Sulfuric Acid → 1,1,2-Trimethyl-1H-benzo[e]indole-7-sulfonic acid

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Reaction Conditions

Reaction Steps

1,1,2-Trimethyl-1H-benz[e]indole, 100 g. was added with stirring to 500 mL of concentrated H2SO4. The mixture was heated at 180° C. for 1/2 h, cooled to 60° C. and poured onto 2 Kg ice. Cautiously 500 ml of 50% aqueous NaOH was added. After 24 hours at room temperature the solid was filtered off, and 500 mL of saturated aqueous Na2SO4 was added. The resulting solid precipitate was collected, added to the previously filtered solid, and recrystallized from 2 L of H2O. Yield 25 g after overnight vacuum drying at 50° C. The location of the sulfo group was determined as being the 7-position by proton nuclear magnetic resonance measurements.

Provenance & Evidence