Question

A fisher esterification was performed for the formation of benzyl acetate from 2.0 mL of benzyl alcohol and 6 mL of glacial acetic acid with 5 drops of concentrated sulfuric acid to catalyze the reaction. The mixture was refluxed for one hour and then water wa added before organic and inorganic layers were drained from a seperatory funnel. The organic layer was then washed with 20 mL of saturated NaCl. Afterward the product was dried with anhydrous Na2SO4.

Did the reaction go to completion? How can you be certain?

Why is NaHCO3 used to neutralize the acid rather than NaOH?

Answer 1

In the present reaction 2mL of benzyl alcohol is used density of benzyl alcohol is 1.04 g/cm3. So it's weight and volume is same so 2 grams of benzyl alcohol is used it's molecular weight is 108.14 g/mole .so 0.0184 moles of benzyl alcohol used. On the other hand 6 mL of glacial acetic acid is used it's density is also1.05 g/cm3. so volume and weight are same. It's molecular weight is 60.052 g/mole. so we used 0.099 moles that means 10 times of benzyl alcohol.so the reaction goes completely. This can be monitored by TLC Plate. NaHCO3 is used to neutralize the excess acid since it is weak base. If we use NaOH it is a strong base it hydrolyses the product benzyl acetate in to benzyl alcohol and sodium acetate.