Which free radical from following is least stable?

Which free radical from following is least stable?
  1. $\dot{\mathrm{C}} \mathrm{H}_3$
  2. $\mathrm{CH}_3-\stackrel{\cdot}{\mathrm{C}} \mathrm{H}_2$
  3. $\left(\mathrm{CH}_3\right)_3 \mathrm{C}$
  4. $\left(\mathrm{CH}_3\right)_2{ }_2 \dot{\mathrm{C}} \mathrm{H}$

Solution

Stability of CFR $\propto$ no. of $a-H$ $\stackrel{\bullet}{\mathrm{C}} \mathrm{H}_3 \Rightarrow 0\mathrm{a}-\mathrm{H}$ $\mathrm{CH}_3-\stackrel{\bullet}{\mathrm{C}} \mathrm{H}_2 \Rightarrow 3 a-H$ $\left(\mathrm{CH}_3\right)_3 \stackrel{\bullet}{\mathrm{C}} \Rightarrow 9 a-H$ $\left(\mathrm{CH}_3\right)_2 \stackrel{\bullet}{\mathrm{C}} \Rightarrow 6 a-H$

Asked in: MHT CET 2022 (08 Aug Shift 1)

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