Thursday, June 22, 2017

organic chemistry - How to be able to tell if a molecule will react via SN1 or SN2?


I've been having a lot of issues with a question.


2 compounds, (1-chloro-2,2-dimethylpropyl)benzene and (1-chloro-2-methylpropyl)benzene react with EtOH in water.



It asks to classify the reaction mechanism for each and to then go on and explain why (1-chloro-2-methylpropyl)benzene has a much faster relative rate.


I am having major issues with the question, because I just cannot tell where there are any major differences between molecules which could make a difference. Both of them have a benzene ring, but this stabilises both the transition state and the carbocation intermediate so will favour both SN1 and SN2. Both reactions are done in the exact same solvent with the same nucleophile.


The only differences I can spot is that in (1-chloro-2,2-dimethylpropyl)benzene, there will be more stabilisation due to the inductive effect and hence it will favour SN1. But this does not help with determining the mechanism for (1-chloro-2-methylpropyl)benzene.


Any help will be much appreciated. Many thanks :)




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