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Topic: Mass action control of alcohol/alchene equilibrium  (Read 4463 times)

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Offline ultrashogun

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Mass action control of alcohol/alchene equilibrium
« on: November 01, 2007, 08:07:35 AM »
In Solomons it says that to push the equilibrium towards the alchene I need to use concentrated sulforic or phosphoric acid with little water. The part about small amounts of water makes sense because that way the production of the alcohol is reduced, however wouldnt large amounts of sulforic acid actually lead to the production of akile sulfates?

Offline Yggdrasil

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Re: Mass action control of alcohol/alchene equilibrium
« Reply #1 on: November 03, 2007, 02:59:43 AM »
Dehydration of alcohols to alkenes produces water as a product.  Sulfuric acid destroys the water that is produced, helping to further drive the equilibrium towards the production of alkenes.

Offline Renium

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H2SO4 doesn't actually destroy water.
« Reply #2 on: November 03, 2007, 08:21:58 AM »
Dear Yggdrasil,

maybe I don't quite understand English language, but I think it's more correct to say "H2SO4 removes H2O from the mixture" than "H2SO4 destroys H2O".

Offline ultrashogun

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Re: Mass action control of alcohol/alchene equilibrium
« Reply #3 on: November 04, 2007, 06:23:12 AM »
Thanks for your answers, its actually so obvious.

Offline Renium

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About alkyl sulfates
« Reply #4 on: November 04, 2007, 11:00:00 AM »
In proper conditions, H2SO4 reacts with C2H5OH:

H2SO4 + C2H5OH = H2O + C2H5OSO3H

and the product, as you see, is alkyl sulfate. It can even be isolated from other substances, as far as I know. But it's an unstable substance, and it easily reacts with C2H5OH:

C2H5OSO3H + C2H5OH = (C2H5)2O + H2SO4

I think, if you increase the amount of H2SO4, it would actually lead to the production of akile sulfates in both reactions, and you would get more alkyl sulfate this way.
« Last Edit: November 04, 2007, 11:15:56 AM by Renium »

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