Anthraquinones solvent dyes

Dyes, Dye Intermediates, and Naphthalene. Several thousand different synthetic dyes are known, having a total worldwide consumption of 298 million kg/yr (see Dyes AND dye intermediates). Many dyes contain some form of sulfonate as —SO H, —SO Na, or —SO2NH2. Acid dyes, solvent dyes, basic dyes, disperse dyes, fiber-reactive dyes, and vat dyes can have one or more sulfonic acid groups incorporated into their molecular stmcture. The raw materials used for the manufacture of dyes are mainly aromatic hydrocarbons (67—74) and include ben2ene, toluene, naphthalene, anthracene, pyrene, phenol (qv), pyridine, and carba2ole. Anthraquinone sulfonic acid is an important dye intermediate and is prepared by sulfonation of anthraquinone using sulfur trioxide and sulfuric acid. 

The new Colour Index volume Pigments and Solvent Dyes lists some 350 solvent dyes and gives their chemical structures, unlike earlier editions which named 800 dyes but included few structures. This fall in numbers is not because of any decreased use but rather the general contraction in numbers of all dyes used in the textile industry. Solvent dyes have been introduced not by attempts to synthesise new colorants but by selection and in some cases modification of known disperse dyes to meet the technical requirements. The majority of solvent dyes are azo compounds but among the blue dyes there are anthraquinones. The aqueous solubility of some of the parent sulphonated dyes has been reduced to acceptable levels by formation of their salts with heavy metals or long-chain alkylamines. 

In a recent study of twenty disperse and solvent dyes, data for water solubility, octanol/ water partition coefficient, entropy of fusion and melting point were subjected to regression analysis. Complicating factors such as impurities, polymorphism, tautomerism, polarisation and hydrogen bonding precluded the development of reliable predictions of solubility and partition coefficient. Anthraquinone dyes exhibited much lower entropy of fusion than many of the azo dyes [64,65]. 

Not many green anthraquinone disperse dyes are available commercially. One example is Cl Disperse Green 6 1 (6.53), which has wider use as Cl Solvent Green 3 and is the precursor of Cl Acid Green 25 (6.27). 

Solvent dyes are really intermediate between dyes and pigments being insoluble in water but soluble in solvents, especially hydrocarbons. Structurally many solvent dyes bear a close similarity and relationship with disperse dyes. The Colour Index has an issne on Solvent Dyes, where several hundred dyes are described, unfortunately many of the strnctnres remain confldential. The structures of the disclosed dyes range from very simple monoazo dyes, e.g. Cl Solvent Yellow 14 (2.78) to the higher performing anthraquinones, e.g. Cl Solvent Yellow 163 (2.79) and Blue 36 (2.80), quinophthalones... 

I -Methylaminoanthraquinonc is an important intermediate for manufacturing solvent dyes and acid dyes, and is prepared from anthraquinone-1-sullonic acid by replacing the SOtH group with methylamine. 

Solvent Dyes. These water-insoluble but solvent-soluble dyes are devoid of polar solubilizing groups such as sulfonic acid, carboxylic acid, or quaternary ammonium. They are used for coloring plastics, gasoline, oils, and waxes. The dyes are predominantly azo and anthraquinone, but phthalocyanine and triarylmethane dyes are also used. 

Cationic functionality is found in various types of dyes, mainly in cationic azo dyes (Section 3.7) and methine dyes (Section 3.8), but also in anthraquinone (Section 3.4), di- and triarylcarbenium (Section 2.6), phthalocyanine dyes (Section 2.7), and in various polycarbocyclic and solvent dyes (Section 3.10). 

Solvent dyes [1] cannot be classified according to a specific chemical type of dyes. Solvent dyes can be found among the azo, disperse, anthraquinone, metal-complex, cationic, and phthalocyanine dyes. The only common characteristic is a chemical structure devoid of sulfonic and carboxylic groups, except for cationic dyes as salts with an organic base as anion. Solvent dyes are basically insoluble in water, but soluble in the different types of solvents. Organic dye salts represent an important type of solvent dyes. Solvent dyes also function as dyes for certain polymers, such as polyacrylonitrile, polystyrene, polymethacrylates, and polyester, in which they are soluble. Polyester dyes are principally disperse dyes (see Section 3.2). 

Solvent dyes for solvent based ink-jet inks and hot melt ink-jet systems are selected 1 2 chromium or cobalt complex azo (C.I. Solvent Yellow 83 1 [61116-27-6], C.I. Solvent Red 91 [61901-92-6]), anthraquinone (C.I. Solvent Blue 45 [37229-23-5]), or phthalocyanine (C.I. Solvent Blue 44 [61725-69-7]) dyes. 

OIL SOLUBLE AZO DYES The oil soluble, water-insoluble, azo dyes dissolve in oils, fats, waxes, etc. Generally, yellow, orange, red, and brown oil colors are azo structures and greens, blues, and violets are primarily anthraquinones (see Dyes, ANTHRAQUINONE). Blacks are usually nigrosines and indulines of the azine type (see Azine dyes). An example is Oil Red [85-85-6] (127) (Cl Solvent Red 24 Cl 26105). Uses include the coloring of hydrocarbons, waxes, oils, candles, etc. 

There are only a few publications in the field of TLC of disperse dyes, although this method provides better resolution and is more time-economical than PC. WoiJiENWEBEB [84] has separated Celliton Fast Red Violet RN (C. I. 61100), CelHton Fast Pink B (C. I. 60710) and qumizarin (C. I. 58050) through TLC on acetyl-ceUulose powder of 10% acetyl content he used the solvent ethyl acetate-tetrahydrofuran-water (6 + 35 + 47) which is suitable also for PC-separations on acetyl-paper (43). Many azo- and anthraquinone disperse dyes have been separated by Rettie and Haynes [61] with the help of TLC on the same adsorbent, using tetrahydrofuran-water-4N acetic acid (80 + 54 + 0.05) and mixtures of similar composition. Better separations of disperse dyes of the anthraquinone class can be obtained by TLC on silica gel 6, using chloroform-acetone (90+ 10) [61] 1-Amino-, 2-amino-, 1,2-diamino- and 1,4-diamino-anthraquinones could be thus separated. 

Anthraquinone Dyes. These dyes have much supeiioi weatheiabihty and heat stabihty compared with the azos, but at higher cost. Typical examples ate Solvent Red 111, Disperse Violet 1, Solvent Blue 56, and Solvent Green 3. 

The anthraquinones are useful in acrylics and are compatible with polystyrene and ceUulosics. Solvent Red 111 has a special affinity for poly(methyl methacrylate) as the red in automobile taillights exposure for a year in Florida or Arizona produces only a very slight darkening. Acid types are usehil for phenohcs (see Dyes, anthraquinone). 

Efforts to raise the alpha-selectivity have been made. Thus nitration of anthraquinone using nitrogen dioxide and ozone has been reported (17). l-Amino-4-bromoanthraquinone-2-sulfonic acid (bromamine acid) [116-81 -4] (8) is the most important intermediate for manufacturing reactive and acid dyes. Bromamine acid is manufactured from l-aminoanthraquinone-2-sulfonic acid [83-62-5] (19) by bromination in aqueous medium (18—20), or in concentrated sulfuric acid (21). l-Aminoanthraquinone-2-sulfonic acid is prepared from l-aminoanthraquinone by sulfonation in an inert, high boiling point organic solvent (22), or in oleum with sodium sulfate (23). 

Water-soluble polymeric dyes have been prepared from water-insoluble chromophores, viz., anthraquinone derivatives. Unreacted chromophore and its simple derivatives, which are all water-insoluble, remain in solution due to solubilization by the polymeric dye. A method has been developed to separate and quantitate the polymeric dye and these hydrophobic impurities using Sephadex column packing. The solvent developed has the property of debinding the impiirities from the polymer, and further allows a separation of the imp irities into discrete species. This latter separation is based on the functional groups on the impurity molecules, having a different interaction with the Sephadex surface in the presence of this solvent. The polymer elutes at the void volume... 

A similar heterogeneous photocatalytic system was applied for the study of the decomposition of the anthraquinone dye, Acid blue 25 (AB25). The chemical structure of the dye and those of the first intermediates tentatively identified by HPLC-MS are shown in Fig. 3.55. RP-HPLC-DAD analysis of AB25 was carried out in a C4 column (250 X 4 mm i.d. particle size 5 //m) at ambient temperature. The isocratic mobile phase was composed of ACN (solvent A)-water (pH adjusted to 4.5 with acetic acid and ammonium acetate) (42 58, v/v). 

Anthracene is obtained from coal lai in the fraction distilling between 300° and 400°C. This fraction contains 5-10% anthracene, from which, by fractional crystallization followed by crystallization from solvents, such as oleic acid, and washing with such solvents as pyridine, relatively pure anthracene is obtained. It may be detected by the formation of a blue-violet coloration on fusion with mellitic add. Anthracene derivatives, espedally anthraquinone, are important in dye chemistry. 

Baughman (1992) measured the disappearance rate constants for a number of solvent and disperse azo, anthraquinone, and quinoline dyes in anaerobic sediments. The half-lives ranged from 0.1 to 140 days. Product studies of the azo dyes showed that reduction of the azo linkages and nitro groups resulted in the formation of substituted anilines. The 1,4-diaminoanthraquinone dyes underwent complex reactions thought to involve reduction and replacement of amino with hydroxy groups. Demethylation of methoxyanthraquinone dyes and reduction of anthraquinone dyes to anthrones also was observed. 

The features of chemical constitution associated with the special requirement of solvent solubility include a number of chemical groups on the chromophores. Sulfo groups are often absent, and only hydroxy or amine groups are present. There are mostly cationic and neutral and sometimes also anionic azo, 1 2 azo metal-complex, and a few anthraquinone dyes. An example is C.I. Solvent Yellow 21, 18690 [5601-29-6] (22, 1 2 Chrome alsoC.7. Acid Yellow 121). 

Solubility data of the dyestuffs are of interest for the optimization of this particular dyeing technique. Therefore an apparatus was developed for the determination of the solubilities in supercritical solvents at temperatures from 250 to 500 K and pressures up to 250 MPa according to the static analytical method [6, 7]. In particular, investigations on the solubility of some selected anthraquinone dyes in supercritical C02 and N20 and more recently of P-carotene in supercritical C02 and CC1F, were performed as a function of temperature and pressure (see section 4.). For the l,4-bis-(n-alkylamino)-9,10-anthraquinones the alkyl chains were systematically varied in the homologous series in order to study the effects of molecular size and polarity on the solubility phenomena [6-10]. 

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