A review with 25 refs. covering organic reactions proceeding in Ionic liquids, regioselective ionic solvents for complexed nickel compound catalysts used to (di, oligo, and poly)merize olefins and for a W(OAr)(2)Cl-2 (ArOH = 2,6-di- or 2,4,6-triphenylphenol) catalyst used to disproportionate olefins; the slightly coordinating [BMI](+)(PF6 or SbF6)(-)(BMI+ = 1-butyl-3-methylimidazolium) used as solvents for catalysts applied to dimerize and hydrodimerize butadiene; the solvents for Osborne's [Rh(norbornadiene)(PPh3)(2)](+)(PF6)(-) catalyst used to hydrogenate, Isomerize, and hydroformylate unsaturated compounds; the (BMICl:AlCl3 < 1) used in alkylation of aliphatics and aromatics; the [EMI]Cl-AlCl3 used in acylation of aromatics and polymerization of arenes; and also the Ionic liquids used to extract the (dissociating and non-dissociating) organic compounds like carboxylic acids (phthalic, benzoic, salicylic, etc.), halogenated arenes, aniline, benzene, and toluene from water.