Results 101 to 110 of about 17,649 (161)

Substituent Constants of Azulene

Journal of Pharmaceutical Sciences, 1980
The ionization constants in water for six 3-substituted azuloic acids were determined spectrophotometrically. Conversion of these physical constants to their pKa values allowed a set of Hammett-type sigma values for the substituents on these acids to be calculated.
M R, Lichtenwalner, T J, Speaker
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Substituent constants for correlation analysis

Journal of Medicinal Chemistry, 1977
Constants for pi and omega ahve been measured for a miscellaneous group of aromatic substituents of interest to medicinal chemists. Swain and Lupton's gamma and kappa values have been calculated from the omego constants. Values for molar refractivity are also given for each of the substituents.
C, Hansch, S D, Rockwell, P Y, Jow, A, Leo, E E, Steller   +4 more
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The ?* constants of ionic substituents

Bulletin of the Academy of Sciences of the USSR Division of Chemical Science, 1976
1. We determined the chemical shifts in the31P NMR spectra of the compounds\((C_2 H_5 O)_2 P(O)SX (X = (CH_2 )_m \mathop S\limits^ + (CH_3 )C_2 H_5 \), (CH2)mSC2H5 (m=2–4 and 6)) and CnH2n+1 (n=6, 8), and obtained a linear correlation between δp and the σ* constants of the X substituents. 2.
Ya. L. Yarv, T. I. Pekhk, A. A. Aaviksaar, D. I. Lobanov, N. N. Godovikov   +4 more
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Hammett Substituent Constants

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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An Efficient Computational Approach for the Evaluation of Substituent Constants

The Journal of Organic Chemistry, 2006
Density functional theory computations at the B3LYP/6-311+G(2d,2p) and BPW91/6-311G(d,p) levels were carried out for a series of 15 monosubstituted benzene derivatives to study dependencies between electronic structure parameters and experimental reactivity constants.
Boris, Galabov, Sonia, Ilieva, Henry F, Schaefer   +2 more
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Reestimation of the Taft's Substituent Constant of the Pentafluorophenyl Group

The Journal of Organic Chemistry, 2004
The Taft's substituent constant of the pentafluorophenyl group (sigma(C(6)F(5))) was reestimated to be 1.50 by correlation between IR spectral data (v(C)(=)(O)) and sigma constants for a series of esters (involving the pentafluorobenzyl group) of 3-phenylpropanoic acid and butanoic acid.
Toshinobu, Korenaga, Koichi, Kadowaki, Tadashi, Ema, Takashi, Sakai   +3 more
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Electrophilic Substituent Constant σ⁺ of Electron Donor Substituents in Nonpolar Media

The Journal of Organic Chemistry, 2009
The electrophilic substituent constant sigma(+) was derived from the relative rate constants of the solvolysis of substituted alpha-cumyl chlorides in an acetone/water solvent mixture in the original work by Brown and Okamoto (J. Am. Chem. Soc. 1958, 80, 4979).
Alexander, Oehlke, Alexander A, Auer, Katja, Schreiter, Katja, Hofmann, Franziska, Riedel, Stefan, Spange   +5 more
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Correlations of coupling constants with alkyl substituent constants

Spectrochimica Acta Part A: Molecular Spectroscopy, 1986
Abstract The one-bond coupling constants ( 1 J XY ) of nine series of organometallic compounds with the part structure R-X-Y (R is an alkyl group attached directly to the metal atom X) have been correlated with two sets of alkyl substituent constants, TAFT's σ* and our σ a .
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The Hammett substituent constants and effects of medium

Collection of Czechoslovak Chemical Communications, 1986
The 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, Miroslav Ludwig, Miroslav Večeřa   +2 more
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NMR Substituent constants in alkylbenzenes

Recueil des Travaux Chimiques des Pays-Bas, 1967
AbstractThe substituent constants of alkyl groups in alkylbenzenes have been determined for dilute solutions in carbon tetrachloride. Especially for compounds with isolated substituents the constants derived satisfactorily correlate the chemical shifts of the ring protons with the substitution type.
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