The rates and mechanism of zinc chloride (Lewis acid) catalysed oxidation of several organic sulfoxides by permanganate have been studied in anhydrous acetone solutions. The kinetic rate law obtained indicates that a complex between permanganate and the Lewis acid (ZnCl2) is formed before oxidation of the sulfoxides occurs. The function of the zinc chloride is to enhance the reactivity of perma...

A 1H NMR study of urocanic acid dissolved in water/dimethyl sulfoxide mixtures together with potentiometric determinations of its two successive acidities in the same solutions reveal that a proton is transferred from the imidazolium ring to the carboxylate group when the amount of dimethyl sulfoxide is increased. An analysis of the potentiometric data by means of the classical Hammett linear r...

We present an application of the recently introduced Localized Pair Model (LPM) [Z. A. Zielinksi and J. K. Pearson, Comput. Theor. Chem., 2013, 1003, 7990] to characterize and quantify properties of the chemical bond in a series of substituted benzoic acid molecules. By computing interelectronic distribution functions for doubly-occupied Edmiston-Ruedenberg localized molecular orbitals (LMOs), ...

This paper describes the synthesis of a series of Pd(IV) complexes of general structure (N~C)(2)Pd(IV)(O(2)CR)(2) (N~C = a rigid cyclometalated ligand; O(2)CR = carboxylate) by reaction of (N~C)(2)Pd(II) with PhI(O(2)CR)(2). The majority of these complexes undergo clean C-O bond-forming reductive elimination, and the mechanism of this process has been investigated. A variety of experiments, inc...

The protonation equilibria of four substituted N-methylbenzenesulfonamides, X-MBS: X = 4-MeO (3a), 4-Me (3b), 4-Cl (3c) and 4-NO(2) (3d), in aqueous sulfuric acid were studied at 25 °C by UV-vis spectroscopy. As expected, the values for the acidity constants are highly dependent on the electron-donor character of the substituent (the pK(BH+) values are -3.5 ± 0.2, -4.2 ± 0.2, -5.2 ± 0.3 and -6....

The Raman intensity versus electrode voltage behavior of a series of substituted pyridines and saturated nitrogen heterocycUc compounds was studied at two laser excitation energies. The voltage (resonance) maximum shifts to more positive potential with increasing excitation energy for the substituted pyridines (case I) and to more negative potential with increasing excitation energy for the sat...

Over 60 lignin-related model compounds were phosphitylated with 2chloro-4,4,5,5-tetramethyldioxaphospholane, a sterically hindered analogue of 2-chloro-1,3,2-dioxaphospholane used in earlier work, and their 31P chemical shifts were recorded. Excellent resolution between the chemical shifts of phosphitylated carboxylic acids, phenols and aliphatic alcohols was obtained. The correlations of the p...

The kinetics of reduction of cytochrome c by catechol(s), quinol(s) and related compounds were investigated by stopped-flow spectrophotometry. Studies on the influence of pH on the rates indicate that only deprotonated forms of these compounds act as reducing agents, with the dianionic forms being the most effective. The pH-independent second-order rate constants are reported. Hammett treatment...

In recent years many efforts have been made aiming to define the conditions of the reaction of substitution which lead to inversion of configuration (Walden inversion). The investigations in this direction of Polanyi et al.,’ of Olson,2 of Hughes, Ingold, et aL3 are most outstanding. Polanyi et al. and Olson came to the conclusion that all reactions of substitution by a negative group or ion ar...

A series of beta-(N-tosyl)amino diazo carbonyl compounds have been prepared by nucleophilic condensation of N-tosylimines with acyldiazomethanes. The diazo decomposition of these diazo carbonyl compounds under various catalytic conditions, including Rh(II) carboxylates, Cu(I) and Cu(II) complexes, PhCO(2)Ag/Et(3)N, TsOH, and SnCl(2).2H(2)O, has been investigated. It was found that, in most case...