The Taft equation is a linear free energy relationship (LFER) used in physical organic chemistry in the study of reaction mechanisms and in the development of quantitative structure activity relationships for organic compounds. It was developed by Robert W. Taft in 1952 as a modification to the Hammett equation. While the Hammett equation accounts for how field, inductive, and resonance effects influence reaction rates, the Taft equation also describes the steric effects of a substituent. The Taft equation is written as:
where log(ks/kCH3) is the ratio of the rate of the substituted reaction compared to the reference reaction, σ* is the polar substituent constant that describes the field and inductive effects of the substituent, Es is the steric substituent constant, ρ* is the sensitivity factor for the reaction to polar effects, and δ is the sensitivity factor for the reaction to steric effects.
Read more about Taft Equation: Polar Substituent Constants, σ*, Steric Substituent Constants, Es, Taft Plots in QSAR
Famous quotes containing the words taft and/or equation:
“The diplomacy of the present administration has sought to respond to the modern idea of commercial intercourse. This policy has been characterized as substituting dollars for bullets.”
—William Howard Taft (1857–1930)
“A nation fights well in proportion to the amount of men and materials it has. And the other equation is that the individual soldier in that army is a more effective soldier the poorer his standard of living has been in the past.”
—Norman Mailer (b. 1923)