How do you do diazotization titration?

Answer 1

The process by which an aromatic primary amine is converted to a diazonium compound. The preparation and reactions of diazonium salts were discovered in 1858 and were the basis of the synthetic dye industry and the development of other industrial chemistry in Europe. In diazotization, sodium nitrite is added to a solution of the amine in aqueous acid solution at 0–5°C (32–41°F). Reaction of the amine with nitrous acid gives a nitrosamine. Tautomerization and loss of water lead to the diazonium ion, which is stabilized by delocalization of the positive charge at the ortho and para carbon atoms of the ring, as in the reaction below. See also Amine; Aromatic hydrocarbon; Delocalization. The overall reaction is simple and very general. Substituents of all types—alkyl, halogen, nitro, hydroxyl, sulfonic acid—can be present at any position. Heterocyclic amines such as aminothiazole or aminopyridines can also be diazotized. Aromatic diamines are converted to bis-diazonium compounds. Diazonium salts are generally used and handled in aqueous solution; they are explosive if isolated and dried. The great importance of diazonium compounds in dye technology lies in the coupling reactions that occur with an activated aromatic ring, such as that in phenols or aromatic amines. Coupling, or electrophilic substitution by ArN2+, gives compounds with an arylazo group at the position para or ortho to OH or NH2. Reaction with amines occurs in weak acid solution. With phenols the phenoxide ion is the reactive species, and slightly basic solution is used. See also Chemical equilibrium. The azo dyes obtained in these coupling reactions are one of the important types of synthetic dyes. The color of the dye can be varied widely by choice of diazonium and coupling components. The coupling reaction lends itself to an important method of applying the dye to fabrics. In this process the coupling reagent, such as a naphtholsulfonic acid, is absorbed onto the fiber, and the coupling reaction is then carried out directly on the fiber by passing the fabric through a bath of the diazonium solution. See also Dye.