Vilsmeier–Haack Bromination of Aromatic Compounds with KBr and N-Bromosuccinimide Under Solvent-Free Conditions

Abstract

Bromination of aromatic hydrocarbons is triggered by Vilsmeier–Haack reagent [N,N-dimethyl formamide (DMF–POCl₃ system)] in the presence of KBr or N-bromosuccinimide (NBS) under solvent-free conditions by grinding the reactants in a mortar with a pestle. The reactions afforded corresponding bromo derivatives in very good yield with high regioselectivity. The results are comparable with those obtained under reflux conditions.

Keywords:

• Bromination
• KBr
• N-bromosuccinimide
• solvent-free conditions
• Vilsmeier–Haack reagent

ACKNOWLEDGMENTS

The authors thank Prof. T. Navaneeth Rao (former vice-chancellor, Osmania University, Hyderabad) and the Management Committee of Siddhartha P. G. College, Hyderabad, for constant encouragement. The authors thank the council of scientific and Industrial research (CSIR), New Delhi, for financial assistance in the form of an emeritus scientist appointment accorded to Prof. P. K. Saiprakash.

Notes

Note. VHR = DMF + POCl₃; temp. = 313 K.