Access to New Endoperoxide Derivatives by Electrochemical Oxidation of Substituted 3‐Azabicyclo[4.1.0]hept‐4‐enes

A series of substituted 3‐azabicyclo[4.1.0]hept‐4‐ene derivatives were prepared and analysed by cyclic voltammetry. Preparative aerobic electrochemical oxidation reactions were then carried out. Three original endoperoxides were isolated, characterised and subjected to antimalarial and cytotoxicity activity assays.     

General Properties of the Nernst-Planck-Poisson-Boltzmann System Describing Electrocapillary Effects in Porous Media

The Nernst-Planck-Poisson-Boltzmann system describes the evolution of ionic concentrations and electrocapillarity effects in porous media. The aim of this paper is a theoretical study of various drift-diffusion modellings. The well-posedness of the systems is proved and some qualitative properties of the global solution are shown to be satisfied (energy law, entropy law in the weak sense of Lyapunov functions, stationary states, Maxwellian distribution, influence of an external electric field). Moreover, some explicit solutions are established in the one-dimensional case.     

Experimental and numerical study of shock wave propagation in water generated by pulsed arc electrohydraulic discharges

The objective of this study is to simulate the propagation of the shock wave in water due to an explosion. The study is part of a global research program on the development of an alternative stimulation technique to conventional hydraulic fracturing in tight gas reservoirs aimed at inducing a distributed state of microcracking of rocks instead of localized fracture. We consider the possibility of increasing the permeability of rocks with dynamic blasts. The blast is a shock wave generated in water by pulsed arc electrohydraulic discharges. The amplitude of these shock waves is prescribed by the electrohydraulic discharges which generate high pressures of several kilobars within microseconds. A simplified method has been used to simulate the injected electrical energy as augmentation of enthalpy in water locally. The finite element code EUROPLEXUS is used to perform fluid fast dynamic computation. The predicted pressure is consistent with the experimental results. In addition, shock wave propagation characteristics predicted with simulation can be valuable reference for design of underwater structural elements and engineering of underwater explosion.     

Progress in Understanding Low‐Temperature Organic Compound Oxidation Using a Jet‐Stirred Reactor

The jet‐stirred reactor (JSR) has become a tool frequently used to study the oxidation of a wide range of reactants and particularly to obtain data for testing detailed kinetic models. This paper aims to discuss recent knowledge pertaining to low‐temperature oxidation of hydrocarbons and oxygenated reactants that has been gained from using a JSR in connection with gas chromatography, especially for the detailed quantification of cyclic ethers. Furthermore, JSR in conjunction with mass spectrometry has been applied to the detection of hydroperoxides, including ketohydroperoxides, acids, and compounds with two carbonyl functions. Finally, along with optical diagnostics, JSR has notably been used for the detection of hydrogen peroxide and OH and HO₂ radicals. These aspects are also discussed here.     

A Cucurbit[8]uril 2:2 Complex with a Negative pKa Shift

A viologen derivative carrying a benzimidazole group ( V-P-I ²⁺; viologen–phenylene–imidazole V-P-I ) can be dimerized in water using cucurbit[8]uril (CB[8]) in the form of a 2:2 complex resulting in a negative shift of the guest pK_a, by more than 1 pH unit, contrasting with the positive pK_a shift usually observed for CB-based complexes. Whereas 2:2 complex protonation is unclear by NMR, silver cations have been used for probing the accessibility of the imidazole groups of the 2:2 complexes. The protonation capacity of the buried imidazole groups is reduced, suggesting that CB[8] could trigger proton release upon 2:2 complex formation. The addition of CB[8] to a solution containing V-P- I ³⁺ indeed released protons as monitored by pH-metry and visualized by a coloured indicator. This property was used to induce a host/guest swapping, accompanied by a proton transfer, between V-P-I ³⁺ ⋅ CB[7] and a CB[8] complex of 1-methyl-4-(4-pyridyl)pyridinium. The origin of this negative pK_a shift is proposed to stand in an ideal charge state, and in the position of the two pH-responsive fragments inside the two CB[8] which, alike residues engulfed in proteins, favour the deprotonated form of the guest molecules. Such proton release triggered by a recognition event is reminiscent of several biological processes and may open new avenues toward bioinspired enzyme mimics catalyzing proton transfer or chemical reactions.