In an electrophilic aromatic substitution, a hydrogen atom on the aromatic ring is substituted by a strong electrophile. Substituents on the aromatic ring affect the rate of the reaction as well as the orientation of the electrophile with respect to the existing substituents. Rates of electrophilic aromatic bromination of hydroxybenzoic acids and methoxybenzoic acids have not been studied in a systematic manner. Therefore, our research has focused on the electrophilic bromination of hydroxybenzoic acids and methoxybenzoic acids. These acids were dissolved in 15 M acetic acid and allowed to react with 0.05 M bromine in acetic acid. In each experiment, determinations were carried out in <i>quintuplicate</i> at minimum and the experiments were repeated at least three times. The rate of the reaction was determined by the disappearance of the bromine color. With 2-hydroxybenzoic acid, the bromine color disappeared in 12.64 ± 1.76 s (mean ± SD) in experiment I and in 10.90 ± 2.14 s in experiment II, whereas with 4-hydroxybenzoic acid, the bromine color disappeared 26.01 ± 1.98 s. Under similar experimental conditions, the reaction of 2-methoxybenzoic acid with bromine was slower than when hydroxybenzoic acid was used and the reaction of 4-methoxybenzoic acid with bromine was much slower than the reaction involving 2-methoxybenzoic acid.

Electrophilic aromatic bromination of hydroxybenzoic acids and methoxybenzoic acids

254th National Meeting (2017)

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