Microdetermination of aminophenols and cresols via their reactions with bromine

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

Reaction kinetics of bromine and aminophenols

The kinetics of reactions of bromine and aminophenols has been studied at different temperatures. The overall order of the reactions determined from the half-life times was found to be 2.1, 2.12 and 2.4 for, 0-, m- and p-aminophenol, respectively. The thermodynamic parameters of activations were calculated and discussed. The final products of the reactions were investigated by elemental analysis, IR and mass spectra. Proposed schemes for these reactions were presented