Chromium complexes salicylic acid

As an example of 1 2 chromation by the chromium(m) salicylic acid method [19], the sodium salt of the azo dye obtained from diazotized 1-amino-2-hydroxy-5-nitrobenzene and acetoacetic acid 3-sulfonamidophenylamide in water and a solution of chromium(m) sodium potasium salicylate are refluxed for several hours. The 1 2 chromium complex 11 is precipitated at below pH 4. It is a yellow brown powder, which is soluble in hot water with a greenish yellow color. 

Good non-colored negative charging CCAs have been obtained by making non-colored analogues of the 2 1 chromium complex azo dyes. This is achieved by making the metal complex of an aromatic ortho-hydroxy carboxylic acid. Typical examples are the chromium, aluminum, and zinc complexes of di-tert-butyl salicylic acid, e.g., BONTRON E-8136 41 (53) and BON-acid36,41,42 e.g., BONTRON E-82 (54). 

Synthetic alizarin (5.1), Cl Mordant Red 5 (5.2) and Cl Mordant Orange 1 (5.3), the first azo dye capable of forming a metal complex, in this case via the salicylic acid residue, are examples of the simple mordant dyes in widespread use at the time when Werner propounded his theory. The first metal-complex dyes to be prepared in substance, rather than within the fibre, were discovered by Bohn of BASF in 1912 by treating hydroxyanthraquinonesulphonic acids with a warm solution of a chromium(III) salt. In the... 

In a bidentate ligand system, three molecules of a dye containing either a terminal salicylic acid unit (as in 5.2) or an o-nitrosonaphthol residue are able to chelate simultaneously with a trivalent metal ion of CN6, such as chromium (III) or iron(III), to form a 1 3 metal-dye complex (as in 5.8). Historically, the most important bidentate ligand system was alizarin (5.1). It has been suggested that both hydroxy groups and the keto group in the peri position are all involved with the metal atom in the chelation mechanism. 

Using these agents, especially the particularly effective 1 2 complex 4 with salicylic acid, metallization can be carried out easily at high pH without precipitation of inert chromium hydroxide. In certain cases a 1 1 chromium complex that still contains chelating organic acid as ligand can also be obtained. 

Salicylic and cresotinic acids are used in the preparation of azo dyes and of tri-phenylmethane dyes of the aurine type (eriochrome azurol B). These acids confer upon the dyes the property of going onto metal mordants, particularly chromium mordants, and also of forming complex compounds, in substance, with suitable metal salts. Salicylic acid is also widely used in the pharmaceutical industry. 

Copper complexes (152) of o-hydroxy-o -(p-aminoethylamino)diarylazo compounds have been prepared ° by the reaction of the corresponding o-chloro-o -hydroxydiarylazo compounds and ethylenediamine in the presence of copper(II) ions (c/. Section 58.2.3. l(iii)(c)). Dyestuffs of this type have been evaluated on nylon but are reported to have very poor fastness properties. Copper complexes such as (153) have been preparedby similar methods. Other, related tetradentate diarylazo compounds, e.g. (154), (155) and (156), are obtained by the reaction of a suitable diazonium salt with the appropriate diarylamine. Chromium(III) and cobalt(III) complexes of dyes of this type, in which the coordination sphere of the metal is completed by a colourless bidentate ligand such as ethylenediamine, salicylic acid or 8-hydroxyquinoline, are reported to have dyeing properties on wool similar to those of the comparably charged 2 1 complexes derived from tri-... 

More recently, 1 2 complexes of the chromium(III) ion with 5-sulphosalicylic [84,85], salicylic and citric acids have been compared with the lactate complex [85]. Like the latter, the citrate (5.79) and 5-sulphosalicylate (5.80 X = S03H) complexes are readily water-soluble but the unsubstituted salicylate (5.80 X = H) is not. If formic acid is added, however, the mixed formate-salicylate complex (5.81) shows moderate solubility. The pH value for maximum uptake of the complexes varied slightly but was always within the range of pH 2-4. Compared with conventional dichromate treatment, the lactate complex sometimes gave inferior wet fastness. Fastness ratings equal to conventional aftertreatment were given by the two salicylate mordant complexes (5.80) without the drawbacks characteristic of the dichromate process [85]. 

Chromiain(ii) Complexes.—The oxidation of chromium(ii) in alkaline solution has been studied polarographically and the reaction shown to be irreversible with = — 1.65 V vs. S.C.E. In the presence of nitrilotriacetic acid, salicylate, ethylenediamine, and edta the values were determined as —1.075, —1.33, — 1.38, and —1.48 V, respectively. The production of [Cr(edta)NO] from [Cr (edta)H20] and NO, NOJ, or NO2 suggests that this complex is able to react via an inner-sphere mechanism in its redox reactions. ... 

Complexes of salicylate with chromium(III) have not been reported but the tris complexes of salicylaldehyde and chromium(III) may be prepared by refluxing [Cr(THF)3Cl3] with salicylal-dehyde and sodium acetate in ethanol.939 The acid hydrolysis of this complex was studied in detail, but the isomerism obviously possible for this complex was not apparently considered. Khan and Tyagi940 studied the formation of phthalate complexes of chromium(III). 

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