Synthesis of Novel Gemini Dicationic Acidic Ionic Liquids and Their Catalytic Performances in the Beckmann Rearrangement

Abstract magnified image A series of novel gemini dicationic acidic ionic liquids (GDAILs), compounds 1 – 3 carrying two SO 3 H groups at the cation moieties and having anions of the type CF 3 SO ₃^ - , were synthesized in good yields ( Scheme 1 ). Some physicochemical properties of 1 – 3 were determined; due to their unique structures, these novel GDAILs showed noticeable hydrophilic properties and strong acidities ( Table 1 ). Beckmann rearrangements of oximes catalyzed by 1, 2 , or 3 /zinc chloride (GDAIL/ZnCl 2 ) were investigated ( Scheme 2 ); the corresponding amides were formed in up to 99% yield in the presence of 5 mol‐% of GDAIL/ZnCl 2 catalyst under optimized conditions ( Tables 2 and 3 ). The peculiar solubilities of 1 – 3 made the separation of the catalysts from the products very facile, and the catalytic system could be recycled and reused for three times.