Sodium Carbonate — Sulfanilic Acid, Diazotized

Iodine-Sodium Carbonate-Sulfanilic Acid, Diazotized... 

Alkaline Coupling Process. Orange II [633-96-5] (21) (Cl Acid Orange 7 Cl 15510) a monoazo dye discovered ia 1876, serves as an example of the production of an azo dye by alkaline coupling. A suspension of diazotized sulfanilic acid (0.1 mol) is added to a solution (cooled to about 3°C) of 14.4 g 2-naphthol dissolved ia 15 g 30% sodium hydroxide, 25 g sodium carbonate, and 200 mL of water. The temperature should not be allowed to rise above 5°C. The reaction is heated until solution occurs and the dye is precipitated with 100 g sodium chloride. The mixture is cooled and filtered, and the product is dried. 

Monoaminoarenesulfonic acids exist in acid solution as zwitterions (2.3 in the case of sulfanilic acid), which are relatively insoluble in contrast to the corresponding bases (such as 2.4). For this reason the indirect method of diazotization is often employed in such cases. The aminoarenesulfonic acid is dissolved as the anion (2.4) by introducing the required amount of sodium carbonate or hydroxide, and nitrite is added to the approximately neutral solution, which is then run into mineral acid. Indirect diazotization is particularly recommended for the aminosulfonic acids of greater molecular mass but, contrary to some statements in the literature, the three anilinesulfonic acids themselves can be diazotized directly in suspension, the reaction proceeding quite smoothly after some practice. 

Note The sulfanilic acid can also ers in this case the chromatogram in 10 mol hydrochloric acid) [5]. I diazotized sulfanilic acid [3]. In tl alcoholic iodine solution to cleave sodium carbonate solution and f 2,4,6-Trichlorophenol and 2,3,4 The detection limits for phenol are 0.1-1 pg substance per chron The reagent can be used, for c lulose layers. 

A) Diazotization of Sulfanilic Acid.—A mixture of 105 g. (0.5 mole) of sulfanilic acid dihydrate, 26.5 g. (0.25 mole) of anhydrous sodium carbonate, and 500 cc. of water is heated and stirred until all the sulfanilic acid has dissolved, and the solution is then cooled in an ice bath to 15° (sodium sulfanilate begins to crystallize at this temperature). A solution of 37 g. (0.54 mole) of sodium nitrite in 100 cc. of water is added and the resulting solution is poured at once onto a mixture of 106 cc. (1.25 moles) (Note 1) of concentrated hydrochloric acid (sp. gr. 1.18) and 600 g. of ice contained in a 2-1. beaker. The solution, from which />-benzenediazonium sulfonate separates on stirring, is allowed to stand in an ice bath for fifteen to twenty-five minutes, during which time the naphtholate solution is prepared. 

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