An account is given of some recent developments in the chemistry of solutions in highly associated strong protonic acid solvents, including sulphuric acid and oleums, fluorosuiphuric acid and hydrogen fluoride. Topics discussed include solvent—solute interactions, super-acid systems, Hammett acidity functions and polyatomic cations of the elements of Groups VI and VII.

1H and 13C NMR spectra of eleven 2-phenacylbenzoxazoles (ketimine form) show that their CDCl(3)-solutions contains also (Z)-2-(benzo[d]oxazol-2-yl)-1-phenylethenols (enolimine form). Intramolecular hydrogen bonding in the latter tautomer was found to be significantly weaker than that one in respective (Z)-2-(2-hydroxy-2-phenylvinyl)pyridines. Integrals of the 1H NMR signals were used to evaluat...

Quantitative structure activity relationship (QSAR) were developed to predict toxicity of chlorophenols by correlating LC50 values with five molecular descriptors, chosen to represent lipophilic, electronic and steric effects: the n-octanol/water partition coefficient (log K(ow)), the constant of Hammett (sigma sigma), the acid dissociation constant (pKa), the order valence molecular connectivi...

The absence of both nonproductive binding and substrate activation and also the good solubility of the substrates make the urokinase-catalysed hydrolysis of specific anilides a very suitable reaction for substrate structure-enzyme activity studies. Derivatives of alpha-N-acetyl-L-lysine anilide with high sigma minus-value substituents in the aniline ring were synthesized. Rate constants kappa-c...

The relative rate constants for the Rh(II)-catalyzed insertion of diazoacetone into the O-H bond have been measured through intermolecular competitions. The kinetic data were subjected to Hammett correlation analysis, and mechanistic implication of the results with respect to a stepwise vs a concerted O-H insertion pathway is discussed.

Divalent silver is stabilized in concentrated sulphuric acid and oleums. The formal redox potential of the Ag(II)/Ag(I) redox pair is markedly dependent on the Hammett acidity function and it reaches +2.90 V vs. NHE in 33% oleum thus rivalling E° for the F2/2F(-) redox pair (+2.87 V).

The O-alkylation of carboxylic acids with diazo compounds provides a means to esterify carboxylic acids in aqueous solution. A Hammett analysis of the reactivity of diazo compounds derived from phenylglycinamide revealed that the (p-methylphenyl)glycinamide scaffold has an especially high reaction rate and ester/alcohol product ratio and esterifies protein carboxyl groups more efficiently than ...

The copper complex Tp(CF3)2,BrCu(NCMe) efficiently catalyses the aziridination of olefins in water using PhI=NTs as nitrene source, with identical activity than that observed when dichloromethane solvent, under same experimental conditions. No specific modification catalyst or substrates are required, nor presence additional phase transfer catalyst. Competition experiments and Hammett plots sho...