Tertiary Carbocation Formation in SN1 Reaction

Steps:

• Identify the molecule: 1-chloro-1-methylcyclohexane has a tertiary carbon at position 1 bonded to Cl, CH3, and two ring carbons.
• Recognize reaction type: Tertiary alkyl halides undergo SN1, involving heterolytic cleavage of C-Cl bond.
• Determine intermediate: Loss of Cl– leaves a tertiary carbocation at the specified carbon.
• Assign charge: The carbocation carbon has a +1 formal charge due to only six valence electrons.

Why D is correct:

• In carbocations, the central carbon bears a +1 charge per formal charge rules (group 14 element with incomplete octet).

Why the others are wrong:

• A: 1– applies to nucleophiles like Cl–, not electron-deficient carbocations.
• B: δ– indicates partial negative charge from inductive effects, absent in carbocations.
• C: δ+ is a partial positive polarity in bonds, not the full +1 charge of a carbocation.

Final answer: D