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Phensuprin (percent composition).
To isolate the acetylsalicylic acid, add the filtrate, i.e., the dichloromethane solution, to a
separatory funnel, and extract it with two 25 ml portions of 5% sodium bicarbonate solution. To
accomplish this, add one portion of the sodium bicarbonate solution to the separatory funnel
containing the dichloromethane solution, stopper the funnel, place one finger over the stopper to
hold it in place, and shake the funnel back and forth gently for 1-2 minutes. Every few seconds,
invert the funnel and open the stopcock to release the pressure (Point the tip of the funnel away
from yourself and anyone else around you before releasing the pressure!), close the stopcock,
and continue to shake the funnel. When the extraction period is finished, release the pressure one
final time, close the stopcock, and place the funnel in a ring or clamp. Immediately remove the
stopper, and, after the layers separate, drain the lower, dichloromethane layer into a 125 mL
Erlenmeyer flask. When the dichloromethane layer is removed, close the stopcock and pour the
aqueous layer from the funnel into a 400 mL beaker. Return the dichloromethane layer to the
funnel and repeat the procedure with the second portion of sodium bicarbonate solution.
Combine the two aqueous layers, and save the dichloromethane layer for the final step.
Cool the combined aqueous layers in an ice bath, and slowly, using a transfer pipet, add 10 ml of
concentrated hydrochloric acid with stirring. A lot of foaming will occur at this step. Swirl the
beaker between the HCl additions. When the addition is complete, test the pH of the solution by
inserting a glass rod, then touching the solution at the tip of the glass rod to a piece of pH paper.
If the pH is not pH 2 or lower, add additional small amounts of concentrated hydrochloric acid
until the pH is 2 or below. Continue to cool the aqueous solution in the ice bath until all of the
solid acetylsalicylic acid forms. Collect the solid by vacuum filtration and wash the solid with...
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