For the solvolysis of benzylic chlorides $Ar - CH X_{2} Cl$ in 80 % aqueous ethanol and their reaction with $NaI$ in dry acetone, select the correct statement(s).

A $(C X_{6} H X_{5}) X_{3} C - Cl$ in 90 % aqueous acetone reacts mainly by an SN2 pathway.
B $p - O X_{2} N - C X_{6} H X_{4} - CH X_{2} Cl$ solvolyses more slowly than $C X_{6} H X_{5} - CH X_{2} Cl$ .
C $p - CH X_{3} O - C X_{6} H X_{4} - CH X_{2} Cl$ solvolyses faster than $C X_{6} H X_{5} - CH X_{2} Cl$ .
D $C X_{6} H X_{5} - CH X_{2} Cl$ reacts faster than $CH X_{3} CH X_{2} CH X_{2} Cl$ with $NaI$ in dry acetone.

Answer: B, C, D

Electron-donating p-methoxy stabilises the benzylic cation (resonance) and speeds SN1 solvolysis, whereas p-nitro destabilises it. Benzylic carbon is also activated in SN2, since the p-orbitals of the ring stabilise the transition state, so benzyl chloride is faster than n-propyl chloride with iodide. The trityl carbon is so hindered that SN2 is impossible; it reacts by SN1.

Practice Organic Reaction Mechanisms III: Nucleophilic Substitution More on SN1 vs SN2: substrate, nucleophile, solvent, leaving group

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For the solvolysis of benzylic chlorides Ar−CHX2​Cl in 80 % aqueous ethanol and their reaction with NaI in dry acetone, select the correct statement(s).

Answer: B, C, D

More questions on SN1 vs SN2: substrate, nucleophile, solvent, leaving group

For the solvolysis of benzylic chlorides $Ar - CH X_{2} Cl$ in 80 % aqueous ethanol and their reaction with $NaI$ in dry acetone, select the correct statement(s).