Preparation of benzoic acid by hydrolysis of ethyl benzoate

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Pheonixfeather3
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What's the equation for the preparation of benzoic acid by hydrolysis of ethyl benzoate? Thanks
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Laurasaur
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(Original post by Pheonixfeather3)
What's the equation for the preparation of benzoic acid by hydrolysis of ethyl benzoate? Thanks
If you want benzoic acid, you'll want to use acid hydrolysis with either dilute HCl or dilute H2SO4. You'll end up making benzoic acid and ethanol.

If this helps, try to write the balanced equation for it.
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Pheonixfeather3
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(Original post by Laurasaur)
If you want benzoic acid, you'll want to use acid hydrolysis with either dilute HCl or dilute H2SO4. You'll end up making benzoic acid and ethanol.

If this helps, try to write the balanced equation for it.
I used HCl, I have most of my report written but can't for the life of me figure out the balanced equation.
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Laurasaur
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(Original post by Pheonixfeather3)
I used HCl, I have most of my report written but can't for the life of me figure out the balanced equation.
The key word is 'dilute' HCl, which means that there is another more important molecule involved

The H+ from HCl acts as a catalyst.
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Pheonixfeather3
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(Original post by Laurasaur)
The key word is 'dilute' HCl, which means that there is another more important molecule involved
C9H10O2+ NaOH + HCl - C7H6O2 + NaCl + H2O
that's what I've managed to get so far, and I've genuinely spent about an hour trying to balance it. Is it balancable?
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Maker
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(Original post by Pheonixfeather3)
C9H10O2+ NaOH + HCl - C7H6O2 + NaCl + H2O
that's what I've managed to get so far, and I've genuinely spent about an hour trying to balance it. Is it balancable?
You end up with a bit of a mess if you add NaOH. The NaOH will react with HCl to produce NaCl and H2O in preference to ethyl benzoate.
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Laurasaur
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(Original post by Pheonixfeather3)
C9H10O2+ NaOH + HCl - C7H6O2 + NaCl + H2O
that's what I've managed to get so far, and I've genuinely spent about an hour trying to balance it. Is it balancable?
What level are you, A level? If so, which exam board? Just for reference so I know what kind of answer to give you.

You seem to have lost 2 carbon atoms somewhere, make sure you add in the ethanol to the products.
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Pheonixfeather3
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(Original post by Maker)
You end up with sodium chloride and ethyl benzoate and water.
Wait... how do I end up with ethyl benzoate if the reaction gave me benzoic acid crystals?
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Pheonixfeather3
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(Original post by Laurasaur)
What level are you, A level? If so, which exam board? Just for reference so I know what kind of answer to give you.

You seem to have lost 2 carbon atoms somewhere, make sure you add in the ethanol to the products.
SQA advanced higher, so equivalent to second year of a level
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Maker
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(Original post by Pheonixfeather3)
Wait... how do I end up with ethyl benzoate if the reaction gave me benzoic acid crystals?
Are you sure its not NaCl crystals you have instead or as well as benzoic acid or sodium benzoate? NaOH will react more with HCl than ethyl benzoate.

Do a melting point test to see what you have.
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Laurasaur
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(Original post by Pheonixfeather3)
SQA advanced higher, so equivalent to second year of a level
Okay! I'd say the NaOH and HCl react to form NaCl and, importantly, H2O. It is the H2O that then reacts with the ester, breaking it up into a carboxylic acid and an alcohol. try that. Ester + water -> alcohol + carboxylic acid.

Then try to incorporate the NaOH and HCl, remembering that the water produced has been used up in the alcohol and carboxylic acid. So you won't need to write H2O on the right hand side.
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Pheonixfeather3
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(Original post by Maker)
Are you sure its not NaCl crystals you have instead or as well as benzoic acid or sodium benzoate? NaOH will react more with HCl than ethyl benzoate.

Do a melting point test to see what you have.
Done the melting point, got benzoic acid. The experiment is for benzoic acid.


(Original post by Laurasaur)
Okay! I'd say the NaOH and HCl react to form NaCl and, importantly, H2O. It is the H2O that then reacts with the ester, breaking it up into a carboxylic acid and an alcohol. try that. Ester + water -> alcohol + carboxylic acid.
Oh my god thank you!
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Laurasaur
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(Original post by Pheonixfeather3)
Oh my god thank you!
No problem, took me a while to figure that out too!
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