Esterification using a Dean-Stark

Goal : Using a Dean-Stark to improve the yield of banana ester synthesis.

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Hi ! Today's lab experiment is an esterification using 3-methylbutan-1-ol and cyclohexane.

Step 1 : Dean-Stark assembly :

I made the Dean-Stark assembly and added in it cyclohexane so that its level is flush with the descending elbow tube. I added in the flask 27.2 mL of 3-methylbutan-1-ol, 11.4 mL of pure ethanoic acid, the remaining cyclohexane (total was 20 mL) and 0,5 g of para-toluene sulfonic acid. And I added some pumice. I heated at reflux until the distillation seemed done ( around 30min ), I stopped the heat and let it reflux for 5 more minutes and then I cooled it at room temperature.

Step 2 : Separating funnel and titration :

I cooled once again the reaction mixture using an ice bath. Then, using a separating funnel with 20 mL of water, I extracted the reaction mixture 3 times. I then regrouped the 3 aqueous phases into one (around 60 mL) which I titrated using a solution of sodium hydroxide and a few drops of thymol blue as my color indicator.

Step 3 : Calculus :

Using my newly obtained Veq, I was able to find the total acid quantity in my reaction mixture. Then I was able to find the molar quantity of ethanoic acid remaining in my reaction mixture. Finally, I calculated the synthesis yield which was 94,7%.

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This lab experiment showed me the importance of the Dean-Stark assembly and how it helps improving the synthesis yield. In the end, my reaction mixture smelled like banana and it made me really proud and happy !