Welcome to LookChem.com Sign In|Join Free

Article Doi

Mechanism of Bleaching by Peroxides Part 1. - Kinetics of Bleaching of Phenolphthalein by Hydrogen Peroxide at High pH

DOI: 10.1039/ft9938901203

Source and publish data:

Journal of the Chemical Society - Faraday Transactions p. 1203 - 1210 (1993)

Update date:2022-08-28

Topics:

Authors:

Thompson, Katherine M.Thompson, Katherine M.

Griffith, William P.Griffith, William P.

Spiro, MichaelSpiro, Michael

Read Full Text PDF DownLoad Join now for total 90,000,000 free articles

Article abstract of DOI:10.1039/ft9938901203

The kinetics of the oxidation of phenolphthalein by alkaline hydrogen peroxide have been studied in aqueous solution over a range of pH, ionic strength and temperature.The rate of reaction was found to be first order in both phenolphthalein and hydrogen peroxide.Use of free radical and singlet oxygen trapping agents have ruled out the involvement of these species in the reaction.The variation of the rate constant with pH and ionic strength has shown that at pH >11 the main reaction is that between the pink bisphenolate form of phenolphthalein and the perhydroxyl anion, HO2(1-).At pH 9, epoxidation by the hydrogen peroxide molecule contributed most of the overall rate constant.Borate-buffered solutions gave a faster rate of reaction than those in hydrogencarbonate or ammonia buffers.Experiments over the temperature range 21.0-45.0 deg C lead to activation energies of 43.3 and 48.4 kJ mol-1 and entropies of activation of -149 and -131 J K-1 mol-1 at 298 K, in carbonate and borate buffers, respectively.A mechanism for the reaction is proposed.

View More

Products guided by the article

Product name:Hydroquinone

Cas No:123-31-9

123-31-9

R&D Labs maybe for 123-31-9

Relevant to this article

Hot Product