Primary alkyl halides generally prefer to undergo nucleophilic substitution via the S _ N 2 mechanism. However, which of the following primary halides readily undergoes the S _ N 1 mechanism?

Step-by-step solution

The rate of an S _ N 1 reaction depends on the stability of the intermediate carbocation formed. 1-Chloropropane forms a highly unstable primary carbocation, thus preferring S _ N 2 . 1-Chloro-2,2-dimethylpropane (neopentyl chloride) forms a primary carbocation initially, making its ionization very slow, though it is sterically hindered for S _ N 2 . Chlorobenzene forms a highly unstable phenyl cation and does not undergo S _ N 1 reactions. 3-Chloroprop-1-ene (allyl chloride) ionizes to form a primary allylic carbo