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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
Corwin. Hansch, A. Leo, R. W. Taft
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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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Hammett analysis of absolute carbene addition rate constants
Tetrahedron Letters, 1983Abstract Absolute rate constants were determined for the additions of 5 5 -X-substituted ArCCl (X=CF 3 , Cl, H, CH 3 , CH 3 O) to tetramethylethylene, trimethylethylene, trans-pentene, and 1-hexene; good Hammett correlations were obtained with ϱ = +1.4 – 1.6.
R.A. Moss +4 more
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Hammett constants of some (Trialkylsilyl)alkyl groups
Bulletin of the Academy of Sciences of the USSR Division of Chemical Science, 19611. The results confirm that in various phenylsilanes silicon can occur in the Si−(V) state on account of free 3d orbitals. 2. The specific effect of a silicon atom on β-functional groups is clearly determined by the specific character of the structure of these compounds together with the induction effects of the silyl and functional ...
E. A. Chernyshev, N. G. Tolstikova
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The Hammett substituent constants and effects of medium
Collection of Czechoslovak Chemical Communications, 1986The dissociation constants measured earlier for 35 substituted benzoic acids in seven solvents (water, methanol, ethanol, dimethylformamide, acetonitrile, sulfolane, and acetone) have been submitted to the principal components analysis and the factor analysis to produce sets of the Hammett substituent constants.
Oldřich Pytela +2 more
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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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Substituent Correlations Characterized by Hammett Constants in the Spiropyran–Merocyanine Transition
The Journal of Physical Chemistry A, 2017The modification of molecular properties by the use of substituents is a versatile route for molecular design. Here we show for the example of multiresponsive spiropyrans that substituent effects and their correlations can be accurately described by Hammett constants, which in turn can be obtained directly from density functional theory calculations ...
Oliver Brügner +3 more
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