Arrange the following free radiacals in order of decreasing stability.
Methyl (I), Vinyl(II), Allyl(III), Benzyl(IV)

Options

A. `I gt II gt III gt IV`
B. `III gt II gt I gt IV`
C. `II gt I gt IV gt III`
D. `IV gt III gt I gt II`

Answer

D

Explanation

Among the alkyl free radicals, tertiary alkyl free radicals are most stable and methyl free radical is least stable. Benzyl and allyl free radicals are resonance stabilized and are more stable than alkyl free radicals. Vinyl radical is least stable as the odd electron is present on `sp^(2)` C-atom

`CH_(2) = CH - underset("Resonance in allyl radical")(CH_(2) rarr CH_(2)) - CH = CH_(2)`
`therefore` Order is
Benzyl (IV) > Allyl (III) > Methyl (I) > Vinyl (II).