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Topic: Transition State Quandary  (Read 2560 times)

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Offline FreddieHg

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Transition State Quandary
« on: July 19, 2013, 07:50:01 PM »
Hello! I've been trying to figure out an organic chem problem for quite awhile, with no luck.  I'm hoping someone can help me out with this:
« Last Edit: July 19, 2013, 08:35:37 PM by FreddieHg »

Offline discodermolide

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Re: Transition State Quandary
« Reply #1 on: July 19, 2013, 11:56:39 PM »
It would be nice if you posted the problem for us all to see.
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Offline FreddieHg

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Butyl Acetate Synthesis
« Reply #2 on: July 20, 2013, 12:45:24 AM »
That would help, wouldn't it?  Sorry about that; I tried to edit my post to give it a better title and everything got deleted below the picture.  Anyway, I'm stuck on the following question:

Which is the best synthesis of butyl acetate?



I know that Fischer esterification is commonly used to prepare esters by the reaction of a carboxylic acid and with an alcohol in the presence of an acid catalyst.  I think the correct answer should be #1 or #2, because those are the only two with alcohol as a reactant (1-butanol).  I'm confused because choice #1 uses HBr as the acid catalyst (H2SO4 and HCl are the ones most often used).  Would HBr be the best choice?  Also, most examples of Fischer esterification use acetic acid, and choice #1 lists sodium acetate. Choice #2 has acetic acid as a reactant, but uses sodium as a catalyst.  I don't understand that at all.  You need to have the acid catalyst to help form oxonium ions to protonate the carboxylic acid, correct?

Any help would be greatly appreciated!

Offline magician4

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Re: Transition State Quandary
« Reply #3 on: July 20, 2013, 06:07:29 AM »
# 3 throughout # 5 would give you an ester, yes, but not the one you're looking for ( look up "Markovnikov's rule" for details)

# 2 would lead to the vehement development of an explosive gas instead of any ester formation whatsoever (what would the reaction of sodium with alcohols be? or with acids?)

# 1 would give you Fischer esterification, yes, and HBr is a very potent acid to catalyse that
on the other hand, HBr is both expensive and somewhat voilatile, too, so in industrial processes you'd prefer to take cheaper acids like sulfuric acid, for example

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Offline orgopete

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Re: Transition State Quandary
« Reply #4 on: July 20, 2013, 05:54:49 PM »

# 1 would give you Fischer esterification, yes, and HBr is a very potent acid to catalyse that
on the other hand, HBr is both expensive and somewhat voilatile, too, so in industrial processes you'd prefer to take cheaper acids like sulfuric acid, for example


Hint, #1 is NOT a Fischer esterification, yet it is the correct answer. Why?
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