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Topic: Trace Acid  (Read 17620 times)

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Offline cundi

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Re: Trace Acid
« Reply #15 on: March 10, 2009, 09:41:51 AM »
I think that all of you are mistaked in the answer.

Dehydratation, isomerization = a,b-insaturated aldehyde

Offline lutesium

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Re: Trace Acid
« Reply #16 on: March 10, 2009, 04:47:53 PM »
Might he be just a purification process??? It can't be dehydration reaction cuz the acid is too dilute!!! It might be a hydration reaction or maybe a rearrangement reaction which seems unlikely!!! I'd still say him to be a purification reaction!!!


Lutesium...

Offline James Newby

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Re: Trace Acid
« Reply #17 on: March 10, 2009, 05:33:41 PM »
My two cents:

The aldehyde is by far the most reactive group here so would get protonated before the alcohol.  The alcohol is tethered to the cyclic ring and one of its lone pair of electrons will be sat right next to an activated aldehyde.  The ring would snap shut as 5 membered cyclic hemiacetals are stable (wiki hemiacetals).
4th year undergraduate at the University of Sheffield

Offline nj_bartel

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Re: Trace Acid
« Reply #18 on: March 10, 2009, 05:47:35 PM »
Might he be just a purification process??? It can't be dehydration reaction cuz the acid is too dilute!!! It might be a hydration reaction or maybe a rearrangement reaction which seems unlikely!!! I'd still say him to be a purification reaction!!!


Lutesium...

It never said the acid was in water.

Offline lutesium

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Re: Trace Acid
« Reply #19 on: March 12, 2009, 04:29:10 PM »
Might he be just a purification process??? It can't be dehydration reaction cuz the acid is too dilute!!! It might be a hydration reaction or maybe a rearrangement reaction which seems unlikely!!! I'd still say him to be a purification reaction!!!


Lutesium...

It never said the acid was in water.
Ok but I really don't see a reaction in here that'd occur with trace amount of acid here!!! Dehydrative cyclization (to the BenzoPentanone) with the phenolic -OH group being eliminated which is so unlikely!!!


Lutesium...

Offline James Newby

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Re: Trace Acid
« Reply #20 on: March 12, 2009, 04:54:28 PM »
trace acid catalyses the ring closing reaction, ill give the mechanism as well:

Can you see how the acid is acting as a catalyst?
4th year undergraduate at the University of Sheffield

Offline lutesium

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Re: Trace Acid
« Reply #21 on: March 13, 2009, 10:37:23 AM »
Ok that's possible but with trace amounts of substrate!!! If the substrate is 1kg / lt trace amounts of acid won't do anything if this reaction is desired long reflux times must also be considered!!!


Lutesium...

Offline sjb

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Re: Trace Acid
« Reply #22 on: March 13, 2009, 10:47:02 AM »
Ok but I really don't see a reaction in here that'd occur with trace amount of acid here!!! Dehydrative cyclization (to the BenzoPentanone) with the phenolic -OH group being eliminated which is so unlikely!!!

What phenolic -OH? All I can see is regular old aliphatic hydroxyl groups....

S

Offline lutesium

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Re: Trace Acid
« Reply #23 on: March 13, 2009, 11:04:05 AM »
Ok ok I didn't pay attention to the molecule!!! Of course he is not a phenolic -OH he is just an aliphatic -OH...

Lutesium...

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