Kinetics of the reduction of nitroxyl radicals by hydrazo compounds in a nematic liquid crystal

Kinetics of alkaline hydrolysis of esters of phosphorus acids in micellar and hexagonal phases in the cetyldimethylethylammonium bromide—NaOH—water system

“…The activation parameters in the hexagonal mesophase at CCDA8 = 0.6 mol L -l have the following effective values: E a = 152 kJ mol -L, logA = 25, AH = 149 kJ mol -I, and AS ~ = -225 Id mol -t. Their unusually high values are probably caused by the superposition of several factors: the contribution of the reaction itself, the contribution of solubilization of the substrate, and the change in the parameters of the liquid-crystalline structure with change in temperature. 3 A smooth decrease in kob s is observed for all substrates during the phase transition Mi--~E, i.e., as the degree of ordering increases and anisotropy appears in the reaction medium (see Fig. 2--4).…”

“…As shown above, these substrates are adsorbed on the surface of supramolecular associates of spherical micelles; the[efore, a decrease in the reactivity of the substrates is caused most likely by a decrease in the diffusion mobility of substrates 2 and 3 rather than by a change in the polarity of the microenviroument of the substrates during the formation of the E-phase. 3 The P3 values fi~dicatc an approximately twofold iw~crease in alkaliue hydrolysis of substrates 2 at~d 3 iI~ the E-phase as compared to the aqueous phase, which can be explained as follows. As known, substrates fall in an aqueous layer between the cylinders in the E-phase and are oriented in a certain way under the action of the anisotropic potential of intermolecular interactions) When the orientation of the reagents is favorable, they can approach each other, and their reactivity increases as compared to the isotropic solutions.…”