In: Chemistry
As a chemist working in a pharmaceutical company you were tasked to separatephanacitin, naproxen and caffeine using acid-base extraction. Construct a flow chartshowing how you would separate a solution of these three compounds if they weredissolved in dichloromethane. You may use sodium bicarbonate, HCl and NaOH as needed in this flow chart. Be sure to include information identifying which layer iswhich.
Dissolve the mixture of phenacitin, naproxen and caffeine in DCM. Transfer it into a separating funnel. Extract the mixture with aqueous HCl. Only caffeine will react to form a salt and dissolve in the aqueous layer. This layer should be removed into a beaker. The remaining DCM layer now contains phenacetin and naproxen. Then the DCM layer is basified with NaOH solution resulting in the formation of the ionic compound of naproxen. It will dissolve in the aqueous layer and removed into another seperate beaker. The remaining DCM layer now contains only neutral compound Phenacetin.
(1) The beaker containing an aqueous layer containing the ionic salt of caffeine is treated with NaHCO3 to regenerate caffeine. (litmus test may confirm the basicity of the solution). The basic solution is then transferred into a separating funnel and extracted with DCM. The top aqueous layer is discarded and the DCM layer dried with anhydrous Na2SO4. The DCM is removed on a rotatory evaporator and pure caffeine obtained.
(2) The naproxen is regenerated from the beaker containing an aqueous layer of it upon treatment with HCl. And then following the step as in (1) gives pure naproxen.
(3) The Phenacetin is obtained by drying the final DCM layer on rotatory evaporator.