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rock.freak667
Mar16-08, 09:41 PM
1. The problem statement, all variables and given/known data
Some students had a disagreement about the esterification reaction between ethanol and ethanoic acid. Student A feels that the -OH group from the acid combines with the H from the alcohol functional group.
Suggest a hypothesis for his feeling and design a lab to test the hypothesis.

2. Relevant equations

C_2H_5OH + CH_3COOH \rightarrow CH_3COOC_2H_5 + H_2O

3. The attempt at a solution

Ok, well my idea would be to somehow label the oxygen on either the acid or the alcohol. I chose O-18. But I am not sure what steps are taken to actually label the oxygen like that.
Then react the two, extract the ester formed, and run it through a mass spectrometer. But when the ester is formed, it is formed in a layer with water,how do I separate the two? (Simple pipette and extract until it looks like all has been pipetted?)

chemisttree
Mar17-08, 07:52 PM
1. The problem statement, all variables and given/known data
Some students had a disagreement about the esterification reaction between ethanol and ethanoic acid. Student A feels that the -OH group from the acid combines with the H from the alcohol functional group.
Suggest a hypothesis for his feeling and design a lab to test the hypothesis.

2. Relevant equations

C_2H_5OH + CH_3COOH \rightarrow CH_3COOC_2H_5 + H_2O

3. The attempt at a solution

Ok, well my idea would be to somehow label the oxygen on either the acid or the alcohol. I chose O-18. But I am not sure what steps are taken to actually label the oxygen like that.

You can buy O-18 labelled water. Any help?

Then react the two, extract the ester formed, and run it through a mass spectrometer. But when the ester is formed, it is formed in a layer with water,how do I separate the two? (Simple pipette and extract until it looks like all has been pipetted?)
If you injected it into a GC-MS you wouldn't have to separate anything...

rock.freak667
Mar17-08, 08:51 PM
Ah well all I need to say is that I labelled the oxygen. So no need to elaborate on it.
But apparently I must use the normal mass spec. I know so I would need to extract it somehow. I'm thinking steam distillation.

chemisttree
Mar18-08, 11:04 AM
I'm thinking steam distillation.
Not a good idea in the presence of either an acid or base. Maybe diluting in solvent and drying with Na2SO4 after washing with bicarb.