[Quantitative determination of phenols by bromination surveyed from an unusual perspective]

The substitution reaction of phenols and bromine yields, beside brominated phenols, hydrogen bromide as well. In the course of the quantitative potentiometric analysis of the latter we may obtain quantitative and structural information with regard to the investigated phenol compound in one step. Such information may include data regarding substitution of the aromatic ring, the detectability of a resorcine-skeleton or phenol-carboxylic acid moiety, etc. With the help of the titration curve, sometimes one can detect two subsequent reaction steps or two simultaneously existing materials on the basis of the measured hydrogen bromide/brominated phenol ratio. We demonstrate here how and old technique can be used to solve analytical problems with new perspective, as exemplified by the cases of phenol, resorcine, 8-oxy-quinoline and salicylic acid.