Mordant black

Diazophenols, ie, o-hydroxyaryldiazonium salts, couple to 1-naphthol in weaMy basic solution primarily in the para position, but as the hydroxyl ion concentration is increased, formation of the ortho isomer is favored and is frequentiy the sole product. Pyridine and pyridine derivatives, urea, and acetate, etc, used as buffers can also catalyze azo coupling reactions (28). l-amino-2-naphthol-4-sulfonic acid [116-63-2] (1,2,4-acid) and 1-naphthol yield the important Eriochrome Black A [3564-14-5] (18a, R = H) (Cl Mordant Black 3 Cl 14640) which is reportedly (20) a mixture of ortho and para isomers. 

The corresponding diazo component with a 6-nitro substituent gives Eriochrome Black T /7787-61-7] (18b, R = NO2) (Cl Mordant Black 11 Cl 14645) which is supposed to consist almost exclusively of the ortho compound. 

Dihydroxynaphthalene [83-56-7] behaves similarly to 1-naphthol coupling takes place mainly in the 4-position by simple diazonium compounds, and in the 2-position with diazophenols. Diazotized 2-arninophenol-4-sulfonic acid [98-37-3] couples with 1,5-dihydroxynaphthalene to produce the important mordant dye Diamond Black PV [2052-25-7] (see stmcture 53) (Cl Mordant Black 9 Cl 16500). 

Disazo JMordant Dyes. Examples of disazo dyes are Diamond Alizarine Black SN [3258-74-0] (55) (Cl Mordant Black 25 Cl 21725) and a secondary disazo dye. Diamond Black F [8027-29-0] (56) (Cl Mordant Black 5 Cl 26695). 

Acid—mordant dyes have characteristics similar to those of acid dyes which have a relatively low molecular weight, anionic substituents, and an affinity to polyamide fibers and mordant dyes. In general, brilliant shades caimot be obtained by acid—mordant dyes because they are used as their chromium mordant by treatment with dichromate in the course of the dyeing procedure. However, because of their excellent fastness for light and wet treatment, they are predominandy used to dye wool in heavy shades (navy blue, brown, and black). In terms of chemical constitution, most of the acid—mordant dyes are azo dyes some are triphenyhnethane dyes and very few anthraquinone dyes are used in this area. Cl Mordant Black 13 [1324-21 -6] (183) (Cl 63615) is one of the few examples of currentiy produced anthraquinone acid—mordant dyes. It is prepared by condensation of purpurin with aniline in the presence of boric acid, followed by sulfonation and finally by conversion to the sodium salt (146,147). 

Mordant dyes generally have the characteristics of acid dyes but with the ability in addition to form a stable complex with chromium. Most commonly, this takes the form of two hydroxy groups on either side of (ortho to) the azo group of a monoazo dye, as illustrated for the case of C. I. Mordant Black 1 (151). The dye is generally applied to the fibre as an acid dye and then treated with a source of chromium, commonly sodium or potassium dichromate. As a result of the process, the chromium(vi) is reduced by functional groups on the wool fibre, for example the cysteine thiol groups, and a chromium(m) complex of the dye is formed within the... 

Mordant dyes are notoriously troublesome from the viewpoint of colour matching because the hue of the chromium complex usually differs greatly from that of the unmetallised parent dye (section 5.4.1). If other metal ions are present in the treatment bath or on the fibre during chroming, the colour obtained is likely to differ from that of the pure chromium complex. Certain important chrome dyes, including Cl Mordant Black 11 (3.29) and Black 17 (3.30), are particularly sensitive to traces of iron or copper. The hue of the black dyeings obtained is redder in the presence of copper and browner with iron contamination. The fastness to light and wet treatments may also prove inferior under these conditions. Even certain 1 2 metal-complex acid dyes show similar effects in the presence of these impurities,... 

This is an alternative method of introducing copper into an o-hydroxyazo dye structure. The azo compound is treated with a copper(II) salt and an oxidant in an aqueous medium at 40-70 °C and pH 4.5-7.0. Sodium peroxide, sodium perborate, hydrogen peroxide or other salts of peroxy acids may be used as oxidants, the function of which is to introduce a second hydroxy group in the o -position [25]. This process is reminiscent of earlier work on Cl Acid Red 14 (5.51 X = H), an o-hydroxyazo dye that will not react with a chromium (III) salt to form a 1 1 complex but will do so by oxidation with an acidified dichromate solution. This oxidation product was later found to be identical with that obtained by conventional reaction of Cl Mordant Black 3 (5.51 X = OH) with a chromium(III) salt [7]. 

Procedure Weigh accurately about 0.8 g of granulated zinc, dissolve by gentle warming in 12 ml of dilute hydrochloric acid and 5 drops of bromine water. Boil to remove excess bromine, cool and add sufficient DW to produce 200 ml in a volumetric flask. Pipette 20 ml of the resulting solution into a flask and neutralize carefully with 2 N sodium hydroxide. Dilute to about 150 ml with DW, add to it sufficient ammonia buffer (pH 10.0) to dissolve the precipitate and add a further 5 ml quantity in excess. Finally add 50 mg of Mordant Black II mixture and titrate with the disodium edetate solution until the solution turns green. Each 0.003269 g of granulated zinc is equivalent to 1 ml of 0.05 M disodium ethylenediaminetetracetate. 

Materials Required Magnesium sulphate heptahydrate 0.3 g strong ammonia-ammonium chloride solution (6.75 g NH4C1 in 74.0 ml strong ammonia solution add water q.s. to produce to 100 ml) 0.05 M disodium edetate Mordant Black II mixture (mixture of 0.2 part mordant black II with 100 parts of NaCl) 0.1 g. 

Procedure Weigh accurately about 0.3 g of magnesium sulphate heptahydrate and dissolve in 50 ml of DW. Add to it 10 ml of strong ammonia-ammonium chloride solution, and titrate with 0.05 M disodium ethylenediaminetetracetate employing 0.1 g of mordant black II mixture as indicator, until the pink colour is discharged from the blue. Each ml of 0.05 M disodium ethylenediaminetetracetate is equivalent to 0.00602 g of MgS04. 

Magnesium chloride 0.5 g Mordant black II mixture Each ml of 0.05 M disodium edetate ee 0.017017 g of MgCl2.6H20... 

Acid alizarine black, acid chrome black, anthracene acid black, anthracene chrome black, chromate black, chrome acid H black, chrome fast black, diamond black, eriochrome black, fast chrome black, fast mordant black, monochrome black, omega chrome black, oxychrome black, palatine chrome black, salicine black. 

Oxidation of the dye during chroming with dichromate creates a naphthoquinone structure in the molecule. Two other important black dyes are C.I. Mordant Black 3, 14640 [3564-14-5] (25, R = H), and C.I. Mordant Black 11 (see Section 3.9.3). 

C.I. Mordant Black 11 is also used as an indicator in the complexometric titration of various bivalent metals with which it forms complexes [8],... 

Analytical Reagents. Various chelators give specific color changes on combining with different metal salts, such as vanadium, iron, cobalt, nickel, copper, and palladium salts and thus identify the corresponding metal ions [74], Other chelators, such as C.I. Mordant Black 11 (Eriochrome Black T) (2 see Section 3.11.1), are employed as indicators for complexometric titrations. 

Acid dyes include metal-complexed azo structures, where the metals used are cobalt, chromium, and iron.10 Examples are 1 1 and 2 3 chromium complexes and 1 2 cobalt complexes, where the numbers employed represent the ratio of metal atoms to dye molecules. Metal-complexed dyes can be formed inside textile fibers by treating suitably dyed fibers with a solution containing metal ions.11 In this case, the metal-free forms of these azo dyes are known as mordant dyes and contain mainly ortho, ortho -bis-hydroxy or ortho-carboxy, ortho -hydroxy groups (e.g., C.I. Mordant Black 11, Mordant Yellow 8, and Mordant Orange 6). When the metal complexes are formed prior to the dye application process, the resultant dyes are known as... 

The indicators used in compleximetric titrations are usually themselves complexing agents, which form weak complexes with the metal ion when added initially As the edetate solution is titrated, the weak complex is displaced by the stronger edetate complex to reveal the free colour of the indicator. The most commonly used indicator is known by the sinister name of mordant black. This indicator forms wine-red complexes with metal ions, but changes to a dark blue colour at the end point when the edetate has displaced all of the metal ions from the indicator complex. 

Solochrome Black WDFA (C. I. Mordant Black 11) is dissolved in a mixture of 75 ml triethanol amine and 25 ml alcohol]. The content is titrated with EDTA solution (0.02 N) until last reddish tinge disappears. Let the titre obtained be T ml. Since 1.0 ml of 0.02 N EDTA solution = 1.0 mg CaCOj,... 

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