Q21 / 120 · JEE Main 2007 · Chemistry

Which of the following is the correct order of decreasing $\mathrm{SN}^2$ reactivity?

  • A
    $\mathrm{RCH}_2 \mathrm{X}>\mathrm{R}_3 \mathrm{CX}>\mathrm{R}_2 \mathrm{CHX}$
  • Correct answer
    B
    $\mathrm{RCH}_2 \mathrm{X}>\mathrm{R}_2 \mathrm{CHX}>\mathrm{R}_3 \mathrm{CX}$
  • C
    $\mathrm{R}_3 \mathrm{CX}>\mathrm{R}_2 \mathrm{CHX}>\mathrm{RCH}_2 X$
  • D
    $\mathrm{R}_2 \mathrm{CHX}>\mathrm{R}_3 \mathrm{CX}>\mathrm{RCH}_2 \mathrm{X}$ $(\mathrm{X}=$ a halogen $)$

Solution

More is the steric hindrance at the carbon bearing the halogen, lesser is the $\mathrm{S}_{\mathrm{N}} 2$ reactivity. Hence, (B) is correct.

Hence, the correct answer is option: 'B'.

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