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The ionization constants of substituted salicylic acids and the Hammett relationship
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A survey of Hammett substituent constants and resonance and field parameters
Chemical Reviews, 1991The Hammett equation (and its extended forms) has been one of the most widely used means for the study and interpretation of organic reactions and their mechanisms. Although the Hammett methodology has been criticized by theoreticians because of its empirical foundation, it is astonishing that u constants, obtained simply from the ionization of organic
R W Taft, Corwin Hänsch, A Leo
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Is the Hammett’s Constant Free of Steric Effects?
The Journal of Physical Chemistry A, 2012In this work, we have explored the validity of the hypotheses on which rest the Hammett's approach to quantify the substituent effect on a reaction center, by applying two DFT energy decomposition schemes. This is performed by studying the change in the total electronic energy, ΔΔE, associated with a proton transfer isodesmic equilibrium.
Luis, Rincón, Rafael, Almeida
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Temperature dependence of the Hammett reaction constant
Journal of the Chemical Society B: Physical Organic, 1970The temperature dependence of the Hammett reaction constant, ρ, for the hydrogen-exchange reactions of various substituted NN-dimethylanilines has been examined over the temperature range 25–96 °C. Empirical and semi-empirical evidence predicts that ρ should be a linear function of T–1, but the experimental data are equally well correlated by five ...
Thomas E. Bitterwolf +2 more
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2021
Benzoic acid ionizes into C6H5CO2− and H+ only partially in water. However, this ionization is rendered facile by electron-withdrawing substituents and more difficult by electron-rich substituents on the aromatic ring. The effect on ionization is also dependent on the position of the substituent on the ring in respect of the carboxylic acid group ...
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Benzoic acid ionizes into C6H5CO2− and H+ only partially in water. However, this ionization is rendered facile by electron-withdrawing substituents and more difficult by electron-rich substituents on the aromatic ring. The effect on ionization is also dependent on the position of the substituent on the ring in respect of the carboxylic acid group ...
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Influence of Pressure on the Hammett Reaction Constant
The Journal of Chemical Physics, 1959The probable effect of pressure on the Hammett reaction constant is predicted for heterolytic and homolytic reactions in polar and nonpolar solvents. There are insufficient data in the literature to test the conclusions reached but some previously unpublished measurements appear to be in line with one prediction.
A. J. Ellis +4 more
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Inter-Hammett: Enhancing Interpretability in Hammett‘s Constant Prediction via Extracting Rules
ChemistrySelect# Inter-Hammett: Enhancing Interpretability in Hammett’s Constant Prediction via Extracting Rules # Reference Implementation of Inter-POL algorithmThis readme file documents all of the required steps to run Inter-POL. Note that the code was implemented and tested on a Linux operating system only.
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Determination of the Hammett σ-Constants for the Picryl Group
The Journal of Organic Chemistry, 1965Abstract : By measuring the rates of reaction of meta and para-picrylbenzoic acids with diphenyldiazomethane in ethanol, the Hammett constants sigma sub meta and sigma sub para for the picryl group were found to be 0.433 and 0.413 respectively. The ordering and magnitude of these constants indicates that there is no resonance interaction of the picryl ...
Howard E. Ruskie, Lloyd A. Kaplan
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A theoretical treatment of Hammett's sigma constants
Recueil des Travaux Chimiques des Pays-Bas, 1953AbstractA theoretical treatment is given of the connection between the structure and the position of a substituent S and the value of σs, from the Hammett equation: log ks/ko = ρ · σs. The theory is based on a wave mechanical calculation of the effect of S on the localisation energy of a reaction. The equations derived make it possible to calculate σs,
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