An acid [A] `C_(8)H_(7)O_(2)Br` on bromination in the presence of `FeBr_(3)` gives two isomers [B] and [C] of the formula `C_(8)H_(6)O_(2)Br_(2).` Vigorous oxidation of [A], [B] and [C] gives acids [D], [E] and [F] respectively. The acid [D], `C_(7)H_(5)O_(2)Br` is the strongest acid among all the isomers whereas [E] and [F] each as molecular formula of `C_(7)H_(4)O_(2)Br_(2)`. Give structures of [A] to [F] with justification.

Explanation

(i) The acid [A] has COOH group and a Br atom. As on bromination, it gives two isomeric dibromoderivatives the two groups in the aromatic acid [A] must be at the ortho positions. The reactions involved are :