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Topic: how i get the purity of ethyl acetate with good yield  (Read 11553 times)

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Offline lubnashraf

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how i get the purity of ethyl acetate with good yield
« on: August 24, 2007, 02:51:07 AM »
how i get the purity of ethyl acetate with good yield? i am preparing ethylacetate through esterification having 98% purity but 70% yield by using excess ethanol as compared to acetic acid, how i get good yield with high purity. i am also prepare butyl acetate and methyl acetate but these acetates give high purity and good yield as compared to ethyl acetate? i cond understand why it happen what kind of  chemistry involve in ethyl acetate?

thanx,
lubna

Offline Yggdrasil

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Re: how i get the purity of ethyl acetate with good yield
« Reply #1 on: August 24, 2007, 02:59:14 AM »
Why is your yield low?  Is the reaction not going all the way to completion?  Are you losing product during the purification?

Offline ryanflag

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Re: how i get the purity of ethyl acetate with good yield
« Reply #2 on: August 24, 2007, 04:36:11 AM »
   I am not sure if you have completed your reaction and any loss in your purification.But according to your description,maybe you could improve the result by modifying your reaction parameters such as rate of materials, reaction temperature and time. I guess,the temprature would be the key to this reaction.

Online AWK

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Re: how i get the purity of ethyl acetate with good yield
« Reply #3 on: August 24, 2007, 06:50:15 AM »
Ethyl acetate form binary and ternary azeotropes with  ethanol and water boiling at 71.8 and 70.3 C, respectively. This is the reason of difficulties in purification of ethyl acetate and relatively low yield of synthesis when an excess of ethanol is used.

see:
http://en.wikipedia.org/wiki/Azeotrope_(data)
AWK

Offline lubnashraf

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Re: how i get the purity of ethyl acetate with good yield
« Reply #4 on: August 27, 2007, 03:24:05 AM »
Why is your yield low?  Is the reaction not going all the way to completion?  Are you losing product during the purification?
yes i am loosing ethyl acetate when i go to purify it. whats the suitable temperature and time for reaction?

Offline lavoisier

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Re: how i get the purity of ethyl acetate with good yield
« Reply #5 on: August 27, 2007, 01:02:40 PM »
I think the easiest way around the problem would be to change the esterification method.
Instead of Fischer esterification, you could react ethanol with acetic anhydride with catalysis of H2SO4, or add 1 Eq of SOCl2 to an equimolar mixture of EtOH and AcOH.
I know it's not a good method for large scale production, but you didn't specify what quantities you need to work with.
And I assume you can't use actual industrial methods, involving gases and special catalysis.

Offline lubnashraf

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Re: how i get the purity of ethyl acetate with good yield
« Reply #6 on: August 30, 2007, 07:19:30 AM »
I think the easiest way around the problem would be to change the esterification method.
Instead of Fischer esterification, you could react ethanol with acetic anhydride with catalysis of H2SO4, or add 1 Eq of SOCl2 to an equimolar mixture of EtOH and AcOH.
I know it's not a good method for large scale production, but you didn't specify what quantities you need to work with.
And I assume you can't use actual industrial methods, involving gases and special catalysis.
ofcourse i am doing my research work in lab so cnt use industrial method. i am using equal molar ratio of ac/acid and ethanol in the presence of sulfuric acid catalyst, my question is that how improve my yield could we got 100% yield? whts the suitable temperature for ethyl acetate reaction?

Offline Yggdrasil

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Re: how i get the purity of ethyl acetate with good yield
« Reply #7 on: August 30, 2007, 02:25:09 PM »
Esterification reactions are readily reversible, so you end up with an equilibrium between products and reactants.  With equimolar ratios, you usually get a poor yield.  Instead, you should use a large (I'd say at least 5x) excess of one reagent to drive the equilibrium toward the production of product.  It will be impossible to get 100% yield, but you should improve your yield.  Also, since water is a product, you want to be sure that you don't have any water in your reaction flask prior to the start of the reaction, as water will shift the equilibrium away from the production of products.  This means using absolute (200 proof) EtOH and not 95% EtOH.

As for temperature, you need to heat or else the reaction won't go forward.  Refluxing should work fine, although I have not looked up the optimal conditions.

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