Question about AlCl3 catalyst!

[jonathankimmm]

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Going over destroyer in one of the questions they had isobutylchloride reacting with AlCl3 and in their answer it shows that after the AlCl3 got rid of the Cl , the carbocation rearranged to be tertiary.
Later on in another question they had CH3CH2CL reacting with AlCl3 again but this time the carbocation did not rearrange to secondary, it stayed primary. Why doesnt it rearrange to go secondary?

 

[paymaant]

what numbers are you referring to?

 

[jonathankimmm]

I have 2012 destroyer
Ochem #129
Isobutylchloride reacts with benzene in the presence of alcl3. To make t-butylbenzene.
This is where the carbocation rearranges

and Ochem #144
This one the Ch3Ch2Cl reacts with AlCl3 and adds onto benzene as just an ethyl. I thought it would rearrange the carbocation and add on as isoproply

 

[jonathankimmm]

Wait nvm im stupid, lol i was looking at this for 15m inutes and never realized it cant make isoprop since theres only two carbons.. ahh haha case closed.

 

[jonathankimmm]

But just to clarify, if it was Ch3Ch2Ch2Cl and reacted with AlCl3 would the carbocation rearrange to secondary?

 

[Moka11]

Going over destroyer in one of the questions they had isobutylchloride reacting with AlCl3 and in their answer it shows that after the AlCl3 got rid of the Cl , the carbocation rearranged to be tertiary.
Later on in another question they had CH3CH2CL reacting with AlCl3 again but this time the carbocation did not rearrange to secondary, it stayed primary. Why doesnt it rearrange to go secondary?

The reactions I believe your referring to is Friedel Craft Alkylations. In your second example there's is no way the Carbocation could have rearranged as there are only 2 carbons there.

 

[Moka11]

But just to clarify, if it was Ch3Ch2Ch2Cl and reacted with AlCl3 would the carbocation rearrange to secondary?

Your not stupid. And yes.