Butylmethylimidazolium tetrachloroferrate

Three papers have reported on phase-transfer types of catalysis. The ionic liquid butylmethylimidazolium tetrachloroferrate catalyses the biphasic Sn reaction between primary and secondary alkyl halides with /3-hydrogens and the Grignard reagent p-FCePUMgBr.90 The yields ranged from 60 to 89%. 

The ionic liquid butylmethylimidazolium tetrachloroferrate (bmim-FeCU) has been found to be a very effective and completely air-stable catalyst for the biphasic Grignard cross-coupling with primary and secondary alkyl halides bearing /3-hydrogens.93 The ionic liquid catalyst has been successfully recycled four times. 

Several metal catalysts have been investigated for Michael reaction of acacH (24e) with MVK (41a) in [bmim][BF4] (bmim = butylmethylimidazolium) as solvent. Ni(acac)2 turned out to be the optimal catalyst (94% yield). With FeCl3-6H20 the yield of product 42m was limited (Scheme 8.27) [87]. It is presumed that the formation of tetrachloroferrates is a rate-limiting factor, as was observed earlier in common organic solvents or under solvent-free conditions (cf. Scheme 8.19) [88]. 

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