Configuration—The spatial arrangement of the atoms or groups in a molecule.
Configurational isomers—Isomers that can only interconvert by breaking bonds; include
enantiomers, diastereomers, and cis–trans isomers.
Conformational isomers—Isomers that are the same molecule, just at different points in their
natural rotation about a σ bond.
Conjugation—Alternating single and multiple bonds that create a system of parallel unhybridized p-
orbitals; thus, electrons can be shared between these orbitals, forming electron clouds above and
below the plane of the molecule and stabilizing the molecule.
Constitutional isomers—Molecules that have the same molecular formulas but different
connectivity; also called structural isomers.
Coordinate covalent bond—A covalent bond in which both electrons in the bond come from the
same starting atom.
Coupling—In NMR spectroscopy, a phenomenon that occurs when there are protons in such close
proximity to each other that their magnetic moments affect each other’s appearance in the NMR
spectrum by subdividing the peak into subpeaks; also called splitting.
Coupling constant (J)—The magnitude of splitting in NMR spectroscopy, measured in hertz.
Covalent—One of two types of chemical bonds in which electrons are shared between atoms.
Cyanohydrin—A functional group containing a nitrile (–C≡N) and a hydroxyl group.
d-orbital—An atomic orbital that is composed of four symmetrical lobes and contains two nodes.
Decarboxylation—The complete loss of a carboxyl group as carbon dioxide.
Deprotection—Reversion of a protecting group to its original functional group.
Deprotonation—The removal of a hydrogen cation (H+) from a molecule.