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Topic: 4-aminophenol --> paracetamol  (Read 10573 times)

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Offline jsmith613

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4-aminophenol --> paracetamol
« on: May 17, 2012, 04:21:59 PM »
I was reading through my textbook and apparently when 4-aminophenol reacts with an acyl chlordie / acid anhydride (as in the synthesis of paracetamol) only the R-NH2 group reacts and NOT the R-OH group.

Why is this?
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Offline sjb

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Re: 4-aminophenol --> paracetamol
« Reply #1 on: May 17, 2012, 05:11:17 PM »
Quote from: jsmith613 on May 17, 2012, 04:21:59 PM
I was reading through my textbook and apparently when 4-aminophenol reacts with an acyl chlordie / acid anhydride (as in the synthesis of paracetamol) only the R-NH2 group reacts and NOT the R-OH group.

Why is this?

It doesn't, not always.  See http://books.google.co.uk/books?id=LXJ_62eaejoC&pg=PP36&lpg=PP36&dq=chemoselectivity+in+aminophenols&source=bl&ots=F3-sPTxWcl&sig=d7yihneo6G1TIZ5170XNj624Xx4&hl=en&sa=X&ei=KGm1T-zsA-XS0QWes5zlAw&ved=0CFEQ6AEwAA#v=onepage&q=chemoselectivity%20in%20aminophenols&f=false
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Offline jsmith613

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Re: 4-aminophenol --> paracetamol
« Reply #2 on: May 17, 2012, 05:29:46 PM »
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Offline AWK

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Re: 4-aminophenol --> paracetamol
« Reply #3 on: May 18, 2012, 03:11:23 AM »
The first page of this link shows you reaction of p-aminophenol with TsCl.
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Offline jsmith613

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Re: 4-aminophenol --> paracetamol
« Reply #4 on: May 18, 2012, 04:27:44 AM »
Quote from: AWK on May 18, 2012, 03:11:23 AM
The first page of this link shows you reaction of p-aminophenol with TsCl.

my question was SPECIFIC to the reaction of acid anhydride / acid chloride (R-COCl) which TsCl is not...
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Offline discodermolide

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Re: 4-aminophenol --> paracetamol
« Reply #5 on: May 18, 2012, 05:22:42 AM »
Quote from: jsmith613 on May 18, 2012, 04:27:44 AM
Quote from: AWK on May 18, 2012, 03:11:23 AM
The first page of this link shows you reaction of p-aminophenol with TsCl.

my question was SPECIFIC to the reaction of acid anhydride / acid chloride (R-COCl) which TsCl is not...


Because the nitrogen is more nucleophillic than the oxygen atom?
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Offline jsmith613

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Re: 4-aminophenol --> paracetamol
« Reply #6 on: May 18, 2012, 07:08:27 AM »
Quote from: discodermolide on May 18, 2012, 05:22:42 AM

Because the nitrogen is more nucleophillic than the oxygen atom?


in excess would the -OH group also react?
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Offline discodermolide

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Re: 4-aminophenol --> paracetamol
« Reply #7 on: May 18, 2012, 07:11:02 AM »
Quote from: jsmith613 on May 18, 2012, 07:08:27 AM
Quote from: discodermolide on May 18, 2012, 05:22:42 AM

Because the nitrogen is more nucleophillic than the oxygen atom?


in excess would the -OH group also react?

Yes
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Offline AWK

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Re: 4-aminophenol --> paracetamol
« Reply #8 on: May 18, 2012, 07:17:04 AM »
Quote from: AWK on May 18, 2012, 03:11:23 AM
The first page of this link shows you reaction of p-aminophenol with TsCl.
TsCl is an acid chloride!
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Offline jsmith613

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Re: 4-aminophenol --> paracetamol
« Reply #9 on: May 18, 2012, 07:32:03 AM »
thanks
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Offline fledarmus

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Re: 4-aminophenol --> paracetamol
« Reply #10 on: May 21, 2012, 08:09:27 AM »
Quote from: AWK on May 18, 2012, 07:17:04 AM
Quote from: AWK on May 18, 2012, 03:11:23 AM
The first page of this link shows you reaction of p-aminophenol with TsCl.
TsCl is an acid chloride!

But not an...
Quote
acid chloride (R-COCl)

which is what AWK limited his question to. TsCl is a sulfonic acid chloride, not a carboxylic acid chloride.

If you want to argue that they will react the same, that is a different issue
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Offline sjb

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Re: 4-aminophenol --> paracetamol
« Reply #11 on: May 21, 2012, 08:44:40 AM »
Sorry, this is probably my fault for muddying the waters. Fundamentally I don't see any reason why the sulfonyl chloride will not react the same way as the acyl chloride. It's possible that I'm wrong.
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