Fat-and Oil-Soluble Dyes

Fat- and oil-soluble dyes are also soluble in waxes, resins, lacquers, hydrocarbons, halogenated hydrocarbons, ethers, and alcohols, but not in water. It is not possible to differentiate clearly between them and the alcohol- and ester-soluble dyes. With the exception of blue anthraquinone derivatives, fat- and oil-soluble dyes are azo dyes, generally based on simple components. According to their degree of solubility they usually contain hydroxyl and/or amino groups, but not sulfonic acid and carboxylic acid groups. Examples of fat- and oil-soluble azo dyes are C.I. 

Further examples of commercial solvent dyes are given in Section 3.10.3. 

The products are sold in powder form, as granules, or as flakes, and some dyes also as liquid brands. The liquid brands are highly concentrated solutions of fat-soluble dyes in aromatic hydrocarbons, in some cases also solvent-free 100% liquid products. 

Fat- and oil-soluble dyes are used on a large scale in a wide variety of industrial sectors. The main fields of application are the coloration of products in the mineral oil and plastics industries, as well as of wax products (e.g., candles, shoe polishes, floor polishes). 

Other fields of application are the pyrotechnics industry (pronounced sublimation tendency of the dyes), the office supplies industry (inks for felt-tip pens, oil-based stamping inks), the lacquers industry (especially coloration of transparent lacquers on aluminum foil), and the cosmetics industry (approval restricted to a few products). 

---

As far as chemical constitution is concerned, there is no precise delineation between alcohol- and ester-soluble dyes, nor between these two groups and the fat- and oil-soluble dyes described below. 

Lakes are prepared by adsorption or precipitation of a soluble dye on an insoluble substrate (e.g., alumina). They are useful in fatty products that have insufficient moisture to dissolve dyes (coated tablets, cake mixes, hard candies, chewing gum). Lakes are insoluble in most solvents including water, have high opacity, are easily incorporated in dry media, and show higher stability to light and heat. They are effective colorants for candies, pills, fats, and oils. The main characteristics and differences between lakes and dyes are well documented. ... 

In general, the sulfonic acids are water soluble and are strong acids because of virtually complete loss of ionizable H+ in aqueous solution. They have some important commercial applications, such as in the hydrolysis of fats and oils (see Section 3.5) to fatty acids and glycerol. Benzenesulfonic acid is fused with NaOH in the preparation of phenol. Dyes and some pharmaceutical compounds are manufactured from p-toluenesulfonic acid. Methanesulfonic acid has been developed as an esterification catalyst in place of sulfuric acid for the synthesis of resins in paints and coatings. 

OIL SOLUBLE AZO DYES The oil soluble, water-iasoluble, azo dyes dissolve ia oils, fats, waxes, etc. Generally, yellow, orange, red, and brown oil colors are azo stmctures and greens, blues, and violets are primarily anthraquiaones (see Dyes, anthraquinone). Blacks are usually nigrosiaes and iaduhnes of the aziae type (see Azinedyes). An example is Oil Red [85-83-6] (127) (Cl Solvent Red 24 Cl 26105). Uses iaclude the coloring of hydrocarbons, waxes, oils, candles, etc. 

Siace there are ao solveat-soluble FD C colors, FD C lakes have provea particularly valuable for coloring water-repelliag foods such as fats, gums, waxes, and oils, and for coloring food-packagiag materials including lacquers, containers, plastic films, and inks from which soluble dyes would be quickly leached. Similarly useful appHcations have been found for D C and Ext. D C lakes ia their respective areas of appHcatioa. 

Aminoazo dyes with only one amino group (aminoazobenzene type) are weak bases giving, in general, difficultly soluble salts which are readily hydrolyzed. If the dye is to be isolated as one of its salts, for example, the hydrochloride, the salt is precipitated from the reactiorr mixture by means of a considerable excess of hydrochloric acid. The precipitate is filtered off and washed with dilute hydrochloric acid, not with water. On the other hand, if the dye is to be used in coloring oils, fats, etc., it must be isolated as the free base and must contain no salts. For this purpose, the coupling reaction mixture is made alkaline and the precipitated dye is filtered off and washed thoroughly with water. The dye can be purified further by.recrystallization from an organic solvent. 

Is a versatile O/w emulsifier and solubilizer of petroleum oils, solvents, and fats. High water solubility enhances its ability to solubilize petroleum solvents. In the textile Industry it is used as an emulsifier for dye carriers, as an antistatic scrooping agent in primary spin finishes, and as a fiber processing aid. 

Sudan . [BASF BASF AG] Oil-and fat-soluble dyes for marking and coloring mineral oil prods., e.g., engine fuels, heating oil, lubricating greases, shoe polishes, flowpolishes and waxes. 

At first reverse phase sorbents were prepared by impregnating the support with long-chain hydrocarbons such as paraffins and silicone oils to give packings of defined composition with the stationary phase held to the support by purely physical forces of attraction [53]. These materials though of use for the analysis of lipophilic substances, fats and waxes, steroids and fat soluble vitamins and dyes were unsatisfactory as the stationary phase can be washed off by the eluant which consequently lowers the capacity and effectiveness of the partition separation. 

Synonyms 4-(phenylazo)benzenamine C.I. Solvent Yellow 1 p-aminodiphenylimide Solvent Yellow 1 Aniline yellow C.I. 11000 p-(Phenylazo)aniline 4-amino-i,i -azobenzene p-aminoazobenzol 4-benzeneazoaniline paraphenolazo aniline p-phenylazopheny-lamine AAB aminoazobenzene Brasilazina Oil Yellow G Cellitazol R Ceres Yellow R C.I. Solvent Blue 7 fast Spirit Yellow fast Spirit Yellow AAB fat yellow AAB induline r oil-soluble Aniline Yellow oil yellow AAB Oil Yellow AN Oil Yellow B Oil Yellow R Organol Yellow Organol Yellow 2A Somalia Yellow 2G Stearix Brown 4R Sudan Yellow R Sudan Yellow RA 4-(phenylazo)-benzamine Uses as a dye for lacquer, varnish, wax products, oil stains and styrene resins in insecticides used as an intermediate in the manufacture of Acid Yellow, diazo dyes and indulines Cross para groups of compounds A... 

Solvent. Solvent dyes are so called because of their solubility in organic solvents including esters, ethers, hydrocarbons, oils, fats and waxes. They are synthetic organic dyes whose molecules contain no water-solubilizing groups such as sulphonic acid or sulphonate ion groups. 

---