Sodium naphthionate

This dyestuff is prepared by tetrazotisiiig benzidine and coupling with sodium naphthionate ... 

In order to obtain a good yield a large excess of sodium naphthionate is employed, the excess being recovered as the free acid on acidifying the mother liquor after filtering off the dyestuff. (B., 19, 1719.)... 

Benzo purpurin.— Tolidine is di-methyl benzidine, that is it bears the same relation to toluene and ortho-toluidine that benzidine does to benzene and aniline. When this is diazotized and the tetrazonium salt coupled with sodium naphthionate the disazo compound resulting is a dye known as benzopmpurin 4B, which is also a substantive dye of a red color. 

From a solution of 6 4 grams of sodium naphthionate and 6 4 grams of mercuric acetate in 150 c.c, of water, treated with a large excess of sodium hydroxide, a colourless product is obtained. This does not react with ammonium sulphide, and towards halogen salts it reacts similarly to hydroxymercuri - j8 - naphthylamine - 6 - sifiphonic acid (sodium salt). Wlien dried over phosphorus pentoxide the body becomes canary yellow, and on addition of water becomes white again. It has been formulated as the sodium salt of 2-hydro xymermri-naphthionic acid. 

Riegler s test. A test for nitrous acid using sodium naphthionate and (3-naphthol. 

In this method, a polymer is prepared which has certain struc-tiiral features which can be chemically transformed to dye structures in one or more steps. Perhaps the most common class of dyes that have been so synthesized on a polymer backbone is the azo dyes, which are simply formed by the coupling of a polymeric aryl diazon-ium salt with an activated aromatic system. The former are prepared from polymeric aromatic amines by diazotization. Thus polymers and copolymers of 2,2 -di vinyl benzidine (XVl) have been diazotized and coupled with sodium naphthionate, sodium anthranilate and sulfanilic acid to give polymeric azo dyes which act as pH indicators,... 

B, 97 42B, 116 CioHbO/ a-Naphthol, 29, 677 CioHbO, /3-Naphthol, 22, 734 CioHb02, Naphthalene-1,4-diol, 32B, 121 C1oH1gNNa07S, Sodium naphthionate tetrahydrate, 31B, 95 C11H7IN2O2 H2O, 3-Carboxy-2-naphthalenediazonium iodide hydrate, 45B, 129... 

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