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Author: Subject: Halobenzene as an N-alkylating agent

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[*] posted on 25-11-2017 at 13:30
Halobenzene as an N-alkylating agent

I couldn't find any info is it possible for halobenzenes to react with primary alkylamines in standard conditions.
My guess is probably not because analogously triphenylamine isn't prepared by bubbling ammonia gas into a halobenzene. Am I right?

IOW halobenzenes can be used as a solvents in the reactions of amines with haloalkanes (SN rxns) replacing toluene or benzene, is that true?

[Edited on 25-11-2017 by biomechem]
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[*] posted on 25-11-2017 at 13:38

Right. Halobenzenes do not react with nucleophiles under normal conditions, and could serve as inert solvent in reactions of amines and haloalkanes. More polar solvents tend to be preferable sometimes though, depending on substrate and desired product.
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[*] posted on 25-11-2017 at 17:14

Iodobenzene and to a lesser extent Bromobenzene, may be somewhat reactive.

Chlorobenzene is pretty much...... not reactive.

When attempting to create a Grignard reagent, Bromobenzene can be convinced to react with Magnesium.....eventually. Chlorobenzene not so much.

Six of one, doesn't necessarily equal half a dozen, of the other.... in chemistry.

But, if that aromatic Chlorine cannot be easily rooted out by very electropositive Magnesium, it is unlikely that it will interact with middle of the road Hydrogen. Excepting of course, under special conditions, or at elevated temperatures.

That being said. I hereby disclaim, all of the aforementioned.

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[*] posted on 25-11-2017 at 17:58

Halobenzenes can N-arylate amides and anilines through a Goldberg reaction. This is the closest you're likely to get to arylation of simple amines.

EDIT Goldberg not Goldman

[Edited on 26-11-2017 by clearly_not_atara]

[Edited on 04-20-1969 by clearly_not_atara]
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[*] posted on 25-11-2017 at 19:25

Amines generally attack haloalkanes via nucleophilic substitution. Haloalkanes don't undergo such unless there are strongly electron-withdrawing groups on it (aniline will react with dinitrochlorobenzene, for example- I don't have a cite, I just remember doing it as a first-year organic lab).

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[*] posted on 26-11-2017 at 03:04

Dinitrochlorobenzene is a solid and unlikely to serve as a solvent.

You can use chlorobenzene as an alkylating agent for ammonia, but only under rather forcing conditions.
"The temperature most favorable with respect to the degree of reaction and to the yield is from about 300 to 450° C."
In that work the production of diphenylamine is regarded as a problem but it shows that aniline is alkylated under those conditions.

[Edited on 26-11-17 by unionised]
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