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:
“That we can come here today and in the presence of thousands and tens of thousands of the survivors of the gallant army of Northern Virginia and their descendants, establish such an enduring monument by their hospitable welcome and acclaim, is conclusive proof of the uniting of the sections, and a universal confession that all that was done was well done, that the battle had to be fought, that the sections had to be tried, but that in the end, the result has inured to the common benefit of all.”
—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)