Sulfuric Acid → 4-(Acetylamino)benzenesulfinic acid

Participants

Reaction Steps

To 4-acetamidobenzenesulphonyl chloride (400 g, 1.72 moles) was added with stirring a solution of sodium sulphite (431.7 g, 3.42 moles) in water (2 liters). A solution of 50% sodium hydroxide (240 ml) was added dropwise over 35 minutes using a cooling bath to keep the temperature below 30° C. The pH was thus maintained in the range 6.5-7.0. The mixture was stirred at room temperature for 2 hours and acidified by adding conc. sulphuric acid (170 ml) with ice-bath cooling. The precipitated white solid was filtered off, washed with water and dried at 50° C. The yield was 324.2 g (94%). This was used in the next stage without further purification.

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