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Topic: Nucleophilic aromatic substitution with Benzamide?  (Read 3064 times)

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Offline Woodwardt84

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Nucleophilic aromatic substitution with Benzamide?
« on: November 26, 2011, 05:22:30 AM »
Hi guys

I have been doing NAS on 4-Bromo-2-fluorobenzonitrile. Is it possible to do NAS on 4-bromo-2-fluorobenzamide? I don't see why it shouldn't but some people in my surroundings claim that it is more difficult on an amide than a nitrile. Any experiences?

Offline Arctic-Nation

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Re: Nucleophilic aromatic substitution with Benzamide?
« Reply #1 on: November 26, 2011, 06:36:47 AM »
The reaction will work, but more slowly than with the nitrile because amide is a weaker electron-withdrawing group.

A different problem that might pop up is that if your nucleophile is a strongish base and your amide is primary or secondary, the amide or its anion might take over the role of the nucleophile. Don't have any practical experience with this, though.

Offline Woodwardt84

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Re: Nucleophilic aromatic substitution with Benzamide?
« Reply #2 on: November 26, 2011, 06:50:07 AM »
The reaction will work, but more slowly than with the nitrile because amide is a weaker electron-withdrawing group.

A different problem that might pop up is that if your nucleophile is a strongish base and your amide is primary or secondary, the amide or its anion might take over the role of the nucleophile. Don't have any practical experience with this, though.

I have substituted the flour in the benzonitrile with Butanol and heptanol, deprotonating the alcohol with Cesiumcarbonate. I don't think the protons on the amide should be a problem. :)

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