Mild and efficient conversion of aldehydes to gem-diacetates using 2nd generation ionic liquids

Aldehydes react readily with acetic anhydride in the absence of any acid catalyst in [bmim]BF4 ionic liquid under mild and neutral conditions to afford the corresponding 1,1-diacetates (acylals) in high to quantitative yields. Aldehydes show enhanced reactivity in ionic liquids thereby reducing reaction times and improving the yields significantly. The use of ionic liquids helps to avoid either Bronsted or Lewis acid catalysts for this conversion. The recovered ionic liquid was reused for four to six times with gradual decrease in activity.