1.The bromination of acetophenone and 2-acetothienone with bromine in conc. H2SO4, in the presence of silver sulfate, is directed predominantly to the aromatic ring.2.The bromination of 2-thiophenecarboxaldehyde and 2-acetothienone gives a mixture of the 4-bromo, 5-bromo, and 4,5-dibromo derivatives. Since under the employed conditions the 4-bromo derivatives are brominated approximately one order of magnitude faster than the 5-isomers, it is possible to assume that the bromination of the unsubstituted carbonyl compounds is directed predominantly to the 4 position of the thiophene ring.