Carbon Dioxide → 2-(3-Phosphonophenylamino)-naphthalene

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

Water (20 parts) is set stirring and 2-hydroxy-3-naphthoic acid (9.5 parts) charged. Sodium hydroxide liquor (70° Tw -- 6.8 parts) is then added until an alkaline reaction is obtained on Brilliant Yellow test paper. 3-aminophenylphosphonic acid (8.7 parts) and sodium bisulphite liquor (40% -- 100 parts) are charged and the mixture is stirred and boiled under reflux for 18 hours. Carbon dioxide is evolved during the early part of the boiling period. After cooling to 80° C the suspension is acidified with hydrochloric acid (36% -- 59 parts) until acid reaction is obtained on Congo Red paper. During acidification the temperature is raised steadily to the boiling point and the suspension is boiled under reflux for 1-2 hours until evolution of sulphur dioxide has essentially ceased. During this period samples are spotted on to Congo Red test paper to confirm a positive acid reaction. The suspension is then cooled to room temperature, filtered and the cake washed with water (10 parts). The paste (18.2 parts) is dried an air at 50° C to give 12.9 parts of 2-(3-phosphonophenylamino)-naphthalene.

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