Background: Imidazoles are important class of heterocyclic compounds showing biological
activities. Several methods have been investigated till today for the synthesis of triaryl imidazoles.
Some of these classical as well as nonclassical methods experiences drawbacks for instance elongated
reaction time, expensive catalyst, low yield of product etc. Hence improvement of a competent method
is still necessary. This paper reveals greener protocol for the synthesis of triaryl imidazoles by
cyclocondensation of aromatic aldehydes, benzil and ammonium acetate in existence of fly ash as an
efficient heterogeneous catalyst by means of microwaves.
Methods: Heterogeneous catalyst fly ash was prepared by simple thermal activation method. The catalyst
was systematically characterized through wet chemical analysis, XRD, FT-IR, SEM and EDS.
The structural analysis was done using XRD and IR. Morphological study was performed using SEM
and elemental composition studied by EDS technique. This activated fly ash catalyst was applied in
the synthesis of trisubstituted imidazoles. The progress of reaction was checked by TLC and the synthesized
compounds were further confirmed by FT-IR, 1H-NMR and 13C-NMR spectroscopy.
Results: To check feasibility of activated fly ash for trisubstituted imidazole synthesis, reactions under
microwave irradiation employed. The products were obtained in higher yield (92-98%).
Conclusion: The fly ash was found to be highly effective in the synthesis of trisubstituted imidazoles
under microwave irradiation. The significant features of this protocol are rate enhancement, uncomplicated
work up process, high yields and employ of ecofriendly catalyst.