Aromatic chemistry - when is it electrophilic substitution

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jazz_xox_
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Considering phenylamine reacting with an acyl chloride..

I have a question to outline the mechanism between dimethylphenylamine and an acyl chloride

How do you know when acylation/electrophilic substitution occurs, and when the nitrogen on phenylamine will act like a nucleophile and attack the d+ carbon on the acyl chloride?

And when the nitrogen atom on the C6H5 attacks a d+ carbon, is this nucleophilic substitution?
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dhruvap
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If acyl chloride is reacting with the lone pair on the nitrogen it is nucleophilic addition-elimination. The nitrogen being the nucleophile adds itself on the acyl chloride and the chlorine is eliminated.

Electrophilic substitution occurs when an electrophile (e.g. NO2+ formed from the H2SO4+HNO3 reaction) substitutes a hydrogen from benzene.

Another example of electrophilic substitution is when an ethanoyl chloride reacts with AlCl3 to produce [AlCl4]- + CH3CO+. The +ve CH3CO acts as an electrophile and replace the H on benzene. Note : the +ve charge is on the C=O carbon as it has lost chlorine.

Hope this helps.
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jazz_xox_
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(Original post by dhruvap)
If acyl chloride is reacting with the lone pair on the nitrogen it is nucleophilic addition-elimination. The nitrogen being the nucleophile adds itself on the acyl chloride and the chlorine is eliminated.

Electrophilic substitution occurs when an electrophile (e.g. NO2+ formed from the H2SO4+HNO3 reaction) substitutes a hydrogen from benzene.

Another example of electrophilic substitution is when an ethanoyl chloride reacts with AlCl3 to produce [AlCl4]- + CH3CO+. The +ve CH3CO acts as an electrophile and replace the H on benzene. Note : the +ve charge is on the C=O carbon as it has lost chlorine.

Hope this helps.
Thanks so much. If the question just has the phenylamine and the acyl chloride- without mention of AlCl3 would you go with nucleophilic addition-elimination?
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dhruvap
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(Original post by jazz_xox_)
Thanks so much. If the question just has the phenylamine and the acyl chloride- without mention of AlCl3 would you go with nucleophilic addition-elimination?
Yep make sure you draw lone pair on Nitrogen going to the d+ carbon and then the C=O bond breaking. The N becomes + so it loses one of its hydrogen. Then only can chlorine be removed.
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jazz_xox_
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(Original post by dhruvap)
Yep make sure you draw lone pair on Nitrogen going to the d+ carbon and then the C=O bond breaking. The N becomes + so it loses one of its hydrogen. Then only can chlorine be removed.

Thank you!!

I'm not sure if I'll be able to word this properly but I'll try.. if you have phenylamine, and in an electrophilic subsitution with NO2+ or a carbocation, could the new electrophile become bonded to the benzene ring as well as the NH2 group? The carbon would still only have 3 bonds.
Usually when you draw the arrow from a single H bond into the positive centre of the benzene ring, it removes the hydrogen, but can you do this with a hydrogen already attached to a nitrogen?
Sorry if it makes no sense at all
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dhruvap
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(Original post by jazz_xox_)
Thank you!!

I'm not sure if I'll be able to word this properly but I'll try.. if you have phenylamine, and in an electrophilic subsitution with NO2+ or a carbocation, could the new electrophile become bonded to the benzene ring as well as the NH2 group? The carbon would still only have 3 bonds.
Usually when you draw the arrow from a single H bond into the positive centre of the benzene ring, it removes the hydrogen, but can you do this with a hydrogen already attached to a nitrogen?
Sorry if it makes no sense at all
Hmmm thats actually a good question, i'm still doing a levels however if i were to guess the NO2+ will be bonded to the benzene not the NH2. The reason being the electron density in the benzene ring is much greater than the lone pair on the NH2. I'm not 100% sure about this though
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jazz_xox_
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(Original post by dhruvap)
Hmmm thats actually a good question, i'm still doing a levels however if i were to guess the NO2+ will be bonded to the benzene not the NH2. The reason being the electron density in the benzene ring is much greater than the lone pair on the NH2. I'm not 100% sure about this though
Okay thanks they probably wouldn't ask in that depth, good luck in your a-levels!

I have my mock at 9am tomorrow
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dhruvap
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(Original post by jazz_xox_)
Okay thanks they probably wouldn't ask in that depth, good luck in your a-levels!

I have my mock at 9am tomorrow
.... i have my mock at 9am tomorrow too lol...
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jazz_xox_
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(Original post by dhruvap)
.... i have my mock at 9am tomorrow too lol...
Hahaha good luck to you!
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dhruvap
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(Original post by jazz_xox_)
Hahaha good luck to you!
good luck to you too
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