Friedel-Crafts Reactions Utilizing Ionic Liquids

摘要

Industrial Friedel-Crafts acylation and alkylation is dominated by the use of homogeneous catalysts, such as aluminum chloride (AICI3) and hydrogen fluoride (HF) (Bandini et al. 2009). In AICl3 systems, a lot of waste is produced during the hydrolysis for product isolation. Where HF is employed, restrictions originating from insufficient solubility of the substrates in the liquid acid are common limitations. Recent legislation involving the use of chlorinated solvents and possible safety issues with HF has seen a dramatic increase in the use of alternative systems. Therefore, a more efficient and practical catalytic system for Friedel-Crafts reactions is still highly desirable. Heterogeneous systems employing zeolites and solid acids have been successful in some applications; however, in some cases, their catalytic performance is poor due to diffusion limitation in the microporous network. This has opened the door for alternative solvent/catalyst systems.