ESR studies on the formation of p-benzosemiquinone anions over manganese dioxide
✍ Scribed by Shun-Ichi Fukuzumi; Yoshio Ono; Tominaga Keii
- Publisher
- John Wiley and Sons
- Year
- 1975
- Tongue
- English
- Weight
- 404 KB
- Volume
- 7
- Category
- Article
- ISSN
- 0538-8066
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✦ Synopsis
The reaction between a hydroquinone aqueous solution and manganese dioxide has been investigated by electron paramagnetic resonance spectroscopy. A very stable pbenzosemiquinone anion is formed when an aqueous solution of hydroquinone is passed through a column of manganese dioxide. The kinetics for the reaction between hydroquinone and manganese dioxide follow the equation where A. is the initial concentration of hydroquinone, C is the concentration of p-benzosemiquinone anions, Wis the amount of manganese dioxide, F is the feed rate of a hydroquinone aqueous solution, and kin and kzo are constants; kI0 = 3.1 X (cm3/g MnOemin), kzo = 3.2 (cm3/g MnO2.min).
A mechanism for the reaction is proposed such that Mn(1V) in manganese dioxide is reduced to Mn(I1) with hydroquinone from which the semiquinone anion is formed via a neutral semiquinone. The formation of semiquinone anions from several substituted hydroquinones is also discussed.