Preparing an ester - adding excess?? (2 Viewers)

[Munkiie]

I prepared an ester with 1-pentanol and ethanoic acid. So I have this question...

I know excess acid was added but "why was an excess of that reagent used rather than an excess of the other one? (Densities of 1-pentanol and glacial acid are 0.81 and 1.04g/ml respectively)"
What has the density got to do with it??

If the esterification did not go to completion, the product could still be contaminated with reactant. How could you purify it further?

 

[golgo13]

Separation funnel but i would look for something with a bigger margin

 

[starshine02]

When you separate the final mixture with a separating funnel, it does so based on density differences I think. You use excess acid as it will one of the heaviest layers (due to it's higher density as you've stated) and can be easily removed as it has quite a different density to the ester created. It's also so that you can use up as much of the alcohol as possible as the ester and the alcohol are both non polar and so they'd be in a similar layer and separating the ester and the alcohol would be quite difficult. If you use more acid, it'd also be able to push the equilibrium further to the products side (thus more ester) as well as using up the alcohol so that a minimal amount of it remains to be separated out.

 

[Munkiie]

When you separate the final mixture with a separating funnel, it does so based on density differences I think. You use excess acid as it will one of the heaviest layers (due to it's higher density as you've stated) and can be easily removed as it has quite a different density to the ester created. It's also so that you can use up as much of the alcohol as possible as the ester and the alcohol are both non polar and so they'd be in a similar layer and separating the ester and the alcohol would be quite difficult. If you use more acid, it'd also be able to push the equilibrium further to the products side (thus more ester) as well as using up the alcohol so that a minimal amount of it remains to be separated out.

Ohh makes sense, thanks