Hydrochloric Acid → 2-Aminobenzenesulfonic acid

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Reaction Steps

12.8 g of 1-amino-8-hydroxynaphthalene-3,6-disulphonic acid are dissolved in 200 ml of water at pH 5.8. After cooling the solution to 0°-5°, 3.8 g of cyanuric fluoride are added dropwise in the course of 10 minutes, and during this the pH value of the solution is kept at 4.0-4.5 by adding 20% strength sodium carbonate solution dropwise. The mixture is subsequently stirred for about 15 minutes and 4.3 g of m-toluidine are then added. The pH value is now kept at 5.5-6.0. After the condensation of the difluorotriazinyl component with the m-toluidine has ended, a diazonium salt suspension which has been obtained from 7.0 g of 2-aminobenzenesulphonic acid in 100 ml and 20 ml of concentrated hydrochloric acid with 20 ml of 2N sodium nitrite solution analogously to Example 2, is allowed to run in at 0°-5°.

Provenance & Evidence