Question

For $S_N1$ reaction, the order of reactivity of haloalkanes is

• A. tertiary halide < secondary halide < primary halide
• B. tertiaty halide < secondary halide > primary halide
• C. tertiary halide > secondary halide > primary halide
• D. tertiary halide > secondary halide < primary halide

Answer 1

Answer: (C)

$S_N1$ reaction is two steps reaction in which. carbocation is . formed as an intermediate in step I (rate determining step). Greater the stability of carbocation, greater will be its ease of formation from alkyl halide and faster will be the rate' of reaction. Thus, the order of reactivity of haloalkanes towards $S_N1$ reaction is Tertiary halide > Secondary halide > Primary halide.