An efficient and green pathway for continuous Friedel-Crafts acylation over α-Fe2O3 and CaCO3 nanoparticles prepared in the microreactors

α-Fe2O3 nanoparticles were prepared by using a continuous precipitation method with a valve assisted micromixer in the presence of iron (III) sulfate and ammonia water. The resulting nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM). Meanwhile, CaCO3 nanoparticles were synthesized in a tube-in-tube flow reactor AF-2400. The acylation process catalyzed by modified lipophilic α-Fe2O3 and CaCO3 nanoparticles in the flow reactor were systematically investigated. Under the optimal conditions, a yield of 97.8% was obtained. Addition of CaCO3 nanoparticles resulted in higher catalytic efficiency compared with pure modified α-Fe2O3 nanoparticles. Moreover, this novel acylation also worked well for other substrates.