Unexpected ring closure of 2-(1-(4-fluorophenyl)-5-methyl-1H-1,2,3-triazole-4-carbonyl)-N-phenylhydrazine-1-carbothioamide (3) on exposure to sulfuric acid at room temperature for an extended duration (12 h) gave 4-((5-(1-(4-fluorophenyl)-5-methyl-1H-1,2,3-triazol-4-yl)-1,3,4-thiadiazol-2-yl)amino)benzenesulfonic acid (4) in 75% yield. The use of sulfuric acid led to sulfonation at the para-position of the benzene ring in phenyl isothiocyanate. The crystal structure comprises two independent types of molecules of 4 and two disordered ether solvent molecules. The synthesized benzenesulfonic acid inhibits the growth of both Listeria monocytogenes and Escherichia...