Microdetermination of aminophenols and cresols via their reactions with bromine

ABSTRACT

The oxidation of aminophenols [APs] and cresols [CRs] with bromine in aqueous solution was investigated and used for microdetermination of these reductants under selected optimum conditions of pH, temperature, catalyst, time of contact of reactants and concentration ratios. The potentiometric-argentimetric titration of the librated bromide using silver amalgam electrode was found to be independent of the bromine concentration. Possible schemes, for the course of these reactions were simply suggested. The reactions were quantitative at concentration ranges of APs, 9.80 to 22.24 mg, percent recovery 98 to 103 percent and SD = 0.11 to 0.023 at [Br[2]]/[APs] ratio 2 to 4 and CRs in the concentration range 3.24 to 25.95 mg, percent recovery = 96.6 to 104.8 percent and SD = 0.19 to 0.03 at Br[2]]/[APs] ratio 2 to 6. The reaction between Br[2] and APs was fast in the order p-AP > o-AP > m-AP and with CRs it was in the order O-CR > m-CR > P-CR under the selected optimum conditions