Question

Azeotropes can be used to shift chemical equilibria by removing products. Treatment of 1-butanol with acetic acid in the presence of sulfuric acid as a catalyst results in formation of butyl acetate and water. The mixture of 1-butanol/butyl acetate/ water forms a ternary azeotrope that boils at 90.7 degree C. This azeotrope separates into two layers; the upper layer is largely butyl acetate, along with 11% 1-butanol, and the lower layer is largely water. Butyl acetate forms by an equilibrium reaction that does not especially favor product formation.

a. Describe an apparatus by which azeotrope formation can be used to drive the equilibrium toward the products, thus maximizing the yield.

b. How would you separate the 1-butanol/butyl acetate mixture that forms the upper azeotropic layer?

Answer 1

a. Dean-Stark apparatus is an apparatus by which azeotrope formation can be used to drive the equilibrium toward the products, thus maximizing the yield.

b. The Dean-Stark apparatus contains a condenser (to be given cold water circulation) on the top, can be used to distill the mixture of compounds, especially azeotropic mixture, which is designed in such a way that the water in the mixture can be separated completely by collecting it in a separate receiver (mostly a beaker or conical). while the organic part will return to the boiling flask. Then the distillate is completely free of water.