Kinetics, Stoichiometry and Mechanism in the Bromination of Aromatic Heterocycles. VI. Aqueous Bromination of Furan, Pyrrole and Thiophen
Australian Journal of Chemistry
32(11) 2423 - 2432
Published: 1979
Abstract
Furan is oxidized to butenedial by electrogenerated bromine in aqueous solution, while thiophen under the same conditions is converted into 2-bromo-and 2,5-dibromo-thiophen. The reaction of pyrrole appears to approach the encounter-controlled limit. For transfer of Br+ from Br2 (aq., 25ºC) to the 2(5)-positions in these systems, bimolecular rate constants, kobi/dm3 mol-1 s-1, are as follows :
furan thiophen 2-bromothiophen 108-1010 2x90 x 104 ± 5% 2 x 5.2 x 104 ± 4% 2.65 x 104 ± 2%
Reaction pathways leading to substitution, addition and oxidation are reviewed.
https://doi.org/10.1071/CH9792423
© CSIRO 1979