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Author Topic: Are Friedel Crafts Acylation ortho driven?  (Read 487 times)

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saippo

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Are Friedel Crafts Acylation ortho driven?
« on: June 24, 2018, 07:46:04 PM »

While I understand why para and ortho are more stable in EAS reactions, I don't understand why ortho seems to be the go to positions unless there's some crazy amount of steric hindrance. For example, when I was practicing friedel crafts acylation, almost all of them assumed that the electrophile would attach at the ortho position. Can someone clarify this for me?

Thank you!
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wildfyr

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Re: Are Friedel Crafts Acylation ortho driven?
« Reply #1 on: June 25, 2018, 03:02:13 AM »

The primary reason ortho/para vs meta substituion occurs is not steric hinderence. Why do you say that ortho and para are more stable in EAS conditions? What does that even mean? There is another major factor in this reaction you are leaving out. What do you think it is?
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spirochete

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Re: Are Friedel Crafts Acylation ortho driven?
« Reply #2 on: June 26, 2018, 11:11:52 AM »

While I understand why para and ortho are more stable in EAS reactions, I don't understand why ortho seems to be the go to positions unless there's some crazy amount of steric hindrance. For example, when I was practicing friedel crafts acylation, almost all of them assumed that the electrophile would attach at the ortho position. Can someone clarify this for me?

Thank you!

Just to clarify your question: Are you asking about relative amounts of ortho vs para when the benzene ring is substituted with an O/P director? For example acylation products of phenol or toluene?

Also, a better way to phrase your initial statement would be to reference factors in the mechanism, especially the rate limiting step of the mechanism. Your phrasing was ambiguous, as Wildfyr pointed out.
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