Methyl violet
Template:Short description Methyl violet is a family of organic compounds that are mainly used as dyes. Depending on the number of attached methyl groups, the color of the dye can be altered. Its main use is as a purple dye for textiles and to give deep violet colors in paint and ink. It is also used as a hydration indicator for silica gel. Methyl violet 10B is also known as crystal violet (and many other names) and has medical uses.<ref name="pyoctanin_Gorgas" />
StructureEdit
The term methyl violet encompasses three compounds that differ in the number of methyl groups attached to the amine functional group. Methyl violets are mixtures of tetramethyl (2B), pentamethyl (6B) and hexamethyl (10B) pararosanilins.<ref>Template:Cite journal</ref>
They are all soluble in water, ethanol, diethylene glycol and dipropylene glycol.
Name Methyl violet 2B Methyl violet 6B Methyl violet 10B (Crystal violet) Structure Formula (salt) C23H26ClN3 C24H28ClN3 C25H30ClN3 CAS no 84215-49-6 8004-87-3 548-62-9 C.I. 42536 42535 42555 ChemSpider ID 21164086 170606 10588 PubChem ID 91997555 164877 11057 Formula (cation) C23H26N3+ C24H28N3+ C25H30N3+ ChemSpider ID 2006225 3349, 9080056, 10354393 PubChem ID 2724053 3468
Methyl violet 2BEdit
Methyl violet 2B (IUPAC name: 4,4′-((4-Iminocyclohexa-2,5-dien-1-ylidene)methylene)bis(N,N-dimethylaniline) monohydrochloride) is a green powder which is soluble in water and ethanol but not in xylene. It appears yellow in solution of low pH (approximately 0.15) and changes to violet with pH increasing toward 3.2.<ref name=b1>Template:Cite book</ref>
Methyl violet 10BEdit
{{#invoke:Labelled list hatnote|labelledList|Main article|Main articles|Main page|Main pages}} Methyl violet 10B has six methyl groups. It is known in medicine as Gentian violet (or crystal violet or pyoctanin(e)<ref name="pyoctanin_Gorgas">Template:Cite journal</ref>) and is the active ingredient in a Gram stain, used to classify bacteria. It is used as a pH indicator, with a range between 0 and 1.6. The protonated form (found in acidic conditions) is yellow, turning blue-violet above pH levels of 1.6.<ref>Kristallviolett – ein pH-Indikator Template:Webarchive</ref>
Methyl violet 10B inhibits the growth of many Gram positive bacteria, except streptococci.Template:Citation needed When used in conjunction with nalidixic acid (which destroys gram-negative bacteria), it can be used to isolate the streptococci bacteria for the diagnosis of an infection.Template:Citation needed
DegradationEdit
Methyl violet is a mutagen and mitotic poison, therefore concerns exist regarding the ecological impact of the release of methyl violet into the environment. Methyl violet has been used in vast quantities for textile and paper dyeing, and 15% of such dyes produced worldwide are released to environment in wastewater. Numerous methods have been developed to treat methyl violet pollution. The three most prominent are chemical bleaching, biodegradation, and photodegradation.
Chemical bleachingEdit
Chemical bleaching is achieved by oxidation or reduction. Oxidation can destroy the dye completely, e.g. through the use of sodium hypochlorite (NaClO, common bleach) or hydrogen peroxide.<ref>Template:Cite journal</ref><ref>XP-Chloro Degradation Malachite green {{#if:2755202
|[{{#ifeq:|uspto|http://patft.uspto.gov/netacgi/nph-Parser?patentnumber=%7Chttps://patents.google.com/patent/US}}{{#iferror:{{#expr:2755202 }}|2755202}} U.S. patent {{#ifeq:Template:Replace|Template:Digits|Template:Replace|2755202}}]
|{{US patent|123456|link text}}}}</ref> Reduction of methyl violet occurs in microorganisms but can be attained chemically using sodium dithionite.
BiodegradationEdit
Biodegradation has been well investigated because of its relevance to sewage plants with specialized microorganisms. Two microorganisms that have been studied in depth are the white rot fungus and the bacterium Nocardia corallina.<ref>Template:Cite journal </ref><ref>Template:Cite journal</ref>
PhotodegradationEdit
Light alone does not rapidly degrade methyl violet,<ref>Template:Cite journal</ref> but the process is accelerated upon the addition of large band-gap semiconductors, titanium dioxide or zinc oxide.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
Other methodsEdit
Many other methods have been developed to treat the contamination of dyes in a solution, including electrochemical degradation,<ref>Template:Cite journal</ref> ion exchange,<ref>Template:Cite journal</ref> laser degradation, and absorption onto various solids such as activated charcoal.