Formation of ionic carbon nitride towards an environmentally friendly synthesis of 2-amino-5-alkylidene-thiazol-4-one

Graphitic carbon nitride (g-C3N4) has a layered structure similar to graphite and presents exciting and unique support in organic transformations. Using the edge-functionalized graphitic carbon nitride by doping it with various functional groups and transforming it into another morphology has become the center of attention in the recent decade. It has a nitrogen-rich structure with weak base properties; therefore, it must improve its properties with various functionalization. Herein, for the first time, templatefree ionic carbon nitride nanotubes (K-g-C3N4) were created via thermal polymerizing and aqueous alkaline liquid-phase exfoliation. The characterization of alkaline K-doped ionic graphitic carbon nitride (K-gC3N4) was determined by FT-IR, SEM, EDS, and TGA analysis. A simple, facile, and efficient synthesis of 2-amino-5-alkylidene-thiazol-4-ones derivatives via a multicomponent reaction of various aldehyde, amines, and rhodanine in ethanol using a reusable K-g-C3N4 as a green catalyst has been developed. The reaction scope was explored by varying the structures of aldehydes and amines with rhodamine. Various 2-amino-5-alkylidene-thiazol-4-ones were established in yields ranging between 65 and 96% for 60-180 min. Due to the heterogeneous nature of K-g-C3N4, the catalyst could be recovered by centrifugation and reused in five cycles without a decrease in catalytic activity. Operational simplicity, facile fabricable catalyst, broad substrate scope, readily available starting materials, nontoxic, highly stable, environment-friendly catalyst and solvent, suitable to excellent yields, and simple work-up are the prominent features of this methodology. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

Graphitic carbon nitride (g-C3N4) has shown unique support properties in organic transformations. In this study, template-free ionic carbon nitride nanotubes were successfully synthesized and used as a green catalyst for the synthesis of 2-amino-5-alkylidene-thiazol-4-ones derivatives. The catalyst exhibited high stability, excellent yields, and could be reused multiple times.