Amino-2-naphthol-4-sulfonic Acid

Sodium hydroxide is added to the bisulfite solution in order to neutralize any acid which has not been removed by washing and which would liberate sulfur dioxide and thus cause some reduction of the nitroso compound before the addition product is formed. An excess of alkali, as employed above, aids in the solution of the material. 

The aminonaphtholsulfonic acid becomes rose colored on long exposure to the light, especially when moist. 

The time required for the process may be shortened somewhat by adding the sodium bisulfite-sodium hydroxide solution to the suspension of the crude nitroso compound, thus avoiding a long filtration. The amount of water employed in the various operations should be reduced to a minimum, and enough additional sodium hydroxide solution should be used to neutralize 

Sodium aesenite is prepared by dissolving 226 g. (1.14 moles) of powdered arsenious oxide, made into a paste with a little water, in a solution of 275 g. (6.88 moles) of sodium hydroxide dissolved in 600 cc. of water. This solution, diluted with 600 cc. of water, is poured into a 2-1. three-neck flask, provided with a reflux condenser and a mechanical stirrer, and 150 g. (1.22 moles) of freshly distilled nitrobenzene is added (Note 1). 

The mixture is refluxed on an oil bath for eight hours with constant and vigorous stirring (Note 2). After removing the oil bath, the reaction mixture is allowed to cool to about 8o°, while stirring is continued, and is then transferred to a separatory funnel previously heated to about the same temperature in an oven (Note 3). 

Submitted by H. E. Eicelow and Albert Palmer. Checked by Henry Gilman and H. J. Harwood. 

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H. Bhandari, V. Bansal, V. Choudhary, and S. K. Dhawan, Influence of reaction conditions on the formation of nanotubes/nanoparticles of polyaniline in the presence of 1-amino-2-naphthol-4-sulfonic acid and applications as electrostatic charge dissipation material, Polym. Int., 58, 489-502 (2009). 

Amino-3-hydroxy-1-naph-thalenesulfonic acid 1-Amino-2-naphthol-4-sulfonic acid C10H9NO4S 116-63-2 239.248 gray nd i H2O, EtOH, bz s alk... 

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