Electron scavenging in ethanol and in water
| Autor: | Dusan Razem, William H. Hamill |
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| Rok vydání: | 1977 |
| Předmět: | |
| Zdroj: | The Journal of Physical Chemistry. 81:1625-1631 |
| ISSN: | 1541-5740 0022-3654 |
| DOI: | 10.1021/j100532a005 |
| Popis: | Rate constants for scavenging solvated electrons, e/sup -//sub s/, mostly in the range k/sub e-/sub s/ less than 10/sup 8/ M/sup -1/ s/sup -1/, have been measured in ethanol and, as needed for comparison, in water. There is a tendency for k/sub e/sup -//sub s/ to equal k/sub e/sup -//sub aq/ over a 10/sup 3/-fold range, but there are instances where k/sub e-/sub s/ is much greater. Inefficient scavengers for e/sup -//sub s/ provide relatively efficient traps for dry electrons e/sup -/ with 37 percent survival often at C/sub 37/ approximately equal to 1 M scavenger but also as low as approximately 0.2 M. The outstanding exceptions are olefins for which k/sub e/sup -//sub s/ less than or equal to 10/sup 7/ M/sup -1/ s/sup -1/, but they do not measurably react with e/sup -/. Negative ion resonances for alkenes as large as 2.2 eV have been reported and neither e/sup -/ nor e/sub s//sup -/ is expected to react. It is proposed that e/sub s//sup -/ is C/sub 2/H/sub 5/OH/sup -/ and e/sub aq//sup -/ is H/sub 2/O/sup -/. The radical anions may transfer either e/sup -/ or H to appropriate acceptors, the latter accounting for possible reaction ofmore » e/sub s//sup -/ with olefins and alkenols. The reaction e/sub aq//sup -/ + e/sub aq//sup -/ = H/sub 2/ is explained in terms of H/sub 2/O/sup -/. Whenever e/sup -/ and e/sub s//sup -/ produce a common electron adduct S/sup -/, and an equilibrium e/sub s//sup -/ + S reversible S/sup -/ is approximated, then C/sub 37//sup -1/ is proportional to k/sub e/sup -//sub s/. This is Hunt's relation, k/sub e/sup -//sub s/C/sub 37/ = Q, with Q = 1.2 x 10/sup 9/ s/sup -1/ in ethanol.« less |
| Databáze: | OpenAIRE |
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