Preferred Label : polar effect;
IUPAC definition : For a reactant molecule RY, the polar effect of the group R comprises all the processes
whereby a substituent may modify the electrostatic forces operating at the reaction
centre Y, relative to the standard R o Y. These forces may be governed by charge separations
arising from differences in the electronegativity of atoms (leading to the presence
of dipoles), the presence of unipoles, or electron delocalization. It is synonymous
with electronic effect or 'electrical effect' of a substituent as distinguished from
other substituent effects, e.g. steric effects. Sometimes, however, the term 'polar
effect' is taken to refer to the influence, other than steric, that non-conjugated
substituents exert on reaction rates, i.e. effects connected with electron delocalization
between a substituent and the molecular framework to which it is attached are excluded.
Polar effect is then not synonymous with electronic effect;
Origin ID : P04709;
See also
For a reactant molecule RY, the polar effect of the group R comprises all the processes
whereby a substituent may modify the electrostatic forces operating at the reaction
centre Y, relative to the standard R o Y. These forces may be governed by charge separations
arising from differences in the electronegativity of atoms (leading to the presence
of dipoles), the presence of unipoles, or electron delocalization. It is synonymous
with electronic effect or 'electrical effect' of a substituent as distinguished from
other substituent effects, e.g. steric effects. Sometimes, however, the term 'polar
effect' is taken to refer to the influence, other than steric, that non-conjugated
substituents exert on reaction rates, i.e. effects connected with electron delocalization
between a substituent and the molecular framework to which it is attached are excluded.
Polar effect is then not synonymous with electronic effect
