Metanilic acid

{{Chembox | Reference =  | Name = Metanilic acid | PIN = 3-Aminobenzene-1-sulfonic acid | OtherNames = 3-Aminobenzenesulfonic acid<br />''m''-Anilinesulfonic acid  | ImageFile = File:Metanilic acid.svg | ImageSize = 120px  | Section1 = {{Chembox Identifiers | 3DMet = | Abbreviations = | Beilstein = | CASNo = 121-47-1 | CASNo_Comment = | ChEBI = | EINECS = 204-473-6 | ChemSpiderID = 8161 | EC_number = 204-473-6 | EC_number_Comment = | Gmelin = | InChI = 1S/C6H7NO3S/c7-5-2-1-3-6(4-5)11(8,9)10/h1-4H,7H2,(H,8,9,10) | KEGG = | MeSHName = | PubChem = 8474 | RTECS = | SMILES = Nc1cccc(S(=O)(=O)O)c1 | UNNumber = 2585 | UNII=OT03NUM20P | UNII_Ref= {{fdacite|correct|FDA}} }} | Section2 = {{Chembox Properties | AtmosphericOHRateConstant = | Appearance = Beige powder | BoilingPt = | BoilingPtC = | BoilingPt_ref = | BoilingPt_notes = | Density = 1.69 | C=6 | H=7 | N=1 | O=3 | S=1 | HenryConstant = | LogP = | MeltingPt = >300 °C (lit.) | MeltingPtC = | MeltingPt_ref = | MeltingPt_notes = | pKa = 3.74 (H<sub>2</sub>O)<ref name="CRC97">{{cite book | editor= Haynes, William M. | year = 2016 | title = CRC Handbook of Chemistry and Physics | edition = 97th | publisher = [[CRC Press]] | isbn = 978-1498754286 | pages=5–88 | title-link = CRC Handbook of Chemistry and Physics }}</ref> | pKb = | Solubility = Less than 1 mg/mL at {{convert|22|C|F}} | SolubleOther = | Solvent = | VaporPressure = }} | Section3 = {{Chembox Structure | Coordination = | CrystalStruct = | MolShape = }} | Section4 = {{Chembox Thermochemistry | DeltaGf = | DeltaHc = | DeltaHf = | Entropy = | HeatCapacity = }} | Section5 = {{Chembox Explosive | ShockSens = | FrictionSens = | DetonationV = | REFactor = }} | Section6 = {{Chembox Pharmacology | ATCvet = | ATCCode_prefix = | ATCCode_suffix = | ATC_Supplemental = | AdminRoutes = | Bioavail = | Excretion = | HalfLife = | Metabolism = | legal_status = | legal_AU = | legal_AU_comment = | legal_CA = | legal_CA_comment = | legal_NZ = | legal_NZ_comment = | legal_US = | legal_US_comment = | legal_UK = | legal_UK_comment = | legal_EU = | legal_EU_comment = | legal_UN = | legal_UN_comment = | pregnancy_category = | pregnancy_AU = | pregnancy_AU_comment = | pregnancy_US = | pregnancy_US_comment = | ProteinBound = | Dependence_liability = | Addiction_liability = }} | Section7 = {{Chembox Hazards | AutoignitionPt = | ExploLimits = | ExternalMSDS = | FlashPt = | LD50 = | LC50 = | MainHazards = | NFPA-F = | NFPA-H = | NFPA-R = | NFPA-S = | PEL = | REL = }} | Section9 = {{Chembox Related | OtherAnions = | OtherCations = | OtherFunction = | OtherFunction_label = | OtherCompounds = }} }}

'''Metanilic acid''' is an [[isomer]] of [[sulfanilic acid]] with molecular formula {{Chem|C|6|H|7|N|O|3|S}} and [[molecular weight]] 173.18968 g/mol.<ref>{{cite web|url=https://pubchem.ncbi.nlm.nih.gov/compound/Metanilic_acid|title=3-AMINOBENZENESULFONIC ACID - C6H7NO3S - PubChem|last=Pubchem|publisher=NIH}}</ref><ref>{{cite web|url=http://chemicalbook.com/ChemicalProductProperty_EN_CB7143612.htm|title=Metanilic acid - 121-47-1}}</ref><ref>{{cite web|url=http://webbook.nist.gov/cgi/cbook.cgi?ID=121-47-1|title=Metanilic acid}}</ref> It is a white powder that is slightly soluble in water.

== Disappearing polymorph == The crystal structure called Form I is a [[disappearing polymorph]] that cannot be produced by researchers anymore while Form II and III still exist.<ref>{{Cite journal | vauthors = Rubin-Preminger JM, Bernstein J |date=2005-07-01 |title=3-Aminobenzenesulfonic Acid: A Disappearing Polymorph |journal=Crystal Growth & Design |language=en |volume=5 |issue=4 |pages=1343–1349 |doi=10.1021/cg049680y |issn=1528-7483}}</ref> The reason for this is that Form I is converted to another polymorph upon contact with a [[seed crystal]] and most places are contaminated with tiny amounts of Form II or III that are enough to prevent any viable amounts of Form I to be produced.

== See also == * [[Orthanilic acid]] * [[Sulfanilic acid]]

==References==

[[Category:Benzenesulfonic acids]] [[Category:3-Aminophenyl compounds]]