DAT destroyer ochem (#53)

[Hoof02010]

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The answer states that when adding (via alkylation) a chain of 3 carbons or more to benzene you get a rearranged product:

I would expect C6H6 + CH3CH2CH2Cl (in AlCl3)===> C6H5CH2CH2CH3
but they state that the rearranged product of this half reaction is C6H5CH(CH3)2

I do not remember learning the fact that when adding a chain of 3 carbons or more would result in rearrangement of the added chain.....and if this is true, how do you come up with the proper rearrangement???

Thanks!

 

[dent4]

You would definitely get rearrangement because it would be more stable with rearrangement. The only way to get a strait chain was if you were to use CH3CH2CH2COCl, AlCl3 then using either the wolff or clemmenson reagent

 

[Hoof02010]

Yep got it! Just referred back to my notes and realized that there is a carbocation intermediate. Thanks for the heads up!

 

[ToBeDDSS]

It does rearrange. The secondary carbocation. Is more stable.
See either Wade or McMurray text book. I got nailed on that question when I did it the first time.
Good luck