Sciencemadness Discussion Board

Para Sulfonation of Aniline

PrussianBlue - 27-1-2018 at 16:11

Would anyone happen to know the best way to para-sulfonate aniline? I'm supposed to draw up a synthesis of 2-bromo-4-chloro-nitrobenzene from benzene and I'd like to be able to assure only ortho bromination of the aniline intermediate. Any thoughts?

clearly_not_atara - 27-1-2018 at 16:48

This paper probably has details:

http://pubs.acs.org/doi/abs/10.1021/ie50399a012

If you're not doing this for a class, you can probably obtain para-aminobenzoic acid and brominate that, followed by decarboxylation, which saves you a few headaches.

CuReUS - 27-1-2018 at 22:01

Quote: Originally posted by PrussianBlue  
I'm supposed to draw up a synthesis of 2-bromo-4-chloro-nitrobenzene from benzene

1.https://link.springer.com/article/10.1007/BF00957338
2.http://www.tandfonline.com/doi/full/10.1081/SCC-120014967
3.http://pubs.rsc.org/en/Content/ArticleLanding/1999/P1/a90153...
4.http://www.nrcresearchpress.com/doi/10.1139/v05-026#.Wm1lj7y...

2-bromo-4-chloronitrobenzene.png - 4kB
Quote: Originally posted by clearly_not_atara  
you can probably obtain para-aminobenzoic acid and brominate that, followed by decarboxylation

followed by oxidation and hunsdiecker,you mean ;)

[Edited on 28-1-2018 by CuReUS]

PrussianBlue - 28-1-2018 at 08:35

Forgot to mention -- I am doing this for my Organic II class and I'm not allowed to use nucleophilic substitution for this one. Here's what I have drawn up so far. Will the amine survive the two rounds of acid and heat?

2-bromo-4-chloro-nitrobenzene Mechanism.jpg - 4.2MB

CuReUS - 1-2-2018 at 07:49

Quote: Originally posted by PrussianBlue  
Will the amine survive the two rounds of acid and heat?

I don't see why not.The 2 things that needs to be changed is the omission of FeBr3 and AlCl3 in the bromination and chlorination of aniline respectively,since aniline is very active to electrophilic substitution anyway and also the lewis acid would complex with the NH2.I wonder if the desulphonation/chlorination could be done in one step ?

[Edited on 1-2-2018 by CuReUS]