Arrange the compounds A,B,C and D in the increasing order of their reactivity towards SN1 reaction. ‌A=C6H5CH2‌Cl ‌B=C6H5‌Cl ‌C=CH2=CH−Cl ‌D=CH3−CH2−Cl
To determine the order of reactivity of the given compounds A,B,C and D towards an SN1 reaction, we need to consider the stability of the carbocation intermediate that forms when each compound undergoes the reaction. The more stable the carbocation, the more reactive the compound will be towards the SN1 mechanism. Let's analyze each compound: 1. A=C6H5CH2‌Cl : The carbocation formed after losing Cl is C6H5CH2+, which is a benzyl carbocation. Benzyl carbocations are highly stabilized by resonance with the phenyl ring. 2. B=C6H5‌Cl : The carbocation formed after losing Cl is C6H5+. This is a phenyl carbocation, which is very unstable since the positive charge cannot be delocalized on the aromatic ring effectively. 3. C=CH2=CH−Cl : The carbocation formed after losing Cl is CH2=CH+, which is a vinyl carbocation. Vinyl carbocations are extremely unstable because the positive charge lies on an sp2 carbon, making them very high in energy. 4. D=CH3−CH2−Cl : The carbocation formed after losing Cl is CH3−CH2+, which is a primary carbocation. Primary carbocations are more stable than vinyl carbocations but much less stable compared to benzyl carbocations. Based on the stability of the carbocations, the order of reactivity towards the SN1 reaction is: B<C<D<A Thus, the correct option is: Option C B<D<C<A