JEE Main 2014 · 9 Apr · Shift 1 · Chemistry Q57

ChemistrySingle correct+4 / -1Question 57 of 90

In which of the following pairs A is more stable than B ?

A: cyclohexenyl radical with the unpaired electron on a ring alkene carbon (vinylic); B: cyclohex-2-en-1-yl radical (allylic)

A: cyclohexyl radical (secondary); B: 1-methylcyclohexyl radical (tertiary)

A: cyclopropyl radical; B: cyclohexyl radical

\ce{Ph3C^.}

; B:

\ce{(CH3)3C^.}

Answer and worked solution

Official answer: D

(1): A is a vinylic radical, less stable than B, the allylic radical.
(2): A is secondary, less stable than tertiary B.
(3): A, cyclopropyl, is less stable than cyclohexyl.
(4): $\ce{Ph3C^.}$ is stabilised by delocalisation into three rings, so it is more stable than $\ce{(CH3)3C^.}$ .

Only (4) has A more stable.

JEE Main 2014 · 9 Apr · Shift 1, Chemistry question 57