Brønsted acidic ionic liquid accelerated halogenation of organic compounds with N-Halosuccinimides (NXS).
The Brønsted-acidic ionic liquid 1-methyl-3-(4-sulfobutyl)imidazolium triflate [BMIM(SO(3)H)][OTf] was demonstrated to act efficiently as solvent and catalyst for the halogenation of activated organic compounds with N-halosuccinimides (NXS) under mild conditions with short reaction times. Methyl aryl ketones were converted into α-halo and α,α-dihaloketones, depending on the quantity of NXS used. Ketones with activated aromatic rings were selectively halogenated, however in some cases mixtures of α-halogenated ketone and ring-halogenated ketones were obtained. Activated aromatics were regioselectively ring halogenated to give mono- and dihalo-substituted products. The [BMIM(SO(3)H)][OTf] ionic liquid (IL-A) was successfully reused eight times in a representative monohalogenation reaction with no noticeable decrease in efficiency. An effective halogenation scale-up in this IL is also presented. The reactivity trend and the observed chemo- and regioselectiivities point to an ET process in these IL-promoted halofunctionalization reactions.
Laboratory for Organic and Bioorganic Chemistry, Jožef Stefan Institute, Jamova, Ljubljana, Slovenia.
Dejan
D
Vražič
Marjan
M
Jereb
Kenneth K
KK
Laali
Stojan
S
Stavber
D000098:Acetophenones / Q000737:chemistry; D000143:Acids; D002384:Catalysis; D054879:Halogenation; D052578:Ionic Liquids / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D013388:Succinimides / Q000737:chemistry*
D000098:Acetophenones; D000143:Acids; D052578:Ionic Liquids; D007659:Ketones; D013388:Succinimides; C038699:acetophenone