June 6, 2013
Title: Extraction of an Unknown Compound
Purpose: The purpose of this experiment was to separate a mixture of two or more unknown compounds and identify them based on their melting point and reactivity with an acid or a base. Compound studied/Reactions: The organic solvent used in this experiment was methyl t-butyl ether (MTBE, 2-methoxy-2-methylpropane). The unknown that dissolved in the MTBE, but was insoluble in water. MBTE is very volatile and flammable. It was determined in the experiment that the unknown was an organic base (an amine) that reacted with aqueous acid (HCl) to form a water-soluble salt. This reaction is seen below: RNH2 + HCl(aq) ( RNH3+Cl-(aq)
Procedure: It was determined prior to carrying out the experiment that the unknown compound that was used contained a basic compound, not the acidic compound. One gram of the unknown was placed into an Erlenmeyer flask with approximately 30mL of MBTE. The solution was swirled and stirred until all of the unknown solid was dissolved, it was then decanted and placed into a separatory funnel. The unknown mixture contained a basic compound so 15mL of HCl was added to the separatory funnel and shaken up to mix. With the stopper in place on the separatory funnel, the two layers separated, the bottom layer was drained into a beaker, this was the water layer of the solution and set aside for further testing later. To recover the neutral compound from the ether solution, 15mL of saturated aqueous NaCl was added to the separatory funnel using the same technique as before. The bottom layer was drained and discarded in the sink. The remaining layer, the ether layer, was poured out of the top of the funnel into a Erlenmeyer flask with several scoops of anhydrous MgSO4 to dry the ether solution. The solution was decanted into a 100mL round bottom flask and the ether was removed using a rotary evaporator. The remaining solid, which was the neutral organic compound, was...
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