Role of graphene oxide as a heterogeneous acid catalyst and benign oxidant for synthesis of benzimidazoles and benzothiazoles

Abstract

Graphene oxide plays a dual role as active metal-free acid catalyst and as non-toxic oxidant for benzothiazole and benzimidazole synthesis. Isolated partially reduced graphene oxide was re-oxidized to regenerate the catalyst and restore its activity.

Graphene Oxide Supported Oxovanadium (IV) Complex for Catalytic Peroxidative Epoxidation of Styrene: An Eye‐Catching Impact of Solvent

“…XRD pattern of GO and VO‐ f ‐GO catalyst depicted in the Figure S2. Typically, XRD pattern of graphite shows only a single characteristic peak at 2θ = 26°, however, on addition/insertion of oxygenated functional groups onto the surface by oxidation process this peak was lessened significantly and a new characteristic peak at 2θ = 10.8° was emerged out . This charateristic peak was due to oxidative functional groups which was experienced reduction on further modification due to functionalization at hydroxyl groups.…”

Role of Degree of Oxidation of Graphene Oxide on Biginelli Reaction Kinetics

“…Aggregation of GO on reaction has been reported in previous studies was not observed in the reaction. GO can also act as an oxidizing agent donating oxygen causing a decrease in zeta potential of GO promoting aggregation . No indication of partial reduction of catalyst, a primary cause of loss of GO activity, is observed, as the catalyst does not exhibit any tendency for aggregation even after 4 th reuse and the colour of the catalyst remains brown, which indicates GO does not undergo self‐reduction or behave as behave as an oxidising agent.…”

“…The degree of oxidation will have a significant effect on the catalytic ability of GO. Graphene oxide has previously been shown to catalyse nucleophilic addition of amino groups to aldehydes . Here we investigated the activity of GO for catalysing multicomponent Biginelli reaction for synthesis of dihydropyrimidinones from ethylacetoacetate, aromatic aldehydes and urea.…”

“…Organic transformations are catalysed by graphene oxide utilizing its acidic protons or its strong oxidising ability and has shown potential to replace the traditional metal catalysed pathways. Numerous one pot syntheses such as α‐aminophosphonate synthesis, benzimidazole synthesis, epoxidation, Michael addition, aldol condensation etc., are accelerated by surface bound hydroxyl and carboxylic acid groups in GO …”

“…Numerous one pot syntheses such as a-aminophosphonate synthesis, benzimidazole synthesis, epoxidation, Michael addition, aldol condensation etc., are accelerated by surface bound hydroxyl and carboxylic acid groups in GO. [5][6][7][8][9] Catalytic activity of graphene oxide is due to presence of functional groups and can be tuned by changing percentage of oxidising agent which can enhance the acidity of GO sheet by the attachment of epoxy and hydroxyl groups at basal plane and carbonyl groups at the edges. Further, the properties of graphene can be tuned by incorporating additional functional groups on the basal planes of GO sheets.…”