Question

Which among the following compounds will undergo $S_{N}2$ reaction at the fastest rate ?

• A. $({\mathrm{CH}}_3{)}_3\mathrm{CCl}$
  
• B. $({\mathrm{CH}}_3{)}_2\mathrm{CHCl}$
  
• C. ${\mathrm{CH}}_3\mathrm{Cl}$
  
• D. ${\left(C_2{H}_5\right)}_2\mathrm{CHCl}$
  

Answer 1

The correct option is C ${\mathrm{CH}}_3\mathrm{Cl}$


Primary alkyl halides undergo $S_{N}2$ reaction in a faster rate than secondary and tertiary. Of the simple alkyl halides, methyl halides react most rapidly in $S_{N}2$ reactions because there are only three small hydrogen atoms. Tertiary halides are the least reactive because bulky groups hinder the approaching nucleophiles. Thus the order of reactivity followed is: Primary halide > Secondary halide > Tertiary halide.