Novel Acidic Ionic Liquids as Efficient and Recyclable Catalysts for the Cyclotrimerization of Aldehydes

Abstract

A mild, efficient, and ecofriendly procedure for cyclotrimerization of aldehydes was realized by using a series of novel Brønsted acidic ionic liquids (BAILs) consisting of double–SO₃H groups in cations as catalysts. Good conversion of aldehydes and selectivity of trialkyl-1,3,5-trioxanes were achieved by using 1 mol% of BAILs. In addition, the catalyst system could be recycled and reused at least eight times without apparent loss of activity.

GRAPHICAL ABSTRACT

Keywords:

• Acidic ionic liquid
• aldehydes
• cyclotrimerization
• trialkyl-1,3,5-trioxane

Notes

^a IL/isobutylaldehyde = 0.5% (molar ratio).

^a Aldehyde (30 mmol), [Bis-BsPy][CF₃SO₃]₂/aldehyde = 1% (molar ratio), reaction temperature 25 °C, reaction time 60 min.

^b [Bis-BsPy][CF₃SO₃]₂/aldehyde = 2% (molar ratio).