Crystal violet

Basic violet 3 is a color additive that functions as nonoxidative hair colorants. Under the US Food and Drug Administration (FDA) voluntary cosmetic registration program (VCRP), manufacturers provide information on their use of individual cosmetic ingredients as a function of product type. No current uses of any of these ingredients are reported in the VCRP. Basic Violet 3 also is used as an acid-base indicator (pH 0, green, to pH 2.0, blue), a bacteria stain, and an antiseptic. It is classified as a class I medical device for its use as a dye and stain.

Crystal violet is used in the office equipment industry for the production of indelible pencils, for making stamping and hectographic inks, and for dyeing paper. The color strength in hectographic coloring matter is particularly high if crystal violet is present as the nitrate.

Gentian Violet is a blue, aniline-derived dye with antifungal and antimitotic properties. Gentian violet (GV) dissociates into positive (GV+) and negative ions (Cl-) that penetrate both gram-positive and gram-negative bacterial cells. The GV+ ions interact with negatively charged components of the bacterial cell wall including lipopolysaccharide, peptidoglycan and DNA. This agent is also a mutagen and mitotic poison. GV elicits a photodynamic action mediated by a free-radical mechanism. Furthermore, this agent dissipates the action potential on prokaryotic or eukaryotic membranes by inducing permeability, thereby leading to respiratory inhibition and subsequent cell death.

The production of crystal violet can also be carried out as a one-pot reaction by condensing dimethylaniline with formaldehyde to 4,4'-methylenebis(N,N-dimethylaniline), which is reacted with dimethylaniline and simultaneously oxidized to the dye by atmospheric oxygen in the presence of (dihydrodibenzotetraaza(14)annulene)iron and chloranil. Vanadium and molybdenum compounds and nitrous gases can also be used as oxidation catalysts together with chloranil.

The dyes are manufactured by oxidizing a mixture of aniline and p-toluidine, the oxidizing agent most commonly used being arsenic acid. Nitrobenzene has also been used. Pure Basic Violet 3 has been made by the action of carbonyl chloride (phosgene) on N,N-dimethylaniline.