Radiolytic reductions and oxidations in dimethyl sulfoxide solutions. Solvent effects on reactivity of halogen atom complexes
- National Institute of Standards and Technology, Gaithersburg, MD (United States)
Radiolysis of dimethyl sulfoxide (DMSO) solutions containing various additives was used to achieve clean one-electron reduction or oxidation of solutes. Pulse radiolysis of benzoquinone in DMSO solutions containing acetone and triethylamine permitted conversion of all primary radicals into reducing species. The total yield of reduction in the {gamma}-radiolysis of methyl viologen solutions was found to be 0.37 {mu}mol/J. In the pulse radiolysis of TMPD and triphenylamine in aerated DMSO containing LiCl and/or CCl{sub 4}, all the primary radicals were converted into oxidizing species and gave a maximum yield of 0.39 {mu}mol/J. In the latter systems, oxidation, was partly by halogen atom complexes. The reactivity of complexes of DMSO (DMSO-Cl DMSO-Br) and of halide ions (Br{sub 2}{sup {sm_bullet}{minus}}, I{sub 2}{sup {sm_bullet}{minus}}) was examined for several organic compounds. DMSO-Cl oxidizes chlorpromazine triphenylamine, and zinc porphyrin with rate constants of the order of 10{sup 7}-10{sup 8} M{sup {minus}1}s{sup {minus}1}, and the rates increase upon addition of CH{sub 2}Cl{sub 2} as well as upon addition of water and formamide. DMSO-Cl also reacts with olefins by addition of Cl to the double bond; the rate constants increase upon increasing the electron-donating properties of the substituents on the double bond. The rate constants for oxidation of chlorpromazine by Br{sub 2}{sup {sm_bullet}{minus}} and I{sub 2}{sup {sm_bullet}{minus}} increase by more than 2 orders of magnitude upon changing the solvent from DMSO gradually to water. The change was less with acetonitrile/water mixtures, and the difference is probably due to differences in ion solvation. 28 refs., 3 figs., 4 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 437078
- Journal Information:
- Journal of Physical Chemistry, Vol. 96, Issue 8; Other Information: PBD: 16 Apr 1992
- Country of Publication:
- United States
- Language:
- English
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