ABSTRACT
Carbonyl dyes, notably alizarin, indigo and carmine, were used as colorants for centuries in many countries. The indigoid chromophore contains a double-bonded carbon–carbon unit substituted by two carbonyl donor groups and two acceptor NH groups. Due to its geometry this system is termed a cross-conjugated or H-chromophore. Traditional dye classes indigoid, anthraquinone and naphthalimide are used. Within these sections the sequence nonionic, anionic and reactive is followed as appropriate. Compounds include neutral species such as some indoxyl esters, and anionic dyes such as indigocarmine. Lucifer yellow CH & VS, and the procion and remazol reactive dyes, bind to proteins via various electrophilic groups. A number of reactive anthraquinone textile dyes have been sold, several of which have been used in biology and medicine. Thin-layer chromatographic methods are available for such reactive dyes. Derivatives are not necessarily based on Lucifer yellow CH (or VS), but merely possess the same substituted naphthalimide chromophore.
