View source for Fuchsine

{{For|the sodium sulfonate derivative|acid fuchsin}}
{{Distinguish|fuscin}}
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 425367120
| ImageFile = Rosaniline hydrochloride.svg
| ImageSize = 200px
| ImageFileL1 = Sample of Basic Fuchsine.jpg
| ImageSizeL1 = 100px
| ImageNameL1 = Solid Basic Fuchsine
| ImageCaptionL1 = Solid basic fuchsine
| ImageFileR1 = Basic Fuchsine in aqueous solution.jpg
| ImageSizeR1 = 100px
| ImageNameR1 = Basic Fuchsine in aqueous solution
| ImageCaptionR1 = Basic fuchsine in aqueous solution
| IUPACName = 4-[(4-Aminophenyl)-(4-imino-1-cyclohexa-2,5-dienylidene)methyl]aniline hydrochloride
| OtherNames = 
|Section1={{Chembox Identifiers
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 8UUC89LHB2
| InChIKey = NIKFYOSELWJIOF-SVFFXJIWBQ
| StdInChI_Ref = {{stdinchicite|changed|chemspider}}
| StdInChI = 1S/C20H19N3.ClH/c1-13-12-16(6-11-19(13)23)20(14-2-7-17(21)8-3-14)15-4-9-18(22)10-5-15;/h2-12,21H,22-23H2,1H3;1H/b20-14-,21-17?;
| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}
| StdInChIKey = NIKFYOSELWJIOF-SVFFXJIWSA-N
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 632-99-5
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 10468578
| ChEBI_Ref = {{ebicite|correct|EBI}} 
| ChEBI = 87665
| PubChem = 12447
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 1979636
| EINECS = 209-321-2
| KEGG = C19252
| SMILES = [Cl-].[NH2+]=C\1/C=C\C(C=C/1)=C(\c2ccc(N)c(C)c2)c3ccc(N)cc3
| InChI = 1/C20H19N3.ClH/c1-13-12-16(6-11-19(13)23)20(14-2-7-17(21)8-3-14)15-4-9-18(22)10-5-15;/h2-12,21H,22-23H2,1H3;1H/b20-14-,21-17?;
| RTECS = 8053-09-6
  }}
|Section2={{Chembox Properties
| Formula = C<sub>20</sub>H<sub>19</sub>N<sub>3</sub>·HCl
| MolarMass = 337.86 g/mol (hydrochloride)
| Appearance = Dark green powder
| Density = 
| MeltingPtC = 200
| BoilingPt = 
| Solubility = 2650 mg/L ({{convert|25|C}})
| LogP = 2.920
| VaporPressure = {{val|7.49|e=-10|u=mmHg}} (25 °C)
| HenryConstant = {{val|2.28|e=-15|u=atm⋅m<sup>3</sup>/mole}} (25 °C)
| AtmosphericOHRateConstant = {{val|4.75|e=-10|u=cm<sup>3</sup>/molecule⋅sec}} (25 °C)
  }}
|Section3={{Chembox Hazards
| MainHazards = Ingestion, inhalation, skin and eye contact, combustible at high temperature, slightly explosive around open flames and sparks.
| NFPA-H = 2
| NFPA-F = 1
| NFPA-R = 0
| NFPA-S = 
| FlashPt = 
| AutoignitionPt = 
 }}
}}

'''Fuchsine''' (sometimes spelled '''fuchsin''') or '''rosaniline hydrochloride''' is a [[magenta]] [[dye]] with [[chemical formula]] C<sub>20</sub>H<sub>19</sub>N<sub>3</sub>·HCl.<ref name="nih-basic">[https://dtp.cancer.gov/dtpstandard/servlet/ChemData?queryHOLD=&searchtype=namestarts&chemnameboolean=and&outputformat=html&searchlist=Rosaniline&Submit=Submit "Basic chemical data"]. ''Discovery Series'' online database, Developmental Therapeutics Program, U.S. National Institutes of Health. Retrieved on 2007-10-08.</ref><ref>Goyal, S.K. [http://www.rsc.org/ej/EM/2001/b106209n.pdf "Use of rosaniline hydrochloride dye for atmospheric SO<sub>2</sub> determination and method sensitivity analysis"]. ''Journal of Environmental Monitoring'', '''3''', 666–670, {{doi|10.1039/b106209n}}. Retrieved on 2007-10-08.</ref> There are other similar chemical formulations of products sold as fuchsine, and several dozen other synonyms of this molecule.<ref name="nih-basic" />

It becomes magenta when dissolved in [[water]]; as a [[solid]], it forms dark [[green]] [[crystal]]s. As well as dying [[textile]]s, fuchsine is used to [[staining (biology)|stain]] [[bacteria]] and sometimes as a [[disinfectant]]. In the literature of biological stains the name of this dye is frequently misspelled, with omission of the [[silent e#Truly silent e|terminal -e]], which indicates an [[amine]].<ref>Baker JR (1958) Principles of Biological Microtechnique. London: Methuen.</ref> American and English dictionaries (Webster's, Oxford, Chambers, etc.) give the correct spelling, which is also used in the literature of industrial dyeing.<ref>Hunger K (2003) Industrial Dyes. Chemistry, Properties, Applications. Weinheim: wiley-VHC.</ref> It is well established that production of fuchsine results in development of bladder cancers by production workers. Production of magenta is listed as a [[List of IARC Group 1 carcinogens|circumstance known to result in cancer]].<ref>{{cite book|title=MAGENTA AND MAGENTA PRODUCTION|year=2010|volume=99|series=IARC MONOGRAPHS ON THE EVALUATION OF CARCINOGENIC RISKS TO HUMANS|pages=297 to 324|url=http://monographs.iarc.fr/ENG/Monographs/vol99/mono99-12.pdf|access-date=January 12, 2013|author=|publisher=International Agency for Research on Cancer, World Health Organization|quote=Magenta production is carcinogenic to humans (Group 1).}}</ref>

==History==

Fuchsine was first created by [[Jakub Natanson]] in 1856 from [[aniline]] and [[1,2-Dichloroethane]].<ref name=":0">{{Cite web|url=https://edu.rsc.org/feature/the-battle-for-magenta/2020242.article|title=The battle for magenta}}</ref> In 1858 [[August Wilhelm von Hofmann]] obtained it from [[aniline]] and [[carbon tetrachloride]].<ref>{{cite journal | doi = 10.1002/prac.18590770130 | first = August Wilhelm | last = von Hofmann  | title = Einwirkung des Chlorkohlenstoffs auf Anilin. Cyantriphenyldiamin | year = 1859 | journal = Journal für Praktische Chemie | volume = 77 | pages = 190–191 }}</ref><ref>{{cite journal | title = Action of Bichloride of Carbon on Aniline | journal = Philosophical Magazine | year = 1858 | pages = 131–142 | first = August Wilhelm | last = von Hofmann | url = http://zs.thulb.uni-jena.de/receive/jportal_jpvolume_00057523?XSL.view.objectmetadata=false&jumpback=true&maximized=true&page=PMS_1859_Bd17_%200089.tif }}</ref> {{ill|François-Emmanuel Verguin|||fr}} discovered the substance independently of Hofmann the same year and patented it.<ref>{{cite journal |author=<!--Staff writer(s); no by-line.-->  |year=1865 |title= Necrologie. Verguin|journal=Le Moniteur Scientifique du Docteur Quesneville: Journal des Sciences pures et appliquées |trans-journal=The Scientific Monitor of Doctor Quesneville: Journal of Pure and Applied Sciences |url={{Google books |plainurl=yes |id=z-MEAAAAQAAJ |page=42 }} |language=fr |location= Paris, France |pages= 42–46}}</ref> Fuchsine was named by its original manufacturer Renard frères et Franc,<ref>Béchamp, M. A. (January–June 1860.) [http://gallica.bnf.fr/ark:/12148/bpt6k3007r "Comptes rendus hebdomadaires des séances de l'Académie des sciences. 1860. (T. 50)."] ''[[French Academy of Sciences]]'', Mallet-Bachelier: Paris, tome 50, page 861. Retrieved on 2007-09-25.</ref> is usually cited with one of two etymologies: from the color of the flowers of the plant genus ''[[Fuchsia]]'',<ref name="fuchsin2004">(2004.) [http://dictionary.reference.com/browse/fuchsin "Fuchsin"] ''The American Heritage Dictionary of the English Language, Fourth Edition,'' [[Houghton Mifflin Company]], via dictionary.com. Retrieved on 2007-09-20</ref> named in honor of botanist [[Leonhart Fuchs]], or as the German translation ''Fuchs'' of the French name Renard, which means fox.<ref>[http://humanities.uchicago.edu/orgs/ARTFL/forms_unrest/webster.form.html "Fuchsine."] {{webarchive|url=https://web.archive.org/web/20070928233032/http://humanities.uchicago.edu/orgs/ARTFL/forms_unrest/webster.form.html |date=2007-09-28 }} (Website.) ''ARTFL Project: 1913 Webster's Revised Unabridged Dictionary''. Retrieved on 2007-09-25</ref> An 1861 article in ''Répertoire de Pharmacie'' said that the name was chosen for both reasons.<ref>Chevreul, M. E. (July 1860). [{{Google books |id=lfIKAAAAYAAJ |page=62 |plainurl=yes }} "Note sur les étoffes de soie teintes avec la fuchsine, et réflexions sur le commerce des étoffes de couleur."] ''Répertoire de Pharmacie'', tome XVII, p. 62. Retrieved on 2007-09-25.</ref><ref>{{cite journal | jstor = 4027004 | pages = 45–63 | last1 = Belt | first1 = H. V. D. | title = Why Monopoly Failed: The Rise and Fall of Société La Fuchsine | volume = 25 | issue = 1 | journal = The British Journal for the History of Science | year = 1992 | doi = 10.1017/S0007087400045325 | last2 = Hornix | first2 = Willem J. | last3 = Bud | first3 = Robert | last4 = Van Den Belt | first4 = Henk | s2cid = 80725880 }}</ref>

== Usage ==
In the 21st century, it remains useful for biological chemistry, particularly for detecting glycogenic material.<ref name=":0" />

Historically, after its discovery it became widely-used in the textile industry in the late 1800s and 1900s for dyeing fabrics pink, and also for dyeing foodstuffs, particularly red wine, despite health concerns.<ref>{{Cite web |title=Fuchsine and Fashion: a Bright Pinkish Trend |url=https://chromobase.huma-num.fr/narratives/fuchsine-and-fashion-a-bright-pinkish-trend/ |access-date=2025-02-10 |website=chromobase.huma-num.fr}}</ref> 

==Acid fuchsine==
[[Acid fuchsine]] is a mixture of homologues of basic fuchsine, modified by addition of [[sulfonic acid|sulfonic]] groups. While this yields twelve possible isomers, all of them are satisfactory despite slight differences in their properties. {{citation needed|date=September 2012}}

==Basic fuchsine==
'''Basic fuchsine''' is a mixture of rosaniline, [[pararosaniline]], [[new fuchsine]] and {{ill|magenta II|qid=Q27159817}}.<ref>Horobin RW & Kiernan JA 20002. ''Conn's Biological Stains'', 10th ed. Oxford: BIOS, p. 184–191</ref> Formulations usable for making of [[Schiff reagent]] must have high content of pararosanilin. The actual composition of basic fuchsine tends to somewhat vary by vendor and batch, making the batches differently suitable for different purposes.

In solution with [[phenol]] (also called carbolic acid) as an [[accentuator (of staining)|accentuator]]<ref>{{Cite web |url=http://stainsfile.info/StainsFile/theory/accent.htm |title=StainsFile - Stain theory - Accentuators |access-date=2012-06-28 |archive-url=https://web.archive.org/web/20161003122706/http://stainsfile.info/StainsFile/theory/accent.htm |archive-date=2016-10-03 |url-status=dead }}</ref> it is called [[carbol fuchsin]] and is used for the [[Ziehl–Neelsen stain|Ziehl–Neelsen]] and other similar [[acid-fast]] staining of the [[Mycobacterium|mycobacteria]] which cause [[tuberculosis]], [[leprosy]] etc.<ref>Clark G 1973 ''Staining Procedures Used by the [[Biological Stain Commission]]'', 3rd ed. Baltimore: Williams & Wilkins, pp. 252–254</ref> Basic fuchsine is widely used in biology to stain the [[cell nucleus|nucleus]], and is also a component of Lactofuchsin, used for [[Lactofuchsin mount]]ing.

==Properties==
[[File:Basic Fuchsine Crystals.JPG|thumb|Basic fuchsine pieces. The two magenta stains on the paper were made by placing one drop of [[ethanol]]-water [[azeotrope]], ''centre'', and water, ''right'', on the streaks remaining on the paper after the 'crystals' were removed. The 'crystals' were then replaced and the photograph taken.]]

The crystals pictured at the right are of basic fuchsine, also known as basic violet 14, basic red 9, pararosanaline or [[Colour Index International|CI 42500]]. Their structure differs from the structure shown above by the absence of the [[methyl group]] on the upper ring, otherwise they are quite similar.

They are soft, with a [[Mohs scale of mineral hardness|hardness]] of less than 1, about the same as or less than talc. They possess a strong metallic lustre and a green yellow color. They leave dark greenish streaks on paper and when these are moistened with a solvent, the strong magenta colour appears.

==Chemical structure==
Fuchsine is an amine salt and has three amine groups, two [[primary amines]] and a [[secondary amine]]. If one of these is [[protonation|protonated]] to form ABCNH<sup>+</sup>, the positive charge is delocalized across the whole symmetrical molecule due to pi cloud electron movement.

The positive charge can be thought of as residing on the central carbon atom and all three "wings" becoming identical [[aromatic ring]]s terminated by a primary amine group.{{clarify|date=November 2012}} Other [[resonance (chemistry)|resonance]] structures can be conceived, where the positive charge "moves" from one amine group to the next, or one third of the positive charge resides on each amine group. The ability of fuchsine to be protonated by a stronger acid  gives it its [[Base (chemistry)|basic]] property. The positive charge is neutralized by the negative charge on the chloride ion. The positive "basic fuchsinium ions" and negative chloride ions stack to form the salt "crystals" depicted above.

==See also==
* [[New fuchsine]] and [[Acid fuchsine]] are related dyes
* Fuchsine is a component in the [[Schiff test]]
* Fuchsine is now often used in the [[Gram stain]] procedure in [[microbiology]].
* Basic Fuchsine is a component in the [[Lactofuchsin mount]]

==References==
{{Reflist}}

==Further reading==
* {{Cite EB1911|wstitle=Fuchsine|volume=11|page=273}} This provides a detailed account of early experimentation on related chemicals.

{{Stains}}

[[Category:Triarylmethane dyes]]
[[Category:Staining dyes]]
[[Category:4-Aminophenyl compounds]]
[[Category:Disinfectants]]
[[Category:IARC Group 2B carcinogens]]
[[Category:Products introduced in 1856]]
[[Category:1856 in science]]
[[Category:19th-century inventions]]
[[Category:Hydrochlorides]]