Making o-bromoaniline from aniline

How can I make *o*-bromoaniline from aniline (as a major product)?


I know how to make *p*-bromoaniline from aniline, by acetylation followed by treatment with $\ce{Br2}$/$\ce{CH3COOH}$ and hydrolysis. But in this process the ortho isomer (if formed) will be the minor product. 




Didn't you consider the way through sulfanilic acid, the *para*-position will be protected. In this case both substituents will direct the electrophilic substitution in *ortho*- position with respect to amino group. Then remove sulfonic acid group by desulfonation and you will obtain your *ortho*-bromoaniline.


 8

As outlined in a comment direct bromination of nitrobenzene with $\ce{Br2}$ and $\ce{FeBr3}$ is likely to give the *meta*-substituted product.


If you want to avoid time-consuming and expensive procedures, your options are:


* Change the order of events. Nitrate bromobenzene under mild(er) conditions, or
* Find conditions, under which bromination of nitrobenzene furnishes the *ortho*-product


For the latter, have a look at *Chem. Commun.*, **1996**, 2679-2680
([DOI](http://dx.doi.org/10.1039/CC9960002679)). The authors state:



> 
> We have observed that monosubstituted benzene derivatives
>  react with a mixture of dimethyl sulfoxide and aqueous
>  hydrobromic acid […] to yield regiospecifically only the
>  monobromo derivatives. It is interesting to note that electron-
>  withdrawing groups such as $\ce{NO2}$, $\ce{CHO}$ yield *ortho*-bromo
>  derivatives, while electron-donating groups such as $\ce{NH2}$, $\ce{OH}$ or $\ce{Me}$ give only *para*-bromo derivatives.
> 
> 
> 


 2

I think that you probably cannot avoid separating ortho from para isomers (and possibly disubstitution products) after using a method like the one you suggest or a method of blocking the para- position.


Another method that is probably not taught to undergraduates (?) is the [Directed ortho metallation (DoM)](http://www.organic-chemistry.org/namedreactions/directed-ortho-metalation.shtm) or Snieckus chemistry. The image below has been copied from that link.
[![enter image description here](https://i.stack.imgur.com/qh6Tu.png)](https://i.stack.imgur.com/qh6Tu.png)


 2