A New Recyclable Ditribromide Reagent for Efficient Bromination under Solvent Free Condition

1,2-Dipyridiniumditribromide−ethane (DPTBE) has been synthesized and explored as a new
efficient brominating agent. The crystalline ditribromide reagent is stable for months and acts as
a safe source of bromine requiring just 0.5 equiv for complete bromination. It has high active bromine
content per molecule and shows a remarkable reactivity compared to other tribromide reagents
toward various substrates by just grinding the reagent and substrates in a porcelain mortar at
room temperature. No organic solvent has been used during any stage of the reaction for substrates
giving product as solid. Product can easily be isolated by just washing the highly water soluble
1,2-dipyridiniumdibromide−ethane (DPDBE) from the brominated product. The spent reagent can
be recovered, regenerated, and reused without any significant loss.