Put the mixture in a separatory funnel containing pH9 aqueous solution and Et2O.
This way will selectively carry benzoic acid into the water phase, while leaving both amine and aldehyde in the ether phase.
Split the 2 phases and work on them separately.
Organic phase: add an acidic water solution at pH around 2-3. This will transform the amine in amonium ion, soluble in water. Split the 2 phases again. The organic one will contain only aldehyde and you need to get it dry through rotavapor. The aqueous one will have to be basified at pH 9 and re-extracted with Et2O in order to recover the purified amine as a free base.
Let come back to the first aqueous phase containing sodium (or K) salt of benzoic acid: add an acidi solution to bring the final pH at around pH 2, thus, the undissociated benzoic acid will precipitate. Filter it out and get it dry at max 60 °C. If you need it purer, you may it recristallize through hot water and filter it again and finally dry it into an oven at around 60 °C.
remove the solvent from the remaining 2 ethereal phases containing the other 2 chemicals.
Separation and purification
A mixture of benzoic acid, benzaldehyde and butylamine. What kind of experiment should you design to obtain each of the three compounds in a pure state.
Just need ideas in order to start this experimental design.
Thanks!!!
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