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) reactor. The MW applicator is a monomode waveguide fitted with power and temperature controls. The flow-through system operates at atmospheric pressure, and 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, mesitylene (3). Although the energy yield was mainly influenced by the nature of the aromatic, the temperature necessary to achieve a high yield was reached in all cases. Methoxybenzophenone (7), 4-chloroethoxybenzophenone (8), and mesityl phenyl sulfone (9) were obtained from 1-3 and the corresponding acid chloride in 85-95% yield with a 1.2 L h(-1) flow rate.