Show how you would use extractions with a separatory funnel to separate a mixture of the following compounds: benzoic acid, phenol, benzyl alcohol, aniline

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Step 1: Begin by understanding the properties of each compound in the mixture. Benzoic acid is a carboxylic acid, phenol is a weak acid, benzyl alcohol is a neutral compound, and aniline is a basic amine. This knowledge will guide the extraction process.

Step 2: Add the mixture to the separatory funnel and dissolve it in a suitable organic solvent, such as diethyl ether or dichloromethane. This solvent should be immiscible with water, allowing for effective separation.

Step 3: Perform the first extraction by adding an aqueous solution of sodium bicarbonate (NaHCO₃) to the separatory funnel. This will convert benzoic acid into its water-soluble sodium benzoate salt, allowing it to be separated into the aqueous layer.

Step 4: Next, add an aqueous solution of sodium hydroxide (NaOH) to the remaining organic layer in the separatory funnel. This will convert phenol into its water-soluble phenoxide ion, allowing it to be separated into the aqueous layer.

Step 5: Finally, add an aqueous solution of hydrochloric acid (HCl) to the remaining organic layer. This will convert aniline into its water-soluble anilinium chloride salt, allowing it to be separated into the aqueous layer. Benzyl alcohol remains in the organic layer as it is neutral and not affected by the acid or base treatments.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Acid-Base Extraction

Acid-base extraction is a technique used to separate compounds based on their acid-base properties. By adjusting the pH of the solution, acidic or basic compounds can be converted into their ionic forms, making them soluble in water, while neutral compounds remain in the organic phase. This allows for selective separation using a separatory funnel.

Solubility and Partition Coefficient

Solubility refers to the ability of a compound to dissolve in a solvent, while the partition coefficient is the ratio of concentrations of a compound in two immiscible solvents. Understanding these properties helps predict how compounds will distribute between aqueous and organic phases during extraction, enabling effective separation of the mixture.

Separatory Funnel Technique

A separatory funnel is a laboratory tool used to separate immiscible liquids based on density differences. By adding solvents and shaking the mixture, compounds distribute between the layers according to their solubility and partition coefficients. Careful draining of each layer allows for the isolation of specific compounds from a mixture.

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