Dye salt

Properties of Colorants. Properties of a number of colorants are shown ia Tables 5—9. Eor other properties see Refereace 15. Most values are from the Hterature and, ia geaeral, refer to commercial colorants and not pure compounds. The composition of certified colorants can vary substantially with regard to the amounts of pure dye, salt, moisture, subsidiary dyes, trace metals, etc. that they contain, and of course the properties of color additives are affected by their composition. 

Salz-farbe,/. metallic dye, dye salt, -fehler, m. salt error, -fleisch, n. salt meat, -fiuss, m.. saline flux salt rheum, eczema, salz-fdrmig, a. saliniform. -frei, a. free from salt, salt-free. 

In the first stage, unfixed dyes, salt and alkali present in the liquor phase must be removed and this is best done by replacing this liquor with fresh water. Sorption, desorption and diffusion processes play only subordinate roles in this stage, the key factors being liquor flow, mechanical action and liquor exchange. The dilution laws are generally applicable. 

Equally popular are azo couplings of diazonium salts that keep the nitrogen atoms in the product. The solid-solid version is very suitable with appropriate phenols such as 296 and 299. The waste-free and quantitatively obtained azo dye salts can be neutralized. The free dyes have the hydrazono structure (297, 298) or the azo structure (300) [99-100] (Scheme 45). The prescription should be carefully followed for safety reasons ... 

Solid diazonium salt 1 (0.50 mmol) and jS-naphthol 2 (0.60 mmol) were separately ground in agate mortars and cautiously mixed. In the case of Id MgSC>4 2H20 (0.50 mmol) was added to the mixture. The mixtures rested for 24 h in test tubes and were then exposed to ultrasound for 24 h in a cleaning bath. The quantitatively obtained azo-dye salts 3-HX were neutralized and freed from excess 2 by washings with 0.5 n NaOH (20 mL) and water (20 mL). The yields of the neutral dyes with the hydrazono structure 3a-d were 100, 98, 99 and 99%. 

Chrysoidine dye salts of dodecylbenzenesulfonic acid are soluble in glycols and glycol ethers and are used in the production of inks, printing inks, and varnishes [2],... 

Such dye salts are converted to azo bases by alkali. Alkylating agents attack the nitrogen atom of the azo bond, forming alkylarylhydrazone dyes which dye polyacrylonitrile in lightfast, yellow to orange shades [26],... 

Solvent dyes [1] cannot be classified according to a specific chemical type of dyes. Solvent dyes can be found among the azo, disperse, anthraquinone, metal-complex, cationic, and phthalocyanine dyes. The only common characteristic is a chemical structure devoid of sulfonic and carboxylic groups, except for cationic dyes as salts with an organic base as anion. Solvent dyes are basically insoluble in water, but soluble in the different types of solvents. Organic dye salts represent an important type of solvent dyes. Solvent dyes also function as dyes for certain polymers, such as polyacrylonitrile, polystyrene, polymethacrylates, and polyester, in which they are soluble. Polyester dyes are principally disperse dyes (see Section 3.2). 

It is understandable that, as is well known, the dye salt itself and the true colour base are coloured in contrast to the colourless carbinol base and the leuco base. In the latter there is no longer an electron hole55 at the central carbon atom. In addition we have probably a tetrahedral structure in contrast to the approximately plane structure of the ion compounds. 

For steric reasons, the dye salts cannot exist in the purely di-cia form according to the energy of the system (depending on the position of the respective dipoles, etc.) they have the linear all-frana or the... 

A number of oxazine dye salts, on dissolving in aqueus alkali, precipitated the free radical thus the dye Meldola s blue, which precipitates even in almost neutral solution, yields a very stable solid free radical which can be kept in air and can be used as standard like 2,2-diphenyl-1 -picrylhydrazyl. 

In the above reaction there is first formed, in the cold, a hydrate salt which is colorless. This on heating loses water, as indicated, yielding an anhydride salt which is the dye and has the constitution as given. The formation of this anhydride dye salt involves the conversion of one of the benzene rings from the normal structure with alternate double and single bonds to a structure found in quinone (p. 636). 

Colored Dye Salt.—(4) The anhydride salt formed by loss of water from the hydrate salt. It has the quinoid structure in the benzene ring linked to the ammonium salt group. This compound is colored and is the dye salt or the actual dye. The formulas of the para-rosaniline compounds may be given all together as follows ... 

Rosaniline then is another dye compound related to para-rosaniline. It is not isomeric but differs in composition by CH2. This at once suggests that it is a homologue and such has been found to be the case. Its constitution has been established by its synthesis from pure compounds. When, instead of using two molecules of aniline and one molecule of />-toluidine as in the synthetic preparation of para-rosaniline, we use one molectde each of aniline, p-toluidine and ortho-toluidine then we obtain the leuco base of rosaniline alone. From the leuco base the dye salt is obtained by the usual methods. The reactions analogous to the ones for para-rosaniline are ... 

Tlhe dye salt may be obtained as the chloride or acetate but usually in beautiful green crystals of the oxalate or as the double chloride with zinc. Other derivatives corresponding to malachite green are dyes of various shades of green and blue. 

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