The rate of substitution at one specific site in an
aromatic compound relative to the rate of substitution at one position in benzene. For example,
the partial rate factor
for
para-substitution in a monosubstituted benzene
C6H5Z is related to the rate constants
and
for the total reaction (i.e. at all positions) of
C6H5Z
and benzene, respectively, and %
para (the percentage
para-substitution in the total product formed from
C6H5Z) by the relation:
Similarly for
meta-substitution:
(The symbols
,
,
are also in use.) The term applies equally to the
ipso position, and it can be extended to other substituted substrates undergoing
parallel reactions at different sites with the same
reagent according to the same
rate law.
Source:
PAC, 1994, 66, 1077
(Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994))
on page 1149
Cite as:
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by
A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997).
XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic,
J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8.
https://doi.org/10.1351/goldbook.
