Organic Chemistry: Separating Acids and Neutral Compounds by Solvent Extraction

Question

Organic Chemistry: Separating Acids and Neutral Compounds by Solvent Extraction

Reagents and Solvents Used

Acetanilide/p-Toluic Acid mixture, diethyl ether, 3M hydrochloric acid, 0.5M sodium hydroxide, sodium sulfate, anhydrous, water-distilled or deionized

PURPOSE OF THE EXPERIMENT: Use solvent extraction techniques to separate a mixture consisting of a carboxylic acid and a neutral compound.

Questions:

1. What product would you obtain if you evaporated the water from the NaOH layer prior to acidifying the layer?

2. Suppose that you used dichloromethane instead of diethyl ether as the nonpolar solvent in this experiment. What changes in the procedure would you make in view of the fact that dichloromethane is more dense than water?

3. Benzoic acid (C6H5—COOH) is a weak acid and naphthalene is neutral, neither acidic or basic. Prepare a flowchart for the separation and recovery of benzoic acid and naphthalene.

Benzoic Acid: solubility in water: poor ; solubility in ether: good

Naphthalene: solubility in water: poor ; solubility in ether: good

Thank You In Advance!

Explanation / Answer

Q1)

If you evaporate water, you will concentrate the base, that is, increase moles of NaOH per liter of solution, making it more basic, i.e. higher pH

Q2)

You will expect the change of layer. Water is "lighter" therefore expect the extraction to differ.

Q3)

If you add NaOH to the mixture

All phenols (benzoic aicd) will remain in the aqueous layer (as carboxylate ion)

The organic layer will have the naphtalene

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