Design and optimization of electrochemical microreactors for continuous electrosynthesis

The study focuses on the design and construction, as well as the theoretical and experimental optimization of electrochemical filter press microreactors for the electrosynthesis of molecules with a high added value. The main characteristics of these devices are firstly a high-specific electrochemical area to increase conversion and selectivity, and secondly the shape and size of themicrochannels designed for a uniform residence time distribution of the fluid. A heat exchanger is integrated into the microstructured electrode to rapidly remove (or supply) the heat required in exo- or endothermic reactions. The microreactors designed are used to perform-specific electrosynthesis reactions such as thermodynamically unfavorable reactions (continuous NADH regeneration), or reactions with high enthalpy changes

A multi-channel microreactor dedicated to the electro-organic synthesis

International audienceno abstrac

Electrochemical Reduction of G3-Factor Endoperoxide and Its Methyl Ether: Evidence for a Competition between Concerted and Stepwise Dissociative Electron Transfer

The reduction of the bicyclic G-factor endoperoxides G3 and G3Me was studied in N,N-dimethylformamide using cyclic voltammetry and convolution analysis. Electron transfer leads to irreversible cleavage of the OO bond. Detailed analysis of the voltammetry curves reveals a non-linear dependence on the transfer coefficient indicating a mechanistic transition from a stepwise mechanism to one with more concerted character with increasing potential. By using quantum calculations to estimate the OO bond dissociation energies, the experimental data was used to evaluate the standard reduction potentials and other pertinent thermochemical information

A multi-channel microreactor dedicated to the electro-organic synthesis

International audienceno abstrac

Mechanochemical Synthesis and Biological Evaluation of Novel Isoniazid Derivatives with Potent Antitubercular Activity.

A series of isoniazid derivatives bearing a phenolic or heteroaromatic coupled frame were obtained by mechanochemical means. Their pH stability and their structural (conformer/isomer) analysis were checked. The activity of prepared derivatives against Mycobacterium tuberculosis cell growth was evaluated. Some compounds such as phenolic hydrazine 1a and almost all heteroaromatic ones, especially 2, 5 and 7, are more active than isoniazid, and their activity against some M. tuberculosis MDR clinical isolates was determined. Compounds 1a and 7 present a selectivity index >1400 evaluated on MRC5 human fibroblast cells. The mechanism of action of selected hydrazones was demonstrated to block mycolic acid synthesis due to InhA inhibition inside the mycobacterial cell

First computational evidence of a competitive stepwise and concerted mechanism for the reduction of antimalarial endoperoxides

We study structural analogues of endoperoxides belonging to the family of G factors which present moderate to good antimalarial activity. Their biological activity is related to the reduction and cleavage of the O-O bond. Generally, the O-O bond reduction of model endoperoxides, as well as artemisinin, occurs by a concerted dissociative electron transfer (ET) mechanism. For the G3 and G3Me compounds, the experimental counterpart indicates an unexpected competition between a concerted and a stepwise mechanism, but no intermediate species can be isolated. We thus perform DFT studies on the reduction of G3 and G3Me compounds. We confirm the formation of an intermediate radical anion followed by cleavage of the O-O bond in a second step. We characterize the stable conformations for the radical anions G3 •- and G3Me•- resulting from the ET and the associated reaction pathway. We also calculate the reorganization energy upon ET in relation to the Marcus theory using the DFT method. These results provide valuable insight into understanding the biological activity of G-factor endoperoxides as potential therapeutic antimalarial agents