Rosaniline Dyestuffs

In the wider sense of the term, this class comprises all the basic dyestuff s obtained from triphenylmethane and its homologues. As has already been remarked, the salts are the real dyestuffs, while the so-called colour-bases are colourless carbinol derivatives. Up to the present, no suitable nomenclature has been applied to the actual dyestuffs, rosaniline for example being generally called triamidotriphenylcarbinol, and this method has been adopted in the present workj although in reality the carbinol bases have little or nothing to do with the dyestuffs, so far as constitution is concerned. 

The tetramethyl derivative bf the above compound comes next in the series, and is a well-characterized substance. 

With a large excess of acid, the pale yellow diacid salt may be obtained. The monoacid salts are characterized by the ease with which they crystallise they are beautiful green dyestuffs of great tinctorial power [5]. 

Hydrochloride, C23H24N2,HC1, forms easily soluble green leaflets. 

Sulphate, C23H24N2,H2S04, crystallises with one molecule of H2O in brilliant green needles, or anhydrous in thick green prisms. 

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Night Blue is obtained from paratolyl-a-haphthylamine (P-C7H7NHC10H7) and tetramethyldiamidobenzophenone. These dyestuffs come into commerce as hydrochlorides. They are beautiful blue dyestuffs, easily soluble, and dye cotton prepared with tannic acid similarly to methylene blue, but unfortunately the shades produced are not very fast to light. In general their reactions resemble those of the rosaniline dyestuffs. Alkalies precipitate a reddish-brown base, and acids turn the blue colour to yellow. 

Fuchsin fyuk-son, - Sen [F fuchsine, prob. fr. NL Fuchsia fr. its color] (1865) n. Synthetic rosaniline dyestuff, a mixture of rosaniline and pararosaniline hydrochlorides. Dark green powder of greenish crystals with a bronze luster faint odor. Soluble in water and alcohol. Used in textile and leather industries as a red dye and as a pharmaceutical. Vigo TL (1994) Textile processing, dyeing, finishing, and performance. Elsevier Science, New York. 

Reaction XL. (a) Condensation of a Phenol with a Methane Carbon Atom. (A., 194, 123 196, 77 B., 28, R., 743.)—Phenols can be condensed with compounds which can yield a nuclear carbon, to give dyes of the rosolic acid series. The fewco-compound—tri-hydroxytriphenyl car-binol—first formed, is unstable and immediately yields the dyestuff, no oxidising agent being necessary. In this respect these compounds differ from the analogous rosaniline compounds (see p. 382). 

Tannin test for basic dyestuffs. The extract obtained with formic acid is shaken with a few drops of tannin solution, and if no precipitate forms immediately, the liquid is left at rest for a few minutes. Certain colouring matters, such as the rhodamines, the gallocyanins and the chrome colours of the rosaniline series (containing carboxyls or hydroxyls besides the basic groups) precipitate slowly and the precipitate, being highly subdivided, is sometimes difficult to see. 

The first dyestuff prepared and applied on an industrial scale was "mauve, introduced by Perkin in 1856. About the same period the formation of rosaniline was noticed by Nathanson, who obtained it by heating aniline with ethylene chloride [2]. 

This compound combines with acids to form beautiful blue salts, which, like the dyestuffs of the rosaniline series, are decolorised by excess of acid. It is probable that in these coloured salts the compound exists as an anhydride, as is the case with the rosaniline salts. The hydrochloride, for instance, has the constitution... 

The chloride of tetramethyldiamidobenzophenone reacts in a similar manner. This compound has a blue colour, and probably belongs to the diphenylmethane dyestuffs, which are analogous to the rosanilines. It has the constitution —... 

Nitrobenzene appears to take no part in the formation of ros-aniline, and simply acts as oxidant being converted to dyestuffs of the indnline class. When nitrobenzene is replaced by chlor-nitrobenzene, rosaniline is produced, and not, as might be expected, a chloro-derivative. Dyestuffs of the rosaniline series are formed by oxidation of numerous bases in presence of aniline and parato-luidine. Rosenstiehl and Gerber divide the homologues of aniline into three classes, according to their behaviour on oxidation with arsenic acid. 

The iodide, C2oHi7(CH3)4NgT,CH3l-l-H20, is prepared by heating rosaniline with methyl iodide and methyl alcohol to 100°. It is freed from any violet dyestuff present in the same manner as methyl green. 

A dyestuff named Bleu de Mulhouse was prepared by Gros-Kenaud and Schaeffer by the action of alkaline shellac solution on rosaniline. 

On treating rosaniline with aldehyde and sulphuric acid, a blue dyestuff is formed, which, on treatment with sodium thiosulphate in acid solution, yields aldehyde green. For its preparation, a mixture of rosaniline, aldehyde, and sulphuric acid is heated, till the product produces ablue-violet solution with water. It is then poured into a very dilute solution of sodium thiosulphate. S ulphur and a grey compound separate, while the green remains dissolved. It may be precipitated by addition of zinc chloride or acetate of soda fin one case a zinc double salt, and in the other a free base, is obtained. 

These dyestuffs are closely related to those obtained from rosaniline, and may be regarded as rosanilines in which the nitrogen is replaced by a group containing oxygen. 

The actual dyestuffs, like rosaniline salts, are anhydrides of a carbinol. For example, aurin, C19H14O3, is the anhydride of an unknown carbinol, trioxytriphenylcarbinol —... 

The phthaleins are derivatives of triphenylmethane, and form a group of dyestuffs which are sharply defined from the rosaniline and rosolic acid derivatives already described. In the latter the chromophorous groups are in para positions, while in the former two adjacent positions are taken up. 

In 1880, Otto Fischer synthesized rosaniline (aniline red) from para-nitrobenzaldehyde. However, the process was not of commercial value due to the difficulty in converting the colorless, reduced, leuco intermediate into the dyestuff. This was a problem with all novel syntheses of aniline red before 1900. Pararosaniline continued to be made by nitrobenzene oxidation of anilines, at least until around 1940, when condensation of aniline with formaldehyde came into more general use. 

When coal is distilled many products are formed. Among these is aniline, one of the greatest dyestuff intermediates. This compound is the basis of many dyes such as aniline black, Rosaniline, and nearly every color of the rainbow. 

Basic violet 14. See p-Rosaniline hydrochloride Basic violet 16 Synonyms Cl 48013 Empirical C23H29CIN2 Properties M.w. 368.94 Uses Dye for polyacrylonitrile Manuf./Distrib. Aakash Chems. Dyestuffs http //members.aoi. com/aakashchem/informati on.htmi] Aashiana Dyestuffs http //www. aashianadyestuffs. com] Al ban 11 Dyestuff Int l. http //www.aibaniidye.com] D G Dyes Leadertech Colors Org. Dyestuffs http //www.organicdye.com]... 

Kolbe and R. Schmitt by heating phenol and oxalic acid with sulphuric acid obtained a red dyestuff which they called rosolic acid. Caro and Wanklyn obtained it by diazotising rosaniline and boiling the product with hydrochloric acid. They, and also Graebe and Caro, gave it an incorrect formula. Schorlemmer and R. S. Dale obtained from it a substance called aurine, which Caro and Graebe synthesised from phenol and dihydroxybenzo-phenone. 

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