Can Oxygen Labeling Prove the Esterification Reaction Mechanism in P&D Lab?

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Discussion Overview

The discussion centers around the esterification reaction between ethanol and ethanoic acid, specifically exploring how oxygen labeling could be used to investigate the reaction mechanism. Participants are considering experimental designs to test hypotheses related to the reaction process.

Discussion Character

  • Homework-related
  • Experimental/applied
  • Debate/contested

Main Points Raised

  • Some participants propose labeling the oxygen in either ethanol or ethanoic acid with O-18 to trace its involvement in the reaction.
  • One participant suggests using O-18 labeled water as a source for the oxygen labeling.
  • There is uncertainty about the method for labeling the oxygen and how to effectively separate the ester from water after the reaction.
  • One participant mentions the possibility of using gas chromatography-mass spectrometry (GC-MS) to avoid separation issues.
  • Another participant expresses concern about using steam distillation in the presence of acid or base and suggests alternative methods like diluting in solvent and drying with Na2SO4.

Areas of Agreement / Disagreement

Participants express differing opinions on the best method for separating the ester from water and the appropriateness of steam distillation. There is no consensus on the optimal experimental design or the validity of the proposed methods.

Contextual Notes

Participants have not fully resolved the assumptions regarding the labeling process and the separation techniques. The discussion reflects a range of experimental approaches and considerations without definitive conclusions.

Who May Find This Useful

This discussion may be useful for students and educators interested in organic chemistry experiments, particularly those focusing on reaction mechanisms and analytical techniques.

rock.freak667
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Homework Statement


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.

Homework Equations



C_2H_5OH + CH_3COOH \rightarrow CH_3COOC_2H_5 + H_2O

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?)
 
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rock.freak667 said:

Homework Statement


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.

Homework Equations



C_2H_5OH + CH_3COOH \rightarrow CH_3COOC_2H_5 + H_2O

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...
 
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.
 
rock.freak667 said:
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.
 

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