ABSTRACT
This reaction (sulphonation) is widely used to convert insoluble dyes into soluble ones. Thus, acidification of basic dyes led to the creation of acid dyes that are used mostly on wool and silk. For example, Magenta – a basic dye can be converted into Acid Magenta by sulphonation. They are also being more widely used for dyeing acetate, nylon, acrylics, modacrylics and spandex as well as blends of the above-mentioned fibers. These anionic dyes have also been found useful in printing chlorinated wool and silk. Approximately 8085% of all acid dyes are sold to the US textile industry and are used for dyeing nylon, 10-15% for wool and the balance for those fibers mentioned above. Majority of acid dyes are sodium salt of aromatic sulphonic acid although some contains only carboxyl groups; the commercially available forms are usually their sodium salts, which exhibit good water solubility.
