Friedel Crafts Alkylation

[LuckMC11]

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Is friedel crafts alkylation tested on the DAT? in the KBB they dont really discuss it, they just say it can occur but that it is less useful since the product is attacked faster than starting material, leading to over alkylation.

anyone that took the DAT confirm if there was ever a question on friedel crafts alkylation?

 

[Troyvdg]

Is friedel crafts alkylation tested on the DAT? in the KBB they dont really discuss it, they just say it can occur but that it is less useful since the product is attacked faster than starting material, leading to over alkylation.

anyone that took the DAT confirm if there was ever a question on friedel crafts alkylation?

I'm sure it is, they gave it to me on my kaplan diagnostic.

But, if you know acylation, you know alkylation

 

[UndergradGuy7]

I'm sure it is, they gave it to me on my kaplan diagnostic.

But, if you know acylation, you know alkylation

Exception is alkylation can rearrange.

 

[LuckMC11]

thats the only difference?

 

[Baylor2011]

Acylation doesn't rearrange because the carbocation formed is on a carbonyl carbon.

Alkylation rearranges because the carbocation isn't restrained by anything like a carbonyl, and is free to rearrange

 

[MowgliR]

also you cant alkylate or acylate when you have a meta director on a benzene ring.

 

[LuckMC11]

alright thanks

randy, i thought u couldnt just alkylate when you have a meta director but you could still acylate?

 

[MowgliR]

alright thanks

randy, i thought u couldnt just alkylate when you have a meta director but you could still acylate?

its actually both. NO2 withdraws electrons from the benzene ring make it more stable (electrons can delocalize around to the substituent. This makes the benzene ring more stable and less reactive for a relatively weak electrophile to attack the ring.

This is my understanding of FC. Why would it be able to do one but not the other?

 

[Baylor2011]

also you cant alkylate or acylate when you have a meta director on a benzene ring.

False. You can't have a Friedel-Crafts reaction when a meta director is the ONLY thing attached to the ring. If you have a meta director mixed with an o-p director on the ring, the reaction will proceed.

 

[LuckMC11]

it says here: http://www.mpcfaculty.net/ron_rinehart/12A/chp12pag.htm

A limitation of Friedel-Crafts Alkylation: rings which are too deactivated will not react.
a) If an -NO2 group is on the ring, no reaction will occur.
b) A ring with a single halogen atom will react, but any greater deactivation will result in no reaction.

but only for alkylation not acylation

 

[MowgliR]

False. You can't have a Friedel-Crafts reaction when a meta director is the ONLY thing attached to the ring. If you have a meta director mixed with an o-p director on the ring, the reaction will proceed.

I was referring to when it is the ONLY substituent attached. Sorry I wasnt clear.

 

[Baylor2011]

I was referring to when it is the ONLY substituent attached. Sorry I wasnt clear.

It's coo 🙂 Just making sure whoever read it didn't get a Q on the DAT w/ a meta director and o-p director and select NoRX as the answer, haha

 

[MowgliR]

it says here: http://www.mpcfaculty.net/ron_rinehart/12A/chp12pag.htm

A limitation of Friedel-Crafts Alkylation: rings which are too deactivated will not react.
a) If an -NO2 group is on the ring, no reaction will occur.
b) A ring with a single halogen atom will react, but any greater deactivation will result in no reaction.

but only for alkylation not acylation

Where does it say only for alkylation?

 

[LuckMC11]

Where does it say only for alkylation?

i assumed it was only for alkylation since it only gives a limitation for alkylation but nothing for acylation..am i wrong to assume this?

 

[Baylor2011]

Any Friedel-Crafts reaction (whether alkylation or acylation) do not react when meta directors (halogens are o-p directors) are the only groups attached to the ring, OR when active hydrogens are present (H attached to S, O, or N)

 

[LuckMC11]

Any Friedel-Crafts reaction (whether alkylation or acylation) do not react when meta directors (halogens are o-p directors) are the only groups attached to the ring, OR when active hydrogens are present (H attached to S, O, or N)

alright thanks!

 

[NarueDaisuki]

Any Friedel-Crafts reaction (whether alkylation or acylation) do not react when meta directors (halogens are o-p directors) are the only groups attached to the ring, OR when active hydrogens are present (H attached to S, O, or N)

hey guys, just wondering why ?

is it because the ring is deactivated or something else?