Question

Alanine is an amino acid and is a zwitterion at pH 7. An alanine crude is contaminated with sodium chloride, can you remove the sodium chloride from the crude with the liquid-liquid extraction technique used in this lab? Explain.

Answer 1

alanine is ionic at pH = 7 ( neutral conditions)

Hence alanine being in ionic form is soluble in water

Sodium chloride being ionic compound is also soluble in water.

For liquid-liquid extraction we need two compounds with different solubilities i.e one should be soluble in polar solvents like water ( either in acidic or basic conditions) and other should be soluble in non polar solvent like ether. Here both solutes soluble in water. Hence we cannot remove sodium chloride using this technique