The carbon attached directly to benzene is known as the benzylic position. In this position, highly stable carbocations, carbanions and radicals are formed due to the possibility of delocalizing the charge on the aromatic ring.

benzylic position 01

SN1 in benzylic positions

Primary haloalkanes on benzylic positions give SN1 since the primary carbocation delocalizes by resonance within benzene.
benzylic position 02
Stage 1. Loss of the leaving group, with formation of a benzylic cation.
benzylic position 03
Stage 2. Nucleophilic attack of water on the benzyl cation
benzylic position 04
Stage 3. Deprotonation
benzylic position 05
Halogenation of the benzylic position.
The benzylic positions are selectively halogenated using NBS.
benzylic position 06
Acidity of benzylic hydrogens
Hydrogens located in benzylic positions can be subtracted using strong bases such as LDA and organometallics.
benzylic position 07