Colouration basic dyes

In this work hybrid method is suggested to determine anionic surfactants in waters. It is based on preconcentration of anionic surfactants as their ion associates with cationic dyes on the membrane filter and measurement of colour intensity by solid-phase spectrophotometry method. Effect of different basic dyes, nature and hydrophobicity of anionic surfactants, size of membrane filter pores, filtration rate on sensitivity of their determination was studied. Various cationic dyes, such as Methylene Blue, Crystal Violet, Malachite Green, Rhodamine 6G, Safranin T, Acridine Yellow were used as counter ions. The difference in reflection between the blank and the sample was significant when Crystal Violet or Rhodamine 6G or Acridine Yellow were used. 

Identification of dyes on dyed textiles is traditionally carried out by destructive techniques [493], TLC is an outstanding technique for identification of extracted dyestuffs and examination of inks. Figure 4.9 shows HPTLC/SERRS analysis of acridine orange [492], Wright et al. [494] have described a simple and rapid TLC-videodensitometric method for in situ quantification of lower halogenated subsidiary colours (LHSC) in multiple dye samples. The results obtained by this method were compared with those obtained by an indirect TLC-spectrophotometric method and those from HPLC. The total time for the TLC-videodensitometric assay of five standards and four samples applied to each plate was less than 45 min. The method is applicable for use in routine batch-certification analysis. Loger et al. [495,496] have chromatographed 19 basic dyes for PAN fibres on alumina on thin-layer with ethanol-water (5 2) and another 11 dyes on silica gel G with pyridine-water... 

The name of this structural class ( quinoline ) in the Colour Index is not ideal because quinoline derivatives feature in other related classes, such as the methine basic dyes with a quinolinium cationic group. The class is more precisely associated with quinophthalone (1.15), the characteristic chromogen derived by condensation of quinoline derivatives with phthalic anhydride. This small class of yellow compounds contributes to the disperse, acid, basic and solvent ranges of dyes. 

Many brilliantly coloured and tinctorially strong basic dyes for silk and tannin-mordanted cotton were developed in the early decades of the synthetic dye industry. Most of these belonged to the acridine, azine, oxazine, triarylmethane, xanthene and related chemical classes their molecules are usually characterised by one delocalised positive charge. Thus in crystal violet (1.29) the cationic charge is shared between the three equivalent methylated p-amino nitrogen atoms. A few of these traditional basic dyes are still of some interest in the dyeing of acrylic fibres, notably as components of cheap mixture navies and blacks, but many modified basic dyes were introduced from the 1950s onwards for acrylic and modacrylic fibres, as well as for basic-dyeable variants of nylon and polyester [44] ... 

Most of these products are azo or anthraquinone types, often with a localised quaternary ammonium group isolated from the chromogen by a saturated alkyl chain, as in Cl Basic Red 18 (1.52). Such products often exhibit higher light fastness than the traditional delocalised types. Improved azomethine, methine and polymethine basic dyes of good light fastness are also available. In contrast to the more specialised traditional classes, the azo and methine dyes have contributed to the basic dye range across the entire spectrum of hues (see Table 1.6) and now account for a clear majority of all basic dyes listed in the Colour Index. 

The Second World War again resulted in a shortage of tungsten and molybdenum and in an effort to overcome this the so-called copper toners were made by precipitating basic dyes with copper(II) hexacyanoferrate. The resulting products were less brilliant in colour... 

Derivatives of triphenylmethane were among the earliest synthetic colorants, and are still in demand where bright, intense colours are needed without the necessity for outstanding fastness to light and chemical reagents. Basic dyes of this type, as well as other cationic dyes, are suitable for dyeing conventional acrylic fibres, on which they show better fastness properties than on natural fibres. The photodegradation of triphenylmethane dyes has been reviewed [42]. 

Petrick and Wilson [137] recently developed an HPLC method using both UV-Vis and ESI-MS detection able to separate and detect 15 basic dyes and 13 disperse dyes. Separation was carried out in RP-mode using an acidified (formic acid) water-acetonitrile mobile phase in gradient mode. The method enabled the discrimination of fibers with the same apparent colour based on their different chromatographic and mass spectrometric profile. 

The nomenclature given for these componnds is a nniversally recognised system for the naming of dyestuffs devised by the Society of Dyers and Colourists as part of their Colour Index (Cl). The Cl Generic Name is made up of the application class, the hne and a nnmber. Acid dyes are nsed on wool and polyamide, direct dyes on cel-lulosic fibres, paper and leather, disperse dyes on polyester fibres, reactive dyes on cellnlosic fibres and basic dyes on polyacrylonitrile and paper. 

Other Dyes. Other dye classes listed in the Colour Index include dyes lor leather, solvents, paper, and food. Leather dyes arc those acid, direct, mordant, and basic dyes that show substamivily for leather, good diffusion into it. and acceptable fastness. They are essentially applied in an analogous... 

Naturally the dyeing procedure varies with the type of colour (basic, acid, mordant, substantive). In order, however, that valid conclusions may be drawn, the procedure should be that used industrially, this being usually indicated in the instructions supplied with the colouring matter. 

D. J. Gale and J. F. K. Wilshire, Fibre-reactive basic dyes. I. Polymethine dyes containing the N-chloroacetyl group, J. Soc. Dyers Colour., 1974, 97-100. 

Very effective retarding/migration aid for dyeing acrylic fibres with basic dyes, particularly recommended for use with K2.5 to K5.0 colours. Low blocking action ensures good exhaustion and the ability to overdye. No effect on softeners applied from dyebath. Acts as an antiprecipitant when dyeing acrylic/ nylon blends. 

Chryso idine, which was discovered by Witt, is one of the few basic azo-dyestuffs, and like all basic colouring-matters dyes cotton mordanted with tannic acid. Its principal application is in cottondyeing, especially for shading purposes. It gives a yellowish-orange colour. 

Acid dyes Azoic colouring matters Basic dyes Developers Direct dyes Disperse dyes Fluorescent dyes Food dyes Ingrain dyes Leather dyes Mordant dyes Natural dyes Oxidation dyes Pigments Reactive dyes Reducing agents Solvent dyes Sulphur dyes Condense sulphur dyes Vat dyes... 

Jute is difficult to bleach, since it suffers degradation when treated with chlorine, especially in alkaline solutions. The best varieties, however, have comparatively little colour and can be dyed without bleaching. Jute differs from other vegetable fibres in having a moderately good affinity for basic dyes. 

The base, containing no quinonoid chromophore, is colourless and the colour only appears on salt formation. Basic dyes as they appear on the market are salts, usually the chlorides but sometimes oxalates or even double salts with zinc chloride. 

The outstanding characteristic of the basic dyes is the brilliance and intensity of their colours. Some of the shades are of such clarity of hue that no other class can compare with them. The intensity is illustrated by a comparison of the dyeing properties of magenta, which is a basic dye, and acid magenta, which has the same molecular structure but has been converted into an acid dye by sulphonation. Whilst 5 per cent of the latter is required to produce a full shade on wool, only 2 to 3 per cent of basic magenta is necessary. The basic dyes are readily soluble in alcohol or methylated spirit. They are not, as a rule, so easily dissolved in water and, unless care... 

By the addition of copolymers during spinning it is possible to modify the affinities for dyes. Three types are in production, namely regular (type 100), deep dye (type 110) and basic dye (type 120) nylons. Type 100 is normal nylon, type 110 is dyed with acid dyes but has a greater affinity and type 120 is dyed by basic dyes and is resistant to acid dyes. It is therefore possible by appropriate mixing of the yarns to obtain coloured and white, tone and tone and cross dye effects. 

Provided only medium shades are selected for the basic dye component there should be no significant staining of the deep dye yarn. For colour and white effects, selected acid dyes are used, and if desired, a fluorescent brightening agent may be added to improve the white of the type 120. Acid dyes reserving basic dyeable yarn in shades up to standard depth are ... 

The method of application is to make up a bath with 3 per cent on the weight of the goods of ammonium acetate and the dye. The goods are entered and the temperature is raised to the boil during twenty to thirty minutes and dyeing is continued for a further 45 minutes. If a two-colour effect is desired the basic dye must be added to the dyebath ten minutes after the acid dye. For shading, the temperature must be lowered to 70°C (158°F) and, to avoid mutual precipitation in concentrated solutions, the acid and basic dyes must be added separately. 

Basic and standard yarns (Types 100 and 120). In colours of above 1/3 standard depth basic dyes will not reserve the type 100 and, unless very carefully selected, the acid dyes will stain the basic dyeable component. 

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