Several small extractions are better than one large one. In this experiment you will separate the components of a pharmaceutical preparation, Extra Strength Excedrin, making use of solubilities and acid-base properties. In addition, each tablet contains a binder, often starch, microcrystalline cellulose, or silica gel, to hold the tablets together. Aspirin is soluble in dichloromethane but relatively insoluble in water. Sodium hydroxide converts aspirin to a salt, sodium acetylsalicylate, which is insoluble in dichloromethane but soluble in water.
Caffeine is a base and is soluble in dichloromethane and insoluble in water.
It is not convert to a salt by NaOH, but by HCl. Mixing the Excedrin with dichloromethane should dissolve the aspirin and caffeine, but leave the starch and acetaminophen behind. As insoluble solids they can be removed by filtration. The difference in solubility of these two substances in ethanol can be use to separate them. Aspirin can then be removed from the dichloromethane solution by extraction with an aqueous solution of sodium hydroxide, which converts the aspirin to its salt.