Tertiary alkyl halides are practically inert to substitution by SN2 mechanism because:

• (A) insolubility
• (B) instability
• (C) steric hindrance
• (D) inductive effect

Tertiary alkyl halides are largely unreactive in substitution reactions via the SN2 mechanism primarily due to steric hindrance. This occurs because the bulky groups surrounding the carbon atom make it difficult for the nucleophile to approach and attack the carbon atom bonded to the halide.

Why Steric Hindrance Matters

Steric hindrance refers to the physical obstruction that larger groups create around a reactive site. In the case of tertiary alkyl halides:

• The central carbon is bonded to three other carbon atoms.
• This crowded environment prevents the nucleophile from effectively reaching the carbon atom.

Other Factors Considered

While factors like solubility, instability, and inductive effects can influence reactions, they are not the primary reasons for the lack of reactivity in SN2 mechanisms for tertiary alkyl halides.