COMEDK2024Evening ShiftChemistryHaloalkanes and HaloarenesActual
Arrange the compounds A , B , C and D in the increasing order of their reactivity towards S_N 1 reaction. aligned & A = C ₆ H ₅ CH ₂ Cl & B = C ₆ H ₅ Cl & C = CH ₂= CH - Cl & D = CH ₃- CH ₂- Cl aligned
Options
- AB < C < D < A
- BD < C < B < A
- CD < B < A < C
- DC < A < D < B
Correct answer
A. B < C < D < A
Step-by-step solution
S_N1 reactivity depends on the stability of the carbocation formed. A ( C₆H₅CH₂Cl ): Forms benzyl carbocation ( C₆H₅CH₂^+ ) — highly stable due to resonance delocalization over the benzene ring. Most reactive. D ( CH₃CH₂Cl ): Forms ethyl carbocation ( 1° ) — moderately stable via hyperconjugation and +I effect of methyl group. C ( CH₂=CH-Cl ): Forms vinyl cation ( CH₂=CH^+ ) — positive charge on sp hybridised carbon (more electronegative), highly unstable. Also has partial double bond character in C-Cl bond due to