There are two tables for ion radicals. The first table lists reduction potentials for organic compounds that produce anion radicals during reduction, a process described as A + e- ⇌ A-·. The second table lists oxidation potentials for organic compounds that produce cation radicals during oxidation, a process described as A ⇌ A+· + e-. To obtain reduction potential for a reverse reaction, the sign for the potential is changed.
Unlike the table of the Electrochemical Series, which lists standard potentials, values for radicals are experimental values with experimental conditions given in the second column. Because the measurements leading to potentials for ion radicals are very dependent on conditions, an attempt to report standard potentials for radicals would serve no useful purpose. For the same reason, the potentials are also reported as experimental values, usually a half-wave potential (E1/2 in polarography) or a peak potential (Ep in cyclic voltammetry). Unless otherwise stated, the values are reported versus SCE (saturated calomel electrode). To obtain a value versus normal hydrogen electrode, 0.241 V has to be added to the SCE values. All the ion radicals chosen for inclusion in the tables result from electrochemically reversible reactions. More detailed data on ion radicals can be found in the Reference.
CV | cyclic voltammetry |
DMF | N,N-Dimethylformamide |
E swp | potential sweep |
E° | standard potential |
Ep | peak potential |
Ep/2 | half-peak potential |
E1/2 | half-wave potential |
M | mol/L |
MeCN | acetonitrile |
pol | polarography |
rot Pt dsk | rotated Pt disk |
SCE | saturated calomel electrode |
TBABF4 | tetrabutylammonium tetrafluoroborate |
TBAI | tetrabutylammonium iodide |
TBAP | tetrabutylammonium perchlorate |
TEABr | tetraethylammonium bromide |
TEAP | tetraethylammonium perchlorate |
THF | tetrahydrofuran |
TPACF3SO3 | tetrapropylammonium trifluoromethanesulfite |
TPAP | tetrapropylammonium perchlorate |
wr | wire |
Name | Conditions/electrode/technique | Potential V (vs. SCE) |
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Acetone | DMF, 0.1 M TEABr/Hg/pol | E1/2 = –2.84 |
1-Naphthyphenylacetylene | DMF, 0.03 M TBAI/Hg/pol | E1/2 = –1.91 |
1-Naphthalenecarboxyaldehyde | -/Hg/pol | E1/2 = –0.91 |
2-Naphthalenecarboxyaldehyde | -/Hg/pol | E1/2 = –0.96 |
2-Phenanthrenecarboxaldehyde | -/Hg/pol | E1/2 = –1.00 |
3-Phenanthrenecarboxaldehyde | -/Hg/pol | E1/2 = –0.94 |
9-Phenanthrenecarboxaldehyde | -/Hg/pol | E1/2 = –0.83 |
1-Anthracenecarboxaldehyde | -/Hg/pol | E1/2 = –0.75 |
1-Pyrenecarboxaldehyde | -/Hg/pol | E1/2 = –0.76 |
2-Pyrenecarboxaldehyde | -/Hg/pol | E1/2 = –1.00 |
Anthracene | DMF, 0.1 M TBAP/Pt dsk/CV | Ep = –2.00 |
DMF, 0.5 M TBABF4/Hg/CV | E1/2 = –1.93 | |
MeCN, 0.1 M TEAP/Hg/CV | E1/2 = –2.07 | |
DMF, 0.1 M TBAI/Hg/pol | E1/2 = –1.92 | |
9,10-Dimethylanthracene | DMF, 0.1 M TBAP/Pt/CV | Ep = –2.08 |
MeCN, 0.1 M TBAP/Pt/CV | Ep = –2.10 | |
1-Phenylanthracene | DMF, 0.5 M TBABF2/Hg/CV | E1/2 = –1.91 |
DMF, 0.1 M TBAI/Hg/pol | E1/2 = –1.878 | |
2-Phenylanthracene | DMF, 0.1 M TBAI/Hg/pol | E1/2 = –1.875 |
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