Ultrasonic and Microwave Effects on the Benzamide/Sulfuryl Chloride Mediated Benzoylation of Benzene Derivatives under VilsmeierHaack Conditions

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) lt; lt; Sonication (minutes) lt; lt; 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.