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The Curtin–Hammett principle is a principle in chemical kinetics proposed by David Yarrow Curtin and Louis Plack Hammett.It states that, for a reaction that has a pair of reactive intermediates or reactants that interconvert rapidly (as is usually the case for conformational isomers), each going irreversibly to a different product, the product ratio will depend both on the difference in ...
The Curtin–Hammett principle bears his name. The awards he obtained included the Priestley Medal in 1961, the Willard Gibbs Award in 1961, [1] the National Medal of Science in 1967, and in 1975 the Barnard Medal for Meritorious Service to Science. Hammett grew up in Portland, Maine, and studied in Harvard and
The Chugaev elimination is a chemical reaction that involves the elimination of water from alcohols to produce alkenes.The intermediate is a xanthate.It is named for its discoverer, the Russian chemist Lev Aleksandrovich Chugaev (1873–1922), who first reported the reaction sequence in 1899.
Reaction rates are highly dependent on the conformation of the reactants. In many cases the dominant product arises from the reaction of the less prevalent conformer, by virtue of the Curtin-Hammett principle. This is typical for situations where the conformational equilibration is much faster than reaction to form the product.
Hammett defined the equation based on two parameters: the reaction constant (ρ) and the substituent parameter (σ). When other reactions were studied using these parameters, a correlation was not always found due to the specific derivation of these parameters from the dissociation equilibrium of substituted benzoic acids and the original ...
Hammond's postulate also helps to explain and rationalize the Bell–Evans–Polanyi principle. Namely, this principle describes the experimental observation that the rate of a reaction, and therefore its activation energy, is affected by the enthalpy of that reaction. Hammond's postulate explains this observation by describing how varying the ...
In the Hooker reaction (1936) an alkyl chain in a certain naphthoquinone (phenomenon first observed in the compound lapachol) is reduced by one methylene unit as carbon dioxide in each potassium permanganate oxidation.
The mechanism requires zinc and acetic acid as catalysts. It will proceed at room temperature. Because α-aminoketones self-condense very easily, they must be prepared in situ.