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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.
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:
For the latter, have a look at Chem. Commun., 1996, 2679-2680 (DOI). 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.
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) or Snieckus chemistry. The image below has been copied from that link.
