Preperation of an ester?

Question

I need to do a write up on the preperation and purification of an ester.

pentan-1-ol and pure ethanoic acid were used. I need an equation for the esterification reaction.

I need to describe observations of:

(i) Before, during and after reflux

(ii) Seperation with water and with sodium carbonate solution

(iii) Describe the product of distillation

Need to identify 2 hazards associated with ester preperation and describe the precauations taken to ensure safety.

Thanks for any help.

Answer 1

Reaction:

CH3CH2CH2CH2CH2OH + CH3CO2H ↔ CH3CH2CH2CH2CH2O2CCH3 + H2O (Acid Catalysis)

Without having been present when the reaction was done (presumably you were there), I can't comment on observations. However, I would have done the reaction with a large excess of ethanoic acid, to drive the equilibrium to the right (limiting the amount of unreacted alcohol), and also because it can be easily removed from the final product mixture. I would expect the ester to have a sweet fruity smell, while the initial mixture would smell like vinegar.

If the whole final reaction mixture is dissolved into ether, extracting with carbonate solution will remove the unreacted ethanoic acid and acid catalyst. The ether solution containing the ester product can then have any water present removed with anhydrous magnesium sulfate, and the ether stripped away after filtration to give the final product ester.

One hazard is that ether is a very volatile and flammable solvent to handle during extractions (Richard Pryor found this out the hard way). Make sure there are no open flame or ignition sources during extraction and other operations involving the ether. Another hazard is handling the strong acid catalysts, in this case make sure proper personal protective equipment (gloves, goggles, etc.) are worn.