Sodium Carbonate → 2,5-Diaminobenzenesulfonamide

Participants

Reaction Conditions

Reaction Steps

A mechanically stirred suspension of N-(1,1,3-trioxo-1,2,3,4-tetrahydro-1λ6-benzo[1,2,4]thiadiazin-7-yl)-methanesulfonamide (Example 3c′, 115.2 g, 0.40 mol) in 9.0 M aqueous sulfuric acid (500 mL) was heated to 130° C. for 2.5 h (considerable gas evolution was noted during this time). The resulting brown solution was cooled to 0° C. and an aqueous solution of sodium hydroxide (351 g in 750 mL water; ca. 11.7 M) was added via addition funnel over 45 min. The pH of the reaction mixture was then adjusted to approximately 7.0 by the dropwise addition of 3.0 M aqueous sodium carbonate solution. The resulting suspension was allowed to warm to 25° C. and stirred for 1 h, then was filtered through medium paper using a Büchner funnel. The collected solid was washed with water (1×300 mL) and was dried in a vacuum oven at 50° C. to afford a mixture of 2-amino-5-methanesulfonylamino-benzenesulfonamide and 2,5-diamino-benzenesulfonamide (1.5:1.0 ratio, 70.0 g, 75% yield) as a brown solid. 1H NMR (400 MHz, DMSO-d6) δ: 2.86 (3H, s), 4.54 (2H, bs), 4.98 (2H, bs), 5.77 (2H, s), 6.55-6.60 (2H, m), 6.76 (1H, d, J=8.6 Hz), 6.87 (1H, d, J=2.2 Hz), 6.99 (2H, bs), 7.11 (1H, dd, J1=8.6 Hz, J2=2.4 Hz), 7.25 (2H, bs), 7.43 (1H, d, J=3.1 Hz), 9.16 (1H, s).

Provenance & Evidence