{{Chembox |ImageFile = Squaramide.svg |ImageSize = 144 |IUPACName = 3,4-diaminocyclobut-3-ene-1,2-dione |Section1={{Chembox Identifiers | CASNo = 5231-89-0 | ChemSpiderID = 2061512 | EC_number = 848-257-5 | PubChem = 2781329 | UNII = 3Q8TZB9ESJ | StdInChI=1S/C4H4N2O2/c5-1-2(6)4(8)3(1)7/h5-6H2 | StdInChIKey=WUACDRFRFTWMHE-UHFFFAOYSA-N | SMILES = C1(=C(C(=O)C1=O)N)N }} |Section2={{Chembox Properties |C=4|H=4|N=2|O=2 |Appearance = white solid |MeltingPtC = 338–340 }} }} '''Squaramide''' is the organic compound with the formula O<sub>2</sub>C<sub>4</sub>(NH<sub>2</sub>)<sub>2</sub>. Not an amide in the usual sense, it is a derivative of squaric acid wherein the two OH groups are replaced by NH<sub>2</sub> groups. Squaramides refer to a large class of derivatives wherein some of the H's are replaced by organic substituents. Exploiting their rigid planar structures, these compounds are of interest as hydrogen-bond donors in supramolecular chemistry and squaramide catalysis.<ref>{{cite journal|author1=Chauhan, P. |author2=Mahajan, S. |author3=Kaya, U. |author4=Hack, D. |author5=Enders, D. |title=Bifunctional Amine-Squaramides: Powerful Hydrogen-Bonding Organocatalysts for Asymmetric Domino/Cascade Reactions|journal=Adv. Synth. Catal.|year=2015|volume=357|issue=2–3|pages=253–281|doi=10.1002/adsc.201401003}}</ref> Squaramides exhibit 10-50x greater affinity for halides than do thioureas.<ref name=Busschaert/> Squaramides also find application in medicinal chemistry, metabolomics and material science due to their ability to selectively conjugate amines<ref>{{Cite journal |last1=Lin |first1=Weifeng |last2=Yang |first2=Zhen |last3=Kaur |first3=Amanpreet |last4=Block |first4=Annika |last5=Vujasinovic |first5=Miroslav |last6=Löhr |first6=J.-Matthias |last7=Globisch |first7=Daniel |date=2021 |title=Squaric acid as a new chemoselective moiety for mass spectrometry-based metabolomics analysis of amines |url=http://xlink.rsc.org/?DOI=D1CB00132A |journal=RSC Chemical Biology |language=en |volume=2 |issue=5 |pages=1479–1483 |doi=10.1039/D1CB00132A |issn=2633-0679 |pmc=8496035 |pmid=34704052}}</ref><ref>{{Cite journal |last1=Wurm |first1=Frederik R. |last2=Klok |first2=Harm-Anton |date=2013 |title=Be squared: expanding the horizon of squaric acid-mediated conjugations |url=http://xlink.rsc.org/?DOI=c3cs60153f |journal=Chemical Society Reviews |language=en |volume=42 |issue=21 |pages=8220–8236 |doi=10.1039/c3cs60153f |pmid=23873344 |issn=0306-0012|url-access=subscription }}</ref>
Squaramide is prepared by ammonolysis of diesters of squaric acid:<ref>{{cite encyclopedia|title=Squaramide|author=Storer, R. Ian|encyclopedia=e-EROS Encyclopedia of Reagents for Organic Synthesis|year=2013|doi=10.1002/047084289X.rn01531 |isbn=978-0-471-93623-7}}</ref><ref>{{cite journal |doi=10.1039/c0cs00200c|title=Squaramides: Physical properties, synthesis and applications|year=2011|last1=Ian Storer|first1=R.|last2=Aciro|first2=Caroline|last3=Jones|first3=Lyn H.|journal=Chemical Society Reviews|volume=40|issue=5|pages=2330–2346|pmid=21399835}}</ref> :O<sub>2</sub>C<sub>4</sub>(OEt)<sub>2</sub> + 2 NH<sub>3</sub> → O<sub>2</sub>C<sub>4</sub>(NH<sub>2</sub>)<sub>2</sub> + 2 EtOH ''N''-Substituted squaramides are prepared similarly, using amines in place of ammonia.
[[File:FAXCEO.png|thumb|left|Chloride-squaramide interaction in O<sub>2</sub>C<sub>4</sub>(NH(C<sub>6</sub>H<sub>4</sub>CF<sub>3</sub>)<sub>2</sub>. The characteristic planarity of a squaramide is evident.<ref name=Busschaert>{{cite journal|title=Squaramides as Potent Transmembrane Anion Transporters|author=Nathalie Busschaert |author2=Isabelle L. Kirby |author3=Sarah Young |author4=Simon J. Coles |author5=Peter N. Horton |author6=Mark E. Light |author7=Philip A. Gale |doi=10.1002/anie.201200729|journal=Angew. Chem. Int. Ed.|year=2012|volume=51|issue=18|pages=4426–4430|pmid=22461434|s2cid=34164978 }}</ref>]]{{clear-left}}
==References== <references/>
Category:Ketones Category:Enamines Category:Cyclobutenes