Abstract
Pulse radiolysis of nitrogen saturated aqueous solutions of 4-carboxybenzophenone below pH 8 has been used to generate the 4-carboxybenzophenone ketyl radical anion to allow the direct observation of the protonation of this radical in neutral and moderately acidic solutions. A transient absorption band with λ max = 650 nm (assigned to the ketyl radical anion) was observed immediately after the pulse which was subsequently converted to an absorption band with λ max = 570 nm (assigned to the ketyl radical). The kinetics of this conversion was of pseudo-first-order with a rate constant linearly dependent on the H + concentration. These findings are interpreted in terms of a protonation of the ketyl radical anion by water (CB- · + H 2O → CBH · + OH -) and by protons (CB-· + H + → CBH ·). The respective rate constants are: 2.5 × 10 2 dm 3 mol -1 s -1 and 6.8 × 10 10 dm 3 mol -1 s -1. The rate constants for the reverse reactions are: k(CBH · + OH -) = 8.7 × 10 9 dm 3 mol -1 s -1 and k(CBH · → CB- · + H +) = 430 s -1.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.