Question

Name an organic solvent that is generally suitable for separating the free base from the salt form of an organic base (e.g. cocaine) using the “dry solvent” extraction technique.

Answer 1

Chloroform, Dichloromethane, Ethyl acetate, etc., can be used to extract the free base of an organic salt from the aqueous solution when the pH of the aqueous solution is raised to alkaline pH either by adding NaHCO₃ or KHCO₃.

Organic salts are usually hydrochloride salts of amine bases. Whereas, when they are treated with bases such as bicarbonate salts, the free base (free amine) is generated. The free amine bases are generally not soluble in water but very much soluble in organic solvents such as chloroform or ethylacetate. The free base after extraction can be obtained by evaporating the organic solvent.