Disperse Red dyes

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). 

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

Figure 2. A, chromatogram from elution of 100 mL of enriched drinking water (Athens, GA) fortified with 1, 0.26 pg of caffeine 2, 0.050 gig of m-nitroaniline 3, 0.44 pg of atrazine 4, 0.75 pg of 2,6-dichloroaniline 5, 0.43 fig of N-nitrosodiphenylamine 6, 0.85 pg of decafluorobiphenyl (not detected) and 7, 0.41 pg of disperse red dye 13. B, chromatogram from elution of 100 mL of enriched drinking water (Athens, GA). Conditions for both enrichments 100-mL samples enriched on an ODS-packed precolumn at 5 mL/min. Analytical separation was on Partisil-10, ODS-2, 250-mm X 4.6-mm i.d. column. Mobile-phase gradient was 10% to 90% (v/v) acetonitrile in distilled-deionized water at 5%/min, and flow rate was 1.0 mL/min. Detection was at 254 nm. (Reproduced with permission from reference 17.

Fig. 2.61 Cross-sectional views of a single drop of a water-dispersible red dye between sections of plain agar from Petri dishes to demonstrate the natural diffusion of nutrients through gels containing major fractions of water...

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. 

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). 

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). 

Later it was found growing in South America where the Indians used the red dye from the seeds as a body paint. An extract of the seeds appears on the market as annatto. This extract is used in coloring butter, margarine, and cheese such as Leicester cheese. In Mexican and South American cuisine, it finds special use as a flavor and coloring matter. The seeds are sold under the name achiote in many Latin grocery stores and markets. Ann at o is available as an aqueous solution, as an oleaginous dispersion, and a spray-dried powder. 

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... 

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 compound exists normally as the trans or ( )-isomer 21a. This molecule is essentially planar both in the solid state and in solution, although in the gas phase there is evidence that it deviates from planarity. When irradiated with UY light, the ( )-isomer undergoes conversion substantially into the cis or (Z)-isomer 21b which may be isolated as a pure compound. In darkness, the (Z)-isomer reverts thermally to the (F)-isomer which is thermodynamically more stable because of reduced steric congestion. Some early disperse dyes, which were relatively simple azobenzene derivatives introduced commercially initially for application to cellulose acetate fibres, were found to be prone to photochromism (formerly referred to as phototropy), a reversible light-induced colour change. C. I. Disperse Red 1 (22) is an example of a dye which has been observed, under certain circumstances, to give rise to this phenomenon. 

Figure 7.7. Numerically, azo dyes form by far the most important chemical class of disperse dyes. Azo disperse dyes may be classified into four broad groupings. The most numerous are the aminoazobenzenes which provide important orange, red, violet and blue disperse dyes. They are exemplified by C. I. Disperse Orange 25 (157), C. I. Disperse Red 90 (158) and C. I. Disperse Blue 165 (159). A comparison of these three aminoazobenzene dyes provides an illustration of the bathochromic shift...

NLO active molecules can be embedded in or chemically anchored to a sol-gel-matrix without changing the optical absorption spectrum. Disperse Red 1, a very efficient molecule for NLO applications, was embedded in a sol-gel-matrix, synthesized by hydrolysis and condensation of 3-glycidoxypropyltrimethoxysilane in the presence of N-methylimidazole. The dye-doped gel was applied to glass substrates and thermally cured to form a layer of perfect optical transparency. Currently, poling experiments and NLO measurements with these layers are being performed. 

In addition to benzenoid diazo components, diazotised heterocyclic amines in which the amino group is attached to a nitrogen- or sulphur-containing ring figure prominently in the preparation of disperse dyes [87,88], since these can produce marked bathochromic shifts. The most commonly used of these are the 6-substituted 2-aminobenzothiazoles, prepared by the reaction of a suitable arylamine with bromine and potassium thiocyanate (Scheme 4.31). Intermediates of this type, such as the 6-nitro derivative (4.79), are the source of red dyes, as in Cl Disperse Red 145 (4.80). It has been found that dichloroacetic acid is an effective solvent for the diazotisation of 2-amino-6-nitrobenzothiazole [89]. Subsequent coupling reactions can be carried out in the same solvent system. Monoazo disperse dyes have also been synthesised from other isomeric nitro derivatives of 2-aminobenzothiazole [90]. Various dichloronitro derivatives of this amine can be used to generate reddish blue dyes for polyester [91]. 

Dyes for cellulose acetate are relatively simple molecules, typified by Cl Disperse Red 15 (6.39 X = OH), Cl Disperse Violet 4 (6.39 X = NHCH3) and Cl Disperse Blue 3 (6.40), the last-named being manufactured from leucoquinizarin and the appropriate amines. The unsymmetrically substituted product inevitably contains significant amounts of the related symmetrical compounds. The widely used Cl Disperse Blue 3 is known to cause skin sensitisation when on nylon [17] and can also provoke an allergic reaction [18]. Bright red 2-alkoxy-l-amino-4-hydroxyanthraquinones, such as Cl Disperse Red 4 (6.41), can be obtained from l-amino-2,4-dibromoanthraquinone by hydrolysis to give l-amino-2-bromo-4-hydroxyanthraquinone (Cl Disperse Violet 17), which is then condensed with the appropriate alcohol. 

Suitable disperse dyes for polyester require good sublimation fastness and generally contain additional or more hydrophobic substituents compared with acetate dyes. Thus, for example, Cl Disperse Red 60 (6.42) is important for the dyeing of polyester fabrics but has only moderate sublimation fastness. It is, however, the most important red dye for transfer... 

A new cross-conjugated methine-type chromogen was introduced in 1984. The dye Cl Disperse Red 356 (6.232) exemplifies this system, which contains two a,co-donor-acceptor dienone segments. The development of such benzodifuranone disperse dyes has been described [87]. 

Fig. 3.59. HPLC-UV chromatogram at 230 nm for the analysis of azo dyes, (a) Disperse red 1 (b) Solvent yellow 14 (c) Solvent red 24. Reprinted with permission from M. C. Garrigos el al. [129].

Colour and Structure. The azo chromogen is one of the many that can be described as falling within the donor-acceptor group. The donor-acceptor system is shown in Figure 2.7 with a simple mono azo dye. Cl Disperse Red 1, to illustrate the point. The donor part of the molecule, as its name implies, contains donor groups such as amino and alkylamino, hydroxy and aUcoxy. Conversely, the acceptor part contains elec-non-acceptor groups such as nitto, cyano etc. These donor and acceptor groups may... 

Red Anthraquinone Dyes. All the most important red disperse dyes are based upon a l-amino-4-hydroxy substitution pattern. The bluish red shade of the parent dye. Cl Disperse Red 15, can be shifted hypsochromically by putting an elecuon-donating group in position 2, e.g. the 2-OCH3 (Cl Disperse Red 4), the important 2-OPh derivative. Cl Disperse Red 60 and Cl Disperse Red 91 and Red 92. The synthetic pathway to these red anthraquinone disperse dyes is shown in Figure 2.11. 

In order to demonstrate the feasibility of the LIDA concept in high density optical recording systems, a number of dyes have been investigated and the results reported (9,10). In this paper, the results for two of these dyes, Disperse Red II, and Disperse Blue 60 are described in detail. Disperse Red II is manufactured by ICI and Disperse Blue 60 is manufactured by Dupont. Both are derivatives of 1,4-diaminoanthraquinone. Their molecular structures are shown in Figure 2. 

Figure 2. Molecular structure of Disperse Red and Disperse Blue dyes.

World dye manufacturers have already begun io develop new types of dyes that can replace the anthraquinones technically and economically. Some successful examples can be found in azo disperse red and blue dyes, in the reactive dye area intensive studies have continued to develop triphenudioxazine compounds to replace anthraquinone blues... 

---