NEET2008ChemistryHaloalkanes and HaloarenesActual
In a S_ N 2 substitution reaction of the type R - Br + Cl ⁻ DMF R - Cl + Br ⁻ , which one of the following has the highest relative rate?
Options
- ACH ₃- CH ₂- CH ₂ Br
- BCH ₃ CH ₂ Br
Correct answer
3
Step-by-step solution
Key Idea: The relative reactivity of alkyl halides towards S _ N 2 reactions is as follows: Primary > Secondary > Tertiary However, if the primary alkyl halide or the nucleophile/base is sterically hindered the nucleophile will have difficulty to getting the back side of the -carbon as a result of this, the elimination product will be predominant. Here CH ₃ CH ₂ Br is the least hindered, hence it has the highest relative rate towards S _ N 2 reaction.