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not_important
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Note that both of the OrgSyn examples given are alcohol-based reductions, one using a copper promoter and the other just hot acidic solution.
The method can produce varying amounts of the corresponding ether of the aromatic substrate, although that is favoured by low temperatures; overly
water-diluted solutions will also give some of the corresponding phenol. Adjustment of the conditions, including choice of alcohol, can minimise
those problems, the reference I gave notes that with your starting material | Quote: | | The diazonium sulphates from p-chloro- and p-bromo-aniline furnish only p-chloro- and p-bromo-benzene with ethyl alcohol, but with methyl alcohol they
give rise mainly to the methyl ethers of p-chloro- and p-bromo-phenol |
For simple compounds you can likely find detailed preparations in older org-lab methods and "practical" org-chem books.
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panziandi
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kclo4 was the poster who originally mentioned the DEA schedule status which i think the author of this thread took up thinking perhaps it meant it was
not possible to buy in this country as it may be scheduled here too, which is not the case.
alcohlysis with hot ethanol say rectified spirit would yield a high % of the arene with very little by product (ether and phenol)
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Sauron
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In this thread people have referred erroneously to p-bromobenzene, but of course there is no such thing. Just bromobenzene. It's an unworthy
mistake.Anyway glad I could be of assistance.
Sic gorgeamus a los subjectatus nunc.
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panziandi
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indeed Sauron you have a point there!
Now with that p-bromoaniline you have there you could open up many possible doorways.
Have you considered making these too:
4-bromophenol and methylating to 1-bromo-4-methoxybenzene (p-bromoanisole), or methylate the diazonium with methanol - can be used for Grignards too!
4-bromobenzonitrile - that bi-functional arene could be quite usefull!
1-chloro-4-bromobenzene and also 1-bromo-4-fluorobenzene possibly interesting chlorophenyl and fluorophenyl Grignards
You can make 4-bromothiophenol by thiolysis with a thiol
Diazoniums are very useful!
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panziandi
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I have just found an interesting paper:
Sasaki, M. et al. Bull. Chem. Soc. Jpn., 65, 1739-1740, 1992
Metallic Nickel-Catalyzed Reduction of Aryl Halides with Zinc Powder and Ethanol
Reports PhI 90% conversion to benzene in 24hrs, PhBr 47% conversion to benzene in 36hrs.
_ _ _
Now I'm thinking perhaps converion of the aniline to the iodo compound with potassium iodide then a reduction of teh compound using the method
outlined in in the ref. Conversion of the iodo would be more favoured than the bromo. Obviously it will not be a straight forward conversion but could
be useful for dehalogenation of a variety of halogenated arenes.
[Edited on 22-9-2008 by panziandi]
Attachment: Nickelcatalyzedzincreduc.pdf (298kB)
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