Preferred Label : Curtin–Hammett principle;
IUPAC definition : In a chemical reaction that yields one product (X) from one conformational isomer
(A') and a different product (Y) from another conformational isomer (A'') (and provided
these two isomers are rapidly interconvertible relative to the rate of product formation,
whereas the products do not undergo interconversion) the product composition is not
in direct proportion to the relative concentrations of the conformational isomers
in the substrate; it is controlled only by the difference in standard free energies
(δ Δ ‡ G) of the respective transition states. It is also true that the product composition
is formally related to the relative concentrations of the conformational isomers A'
and A'' (i.e. the conformational equilibrium constant) and the respective rate constants
of their reactions; these parameters are generally — though not invariably — unknown.
The diagram below represents the energetic situation for transformation of interconverting
isomers A and A' into products X and Y.;
Origin ID : C01480;
See also
In a chemical reaction that yields one product (X) from one conformational isomer
(A') and a different product (Y) from another conformational isomer (A'') (and provided
these two isomers are rapidly interconvertible relative to the rate of product formation,
whereas the products do not undergo interconversion) the product composition is not
in direct proportion to the relative concentrations of the conformational isomers
in the substrate; it is controlled only by the difference in standard free energies
(δ Δ ‡ G) of the respective transition states. It is also true that the product composition
is formally related to the relative concentrations of the conformational isomers A'
and A'' (i.e. the conformational equilibrium constant) and the respective rate constants
of their reactions; these parameters are generally — though not invariably — unknown.
The diagram below represents the energetic situation for transformation of interconverting
isomers A and A' into products X and Y.
