Sodium Carbonate → 2-Naphthalenesulfonic acid, 5-amino-6-ethoxy-

Participants

Reaction Conditions

Reaction Steps

6.42 kg (62% pure=4 kg of 100% pure) of 1-acetamino-2-hydroxy-naphthalene-6-sulphonic acid, prepared according to Example 4, 0.98 kg of potassium carbonate and 0.75 kg of sodium carbonate are introduced into a 150 l autoclave. After flushing the autoclave with nitrogen, 22 kg (28 l) of ethanol are added to the mixture. The autoclave is closed and heated to 120° C., whilst stirring thoroughly. 7 kg (6.5 l) of 2 N potassium hydroxide solution and 2.75 kg (about 3 l) of ethyl chloride are now pumped into the autoclave in the course of 1 to 2 hours. The entire reaction mixture is stirred for a further 5 hours at 120° C. After cooling the reaction mixture to room temperature, the autoclave is let down and flushed twice with nitrogen. The contents of the autoclave are then introduced into a 250 ml V4A steel kettle. The autoclave is rinsed out with 5 kg of 80% pure ethanol and the rinsing solution is likewise introduced into the steel kettle. The mixture in the steel kettle is heated to the boiling point, about 20 kg of alcohol being distilled off. 13 kg of water are then allowed to run slowly into the boiling solution and the mixture is distilled until no further alcohol passes over. After adding 4.3 kg of 50% strength sodium hydroxide solution, the mixture is stirred at 100° C. for 4 hours. The mixture is then cooled to 20° C. and the product which has precipitated is filtered off and washed with 25 kg of sodium chloride solution. After drying, 3.6 kg of 1-amino-2-ethoxy-naphthalene-6-sulphonic acid (content: 84.2% pure, corresponding to 3.03 kg of 100% pure=80% of theory, relative to 1-acetamino-2-hydroxy-naphthalene-6-sulphonic acid, or 61.6% of theory, relative to 2-hydroxy-naphthalene-6-sulphonic acid) are obtained.

Provenance & Evidence