Oil-soluble dyes

Also known as oil-soluble dyes. Dyes that are soluble in many organic solvents, including mineral oil and fats. They have a relatively small molecular weight and contain hydroxyl and amino groups as auxochromes, but lack highly dissociable groups such as sulfonic acid groups and carboxyl groups, making them insoluble in water. Some dyes have long alkyl groups added to increase their oil solubility. In terms of chemical structure, many belong to the azo dye category, but anthraquinone dyes are used for blue colors. They are used to color oils and fats, gasoline, soap, shoe polish, plastics, butter, margarine, candles, etc. Examples are shown below.

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

油溶性染料ともいう．鉱油，油脂をはじめ，多くの有機溶媒に可溶の染料．分子量は比較的小さく，助色団としてのヒドロキシ基やアミノ基を含んでいるが，スルホン酸基，カルボキシル基など解離性の強い基はなく水に溶けない．長いアルキル基を入れて油溶性を増加させたものもある．化学構造上はアゾ染料に属するものが多いが，青色系にはアントラキノン染料が用いられている．油脂，ガソリン，せっけん，靴墨，プラスチック，バター，マーガリン，ろうそくなどの着色に用いる．次にその例を示す．

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