# Is 1,2- Hydride shift possible in ketonic cations?

The question in my worksheet asks me to predict the result of the reaction between benezene and $\ce{(CH3CH2CH2CO)2O}$ in presence of anhydrous $\ce{AlCl3}$.

My attempt:

After complex formation with $\ce{AlCl3}$ we get this carbocation: $\ce{CH3CH2CH2CO+}$ that has two resonance structures.

But, if we consider hydride shift we get $\ce{CH3CH2C^+HC=O}$ which is not only stabilised by resonance but also by the $\text{+I}$ effect of ethyl group.

However, the answer is $\ce{PhCOCH2CH2CH3}$ which isn't formed by the second carbocation with hydride shift .

So I'd like to know if hydride shift is possible in ketonic carbocations or not? And if it is, is the answer wrong?

• If hydride transfer were to occur, the resultant carbonyl would be stabilizing a cation. A definite NO_NO! Read up on the the Friedel-Crafts reaction. Mar 21 '18 at 16:09

## 1 Answer

The carbocation doesn't rearrange since oxygen donates it's lone pair and the resulting carbocation is quite stable since the octet of all the atoms is complete.