Glossary

α-Carbon—The carbon adjacent to a carbonyl; in amino acids, the chiral stereocenter in all amino
acids except glycine.

α-Hydrogen—Hydrogen atoms connected to α-carbons adjacent to carbonyls.

α-State—A magnetic state seen in NMR spectroscopy in which nuclei have magnetic moments that
are aligned with an incident magnetic field, thus having lower energy.

Absolute conformation—The exact spatial arrangement of atoms or groups in a chiral molecule
around a single chiral atom, designated by (R) or (S).

Acetal—A functional group that contains a carbon atom bonded to two –OR groups, an alkyl chain,
and a hydrogen atom.

Achiral—A molecule that either does not contain a chiral center or contains chiral centers and a
plane of symmetry; as such, it has a superimposable mirror image.

Acid dissociation constant (Ka)—A measurement of the strength of an acid in solution; the higher
the Ka, the lower the pKa and the stronger the acid.

Affinity chromatography—A special type of column chromatography in which a column is
customized to bind a substance of interest.

Aldehyde—A functional group containing a carbonyl and a hydrogen (RCOH); always found at the
end of a chain.

Aldol condensation—A reaction in which an aldehyde or ketone acts as both the electrophile and
nucleophile, resulting in the formation of a carbon–carbon bond in a new molecule called an aldol.

Alkane—A simple hydrocarbon molecule with the formula CnH 2 n + 2.