?The compound \(\alpha \text {-tocopherol }\), a form of vitamin E, is a powerful

Chapter 18, Problem P18B.4

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The compound \(\alpha \text {-tocopherol }\), a form of vitamin E, is a powerful antioxidant that may help to maintain the integrity of biological membranes. R.H. Bisby and A.W. Parker (J. Amer. Chem. Soc. 117, 5664 (1995)) studied the reaction of photochemically excited duroquinone with the antioxidant in ethanol. Once the duroquinone was photochemically excited, a bimolecular reaction took place at diffusion-limited rate. (a) Estimate the rate constant for a diffusion-limited reaction in ethanol. (b) The reported rate constant was \(2.77 \times 10^{9} \mathrm{\ dm}^{3} \mathrm{\ mol}^{-1} \mathrm{\ s}^{-1}\) . Estimate the critical reaction distance if the sum of diffusion coefficients is \(1 \times 10^{-9} \mathrm{\ m}^{2} \mathrm{\ s}^{-1}\) .

Text Transcription:

alpha-tocopherol

2.77 times 10^9 dm^3 mol^-1 s^-1

1 times 10^-9 m^2 s^-1