Sulfuric Acid → [2-(4-Chlorophenylsulfanyl)phenyl]-3-methylpiperazine

Participants

Reaction Conditions

Reaction Steps

2-(3-Methylpiperazin-1-yl)phenylamine (0.96 g, 5 mmol) was dissolved in water (30 mL) containing concentrated sulfuric acid (0.28 mL, 5.2 mmol), the solution was cooled to 0° C. and sodium nitrite (0.36 g, 5.2 mmol) was added. The reaction was stirred for 30 minutes before the pH of the reaction was adjusted to pH 7 with sodium acetate. The diazonium salt solution was then added dropwise to a solution of 4-chlorothiophenol in 2 M NaOH (4 mL) containing a copper suspension (0.3 g, 5 mmol). After addition, the mixture was heated to 60° C. for 30 minutes before being allowed to cool to room temperature and ethyl acetate (10 mL) was added. The mixture was filtered and the organic layer was separated. The aqueous layer was extracted with ethyl acetate (2×10 mL). The combined organic extracts were dried over magnesium sulfate, filtered and evaporated in vacuo. The crude product was purified by flash chromatography using silica gel, eluting with ethyl acetate/methanol/ammonia 96:3:1. The pure product was isolated as a colourless oil. Yield (0.18 g, 11%) 1H NMR (CDCl3, 500 MHz) 1.12 (d, 3H); 2.6–2.72 (br m, 2H); 3.0–3.15 (m, 5H); 6.9 (m, 2H); 7.08 (d, 1H); 7.15 (m, 1H); 7.25–7.35 (m, 4H); MS (MH+) 319.1.

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