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Revision as of 08:14, 7 September 2011 editCheMoBot (talk | contribs)Bots141,565 edits Updating {{chembox}} (no changed fields - added verified revid - updated 'DrugBank_Ref', 'UNII_Ref', 'ChEMBL_Ref', 'ChEBI_Ref', 'KEGG_Ref', 'ChEBI_Ref') per Chem/Drugbox validation (report [[Wikipedia_talk:WikiProject_Chemicals|error← Previous edit		Latest revision as of 15:10, 6 June 2024 edit undo96.252.13.92 (talk)No edit summary
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	{{chembox		{{chembox
			| Watchedfields = changed
	| verifiedrevid = 447247968		| verifiedrevid = 448903948
	| ImageFile = Methyl-orange-2D-skeletal.png		| ImageFile = Methyl-orange-2D-skeletal.png
	| ImageFile1 = Methyl-orange-3D-vdW.png		| ImageFile1 = Methyl-orange-3D-vdW.png
	| ImageFile2 = Methyl-orange-sample.jpg		| ImageFile2 = Methyl-orange-sample.jpg
			| PIN = Sodium 4-<nowiki>{</nowiki>diazenyl}benzene-1-sulfonate
	| IUPACName = 4-dimethylaminoazobenzene-4'-sulfonic acid sodium salt
	| OtherNames = p-dimethylamino-azobenzenesulfonic acid		| OtherNames = Sodium 4-benzenesulfonate
	| Section1 = {{Chembox Identifiers		|Section1={{Chembox Identifiers
	| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}		| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
	| ChemSpiderID = 16736152		| ChemSpiderID = 16736152
	| InChI = 1/C14H15N3O3S.Na/c1-17(2)13-7-3-11(4-8-13)15-16-12-5-9-14(10-6-12)21(18,19)20;/h3-10H,1-2H3,(H,18,19,20);/q;+1/p-1		| InChI = 1/C14H15N3O3S.Na/c1-17(2)13-7-3-11(4-8-13)15-16-12-5-9-14(10-6-12)21(18,19)20;/h3-10H,1-2H3,(H,18,19,20);/q;+1/p-1
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	| CASNo_Ref = {{cascite|correct|CAS}}		| CASNo_Ref = {{cascite|correct|CAS}}
	| CASNo = 547-58-0		| CASNo = 547-58-0
	| PubChem =		| PubChem = 23673835
			| EC_number = 208-925-3
⚫	| SMILES = .CN(C)c2ccc(/N=N/c1ccc(cc1)S()(=O)=O)cc2
			| UNNumber = 3143
			| UNII = 6B4TC34456
		⚫	| SMILES = .CN(C)c2ccc(/N=N/c1ccc(cc1)S()(=O)=O)cc2
	}}		}}
	| Section2 = {{Chembox Properties		|Section2={{Chembox Properties
			| C=14 | H=14 | N=3 | Na=1 | O=3 | S=1
	| Formula = C<sub>14</sub>H<sub>14</sub>N<sub>3</sub>NaO<sub>3</sub>S
			| Appearance = Orange or yellow solid<ref name=crc/>
	| MolarMass = 327.33 g/mol
		⚫	| Density = 1.28 g/cm<sup>3</sup>
	| Appearance =
			| MeltingPt = >
⚫	| Density = 1.28 g/cm<sup>3</sup>, solid
			| MeltingPtC = 300
	| MeltingPt = >300 °C (Not precisely defined.)		| MeltingPt_notes=(not precisely defined)
	| BoilingPt = Decomposes.
			| BoilingPt = Decomposes<ref name=crc>{{cite book | editor= Haynes, William M. | date = 2016| title = ] | edition = 97th | publisher = ] | isbn = 9781498754293|page=3.384}}</ref>
	| Solubility = Soluble in hot water		| Solubility = 5 g/L (20 °C)
			| SolubleOther = Insoluble<ref name=sciencelab />
			| Solvent = ]
	}}		}}
	| Section3 = {{Chembox Hazards		|Section3={{Chembox Hazards
			| GHSPictograms = {{GHS06}}
⚫	| MainHazards =
	| FlashPt =		| GHSSignalWord = Danger
			| HPhrases = {{H-phrases|301}}
	| Autoignition =
			| PPhrases = {{P-phrases|308|310}}
		⚫	| MainHazards = Toxic (T)
			| NFPA-H = 1
			| NFPA-F = 0
			| NFPA-R = 0
			| NFPA_ref = <ref name=sciencelab />
			| FlashPt =
			| AutoignitionPt =
			| LD50 = 60 mg/kg (rat, oral)
	}}		}}
	}}		}}
			'''Methyl orange''' is a ] frequently used in ] because of its clear and distinct color variance at different pH values. Methyl orange shows red color in acidic medium and yellow color in basic medium. Because it changes color at the p''K''<sub>a</sub> of a mid strength acid, it is usually used in titration of strong acids in weak bases that reach the equivalence point at a pH of 3.1-4.4.<ref name="A/B Indicators">{{cite web |last1=Clark |first1=J |title=Acid Base Indicators |url=https://www.chemguide.co.uk/physical/acidbaseeqia/indicators.html. |website=ChemGuide |access-date=November 12, 2022}}</ref> Unlike a ], methyl orange does not have a full spectrum of color change, but it has a sharp end point. In a solution becoming less acidic, methyl orange changes from red to orange and, finally, to yellow—with the reverse process occurring in a solution of increasing acidity.
	'''Methyl orange''' is a ] frequently used in ].
			== Indicator colors ==
	It is often used in titrations because of its clear colour change. Because it changes colour at the pH of a mid-strength acid, it is usually used in titrations for acids. Unlike a ], methyl orange does not have a full spectrum of colour change, but has a sharper end point.
			]
			In a solution that decreases in acidity, methyl orange moves from the color red to orange and finally to yellow with the opposite occurring for a solution increasing in acidity. This color change from yellow to red occurs because the protons in the acidic solution react with the N=N bond of the molecule, protonating one of them and changing the visible light absorption of the molecule to reflect more red light than orange/yellow.
		⚫	{{pH_indicator_template|indicator_name=Methyl orange|low_pH=3.1|high_pH=4.4|low_pH_color=red|low_pH_text=white|high_pH_color=yellow}}
		⚫	In an acid, it is reddish and in alkali, it is yellow. Methyl orange has a p''K''<sub>a</sub> of 3.47 in water at {{convert|25|C}}.<ref>{{cite journal | doi = 10.1021/j100670a024 | title = Kinetics of acid dissociation-ion recombination of aqueous methyl orange | year = 1972 | last1 = Sandberg | first1 = Richard G. | last2 = Henderson | first2 = Gary H. | last3 = White | first3 = Robert D. | last4 = Eyring | first4 = Edward M. | journal = The Journal of Physical Chemistry | volume = 76 | issue = 26 | pages = 4023–4025}}</ref>
	== Indicator colours ==		== Other indicators ==
			{{Main|pH indicator}}
⚫	{{pH_indicator_template|indicator_name=Methyl orange|low_pH=3.1 |high_pH=4.4 |low_pH_color=red |high_pH_color=yellow}}
	{{pH_indicator_template|indicator_name=Methyl orange in xylene cyanol solution|low_pH=3.2 |high_pH=4.2 |low_pH_color=purple |high_pH_color=#00CD00}}		{{pH_indicator_template|indicator_name=Methyl orange in xylene cyanol solution|low_pH=3.2|high_pH=4.2|low_pH_color=#884488|low_pH_text=white|high_pH_color=#00CD00}}
		⚫	Modified (or screened) methyl orange, an indicator consisting of a solution of methyl orange and ], changes from grey-violet to green as the solution becomes more basic.
			==Safety==
			Methyl orange has ]ic properties.<ref name=sciencelab> {{Webarchive|url=https://web.archive.org/web/20140512223610/https://www.sciencelab.com/msds.php?msdsId=9926081 |date=2014-05-12 }} from ScienceLab.com, Inc. Retrieved 2011-09-24</ref> When methyl orange is put under ], one of the double-bonded nitrogen atoms that connects the aromatic rings gets radicalized and can further break down into ] or ]s, which are ]ic and can mutate DNA.<ref name="Radiat. Phys. Chem.">{{cite journal |last1=Wojnárovits |first1=L |last2=Takács |first2=E |date=2008 |title=Irradiation treatment of azo dye containing wastewater: An overview |url=https://www.sciencedirect.com/science/article/pii/S0969806X07002411 |journal=Radiat. Phys. Chem. |volume=77 |issue=3 |pages=225–244 |doi=10.1016/j.radphyschem.2007.05.003|bibcode=2008RaPC...77..225W }}</ref> Various bacteria and enzymes can also cause this breakdown to occur.
			==Synthesis==
			Methyl orange is an azobenzene derivative that can be formed from ] and ], first through a diazonium salt formation with the sulfanilic acid, followed by a nucleophilic attack from the dimethylaniline and ].<ref>{{Cite journal |last1=Liu |first1=Ting-ting |last2=Shi |first2=Chun-ling |date=January 2005 |title=Improvement of Methyl Orange Preparation |journal=Guangzhou Chamical Industry |volume=43 |issue=1 |pages=76–77}}</ref>
			==UV-vis spectrum==
			The absorption of methyl orange on the ] is between 350-550 nm, with its peak at 464 nm. This is in the green-purple visible light range and explains why methyl orange is, in fact, orange.<ref>{{Cite journal |last1=Ayed |first1=Lamia |last2=Khelifi |first2=Eltaief |last3=Jannet |first3=Hichem Ben |last4=Miladi |first4=Hanene |last5=Cheref |first5=Abdelkarim |last6=Achour |first6=Sami |last7=Bakhrouf |first7=Amina |date=2010-11-15 |title=Response surface methodology for decolorization of azo dye Methyl Orange by bacterial consortium: Produced enzymes and metabolites characterization |url=https://www.sciencedirect.com/science/article/pii/S138589471000848X |journal=Chemical Engineering Journal |language=en |volume=165 |issue=1 |pages=200–208 |doi=10.1016/j.cej.2010.09.018 |issn=1385-8947}}</ref>
	In a solution becoming less acidic, methyl orange moves from red to orange and finally to yellow with the reverse occurring for a solution increasing in acidity. The entire colour change occurs in acidic conditions.
⚫	In an acid it is reddish and in alkali it is yellow. Methyl orange has a pKa of 3.47 in water at 25 degrees Celsius.<ref>{{cite journal | doi = 10.1021/j100670a024 | title = Kinetics of acid dissociation-ion recombination of aqueous methyl orange | year = 1972 | last1 = Sandberg | first1 = Richard G. | last2 = Henderson | first2 = Gary H. | last3 = White | first3 = Robert D. | last4 = Eyring | first4 = Edward M. | journal = The Journal of Physical Chemistry | volume = 76 | issue = 26 | pages = 4023–4025}}</ref>
	]
	== Other Indicators ==
⚫	*Modified (or screened) methyl orange, an indicator consisting of a solution of methyl orange and ], changes from grey to green as the solution becomes more basic.
	*A number of other common indicators are tabulated in the article on ]s.
	==See also==		==See also==
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	==External links==		==External links==
			{{Commons category|Methyl orange}}
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