Question

Methyl benzoate was prepared by the reaction of benzoic acid with methanol in the presence of a mineral acid. The ester product was extracted into dichloromethane and then shaken with saturated sodium chloride solution. What is the purpose of the sodium chloride? To cause the water to be immiscible with the methylene chloride. To raise the density of the aqueous layer so that it will be the bottom layer. To lower the boiling point of the water. To decrease the solubility of the organic product in water.

Answer 1

To decrease the solubility of the organic product in water.

Step-by-step explanation:

Methyl benzoate is prepared via Fischer esterification reaction between benzoic acid and methanol in the presence of a mineral acid. The following steps are involved:

1. Benzoic acid is dissolved in methanol in a round bottom flask.
2. Concentrated sulphuric acid is added and heated under reflux on a steam bath
3. Reaction is poured into ice, reaction flask is rinsed with dichloromethane. Layers collected in a test tube.
4. Dichloromethane layer is then washed with first sodium carbonate solution(this is done inorder to neutralize and remove the residual benzoic acid) and then with sodium chloride solution(to decrease the solubility of the organic product in water).
5. Then Dichloromethane solution is dried over magnesium sulphate.
6. Dichloromethane is removed via distillation on a steam bath.
7. Collect distillate in a vial on a heating mantle.