Overcoming solid handling issues in continuous flow substitution reactions through ionic liquid formation

Abstract

Substitutions such as acylations, arylations, and alkylations are some of the most commonly run reactions for building complex molecules. However, the requirement of a stoichiometric base to scavange acid by-products creates significant challenges when operating in continuous flow due to solid handling issues associated with precipitating base·HX salts. We present a general and simple strategy to overcome these solid handling issues through the use of acid scavenging organic bases that generate low- to moderate-melting ionic liquids upon protonation. The application of these bases towards the most commonly run substitutions are demonstrated, enabling reactions to be run in flow without requiring additional equipment, specific solvents, or dilute reaction conditions to prevent clogging.