Carbodiimide

In organic chemistry, a carbodiimide is a functional group with the formula RN=C=NR. They are exclusively synthetic. A well known carbodiimide is dicyclohexylcarbodiimide, which is used in peptide synthesis. Dialkylcarbodiimides are stable. Diaryl derivatives tend to convert to dimers and polymers upon standing at room temperature. In organic chemistry, a carbodiimide is a functional group with the formula RN=C=NR. They are exclusively synthetic. A well known carbodiimide is dicyclohexylcarbodiimide, which is used in peptide synthesis. Dialkylcarbodiimides are stable. Diaryl derivatives tend to convert to dimers and polymers upon standing at room temperature. From the perspective of bonding, carbodiimides are isoelectronic with carbon dioxide. Three principal resonance structures describe carbodiimides: Relevant to the significance of the polar resonance structures, no carbodiimide has been separated into its optical isomers. The N=C=N core is nearly linear and the C-N=C angle is approximately 120″. The C=N distances are short, near 1.20 Å, characteristic of double bonds. The molecule are chiral, possessing C2-symmetry. The parent compound, methanediimine (HN=C=NH), is a tautomer of cyanamide. A classic route to carbodiimides involves dehydrosulfurization of thioureas. A typical reagent is mercuric oxide: