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3-Bromobenzhydrazide is used to produce 5-(3-bromo-phenyl)-3H-[1,3,4]oxadiazole-2-thione. This reaction will need reagent potassium hydroxide and solvent ethanol.

General procedure for the synthesis of 3-bromobenzoic acid hydrazide from ethyl 3-bromobenzoate: Hydrazide was synthesized routinely using the one-pot method (30-58% yield). Ethyl 3-bromobenzoate (10 mmol) was dissolved in ethanol (20 mL). 3N sulfuric acid (2 mL) was added to the solution and the reaction mixture was refluxed for 6 hours. The reaction process was monitored by thin layer chromatography (TLC). Upon completion of the reaction, the reaction mixture was neutralized by addition of solid sodium bicarbonate (NaHCO3) and filtered to remove excess NaHCO3. To the neutralized reaction mixture, hydrazine monohydrate (1.5 mL, 3 mmol) was added and refluxing was continued for 3-6 hr to ensure the reaction was complete. The volume of the reaction mixture was reduced to 1/3 of the original volume by distillation to remove ethanol and unreacted hydrazine monohydrate. The reaction mixture was cooled to room temperature, the precipitate was collected by filtration and recrystallized from methanol to give pure 3-bromophenylhydrazine crystals (see Supporting Information for specific data).

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