2-Chloro-5-nitrobenzenesulfonic acid → 2-Chloro-5-nitrobenzenesulfonamide

Beteiligte Stoffe

Reaktionsschritte

To a solution of thionyl chloride (11 mL) and 2-chloro-5-nitro-benzenesulfonic acid (4.78 g, 20.1 mmol) was added N,N-dimethylformamide (0.92 μL) and the reaction mixture was heated at reflux for 4 h. The reaction mixture was then carefully quenched by pouring it into water and the product was isolated by vacuum filtration. The sulfonyl chloride was dissolved in a minimal amount of toluene and then added to a mixture of concentrated aqueous ammonium hydroxide solution (25 mL) and tetrahydrofuran (25 mL) at −10° C. After stirring for 2 h the reaction was quenched by adding a 6.0 M aqueous hydrochloric acid solution until pH 4 was reached. The layers were separated and the organic layer was concentrated in vacuo to a slurry. Pentane was added and the product was isolated by vacuum filtration to afford 2-chloro-5-nitrobenzenesulfonamide (2.0 g, 8.48 mmol, 42.4%), as a solid. 1H NMR (400 MHz, DMSO-d6) δ: 7.94 (d, 1H, J=8.8 Hz), 7.97 (bs, 2H), 8.40 (dd, 1H, J1=8.6 Hz, J2=3.1 Hz), 8.64 (d, 1H, J=3.1 Hz).

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