Rachid Barhdadi

Room-temperature ionic liquids as new solvents for organic electrosynthesis. The first examples of direct or nickel-catalysed electroreductive coupling involving organic halides

Direct or Ni-catalysed electroreductive homocouplings of organic halides and couplings of organic halides with activated olefins are efficiently conducted by constant current electrolyses in an undivided cell in room-temperature ionic liquids as the solvent-electrolyte media.

Electrochemical Determination of pKa of N-Bases in Ionic Liquid Media

Two electrochemical techniques have been used to measure the pK(a) of N-bases in several ionic liquids (ILs). The first method corresponds to a potentiometric titration of a strong acid with the N-base using a platinized Pt indicator electrode immersed in the IL solution and maintained under dihydrogen atmosphere via gas bubbling. The second approach involves performing cyclic voltammetry at a platinized Pt electrode in a solution containing both strong acid and the conjugate weak acid of the N-base. Values of pK(a) obtained by one or the other approach are in good agreement with each other. The experimental data clearly demonstrated that acid/base chemistry in ILs is similar to that observed in molecular nonaqueous solvents; i.e., the relative strengths of the bases were in the right order and spaced (ΔpK(a)). It was also observed that the strength of N-bases is highly dependent on the anion of the ionic liquid; this observation indicates that pH-dependent reactions could be controlled by the appropriate choice of anion for bulk ILs or as an added co-ion to bulk IL.

Electroreductive coupling of organic halides in alcoholic solvents. An example: The electrosynthesis of biaryls catalysed by nickel-2,2′ bipyridine complexes

Abstract Alcohols like methanol or ethanol are suitable solvents for achieving the electrosynthesis of biaryls from aryl halides according to a procedure which involves a catalysis by nickel-2,2′-bipyridine complexes. All electrolyses were carried out at constant current in an undivided cell fitted with an iron or duralumin sacrificial anode.

Water as Solvent for Nickel‐2,2′‐Bipyridine‐Catalysed Electrosynthesis of Biaryls from Haloaryls

Reductive homocoupling of aryl halides into biaryls was achieved by electrolysis of aqueous emulsions, either in an undivided cell fitted with a sacrificial anode, or in a divided diaphragm cell, and in the presence of nickel-2,2′-bipyridine as catalyst. Reactions were also run in a filter-press cell.

Nickel catalysed electrosynthesis of ketones from organic halides and iron pentacarbonyl. Part 2: Unsymmetrical ketones

Abstract Unsymmetrical aryl–benzyl or aryl–alkyl ketones are obtained by electrolysing in an undivided cell a DMF solution containing two organic halides, iron pentacarbonyl and a catalytic amount of a nickel-2,2′-bipyridine complex.

Catalysis by nickel-2,2′-dipyridylamine complexes of the electroreductive coupling of aromatic halides in ethanol

Abstract Nickel-2,2′-dipyridylamine complexes are efficient catalysts for achieving in pure ethanol electroreductive dimerisation of aromatic halides or arylation of activated olefins.

Aryl halides as precursors of electrogenerated bases. Utilization in coupling reactions of acetonitrile with various electrophilic compounds.

Abstract An electrochemical alternative to classical cyanomethylation is possible by using electrogenerated bases (EGBs), obtained by electroreduction of aryl halides in an undivided cell fitted with a cadmium coated cathode and a sacrificial magnesium anode. Acetonitrile is used both as solvent and as hydrogen-active compound. A coupling reaction with various electrophilic compounds was carried out. When the electrophilic compound was present from the beginning of the electrolysis, the expected coupling product with the cyanomethyl anion was obtained. If the electrophilic compound was added only after complete electrolysis of the aryl halide, dimerization of the cyanomethyl anion and a coupling reaction between the dimer anion and the electrophilic compound were observed.

Direct electroreduction or use of an electrogenerated base : two ways for the coupling of polyhalogenated compounds with aldehydes or ketones.

Abstract The electrochemical coupling of polyhalogenated compounds with carbonyl compounds is achieved in two ways. A carbanion RX n − is generated either by the direct electroreduction of RX n Cl or by deprotonation of RX n H. In this latter case the base Ph − is electrogenerated by reduction of iodobenzene. All electrolysis were carried out in an undivided cell fitted with a cadmium-coated cathode and an aluminium or magnesium sacrificial anode.