# Redox properties of methyl radical

The methyl radical, $\ce{.CH3}$, is a strong oxidant and a strong reductant according to Wikipedia.

Why is this so? Any additional reasons to the ones below?

I know that an oxidant itself is reduced; an oxidant helps something else lose electrons, so the oxidant must be the one gaining electrons. Given that the methyl radical has an unpaired electron, it is quite reasonable that it would be amenable to having an extra electron to pair up with its lone electron.

I know that a reductant itself is oxidized; a reductant helps something else gain electrons. The carbon in the methyl radical has an oxidation state of -3, and I know that carbon can adopt a variety of higher oxidation states, such as +3 in acetic acid.

## 1 Answer

Why is this so?

Is this so?

Following is a tabulation of the ionization potentials (IP) and electron affinities (EA) for some alkali metals and halogens (kJ/mol):

\begin{array}{|c|c|c|c|c|c|c|}\hline & IP & EA & && IP & EA \\ \hline F & 1681 & 331 && Li & 520 & 60 \\ \hline Cl & 1251 & 352 && Na & 496 & 53 \\ \hline Br & 1140 & 328 && K & 419 & 49 \\ \hline I & 1008 & 298 && Rb & 403 & 47 \\ \hline \end{array}

A good reducing agent readily donates electrons and would be expected to have a low IP. Sodium would be expected to act as a good reducing agent and chlorine as a poor one, and, indeed the IP of sodium is much lower than that of chlorine.

A good oxidizing agent readily accepts electrons and would be expected to have a large EA. Chlorine would be expected to act as a good oxidizing agent and sodium as a poor one, and, indeed, the EA of chlorine is much higher than that of chlorine.

This NIST webpage tabulates experimental IP's and EA's for the methyl radical. The IP is given as (9.84 eV) 945 kJ/mol and the EA appears to be less than (0.6 eV) 58 kJ/mol.

Let's compare the IP and EA of the methyl radical to values in the above table for strong oxidizing and reducing agents. The IP of the methyl radical is significantly larger than those reported for the alkali metals and a bit less, but relatively close to the IP's for all of the halogens except fluorine. This comparison suggests that methyl radical is, at best, a weak reducing agent. The EA of methyl radical is significantly less than those reported for the halogens and right around those reported for the alkali metals. This comparison suggests that methyl radical is, at best, a very weak oxidizing agent.