Gentian Violet (CAS: 548-62-9)

Basic Information

Crystal violet or gentian violet (also known as methyl violet10B, hexamethyl pararosaniline chloride,

or pyoctanin(e)) is a triarylmethane dye. The dye is used as a histological stain and in Gram’s

method of classifying bacteria. Crystal violet has antibacterial, antifungal, and anthelminticproperties and

was formerly important as a topical antiseptic. The medical use of the dye has been largely superseded by

more modern medicine, although it is still listed by the World Health Organization.

Preparation

A number of possible routes can be used to prepare crystal violet. The original procedure developed by Kern

and Caro involved the reaction ofdimethylaniline with phosgene to give 4,4′

bis(dimethylamino)benzophenone (Michler’s ketone) as an intermediate. This was then reacted with additional

dimethylaniline in the presence of phosphorus oxychloride and hydrochloric acid.

The dye can also be prepared by the condensation of formaldehyde and dimethylaniline to give a leuco dye:

CH2O + 3 C6H5N(CH3)2 → CH(C6H4N(CH3)2)3 + H2O

Second, this colourless compound is oxidized to the coloured cationic form:

(A typical oxidizing agent is manganese dioxide).

CH(C6H4N(CH3)2)3 + HCl + 1/2 O2 → [C(C6H4N(CH3)2)3]Cl + H2O

Applications

Crystal violet is not used as a textile dye. Instead it is used to dye paper and as a component of navy blue and

black inks for printing, ball-point pens and ink-jet printers. It is also used to colourize diverse products such

as fertilizers, anti-freezes, detergents, and leather jackets.

The dye is also used as a histological stain, particularly in Gram’s method for classifying bacteria.

When conducting DNA gel electrophoresis, crystal violet can be used as a non-toxic DNA stain as an alternative

to fluorescent, intercalating dyes such asethidium bromide. Used in this manner it may be either incorporated into

the agarose gel or applied after the electrophoresis process is finished. Used at a 0.001% concentration and allowed

to stain a gel after electrophoresis for 30 minutes, it can detect as little as 16ng of DNA. Through use of amethyl

orange counterstain and a more complex staining method, sensitivity can be improved further to 8 ng of DNA.

When crystal violet is used as an alternative to fluorescent stains, it is not necessary to use ultraviolet illumination;

this has made crystal violet popular as a means of avoiding UV-induced DNA destruction when performing 

DNA cloning in vitro.

Gentian violet has antibacterial, antifungal, and anthelmintic properties.[10] It is used medically for these

properties, in particular for dentistry, and is also known as “pyoctanin” (or “pyoctanine”),It is commonly used for:

1.Marking the skin for surgery preparation and allergy testing

2.Tinea; e.g. athlete’s foot, jock itch, and ringworm

3.Candida albicans and related infections; e.g. thrush, yeast infections

4.Mouth ulcers

5.Impetigo, used primarily before the advent of antibiotics, but still useful to persons who may be allergic to penicillin.

Adverse reactions

1.Can irritate the mucous membrane, can cause contact dermatitis
2.When face with ulcerative damage should be careful, otherwise can cause the skin color.

3.To treat thrush, only in the affected area coated, such as the solution to swallow, can lead to esophagitis, laryngitis.

4.Should not be coated after seal packages