Triphenylmethane and Related Dyes

Abstract A brief introduction describing the structure and dyeing properties, eg, lightfastness and color, of the triphenylmethane dyes is given. The dyes are also classified in terms of their application class, giving their historical and present‐day usage in textiles and paper. Further details on the relationship of the structure and the various substituents on the reactivity, spectral characteristics, and fastness properties are discussed. The significant industrial processes for the manufacture of triphenylmethane dyes are outlined through examples of the synthesis of the more important dyes like malachite green, methyl violet, and crystal violet. New reagents and kinds of chemical technology are described where these have been used to improve the older processes and alleviate environmental problems. The toxicology associated with the triphenylmethane dyes is also mentioned in relation to their use as food colorants or dyes, and the environmental concerns of effluent treatment is briefly mentioned. Production statistics for triphenylmethane dyes in the United States are given for the period between 1975 and 1995, with suitable references also provided giving world figures. The many different areas in which these dyes are employed are described, along with more recent high technology uses.