Goldbook title
IUPAC > Gold Book > alphabetical index > L > linear free-energy relation
Gold G Icon
Indexes Download
PREVIOUS L03551 NEXT
linear energy transfer linear macromolecule

linear free-energy relation

Also contains definition of: linear Gibbs energy relation

A linear correlation between the logarithm of a rate constant or equilibrium constant for one series of reactions and the logarithm of the rate constant or equilibrium constant for a related series of reactions. Typical examples of such relations (also known as linear Gibbs energy relations) are the Brønsted relation, and the Hammett equation (See also: σ-constant).
The name arises because the logarithm of an equilibrium constant (at constant temperature and pressure) is proportional to a standard free energy (Gibbs energy) change, and the logarithm of a rate constant is a linear function of the free energy (Gibbs energy) of activation.
It has been suggested that this name should be replaced by linear Gibbs energy relation, but at present there is little sign of acceptance of this change.
The area of physical organic chemistry which deals with such relations is commonly referred to as 'Linear Free-Energy Relationships'.
Source:
PAC, 1994, 66, 1077 (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1136
Interactive Link Maps
First Level Second Level Third Level
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.
Last update: 2014-02-24; version: 2.3.3.
DOI of this term: https://doi.org/10.1351/goldbook.L03551.
Original PDF version: http://www.iupac.org/goldbook/L03551.pdf. The PDF version is out of date and is provided for reference purposes only. For some entries, the PDF version may be unavailable.
Current PDF version | Version for print | History of this term
picture