Dyes synthetic Malachite Green

The relentless search for new and cheaper colors produced its own casualties. The Empress aldehyde green was swept aside by iodine green, methyl green, malachite green, and so on. Natural dyes were also falling by the wayside. Canary Island farmers who raised cacti for tiny cochineal beetles were bankrupted 70,000 of the dried beetles made only 1 pound of crimson dye, and the new synthetic colors were much cheaper. 

Diphenylmethane and triphenylmethane dyes are monomethine dyes with two or three terminal aryl groups, of which at least one, but preferably two or three, are substituted by a donor group para to the methine carbon atom. The most important donor is the amino group. Important dyes belonging to this class include the well-known malachite green (12) [9] and crystal violet (13) [10], which are some of the oldest synthetic cationic dyes ... 

Another group of dyes belonging to the tri-phenyl methane series but which differ from the rosanilines in not being derived from triamino tri-phenyl methane is represented by malachite green. It is one of the oldest of the synthetic dyes, having been first prepared by O. Fischer in 1877. The immediate mother substance is di-amino tri-phenyl methane of which the leuco base of the dye is the tetra-methyl derivative. 

The basic dyes are historically interesting because Perkin s mauve (see Chapter 1) belonged to this class, as do Magenta and Malachite Green which were amongst the earliest synthetic dyes. 

The above hypercrosslinked samples have been tested under identical conditions for their ability to extract from aqueous solutions three synthetic organic dyes Malachite Green (MG), Methylene Blue (MB), and Direct Bordeaux (DB) ... 

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