Disperse Red

Commercial Disperse Azo Dyes. The first proposal to use insoluble dyes in suspension in an aqueous foam bath, ie, disperse dyes, to dye cellulose acetate was in 1921 (60). Commercialization of disperse dyes began in 1924 with the introduction of the Duranol dyes by British Dyestuffs Corporation (61) and the SRA dyes by British Celanese Company (62). In contrast to the acid monoazo dyes, derivatives of benzene rather than of naphthalene are of the greatest importance as coupling components. Among these components mono- and dialkylariifines (especially A/-P-hydroxyethyl-and A/-(3-acetoxyethylanifine derivatives) are widely used couplers. Nitrodiazobenzenes are widely used as diazo components. A typical example is CeUiton Scarlet B [2872-52-8] (91) (Cl Disperse Red 1 Cl 11110). 

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. 

The synthesis of an anthraquinone dye generally involves a large number of steps. For example. Cl Disperse Red 60 [17418-58-5] (10) (Cl 60756) (a typical disperse red dye) requites five steps starting from anthraquinone, and Cl Disperse Blue 56 [31810-89-6] (11) (Cl 63285) requites six steps. 

Efforts have also been made to overcome compHcated processes. Methods to reduce the number of steps or to use new starting materials have been studied extensively. l-Amino-2-chloro-4-hydroxyanthraquinone (the intermediate for disperse red dyes) conventionally requires four steps from anthraquinone and four separation (filtration and drying) operations. In recent years an improved process has been proposed that involves three reactions and only two separation operations starting from chloroben2ene (Fig. 2). 

World dye manufacturers have already begun to develop new types of dyes that can replace the anthraquinones technically and economically (1). Some successful examples can be found in a2o disperse red and blue dyes. Examples are brilliant red [68353-96-6] and Cl Disperse Blue 165 [41642-51 -7] (Cl 11077). They have come close to the level of anthraquinone reds and blues, respectively, in terms of brightness. In the reactive dye area intensive studies have continued to develop triphenodioxa2ine compounds, eg, (13), which are called new blues, to replace anthraquinone blues. In this representation R designates the substituents having reactive groups (see Dyes, reactive). 

Table 4. Disperse Red Dyes, 2-Substituted l-Amino-4-hydroxyanthraquinones...

A study of the degradation of two azo disperse dyes. Disperse Orange 5 [6232-56-0] (1) Cl 11100) and Disperse Red 5 [3769-57-1] Cl 11215) showed reduction of the azo linkage into aromatic amines and further dealkylation to -phenylene-diamine [106-50-3] (2) (255). 

To find the most efficient selectors in the library, blue and red dye-labeled enantiomeric probe molecules 6 and 7 were prepared by linking pentafluorophenyl esters of L- and D-proline with Disperse Blue 3 and Disperse Red 1, respectively, through an isophthaloyl (shown in structures 6 and 7) or a succinyl moiety. Eor detection, a... 

To a 50-mL polypropylene vial (Note 1) are added 0.839 g (2.67 mmol) of 2-[ethyl[4-[(lE)-(4-nitrophenyl)azo]phenyl]amino]ethanol (Disperse Red 1, Note 2), 0.985 g of (2.39 mmol) N-[(9H-fluoren-9-ylmethoxy)carbonyl]-L-aspartic acid,l-(l, 1-dimethylethyl) ester (Fmoc-L-Asp-OtBu, Note 3), 3.26 g (4.73 mmol) of polystyrylsulfonyl chloride resin (Note 4), and 30 mL anhydrous methylene chloride (Note 5). The vial is capped and the mixture is shaken for five min (Note 6). N-Methylimidazole (0.764 mL, 9.58 mmol) is then added to the deep red mixture (Note 7) and the resulting mixture is shaken for 2 hr (Note 8). 

Disperse Red 1, dye content ca. 95%, is available from Aldrich, Sigma-Aldrich Chemie GmbH. The checkers obtained Disperse Red 1 from Sigma-Aldrich Corporation. 

The submitters performed the reaction using a 0.12 mmol excess of Fmoc-L-Asp-Ot-Bu, under which conditions aminomethylated polystyrene resin was required to remove the excess carboxylic acid (Note 13). The checkers modified the reaction to use 0.28 mmol excess Disperse Red 1. The initial Amberlyst-15 filtration removes this material. 

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