Hydroxylation of Alkyl Halides with Water in Ionic Liquid: Significantly Enhanced Nucleophilicity of Water

A facile method for the nucleophilic hydroxylation of alkyl halides and mesylates with water has been developed in which the use of ionic liquid as an alternative reaction medium not only enhanced the nucleophilicity of water but also reduced the formation of elimination products predominantly formed under the conventional basic reaction conditions. For example, hydroxylation of model compound 2-(3-bromopropyl)naphthalene (1) to 2-(3-hydroxypropyl)-naphthalene (2) with water in 1-n-butyl-3-methylimidazolium tetrafluoroborate ([bmim] [BF ₄]) and 1,4-dioxane proceeded selectively in high yield (94%). The reactivity of other nucleophilic oxygen sources such as alcohol, phenol, and acetic acid in an ionic liquid was also investigated.