-1
$\begingroup$

I'm a beginning chemistry student, and I was wondering what the best way of removing sulfuric acid was following the creation of benzyl acetate. So far, I have that benzyl alcohol and glacial acetic acid are mixed in a 1:1 ratio to create the benzyl acetate in a beaker filled with molecular sieves (to remove the water and shift the reaction to the right). However, I am unsure as to how much sulfuric acid to add and how best to remove it from the final solution of ester, water, and sulfuric acid.

Thanks!

$\endgroup$
  • $\begingroup$ Welcome to ChemSE. If you accessed a reference stating the molar ratio of alcohol and acetic acid (why not acetanhydride?), likely the same reference will provide you a hint about the catalytic amount of sulfuric acid necessary. Give you a mid- and longterm favour, narrow your question, and show evidence you read further the lab protocol provided to you. Or take bus #69 to either Irchel or Hönggerberg. $\endgroup$ – Buttonwood Sep 14 '18 at 23:18
0
$\begingroup$

In a typical esterification, the sulfuric acid plays a catalytic role, so you don't need a lot, and removing it should not be a concern. Also, to drive the equilibrium reaction forward, you would want a slight excess of one of the reactants, usually the cheaper one of the acid or the alcohol (acetic acid in your particular case). The sulfuric acid is also a good dehydrating agent, so the sieves seem excessive. Finally, the ester is a bit more volatile than the other components (check a handbook for boiling points!), so distillation is standard. Otherwise, look into a Dean-Stark trap.

For other ideas on how one usually conducts an esterification, look up related syntheses in Organic Synthesis; e.g. this one or this one or this one.

$\endgroup$
0
$\begingroup$

Catalytic sulfuric acid is required so just a few drops should do it. To remove (or as it normally expressed work up) dilute the mixture with a relatively low boiling point organic solvent - ethyl acetate is good - and wash the solution with dil. sodium hydrogen carbonate solution. Separate off the organic phase (upper phase if you used EtOAc), dry it with a solid drying agent such as anhydrous magnesium sulfate, filter and remove the solvent under reduced pressure.

$\endgroup$
  • $\begingroup$ If the use of acetic acid/H2SO4 isn't mandatory, why not use acetic anhydride? $\endgroup$ – user55119 Sep 10 '18 at 0:56

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for?Browse other questions tagged or ask your own question.