Ultrasonic and Microwave effects on the Benzamide/Sulfuryl Chloride mediated benzoylation of Benzene derivatives under Vilsmeier-Haack conditions

Abstract

Benzamide/ Sulfuryl Chloride (SO2Cl2) reagent has been developed as a Vilsmeier- Haack(VH) reagent for benzoylation of aromatic compounds by using the conventional and ultrasonic sonication (US), and microwave (MW) conditions. Benzoylation is much more competent and faster than the analogous VH ((Benzamide/ POCl3) or (Benzamide/ SOCl2)) reagents and afforded benzoyl derivatives in good yields. Reaction times are moderately less than those observed with [Benzamide/ POCl3] and (Benzamide/ SOCl2) reagents. Reaction times are far less in microwave assisted (MWAR) reactions than ultrasonically assisted (USAS) reactions , which in turn are less than the conventional method with a decreasing trend: MWAR (seconds) << Sonication (minutes) << conventional (hrs). The highly remarkable rate accelerations in MW assisted reactions are attributed to the bulk activation of the molecules; while US assisted reactions could be accounted for cavitation effects.