Potassium hydrogenoxalate: Difference between revisions

{{short description|Chemical compound, salt of sorrel}}

|Verifiedfields = changed

|Watchedfields = changed

|verifiedrevid = 428811294

|CASNo_Ref = {{cascite|correct|??}}

|CASNo=127-95-7

|UNII_Ref = {{fdacite|correct|FDA}}

|UNII = L3W2519LG2

|PubChem = 31394

|ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}}

|ChemSpiderID = 29125

|SMILES = [K+].[O-]C(=O)C(=O)O

|InChI = 1/C2H2O4.K/c3-1(4)2(5)6;/h(H,3,4)(H,5,6);/q;+1/p-1

|InChIKey = JMTCDHVHZSGGJA-REWHXWOFAF

|StdInChI_Ref = {{stdinchicite|changed|chemspider}}

|StdInChI = 1S/C2H2O4.K/c3-1(4)2(5)6;/h(H,3,4)(H,5,6);/q;+1/p-1

|StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}

|StdInChIKey = JMTCDHVHZSGGJA-UHFFFAOYSA-M

}}

|C=2 | H=1 | K=1 | O=4

|Appearance=White crystalline solid

|Odor = odorless

|Density= 2.0 g/cm³

|MeltingPt=

|BoilingPt=

|Solubility= 2.5 g/100 g

|SolubleOther = slightly soluble in alcohol

}}

'''Potassium hydrogenoxalate''' is a [[salt (chemistry)|salt]] with formula KHC₂O₄ or K⁺·HO₂C-CO₂^−. It is one of the most common salts of the [[hydrogenoxalate]] anion, and can be obtained by reacting [[potassium hydroxide]] with [[oxalic acid]] in 1:1 mole ratio.

The salt is also known as: '''potassium hydrogen oxalate''', '''potassium bioxalate''', '''acid potassium oxalate''', or '''monobasic potassium oxalate'''. In older literature, it was also called: '''Salt of sorrel''',<ref name=DDN>{{cite web |url=http://dictionary.die.net/salt%20of%20sorrel |archive-url=https://web.archive.org/web/20120519132330/http://dictionary.die.net/salt%20of%20sorrel |url-status=dead |archive-date=19 May 2012 |title= Die Net Dictionary: "Salt of Sorrel" |accessdate= 19 May 2012}} (retrieved via Internet Archive)</ref> '''sorrel salt''', '''''sel d'oseille''''',<ref name=SEL>{{cite web |url=https://www.selency.nl/product/DxMFZuL/old-bottle-at-pharmacy-salt-of-sorrel.html |title= Selency: Old bottle at pharmacy—‘Salt of Sorrel}} Salt of Sorrel labelled “sel d'oseille”.</ref><ref name=SNL>{{cite web |url=https://selency.imgix.net/8bd30dba-d2c2-41bf-b186-96481fedb166/old-bottle-at-pharmacy-salt-of-sorrel_original.png?bg=FFF&fit=fill&auto=format,compress&w=579&h=475&meta_format=product_gallery_main&fm=jpg |title= Salt of Sorrel: labelled ‘sel d'oseille’}} Old dark-amber glass vial marked “sel d'oseille” with protective leaden cap.</ref> '''''sal acetosella'''''; or, ''inaccurately, '''salt of lemon''''' (due to the similar acidic ''“lemony”'' taste of the edible ''common sorrel'' or ''garden sorrel'')<ref name=TKC>{{cite web |url=https://www.thekitchn.com/its-green-fresh-and-super-tang-144842 |title= ''kitchn™'' It’s Fresh, Green, and Super Tangy: Sorrel Is In Season!}} “This fresh, “lemony” sourness has been highly prized in cuisines all over the world.”</ref>

Potassium hydrogenoxalate occurs in some plants, notably [[sorrel]]. It is a commercial product used in photography, marble grinding, and removing ink stains.

The [[anhydrous]] product is a white, odorless, crystalline solid, hygroscopic and soluble in water (2.5 g/100 g at room temperature). The solutions are basic. Below 50&nbsp;°C the much less soluble "[[potassium tetraoxalate]]" {{chem2|K(+)}}{{chem2|[C2HO4](-)}}•{{chem2|C2H2O4}} forms and precipitates out of solution.<ref name="chembook">ChemicalBook (2007) [http://www.chemicalbook.com/ChemicalProductProperty_EN_CB1199602.htm ''Potassium binoxalate Product Description'']</ref>

The mono[[hydrate]] KHC₂O₄·H₂O starts losing the water at 100&nbsp;°C.<ref>Mark Dugan (2009) [http://www.hummelcroton.com/msdspdf/kbox_m.pdf ''Potassium binoxalate'' product data sheet] Hummel Croton</ref>

The anhydrous salt was found to have remarkable [[elasticity (physics)|elastic anisotropy]], due to its [[crystal structure]] that consists of relatively rigid columns of [[hydrogen bond|hydrogen-bonded]] hydrogenoxalate anions, joined into sheets by [[ionic bond|ionic]] K–O bonds.<ref>H. Koppers (1973), 'The Elastic Constants of Monoclinic Potassium Hydrogen Oxalate'' Acta Crystallographica,volume A29, p. 415</ref>

{{Oxalates}}