Ochem question 143 on DAT Destroyer

[CherryBlossom1412]

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Hi guys! I have a question about which compound would react fastest in Sn1 type of reaction (image is attached). I don't quite understand the explanation on why choice B is horrible. Also, why does C, which is antiaromatic, would be horrible answer? Also Why is D a better answer than C (and isn't C also anti-aromatic and would be a horrible answer? but the answer choice said it's fair?

Thanks in advance!!

 

[deleted678432]

Cannot be B because you need an SP3 hybridized carbon to do SN1/SN2. C is horrible because the leaving of the Cl would cause there to be an empty P orbital at that carbon, which would cause the molecule to be anti-aromatic. You NEVER want to form anti-aromatic because it is extremely unstable. D would form a regular resonance stabilized carbocation. Lastly, E, would form an aromatic compound so it would therefore be the best option.

 

[CherryBlossom1412]

Cannot be B because you need an SP3 hybridized carbon to do SN1/SN2. C is horrible because the leaving of the Cl would cause there to be an empty P orbital at that carbon, which would cause the molecule to be anti-aromatic. You NEVER want to form anti-aromatic because it is extremely unstable. D would form a regular resonance stabilized carbocation. Lastly, E, would form an aromatic compound so it would therefore be the best option.

Thank you so much!! It makes much more sense now 🙂 I really appreciate your help