Aniline violets, production

Acid rhodamines are made by the iatroduction of the sulfonic acid group to the aminoxanthene base. The preferred route is the reaction fluorescein (2) with phosphorous pentachloride to give 3,6-dichlorofluoran (fluorescein dichloride) (23), which is then condensed with a primary aromatic amine in the presence of 2inc chloride and quicklime. This product is then sulfonated. For example, if compound (23) (fluorescein dichloride) is condensed with aniline and the product is sulfonated. Acid Violet 30 Cl45186) (24) is produced. 

Trypan Red Paper. Prepd as above from product supplied by the Allied Chemical Dye Corp Rose-red - Light violet -> Bleached 0.1% Ethyl Violet Paper. Prepd as above from product supplied by National Aniline Dye Co Medium violet Blue - Bleached... 

Phthalic anhydride condenses with the aniline derivative in the presence of zinc or aluminum chlorides to yield the intermediate benzoyl-benzoic acid, which subsequently reacts with l,3-bis-V,V-dimethylaniline in acetic anhydride to yield the phthalide. The above compound gives a violet-gray image when applied to a clay developer. Clearly this synthesis is also very flexible and variations in shades of color formers have been obtained by varying the aniline components and also by using phthalic anhydrides substituted, for example, by nitro groups or chlorine atoms. Such products have excellent properties as color formers and have been used commercially. Furthermore, this synthetic route is of great importance for the preparation of heterocyclic substituted phthalides, as will be seen later. 

A few triphenylmethane dyes are still obtained by empirical methods first used in the early processes of dye manufacture. For example, in the production of magenta (Cl Basic Violet 14), a mixture of aniline, toluidines and nitrotoluenes is heated with zinc and iron(II)... 

Besides the compound described in detail, aniline black generally contains others. One of these is the product of a less energetic oxidation, and is distinguished from the former compound by the brighter green colour of its salts and a brighter violet... 

The new aniline dye companies in Europe displayed their wares at the 1862 London International Exhibition, where Hofmann, as juror, acquired a number of samples. They included a blue (7) discovered, almost by chance, by two French chemists working near London in 1861. It had first appeared when excess aniline was erroneously added to the aniline red reaction mixture. E. C. Nicholson in 1862 treated the aniline blue with sulfuric acid to yield a more valuable product, the soluble alkali blue, later better known as Cl [Colour Index] Pigment Blue 61. In May 1863, Hofmann found that the aniline blue was a substitution product of aniline red in which three phenyl groups had replaced three hydrogens (Scheme 2). This immediately suggested that other substituted derivatives might be made and perhaps even provide new aniline dyes. Alkylation with ethyl iodide showed that this was indeed correct. Hofmann achieved stepwise replacement of three hydrogens to afford colorants that were, successively, reddish violet, violet blue and then violet, what were soon known as the Hofmann s violets (8). Hofmann next turned to the aniline red process, and found that the colorant was formed not from aniline alone... 

In situ polymerization of aniline is generally carried out in aqueous (NH4)2S208/HC1. The glass support is typically removed from the reaction mixture during the polymerization at the stage when a blue/violet film of pernigraniline salt has formed on its surface. This film is then reduced to the green ES product by reaction with a separate... 

Production of coal-tar dyes developed dramatically on the European continent too, following Perkin s discovery. In Lyons in 1859, Francois Emanuel Verguin produced the red-violet fuchsin (Basic Violet 14) by oxidation of technical aniline, a mixture of aniline and toluidines. This dyestuff provided the basis for the production of coal-tar dyestuffs in France it is still important today. At the World Exhibition in London in 1862, the coal-tar dyestuffs industry celebrated great triumphs. The thirteen prize winners were almost exclusively English and French dye manufacturers. 

Kinetic studies by Shim and Park [132] determined the autocatalytic rate for polyaniline growth. Other reaction kinetic studies and comparison of the properties of the chemically synthesized emeraldine to the electrochemical product led Mohilner et al. [131] to conclude that the oxidation of aniline occurs via a free radical mechanism that produces the emeraldine octamer as the primary product. Emeraldine is a blue-violet base form of polyaniline that forms dark green salts as described by Green and Woodhead [133]. Emeraldine loses two protons upon ox-... 

Using a mixed phosphonate a-ZrRiR2P (Ri = CH2CH2CH2COOH, R2 = OH), polymerization of aniline was achieved with a concomitant increase in interlayer spacing. The resulting product was violet in color, and it did not undergo protonation by HCl (172). 

Those completely resolvable under the ultramicroscope. To those belong the salts of sulfoacids with high molecular weights, such as. niline Blue, water soluble Induline, Bayrisch Blue, Violet Black in addition, certain pseudo solutions such as Fuchsine in aniline water, Fuchsine in sodium chloride (prepared hot, turbid when cold turning violet to blue) also the product which is obtained when alcoholic solutions of Scharlack are poured into water. 

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