Question

Which isomer of C\(_4\)H\(_9\)Br is most reactive towards \(S_N2\) reaction?

Hint:

SN2 reactivity: Methyl>1°>2° >> 3°.

Answer 1

\(S_N2\) reactions are favoured by least steric hindrance. Among isomers:

• tert-butyl bromide → least reactive
• isobutyl bromide → moderate
• sec-butyl bromide → moderate
• n-butyl bromide → least hindered

\[ \therefore \text{n-butyl bromide is most reactive in } S_N2. \]