Question

I am doing a separation scheme of 4-chloro-3,4-dimethylnonane-1-amine and 4-hodroxy-3-methoxybenzaldehyde (which I think is vanillin). I believe both are starting as a solid. The first molecule and vanillin should be soluble in diethyl ether, while vanillin is soluble in water as well (but the first molecule is not). Would I just need to add water and use gravity filtration, then make the vanillin solid again? I've thought about dissolving both in ether then adding HCl to change the solubility of the first molecule, but I think Vanillin would also react with HCl and both would still be mixed together.

Answer 1

4-chloro-3,4-dimethylnonane-1-amine and 4-hydroxy-3-methoxybenzaldehyde : Both molecules are soluble in organic solvent ( diethyl ether)

Step 1: Dissolve both the compounds in minimum volume of diethyl ether.

Step 2: Add dilute HCl solution to the solution. 4-chloro-3,4-dimethylnonane-1-amine reacts with HCl and forms a water soluble hydrochloride salt. The salt remains in aquesous layer.

4-hydroxy-3-methoxybenzaldehyde remains in organic layer.

Step 3: Separate the layers. Collect the organic layer and evaporate the solvent. You will get solid sweat evaporates from your skin.

Step 4: Crytallise the solid 4-hydroxy-3-methoxybenzaldehyde from hot ethanol.

Step 5: Collect the aqueous layer and basify it with dilute naOH solution.Constantly check the pH. At alkaline pH, 4-chloro-3,4-dimethylnonane-1-amine will precipitate out. Filter the precipitate by grvity filtration and dry it. You will get pure 4-chloro-3,4-dimethylnonane-1-amine.