduced graphene oxides (rGOs) are active (quantitative yields in 23 h) under mild conditions (130 ºC) and act as efficient heterogeneous carbocatalysts. rGO exhibits reusability and stability at least during eight consecutive runs. Mechanistic investigations supported by experimental evidence (i.e. organic molecules as model compounds, purposely addition of metal impurities and selective functional group masking experiments) suggest a preferential contribution of ketone carbonyl groups as active sites for this transformation.

Chemically Activated Spruce Organosolv Lignin as a Carbocatalyst for Heterogeneous Oxidative Dehydrogenations in the Liquid Phase

“…No noticeable decrease in catalytic activity was observed, indicating that oxygen radicals are not responsible for the promotion of the oxidative process. As carbon materials have been previously reported to promote the acceptorless dehydrogenation of THQ, 40 the performance of oLAC-2-700 in the absence of O 2 was further explored by evaluating its capability for hydrogen production: the reaction was run under Ar flow and the evolved gases were analyzed via an in-line gas chromatographer. H 2 formed for the initial 15 min with a relatively high rate of 3.8 mmol h −1 g cat −1 .…”

Solvent- and Additive-Free Dehydrogenation of N-Heterocycles with Oxygen Catalyzed by Polyoxovanadate-Based Metal–Organic Frameworks

“…To this end, researchers have been pursuing the development of various heterogeneous catalysts for catalyzing the ODH of PSNHCs (Scheme ). − For example, Li and co-workers reported the ODH of THQL catalyzed by Co@N-doped graphene shells with K 2 CO 3 as an additive . Dyson et al used Pd-Au nanoparticles immobilized on multiwall carbon nanotubes to catalyze the dehydrogenation of PSNHCs .…”

On the mechanism of acceptorless dehydrogenation of N-heterocycles catalyzed by tBuOK: a computational study

“…With the aim of providing low-cost and environmentally benign protocols, the transition-metal-free catalysts represent appealing alternatives, although such catalysts are less exploited, especially under acceptor-free conditions. The heterogenous metal-free carbocatalysts such as nitrogen-assembly carbons (NCs) 16 a and reduced graphene oxides (rGOs) 16 b were demonstrated efficient with high reusability and stability even under ambient temperature. The homogenous B(C 6 F 5 ) 3 catalyst was used by Kanai et al in 2016, to catalyze the ADH of N-heterocycles with high functional group tolerance.…”