when iodide and iodate ions react to form elemental
iodine. The reverse of DISPROPORTIONATION.
computational chemistry A discipline using mathe-
matical methods to calculate molecular properties or to
simulate molecular behavior.
computer-assisted drug design(CADD) Involves
all computer-assisted techniques used to discover,
design, and optimize biologically active compounds
with a putative use as DRUGs.
concanavalin A A protein from jack beans, contain-
ing calcium and manganese, that agglutinates red
blood cells and stimulates T lymphocytes to undergo
mitosis.
concentration A quantitative measure of the amount
of a solute in a solution. Can be an amount of solute
per unit volume or mass of solvent or of solution.
concerted process Two or more PRIMITIVE CHANGEs
are said to be concerted (or to constitute a concerted
process) if they occur within the same ELEMENTARY
REACTION. Such changes will normally (though perhaps
not inevitably) be “energetically coupled.” (In the pres-
ent context, the term energetically coupledmeans that
the simultaneous progress of the primitive changes
involves a TRANSITION STATEof lower energy than that
for their successive occurrence.) In a concerted process,
the primitive changes may be SYNCHRONOUSor asyn-
chronous.
See also BIFUNCTIONAL CATALYSIS; POTENTIAL-
ENERGY(REACTION) SURFACE.
condensation The transformation of gas to a liquid.
condensation polymer A polymer made by conden-
sation polymerization; formed by the combination of
MONOMERs and the release of small molecules at the
point where monomers are joined.
condensation reaction A (usually stepwise) reaction
in which two or more reactants (or remote reactive
sites within the same MOLECULAR ENTITY) yield a single
main product, with accompanying formation of water
or of some other small molecule, e.g., ammonia,
ethanol, acetic acid, hydrogen sulfide.
The mechanismof many condensation reactions
has been shown to comprise consecutive ADDITION
and ELIMINATIONreactions, as in the base-catalyzed
formation of (E)-but-2-enal (crotonaldehyde) from
acetaldehyde, via 3-hydroxybutanal (aldol). The
overall reaction in this example is known as the aldol
condensation.
The term is sometimes also applied to cases where
the formation of water or another simple molecule does
not occur. Also called dehydration reaction.condensed phases The liquid and solid phases, not
gases; phases in which particles interact strongly.conduction band A partially filled or empty energy
level in which electrons are free to move. It allows the
material to conduct an electrical current when an elec-
tric field is applied by means of an applied voltage.confidence limits The results of a statistical analysis.
The lower and upper boundaries or values of a confi-
dence interval. A range of values that is estimated from
a study group that is highly likely to include the true,
although unknown, value.configuration In the context of stereochemistry, the
term is restricted to the arrangements of atoms of a
molecular entity in space that distinguishes STEREOISO-
MERs, the isomerism between which is not due to CON-
FORMATIONal differences.configuration (electronic) A distribution of the elec-
trons of an atom or a MOLECULAR ENTITYover a set of
one-electron wave functions called ORBITALs, according
to the Pauli principle. From one configuration, several
states with different multiplicities may result. For56 computational chemistry