Clotrimazole imidazole ring

The mechanism of the reaction has not been eiuddated. Presumably iodine eliminates the imidazole ring from N-substituted imidazole derivatives such as clotrimazole, and this then couples with diazotized sulfanilic acid to yield an azo dye. 

Clotrimazole fonnally also is an imidazole derivative because of the presence of an imidazole ring in its structure. It is believed that, like miconazole, econazole, and other pure representatives of the imidazole class, it also inhibits the biosynthesis of ergosterin in the cytoplasmatic membrane of fungi. 

Note The sulfanilic acid can also be diazotized in situ on nitrite-impregnated TLC layers in this case the chromatograms are merely sprayed with sulfanilic acid solution (2<7o in 10 mol hydrochloric acid) [5]. Diazotized 4-nitroaniline can also be used in place of diazotized sulfanilic acid [3]. In the case of clotrimazole, the layer is first sprayed with alcoholic iodine solution to cleave the imidazole ring bound to the molecule, then with sodium carbonate solution and finally with diazotized sulfanilic acid [12]. 

Azoles are synthetic compounds that can be classified as either imidazoles or triazoles according to the number of nitrogen atoms in the five-membered azole ring, as indicated below. The imidazoles consist of ketoconazole, miconazole, and clotrimazole (Figure 48-2). The latter two drugs are now used only in topical therapy. The triazoles include itraconazole, fluconazole, voriconazole, and posaconazole. 

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