Squaramide
Names
IUPAC name
3,4-diaminocyclobut-3-ene-1,2-dione
Identifiers
3D model (JSmol)
  • InChI=1S/C4H4N2O2/c5-1-2(6)4(8)3(1)7/h5-6H2
    Key: WUACDRFRFTWMHE-UHFFFAOYSA-N
  • C1(=C(C(=O)C1=O)N)N
Properties
C4H4N2O2
Molar mass 112.088 g·mol−1
Appearance white solid
Melting point 338–340 °C (640–644 °F; 611–613 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Squaramide is the organic compound with the formula O2C4(NH2)2. Not an amide in the usual sense, it is a derivative of squaric acid wherein the two OH groups are replaced by NH2 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 organocatalysis.[1] Squaramides exhibit 10-50x greater affinity for halides than do thioureas.[2]

Squaramide is prepared by ammonolysis of diesters of squaric acid:[3][4]

O2C4(OEt)2 + 2 NH3 → O2C4(NH2)2 + 2 EtOH

N-Substituted squaramides are prepared similarly, using amines in place of ammonia.

Chloride-squaramide interaction in O2C4(NH(C6H4CF3)2. The characteristic planarity of a squaramide is evident.[2]

References

  1. ↑ Chauhan, P.; Mahajan, S.; Kaya, U.; Hack, D.; Enders, D. (2015). "Bifunctional Amine-Squaramides: Powerful Hydrogen-Bonding Organocatalysts for Asymmetric Domino/Cascade Reactions". Adv. Synth. Catal. 357 (2–3): 253–281. doi:10.1002/adsc.201401003.
  2. 1 2 Nathalie Busschaert; Isabelle L. Kirby; Sarah Young; Simon J. Coles; Peter N. Horton; Mark E. Light; Philip A. Gale (2012). "Squaramides as Potent Transmembrane Anion Transporters". Angew. Chem. Int. Ed. 51 (18): 4426–4430. doi:10.1002/anie.201200729. PMID 22461434. S2CID 34164978.
  3. ↑ Storer, R. Ian (2013). "Squaramide". e-EROS Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rn01531. ISBN 978-0-471-93623-7.
  4. ↑ Ian Storer, R.; Aciro, Caroline; Jones, Lyn H. (2011). "Squaramides: Physical properties, synthesis and applications". Chemical Society Reviews. 40 (5): 2330–2346. doi:10.1039/c0cs00200c. PMID 21399835.
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