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Squaramide is the 
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organic compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...
with the formula O2C4(NH2)2. Not an amide
In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a compound with the general formula , where R, R', and R″ represent organic groups or hydrogen atoms. The amide group is called a peptide bond when it is ...
in the usual sense, it is a derivative of squaric acid
Squaric acid, also called quadratic acid because its four carbon atoms approximately form a square, is a diprotic organic acid with the chemical formula C4O2(OH)2.
The conjugate base of squaric acid is the hydrogensquarate anion ; and the conjug ...
wherein two OH centers are replaced by NH2. 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
In chemistry, a hydrogen bond (or H-bond) is a primarily electrostatic force of attraction between a hydrogen (H) atom which is covalently bound to a more electronegative "donor" atom or group (Dn), and another electronegative atom bearing ...
donors in supramolecular chemistry and organocatalysis
In organic chemistry, organocatalysis is a form of catalysis in which the rate of a chemical reaction is increased by an organic catalyst. This "organocatalyst" consists of carbon, hydrogen, sulfur and other nonmetal elements found in organic com ...
. Squaramides exhibit 10-50x greater affinity for halides than do thioureas.
Squaramide is prepared by ammonolysis of diesters of squaric acid:
:O2C4(OEt)2 + 2 NH3 → O2C4(NH2)2 + 2 EtOH
''N''-Substituted squaramides are prepared similarly, using amines in place of ammonia.
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