67515-59-7

10 mmol of 3-trifluoromethyl-4-haloaniline was dissolved in 10 mL of slightly heated glacial acetic acid. 2.5 mL of 12 mol·L⁻¹ sulfuric acid solution was slowly added and stirred until a dark yellow solution was formed. The solution was then cooled to 0–5 °C in an ice-salt bath and stirred until a white paste was formed. 10 mL of 2 mol·L⁻¹ NaNO₂ solution, cooled to 0–5 °C, was then added dropwise to the white paste under vigorous stirring (approximately 30 min) to form a reddish-brown diazonium salt solution. The solution was continued until the solution turned blue on starch-potassium iodide test paper. Finally, the glacial acetic acid was neutralized with Na₂CO₃ to pH = 7.0.