Studies on toluidine blue reaction with sulfite in aqueous solution and role of Cu(II) as promoter
✍ Scribed by S. B. Jonnalagadda; N. R. Gollapalli
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 188 KB
- Volume
- 31
- Category
- Article
- ISSN
- 0538-8066
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✦ Synopsis
The kinetic and mechanistic details of the reaction between toluidine blue and sulfite were studied spectrophotometrically by monitoring the depletion of toluidine blue at 633 nm. The reaction had first-order dependence on both the reactants, a stoichiometric ratio of 1:1 and a negative salt effect indicating the participation of TB ϩ and SO 3 2Ϫ ions in the ratelimiting step. The reaction products were leuco base of toluidine blue and sulfate. The reaction was pH dependent and hence studied at its optimum pH 7.2. Cu(II) acted as promoter by facilitating the formation of a ternary complex with the reactants. The protonation and stability constants of the reactants were determined and used in validating the mechanism. The activation parameters for the reactions in absence and presence of Cu(II) were determined and compared with other systems.