{{Short description|Chemical compound}} {{distinguish|methyl violet|methylene blue}} {{chembox | verifiedrevid = 400308223 | ImageFile1 = Methyl blue.png | ImageFile2 = Methyl Blue 3D.png | ImageFileL2 = Sample of Methyl Blue.jpg | ImageCaptionL2 = Solid methyl blue | ImageFileR2 = Methyl Blue aqueous solution.jpg | ImageCaptionR2 = Methyl blue aqueous solution | IUPACName = | OtherNames = Cotton blue, Helvetia blue, Acid blue 93, C.I. 42780 |Section1={{Chembox Identifiers | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 8051359 | InChI = 1/C37H29N3O9S3.2Na/c41-50(42,43)34-19-13-31(14-20-34)38-28-7-1-25(2-8-28)37(26-3-9-29(10-4-26)39-32-15-21-35(22-16-32)51(44,45)46)27-5-11-30(12-6-27)40-33-17-23-36(24-18-33)52(47,48)49;;/h1-24,38-39H,(H,41,42,43)(H,44,45,46)(H,47,48,49);;/q;2*+1/p-2 | InChIKey = MCPLVIGCWWTHFH-NUQVWONBAI | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/C37H29N3O9S3.2Na/c41-50(42,43)34-19-13-31(14-20-34)38-28-7-1-25(2-8-28)37(26-3-9-29(10-4-26)39-32-15-21-35(22-16-32)51(44,45)46)27-5-11-30(12-6-27)40-33-17-23-36(24-18-33)52(47,48)49;;/h1-24,38-39H,(H,41,42,43)(H,44,45,46)(H,47,48,49);;/q;2*+1/p-2 | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = MCPLVIGCWWTHFH-UHFFFAOYSA-L | CASNo_Ref = {{cascite|correct|??}} | CASNo = 28983-56-4 | UNII_Ref = {{fdacite|correct|FDA}} | UNII = 9ZI2A1BMBB | PubChem = 9875677 | SMILES = [Na+].[Na+].[O-]S(=O)(=O)c1ccc(cc1)Nc2ccc(cc2)C(=C4C=CC(=[NH+]c3ccc(cc3)S([O-])(=O)=O)C=C4)c6ccc(Nc5ccc(cc5)S([O-])(=O)=O)cc6 }} |Section2={{Chembox Properties | Formula = C<sub>37</sub>H<sub>27</sub>N<sub>3</sub>Na<sub>2</sub>O<sub>9</sub>S<sub>3</sub> | MolarMass = 799.814 g/mol | Appearance = red solid | Density = | MeltingPtC = | BoilingPtC = | Solubility = Soluble in water, slightly soluble in ethanol }} |Section3={{Chembox Hazards | MainHazards = | FlashPtC = | AutoignitionPtC = | NFPA-H = 1 | NFPA-F = 1 | NFPA-R = 0 | NFPA-S = }} }} '''Methyl blue''' is a chemical compound with the molecular formula C<sub>37</sub>H<sub>27</sub>N<sub>3</sub>Na<sub>2</sub>O<sub>9</sub>S<sub>3</sub>. It is used as a stain in histology,<ref>{{Cite book | title = Handbook of Biological Dyes and Stains: Synthesis and Industrial Applications | author = R. W. Sabnis | publisher = John Wiley & Sons | date = 2010 | page = 24}}</ref> and stains collagen blue in tissue sections. It can be used in some differential staining techniques such as Mallory's trichrome stain and Gömöri trichrome stain, and can be used to mediate electron transfer in microbial fuel cells. Fungal cell walls are also stained by methyl blue.
Methyl blue is also available in mixture with water blue, under name Aniline Blue WS, Aniline blue, China blue, or Soluble blue; and in a solution of phenol, glycerol, and lactic acid under the name Lactophenol cotton blue (LPCB), which is used for microscopic visualization of fungi.
== Chemistry == Methyl blue ([[4-[Bis[4-[(sulfophenyl)amino]phenyl]methylene]-2,5-cyclohexadien-1-ylidene]amino]-benzenesulfonic acid disodium salt) is distinctly different from methylene blue ([7-(dimethylamino)phenothiazin-3-ylidene]-dimethylazanium;chloride) in structure, function and uses, and must not be confused.<ref>{{cite web|title=Methyl Blue | website=sigmaaldrich.com | url=https://www.sigmaaldrich.com/US/en/substance/methylblue7998028983564 | access-date=11 September 2023}}</ref>
Its uses include staining histology samples for collagen,<ref>{{cite web |url=https://www.abcam.com/en-us/products/biochemicals/methyl-blue-sodium-salt-histology-stain-for-collagen-ab146271 | title=Methyl blue sodium salt, Histology stain for collagen (CAS 28983-56-4) (Ab146271) }}</ref> and for fungal structures.<ref>{{Cite web |url=https://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma-Aldrich/Datasheet/1/61335dat.pdf |title=61335 Lactophenol Blue Solution |access-date=2020-08-29 |archive-date=2021-01-12 |archive-url=https://web.archive.org/web/20210112034259/https://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma-Aldrich/Datasheet/1/61335dat.pdf |url-status=dead }}</ref>
==See also== * Potassium ferrocyanide * Potassium ferricyanide * Methylene blue * Egyptian blue * Han Purple * Crystal violet * Fluorescein
==References== {{reflist}}
{{Stains}}
Category:Triarylmethane dyes Category:Staining dyes Category:Aromatic amines Category:Acid dyes