Results 121 to 130 of about 2,396 (173)

A hammett correlation for the addition of organotin hydride to benzaldehydes

Journal of Organometallic Chemistry, 1972
Abstract The relative rates for tri-n-butyltin hydride additions to substituted benzaldehydes under free radical and polar conditions have been determined from competitive reactions. The relative rates have been correlated by the Hammett σ or σ+ constants. The polar addition is correlated best by σ and the free radical addition by σ+. Interpretations
Gilbert L. Grady, John R. Saucier, William J. Foley, Daniel J. O'hern, William J. Weidmann   +4 more
openaire   +1 more source

Substituent Correlations Characterized by Hammett Constants in the Spiropyran–Merocyanine Transition

The Journal of Physical Chemistry A, 2017
The 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, Thomas Reichenbach, Michael Sommer, Michael Walter   +3 more
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Ultrafast Spectroscopy of Arylchlorodiazirines: Hammett Correlations of Excited State Lifetimes

Journal of the American Chemical Society, 2009
Experimental and computational studies suggest that 375 nm excitation of arylchlorodiazirines furnishes their S(1) excited states with lengthened C-N bonds, a positive charge at the para and diazirine carbon atoms, and a negative charge at the nitrogen atoms. These structures rationalize the observed solvent and substituent effects on the excited state
Yunlong, Zhang, Lei, Wang, Robert A, Moss, Matthew S, Platz   +3 more
openaire   +2 more sources

Hammett Correlations of Electronic Absorption Spectral Parameters of Pyrimidines

Bulletin des Sociétés Chimiques Belges, 1993
AbstractThe wavenumbers of the long‐wavelength electronic absorption band maxima of substituted uracils give good linear correlations (r = 0.945 to 0.992) with the excited‐state Hammett substituent constants, σ*, in several solvents.
Cyril Párkányi, Christian Boniface, Jean‐Jacques Aaron, Mame Diabou Gaye   +3 more
openaire   +1 more source

Mechanism of photocatalytic oxidation of amino acids: Hammett correlations

Catalysis Today, 2014
Abstract Amino acids are important constituents of microorganisms and organic matter in water and may contribute to generation of nitrogenous disinfection by-products (N-DBPs) during chlorination and chloramination. The photocatalytic oxidation of amino acids has thus been carried out to seek their mineralization and to understand their interactions ...
Virender K. Sharma, Jincai Zhao, Hisao Hidaka   +2 more
openaire   +1 more source

Expanding the Hammett Correlations for the Vinylheptafulvene Ring‐Closure Reaction

European Journal of Organic Chemistry, 2017
A selection of 2,3‐diarylated photochromic dihydroazulenes (DHAs) was prepared by following two different protocols. The first protocol relies on the synthesis of a 3‐bromo‐substituted dihydroazulene, which is subjected to a Suzuki cross‐coupling reaction in the final step.
Martin Drøhse Kilde, Mia Harring Hansen, Søren Lindbæk Broman, Kurt V. Mikkelsen, Mogens Brøndsted Nielsen   +4 more
openaire   +2 more sources

Observations Concerning the Correlation of In Vitro Sulfonamide Activity with pKa and the Hammett Values

Journal of Pharmaceutical Sciences, 1967
Linear correlations of the in vitro bacteriostatic activity of sulfonamides with pKa provide little evidence in support of there being a definite pKa which a sulfonamide must possess in order to exhibit maximum activity.
A, Cammarata, R C, Allen
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Developing a Modern Approach To Account for Steric Effects in Hammett-Type Correlations

Journal of the American Chemical Society, 2016
The effects of aryl ring ortho-, meta-, and para-substitution on site selectivity and enantioselectivity were investigated in the following reactions: (1) enantioselective Pd-catalyzed redox-relay Heck reaction of arylboronic acids, (2) Pd-catalyzed β-aryl elimination of triarylmethanols, and (3) benzoylformate decarboxylase-catalyzed enantioselective ...
Celine B, Santiago, Anat, Milo, Matthew S, Sigman   +2 more
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Hammett ϱσ correlation for reactions of horseradish peroxidase compound II with phenols

Archives of Biochemistry and Biophysics, 1986
The rates of reduction of horseradish peroxidase compound II by p-methoxyphenol (4-hydroxyanisole) have been studied from pH 6.0 to 10.5. The kinetics are influenced by an acid group of pKa 8.7 on compound II. The acidic form of compound II is reactive; the basic form is not. Only the electrically neutral, unionized form of p-methoxyphenol is reactive.
H B, Dunford, A J, Adeniran
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Correlation of stability constants of metal complexes with hammett's σ-factor

Journal of Inorganic and Nuclear Chemistry, 1966
Abstract A parameter is derived on thermodynamical grounds, which measures the variations in the stability of the metal complexes formed with a series of aromatic ligands, when the basicity of these ligands is altered by changes in substituents. This parameter is shown to be a linear function of Hammett's σ-factor for the substituents, using several
J.J.R.Fraústo da Silva, J.Gonçalves Calado   +1 more
openaire   +1 more source