Acid dissociation constant (pKa) of some para-substituted benzohydroxamic, 4-XC6H4CONHOH, and N-methyl parasubstituted benzohydroxamic acids, 4XC6H4CON(OH)CH3, where X = H, CH3, CH3O, NO2, Cl, have been determined spectrophotometrically by nucleophilic substitution reactions of pnitrophenyl acetate with hydroxamate ions at 27± 0.1C. All reactions in this study follow pseudo-first order kinetics...

The paper is an overview of the application of the concept of linear free energy relationships (LFER), most notably through the Hammett equation, to investigations of reversible organic electrochemical reactions in aprotic solvents. In sequence the following topics are covered: the effect of solvent properties on the equilibrium, ion pairing effects, the direct application of Hammett's equation...

Chiral dirhodium(II) carboxamidates are highly efficient catalysts for reactions between a variety of aldehydes and activated dienes. Catalyst loadings as low at 0.01 mol % have been realized with enantioselectivities up to 97%. Kinetic investigations reveal a pronounced electronic influence on the rate of the hetero-Diels-Alder reaction with a Hammett rho value of +1.9 (versus sigma(+)). Inhib...

The relative rate constants for the Rh(II)-mediated diazo decomposition of a series of para- or meta-substituted diazophenylacetates were measured through intermolecular competition. The kinetic data were further subjected to Hammett correlation analysis and were found to have better linear correlation with sigma(+). Reaction constants for four Rh(II) catalysts have been obtained, Rh(2)(OAc)(4)...

-The hydrolysis of several ring substituted methyl benzoates was investigated in aqueous solution over a pH range of 3-10. Both the pH dependence (at pH > 5) and the variation of hydrolysis rates with ring substitution are consistent with a mechanism involving the addition of hydroxide ion to the ester carbonyl group. Extrapolation of the rate data to a pH and temperature that would be consiste...

Density function theory with B3LYP parameterization and 6-31++G(d,p) basis set has been used to investigate the structure and stability of many mono-substituted naphthalene molecules. The Molecular Electrostatic Surface Potential (MESP) topography for all the mono-substituted naphthalene molecules was obtained. It is shown that the nature of the substituent and its orientation in the molecule p...

A series of new 8-arylhydrazono-2-(benzylsulfanyl)-7H-purin-6-ones 6 were synthesized, their electronic absorption spectra in different organic solvents of varying polarities were investigated and their acid dissociation constants in both the ground and excited states were determined spectrophotometrically. The tautomeric structures of such products were elucidated by spectral analyses and corr...

Strain-promoted cycloadditions of cyclic nitrones with biaryl-aza-cyclooctynone (BARAC) proceed with rate constants up to 47.3 M(-1) s(-1), this corresponds to a 47-fold rate enhancement relative to reaction of BARAC with benzyl azide and a 14-fold enhancement over previously reported strain promoted alkyne-nitrone cycloadditions (SPANC). Studies of the SPANC reaction using the linear free ener...