Acylation and related reactions under microwaves. 5. Development to large laboratory scale with a continuous-flow process

Iron(III) chloride-catalyzed Friedel-Crafts acylation and sulfonylation of aromatics have been carried out using a continuous-flow microwave (MW) reac tor. The MW applicator is a monomode waveguide fitted with power and temper ature controls. The flow-through system operates at atmospheric pressure, a nd homogeneous conditions were ensured by using an excess of the aromatic. Factors that influence the reaction yield (MW power, ratio and flow rate of reactants) were optimized for two different types of substrate, two polar aromatic ethers, anisole (1) and phenetole (2), and a nonpolar arene, mesit ylene (3). Although the energy yield was mainly influenced by the nature of the aromatic, the temperature necessary to achieve a high yield was reache d in all cases. Methoxybenzophenone (7), 4-chloroethoxybenzophenone (8), an d mesityl phenyl sulfone (9) were obtained from 1-3 and the corresponding a cid chloride in 85-95% yield with a 1.2 L h(-1) flow rate.