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Trichloroisocyanuric Acid (TCCA) used as reagents or catalysts

Trichloroisocyanuric acid (TCCA),38 tetrabutyl ammonium bromide (TBABr),39 1-methylimidazolium triuoroacetate ([Hmim]TFA), and without any catalyst. Many of the synthetic methods for imidazoles suffer from one or more disadvantages such as low yields, harsh reaction conditions, difficult work-up, prolonged time period and the application of hazardous and expensive catalysts. Hence the development of clean, high yielding, and environmentally benign approaches is still desirable and much in demand. In the last decades, many methods have been developed for the synthesis of tri- and tetrasubstituted imidazoles by the reaction of aldehydes, and benzil or benzoin with (1) ammonium acetate, and (2) ammonium acetate and amines in the presence of various reagents or catalysts. Hence the development of clean, high yielding, and environmentally benign approaches is still desirable and much in demand.
Trichloroisocyanuric Acid (TCCA) was used as reagents or catalysts for the synthesis of tri- and tetrasubstituted imidazoles. The optimal conditions were then applied for the preparation of a series of 2,4,5-trisubstituted imidazoles. In 
each case, no side product formation was observed, as is normally the case in such reactions under the inuence of strong acids. This method not only affords the products in excellent yields but also avoids the problems associated with catalyst cost, handling, safety, and pollution. The use of benzoin in place of benzil also gave similar results. Encouraged by this success, a study on the synthesis of 1,2,4,5-tetrasubstituted imidazoles from benzil or benzoin, amine, ammonium acetate and various aromatic aldehydes was carried out.
Trichloroisocyanuric Acid (TCCA) for preparation of the catalyst. The silica coated NiFe2O4 MNPs were synthesized according to our previous reports 46–48 and then, for the immobilization of PMA on NFS, 0.5 g of PMA was dissolved in 5mL of methanol.49 This solution was added dropwise to a suspension of 1.0 g NFS in methanol (50 mL) and then the mixture was heated at 70 ℃ for 48 h under vacuum while being mechanically stirred and gave the supported nanomagnetic catalyst (NFS–PMA). The catalyst was collected by a permanent magnet and dried under vacuum overnight and after the first drying, the supported nanocatalyst was calcined at 250 ℃ for 2 h.