Toluidines Dyes from

The preparation of the first cationic azo dye, Vesuvin, was described by C. Martius in 1863. It is obtained by coupling diazotized m-phenylcncdiamine to an excess of the same amine. An analogous dye from toluylenediamine was reported by P. Gries in 1878. Chrysoidines, coupling products of aniline or toluidines to m-phenylenediamine or toluylenediamine, were reported by H. Caro in 1875 and O. N. Witt in 1876. 

The sepMation of the production unit of mononitrotoluene from the next stages of nitration is desirable so as to provide the mononitration unit with a unit for removing m-nitrotoluene by distillation. A mixture of o and p- nitrotoluene or o- nitrotoluene alone is then used for further nitration. In the latter case p- nitrotoluene is utilized for the preparation of dyes (from p- toluidine, derivatives of stilbene, etc.) and pharmaceuticals (p- aminobenzoic acid.)... 

Dyes—in the manufacture of derivatives of aniline produced from nitrobenzene and derivatives of toluidine produced from ni-trotoluene. 

BenZotrichloride Method. The central carbon atom of the dye is supphed by the trichloromethyl group from iJ-chlorobenzotrichloride. Both symmetrical and unsymmetrical triphenyhnethane dyes suitable for acryhc fibers are prepared by this method. 4-Chlorobenzotrichloride is condensed with excess chlorobenzene in the presence of a Lewis acid such as aluminium chloride to produce the intermediate aluminium chloride complex of 4,4, 4"-trichlorotriphenylmethyl chloride (18). Stepwise nucleophihc substitution of the chlorine atoms of this intermediate is achieved by successive reactions with different arylamines to give both symmetrical (51) and unsymmetrical dyes (52), eg, N-(2-chlorophenyl)-4-[(4-chlorophenyl) [4-[(3-methylphenyl)imino]-2,5-cyclohexadien-l-yhdene]methyl]benzenaminemonohydrochloride [85356-86-1J (19) from. w-toluidine and o-chloroaniline. 

Disperse reds are second only to blues as the most important disperse color manufactured. AU. commercial disperse reds are monoazo dyes. In 1988, Disperse Red 73 (98, R = CN) had production of 270 tons valued at nearly 1.6 million. Disperse Violet 24 (99) is produced from diazotized 2-hromo-4,6-dinitroani1ine by coupling with 2-(A/-butyl-y -toluidine)ethanol. 

A Substituted-l-Amino-4-hydroxyanthraquinones. These dyes show good affinity and hghtfastness and give violet to blue shades. However, the sublimation fastness is in general not satisfactory. An example is Cl Disperse Blue 72 [81-48-1] (117) (Cl 60725), prepared from leucoquinizarin and -toluidine. 

Cl Acid Violet 43 [4430-18-6] (2) (Cl 60730) is one of the first acid dyes, invented in 1894. This dye exhibits good leveling and is available from leiicoquinizarin by reaction with -toluidine in the presence of boric acid, followed by oxidation and subsequent sulfonation (133). 

Cl Acid Gieen 25 [4403-90-1] (3) (Cl 61570) was also invented in 1894. This dye shows improved wetfastness, and is prepared from leucoquinizarin by reaction with 2 moles of i)-toluidine in a similat manner to the preparation of Cl Acid Violet 43 (134). Wetfastness and leveling properties may be altered by choosing the substituents of arylamines. The introduction of alkyl groups into aromatic amines improves the wetfastness and affinity in neutral or weekly acid baths. Examples ate Cl Acid Blue 80 [4474-24-27] (131) (Cl 61585) and Cl Acid Gieen 27 [6408-57-7] (132) (Cl 61580). 

Calcon carboxylic acid [3-hydroxy-4-(2-hydroxy-4-sulfo-l-napbtbylazo)napbtbalene-2-carboxylic acid] [3737-95-9] M 428.4, m 300°, X,max 560nm, pKj 1.2, pK2 3.8, PK3 9.26, PK4 13.14. Purified through its p-toluidinium salt. The dye was dissolved in warm 20% aq MeOH and treated with p-toluidine to ppte the salt after cooling. Finally recrystd from hot water. [Itoh and Ueno Analyst (London) 95 583 1970.] Patton and Reeder (Anal Chem 28 1026 1956) indicator and complexes with Ca in presence of Mg and other metal ions. 

This noble but naive attempt - bearing in mind that only the molecular formula of C20H24N2O2 was known at the time - was doomed to fail. In subsequent experiments with aniline, which was fortunately contaminated with toluidines, Perkin obtained a purple product in low yield. Perkin was quick to recognize the commercial potential of his findings the natural dye, Tyrian purple, which was extracted from a species of Mediterranean snail, cost more per kilogram than gold in 1856. Within a few years the first commercial plant for the production of mauveine was in operation. 

Reaction (12) is under control of G-6-PDH, reaction (13) is catalyzed by MHbR and provides the limiting rate, while reaction (14) is nonenzymatic and indicates the measurable oxygen uptake. The blank in this method contains no dye and the unit of MHbR system is defined as the increase of 02 uptake of one micromole per hour after the addition of an excess of toluidine blue (L7). The determination of MHbR activity in hemolyzates demands the further addition of G-6-P, G-6-PDH, and NADP to the system (W3), the enzyme activity being thus assayed independently from the physiological function of G-6-PDH system. 

Measurements in the 1940s in a United States dye production plant indicated that the concentration of ort/zo-toluidine was < 0.5 ppm [2.19 mg/m j in the workroom air in the breathing zone and area samples and from < 0.3 ppm to 1.7 (mg/L) ppm in the urine of workers engaged in the production of thioindigo. In addition to inhalatory... 

The production of ort/ro-toluidine and its use as an intermediate in the production of dyes and pigments, mbber chemicals and other products may result in its release to the environment through various waste streams. The primary routes of potential human exposure to ort/ro-toluidine and its hydrochloride salt are inhalation and dermal contact. Consumer exposure may occur from residues present in commercial dyes and on textiles and via smoking (lARC, 1982 Department of Health and Human Services, 1982 Environmental Protection Agency, 1984, 1997 Department of Health and Human Services, 1999). 

Three pertinent epidemiological studies have been published since the last lARC review. Ott and Langner (1983) studied the mortality of 342 employees assigned to three aromatic amine-based dye production areas from 1914 to 1958 in the United States. One of these areas, the bromoindigo and thioindigo production area, involved potential exposure to ort/io-toluidine, 4-chloro-ort/io-toluidine and 4-chloroacetyl-ort/io-toluidine. 

The Berry spot test provides a rapid qualitative evaluation of urine. GAGs react with toluidine blue, a cationic dye, to yield a pink-colored compound. Alternative spot tests have been published but suffer from the same drawbacks regarding false-negative and false-positive specimens [2, 10, 15, 34]. Nevertheless, this fast procedure may pick up patients who have been referred to a laboratory for other metabolic examinations. For specific, initial MPS testing, the 1,9-dimethylene blue (DMB) assay, described below, is recommended. 

Calcon carboxylic acid [3737-95-9] M 428.4, m 300". Purified through its p-toluidinium salt. The dye was dissolved in warm 20% aq MeOH and treated with p-toluidine to ppte the salt after cooling. Finally recrystd from hot water. [Itoh and Ueno Analyst 95 583 1970]. 

The first commercial synthetic dye, Mauveine (3), discovered by Perkin in 1856, was also a heterocycle, an azine of the Safranine class prepared by oxidation of aniline containing o- and p-toluidines. Since that time the contribution to colour chemistry from heterocyclic synthesis has been considerable and the present review can only hope to present some of the more salient features and at that only briefly. As an illustration it can be noted that since the late 1960s there have been in excess of 230 patents covering the use of azo dye couplers based on 2,6-dihydroxypyridine alone and the number of disclosures describing pyrazolones is probably greater than 1000. 

C. I. Direct Yellow 50, 29025 [3214-47-9] (26) is obtained, for example, by phosgene treatment of two equivalents of the aminoazo dye prepared from diazo-tized 2-aminonaphthalene-4,8-disulfonic acid coupled to w-toluidine. 

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