Лако-красочные материалы — производство

The optimum coupling conditions depend on the nature of the diazo and coupling components used. The acidic diazonium salt solution is generally added to the so­lution of the coupling component. Because, in addition to acid derived from the diazotization process, additional acid is released during coupling, the optimum pH value must be adhered to by […]

The most important coupling components can be divided into the following groups. Where there are several possibilities for coupling, the preferred coupling positions are marked by bold arrows and the other possible coupling positions by ordinary arrows. Anilines, diamin obenzenes (e. g., 26-32). When treated with aniline, diazotized aniline (benzenediazonium chloride) yields, apart from a […]

Depending on the basicity and solubility of the amines being diazotized, the fol­lowing diazotization methods find industrial use: a) Direct Diazotization. The primary aromatic amine is dissolved or suspended in aqueous hydrochloric or sulfuric acid, and a concentrated aqueous sodium nitrite solution is added. An excess of 2.5-3 equivalents of acid per equivalent of amine […]

Diazo components for the production of azo dyes can be divided into the follow­ing groups of aromatic amines: Aniline and Substituted Anilines. Methyl, chloro, nitro, methoxyl, ethoxyl, phe — noxyl, hydroxyl, carboxyl, carbalkoxyl, carbonamide, and sulfonic acid groups are primarily used as substituents. Examples: Toluidines, nitroanilines, amino benzoyl amides, and the sulfonic acids thereof. Naphthylamines […]

Almost without exception, azo dyes are made by diazotization of a primary aro­matic amine followed by coupling of the resultant diazonium salt with an elec­tron-rich nucleophile. The diazotization reaction is carried out by treating the pri­mary aromatic amine with nitrous acid, normally generated in situ with hydro­chloric acid and sodium nitrite. The nitrous acid nitrosates […]

2.1.1 Introduction The azo dyes are by far the most important class, accounting for over 50% of all commercial dyes, and having been studied more than any other class. Azo dyes contain at least one azo group (—N=N—) but can contain two (disazo), three (trisazo), or, more rarely, four (tetrakisazo) or more (polyazo) azo groups. […]

Introduction A principle focus of this book is the classification of dyes by chemical structure. This is certainly not the only possible classification scheme for dyes: ordering by application properties, e. g., naming according the substrate to be dyed is another alternative. Neither of these two categories can be used with the exclusion of the […]

General References “Dyes and Dye Intermediates” in Kirk-Othmer Encyclopedia of Chemical Tech­nology ,Wiley, New York; in 1st ed., Vol. 5, pp. 327-354, by G. E. Goheen and J. Werner, General Aniline & Film Corp., and A. Merz, American Cyanamid Co.; in 2nd ed., Vol. 7, pp. 462-505, by D. W. Bannister and A. D. Olin, […]

In the early 1900s, about 85 % of world dye requirements were manufactured in Germany, with other European countries (Switzerland, UK, and France) accounting for a further 10%. Eighty years and two world wars have seen dra­matic changes in this pattern. Table 1.2 shows that, in weight terms, the Western European share of world production […]

The basic steps of dye (and intermediate) manufacture are shown in Figure 1.1. There are usually several reaction steps or unit processes. The reactor itself, in which the unit processes to produce the intermediates and dyes are carried out, is usually the focal point of the plant, but this does not mean that it is […]