I. A. Belousova

The micellar effects in the perhydrolysis and base-catalyzed hydrolysis of 4-nitrophenyl esters of phosphoric, phosphonic, and toluenesulfonic acids in organized microheterogeneous systems based on dicationic [Gemini surfactant AlkIm⁺–(CH₂)₃–Im⁺Alk∙2Br^–, where Alk = C₁₂H₂₅ or C₁₄H₂₉ (GS)] and monocationic (AlkIm⁺CH₃∙Br^–, where Alk=C₁₂H₂₅ or C₁₄H₂₉) surfactants have been analyzed. The reagent concentrations have been found to be the main factor responsible for micellar catalysis. The hydroperoxide α-effect defined as the ratio of the second-order rate constants of perhydrolysis and base-catalyzed hydrolysis is preserved and, depending on the nature of the surfactant and the substrate, may reach ~ 100.

Design of organized microheterogeneous systems for fast disrupting (disintegration) of acylcontaining substrates (including organophosphorus compounds) is based on the use of highly reactive compounds. Reagents (catalysts) ability to provide “turnover” is of great impotence. Kinetic regularities for 4- nitrophenylacetate (PNPA) deacylation with 1-methyl-3-(2-hydroximinoethyl)-imidazolium chloride (oxime), chloral, and their mixtures were studied in water and cetyltrimethylammonium bromide (CTAB) solutions, under pH = const and [CTAB] = 10-2 M. Rate constants dependences upon nucleophile (catalyst) and detergent concentration are typical for reactions in water and micellar pseudophase. Transferring of PNPA deacylation from water into surfactant micelles leads to three orders rate enhancement. Kinetic experiments at different substrate concentrations indicate that a) first order rate constant in the chloral-CTAB system does not change up to tenfold excess of PNPA; b) first order rate constant in the oxime-CTAB system decreases for approx. 40% at PNPA excess; c) all advantages of “turnover” are achievable in the system chloral-oximeCTAB, where chloral provides first disintegration of acylated oxime with generation of highly reactive oximate-ion. Results obtained pave the way to modifying organized microheterogeneous systems, first of all, by surfactant structure changes.

Dicationic imidazolium surfactants of the 1,1′-(2-hydroxypropan-1,3-diyl)bis(3-alkyl-1H-imidazol-3-ylium)chloride series with a variable hydrophobic chain length have been synthesized and characterized. The values of their critical micelle concentration have been determined by tensiometry, conductometry and spectrophotometry. Significant antimicrobial activity of these surfactants against a number of pathogenic bacteria and fungi was revealed. It was found that decyl and dodecyl derivatives turned out to be leader compounds, which surpassed reference antibiotics in their action and showed activity against resistant strains. The kinetic parameters reflecting the high catalytic effect of the tested dicationic imidazolium surfactants in the alkaline hydrolysis of 4-nitrophenyl esters of phosphonic, phosphoric, and toluenesulfonic acids have been obtained.