EAS rxn question

[virtualmaster999]

Hi everyone!

I got a quick question on EAS tat I came across.

So if you have Aniline with Cl2/H2O, you get double chlorination. Is this reaction specific for aniline/ donating groups, and does it work for all halogens?

Thanks in advance!

 

[510586]

Br2/FeBr3 does this as well. I wonder if there are any others?

 

[DAT Destroyer]

Hi everyone!

I got a quick question on EAS tat I came across.

So if you have Aniline with Cl2/H2O, you get double chlorination. Is this reaction specific for aniline/ donating groups, and does it work for all halogens?

Thanks in advance!

The is a good question. Aniline contains THE MOST ACTIVATING GROUP to likely be found on a benzene ring. If chlorinated, the reaction will give chlorine in both ortho and para positions.

As a matter of fact, a Lewis acid catalyst is not even needed!!!!

This often poses a problem when doing organic synthesis and a protecting group which partially deactivates the molecule is employed. Bromine would also pose a problem when using aniline.

Iodine and fluorine are added on by different techniques which you likely will not encounter.

Hope this helps

Dr. Romano

 

[virtualmaster999]

The is a good question. Aniline contains THE MOST ACTIVATING GROUP to likely be found on a benzene ring. If chlorinated, the reaction will give chlorine in both ortho and para positions.

As a matter of fact, a Lewis acid catalyst is not even needed!!!!

This often poses a problem when doing organic synthesis and a protecting group which partially deactivates the molecule is employed. Bromine would also pose a problem when using aniline.

Iodine and fluorine are added on by different techniques which you likely will not encounter.

Hope this helps

Dr. Romano

So this reagent is specific for Aniline then? And it will always induce excess chlorination/ bromination at both ortho positions and the para position?

 

[super112]

So to clarify, is it double chlorination or triple? (2 ortho, 1 para)
Also can one do this with Cl2/FeCl3 OR Cl2/H20 in order to get this?
Thanks

 

[DAT Destroyer]

So to clarify, is it double chlorination or triple? (2 ortho, 1 para)
Also can one do this with Cl2/FeCl3 OR Cl2/H20 in order to get this?
Thanks

The tri- substituted product is obtained in high yield. The reaction may go with using FeCl3 or just plain water due to the high reactivity. Consult any organic text book and look at the yield it would probably be over 90 percent in favor of the tri - substituted product. Even though you see 3 bromines it is not easy to stop the reaction at a single or double substituted product....as you can see a tri - substituted product results.

 

[DAT Destroyer]

So this reagent is specific for Aniline then? And it will always induce excess chlorination/ bromination at both ortho positions and the para position?

Whoa Whoa Whoa!!!!! NOT specific for aniline. This is simply halogenation. The point is... normally we get ortho and para products if an activating group is present, but with aniline, the tri - substituted product results. This is due to the high reactivity of this group.

Dr. Romano

 

[virtualmaster999]

Whoa Whoa Whoa!!!!! NOT specific for aniline. This is simply halogenation. The point is... normally we get ortho and para products if an activating group is present, but with aniline, the tri - substituted product results. This is due to the high reactivity of this group.

Dr. Romano

Ohhhh I see! Thanks for clarifying that Dr. Romano, I appreciate it! 🙂

 

[virtualmaster999]

Whoa Whoa Whoa!!!!! NOT specific for aniline. This is simply halogenation. The point is... normally we get ortho and para products if an activating group is present, but with aniline, the tri - substituted product results. This is due to the high reactivity of this group.

Dr. Romano

Just to make sure, so since you said the reagent is not specific for aniline, does that mean that all benzene derivatives give tri- substituted products unless with a catalyst? Or is it because of aniline's reactivity? I believe I saw this come up with anisole as well.

 

[DAT Destroyer]

Just to make sure, so since you said the reagent is not specific for aniline, does that mean that all benzene derivatives give tri- substituted products unless with a catalyst? Or is it because of aniline's reactivity? I believe I saw this come up with anisole as well.

Anisole usually gives an ortho and a para isomer respectively. The para isomer is the major product. Virtually all benzene derivatives for the DAT exam will give a single isomeric product. For example, if anisole is brominated or chlorinated the para isomer would be major.

Dr. Romano

 

[virtualmaster999]

Anisole usually gives an ortho and a para isomer respectively. The para isomer is the major product. Virtually all benzene derivatives for the DAT exam will give a single isomeric product. For example, if anisole is brominated or chlorinated the para isomer would be major.

Dr. Romano

And this is for the use of catalyst right?

 

[DAT Destroyer]

And this is for the use of catalyst right?

LOL, relax son, all benzene reactions on the DAT will have Lewis Acid Catalyst.

 

[virtualmaster999]

LOL, relax son, all benzene reactions on the DAT will have Lewis Acid Catalyst.

Perfect. Thank you again! Sometimes I let paranoia get the best of me, even for little things!

 

[starsbeneathme]

Anisole usually gives an ortho and a para isomer respectively. The para isomer is the major product. Virtually all benzene derivatives for the DAT exam will give a single isomeric product. For example, if anisole is brominated or chlorinated the para isomer would be major.

Dr. Romano

i've read that halogenation of phenols with a lewis acid catalyst also lead to a tri-substituted product. is that correct?

 

[DAT Destroyer]

i've read that halogenation of phenols with a lewis acid catalyst also lead to a tri-substituted product. is that correct?

Yes.....This is often a problem when we have very activating groups such as phenols and especially aniline. To get around this, in the case of phenols, when can change the solvent to CS2, and even use PROTECTING groups such as acetyl chloride.

Hope this helps

Dr. Romano