Matter in Naturally Occurring Fats and Oils

In order to isolate the colouring material of fats, 25 g of the fat is saponified with 200 ml 60% alcoholic potassium hydroxide solution by refluxing 30 min on the water bath (DAvfDBK and JANidEK [11]). 160 ml water is then added and the solution extracted with three 60 ml portions of pentane. The combined pentane extract is shaken with water, dried and the solvent distilled off in vacuo. The solution of the residue in 2 ml ethanol is used for TLC. 

Disperse colouring materials are used principally for colouring cellulose acetate, polyamide and polyester fibres. Their chemical structure is similar to that of the fat-soluble dyes. They belong to the compound classes of nitrodiphenylamine derivatives and azo- and anthraquinone dyes without a sulphonate group. They are more or less easily soluble in organic solvents but insoluble or difficultly soluble in water. Mixtures of disperse dyes can be separated on alumina columns, using solvents such as ether, methylene dichloride, ethyl acetate and tetrahydrofuran [71]. PC-separations on cellulose paper are incomplete [14, 30, 31, 73, 85]. Separations are better on acetyl-paper [29, 30, 43] or pre-treated paper [19, 20, 25, 44, 73]. 

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. 

Our own experience [34, 71] shows that the solvent chloroform-methanol (95 + 5) is suitable for separating many disperse dyes on 

Basic dyes are water-soluble in the form of their salts and are used for colouring paper, leather, cellulose- and polyacrylonitrile fibres. The free bases dissolve in many organic solvents and find application similar to that of the solvent dyes. Basic dyes can function as pigments in lacquer form. Mixtures of basic dyes are usually responsible for brown, green and black tones. 

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