Лако-красочные материалы — производство

2.11.1 Quinophthalone Dyes Like the hydroxy azo dyes, quinophthalone dyes can, in theory, exhibit tautomer- ism. Because the dyes are synthesised by the condensation of quinaldine deriva­tives (1) with phthalic anhydride, they are often depicted as structure (2), but this is incorrect, since the two single bonds prevent any conjugation between the two halves of […]

Metal-Containing Bidentate Formazans. The most outstanding property of forma — zans is their ability to form coordination compounds with metals. They behave as monovalent, bidentate ligands and form neutral 1:2 metal chelates with divalent metals. Opinions about the geometry of these compounds vary. A planar structure has been proposed on account of their magnetic properties […]

Coupling of Diazonium Compounds with Hydrazones. The most common method for the production of formazans is the coupling of diazonium salts with aryl hydrazones in an alkaline medium, possibly in presence of an organic sol­vent. The industrially important 1-(2-hydroxyaryl)-3-aryl-5-(2-carboxyaryl)forma — zans are obtained by this process. The corresponding bis(2-hydroxy) compounds cannot be produced by this […]

2.9.3.1 Introduction Formazan dyes are closely related to azo dyes and are derived from the following basic structure: 12 3 4 5 -N=N-C=N-N- I H (N1 me. so 1ST ) The position of the substituents is given according to IUPAC nomenclature using the prefixes 1-, 3-, and 5-. Formazans unsubstituted in the 1- and 5-positions […]

The coordination number of the chelated metal atom determines the number of linkages to functional groups. It is typically greater than the valency of the metal ion; for example, the divalent ions of copper and nickel have coordination num­bers of four, and the trivalent ions of chromium, cobalt, iron a coordination num­ber of six. In […]

2.9.2.1 General Synthesis In general, metallization is accompanied by the lost of protons, and therefore it can be monitored potentiometrically, similar to a neutralization reaction. With the exception of 1:1 chromium complex formation, all metallization reactions are promoted by acid-binding agents. CopperComplexes. The preparation of copper and nickel complexes of tridentate metallizable azo and azomethine […]

2.9.1 Introduction Metal-complex dyes are coordination compounds in which a metal ion is linked to one or more ligands containing one or more electron-pair donors. Ligands with one and more donor groups are called mono-, di-, trifunctional ligands, etc. Coordination of two or more of the donor groups of such ligands to the same metal […]

With a few exceptions, sulfur dyes are used for dyeing cellulosic fibres. They are insoluble in water and are reduced to the water-soluble leuco form for application to the substrate by using sodium sulfide solution. The sulfur dye proper is then formed within the fiber pores by atmospheric or chemical oxidation. Sulfur dyes constitute an […]

The term “pseudo (or synthetic) sulfur dyes” refers to dyes that have application properties similar to those of sulfur dyes but are obtained by the insertion of mer — capto groups or their precursors into the dye precursors or pigments rather than by the classical sulfurization method. These dyes thus have some of the character­istics […]

The starting products for reflux thionation in aqueous or solvent media are chiefly derivatives of indophenol (10, Y = OH) and indoaniline (10, Y = NH2). The starting compounds are often in the leuco form 11. This class of compounds also includes phenazone, phenothiazone, and phe — noxazone derivatives (12), and so these polysulfide melt […]