Purpose

Extraction is a method used to separate or isolate a particular component of a mixture. This process requires a solvent which allows the desired compound (or compounds) to separate from a solid into a solvent or from a solution into another solvent. In this experiment three compounds were separated; a neutral compound and two weak acids, these compounds are then measured before and after the process in order to determine the efficacy of the separation technique.

Reactions

1. Reaction 1: the reaction of p-toluic acid with sodium bicarbonate

2. Reaction 2: the reaction of sodium bicarbonate with acid

3. Reaction 3: the reaction of the major organic product from reaction 1 with hydrochloric acid

4. Reaction 4: the reaction of p-t-butylphenol with sodium hydroxide

5. Reaction 5: the reaction of the major organic product of reaction 4 with hydrochloric acid

Calculations

1. The percent composition of the unknown mixture:

2. The percent recovery of the mixture:

Results

Recovered Mass Percent Compositionp-Toluic Acid 0.7 58.3p-t-Butylphenol 0.5 41.7Acetanilide

Discussion

The extraction of p-toluic acid was a result of two chemical reactions. To begin the procedure, 25 mL of t-butyl methyl ether was placed into a 100mL beaker. Approximately 1.5 grams of the extraction mixture was added and allowed to dissolve; the resulting mixture was then poured into a 125 mL separatory funnel (Reaction 1). Next, 10 mL of 0.5M aqueous NaHCO3 is added to the ether solution and mixed and shaken until the mixture is gas-free (Reaction 2). The newly formed solution was allowed to separate into two layers: an ether layer and an aqueous layer; the aqueous layer was drained, leaving only the ether layer remaining within the funnel. This process was repeated twice, and two more portions of 10 mL NaHCO3 were added, mixed, and shaken in order to remove any remaining p-toluic acid within the ether layer. The addition of 3M HCl to the NaHCO3 solution caused a reaction which led to foaming, ultimately resulting in the precipitation of p-toluic acid (Reaction 3). 3M HCl was then continuously added until no more solid is produced and the solution tests acidic (blue litmus paper turns red). The mass of filter paper was recorded and then used to separate the crystals from the solution using vacuum filtration with a Buchnel funnel. The crystals on the paper were placed on a watch glass and allowed to air dry.

The remaining ether solution in the separatory funnel is then mixed and allowed to react with 10 mL of 0.5M NaOH (Reaction 4). Following this reaction, two layers are formed; drain the NaOH layer from the separatory funnel into the 100 mL beaker containing the first NaOH extract. Repeat the extraction of the ether layer by adding a second portion of 10 mL NaOH, and then drain the NaOH layer from the funnel into the 100 mL beaker containing the first NaOH extract. After repeating this process with a third 10 mL NaOH portion, the NaOH solution was then heated to about 60°C on a hot plate in a fume hood. 3M HCl was added to the NaOH solution until it became acidic. Next, the mass of the filter paper was measured, recorded and then used to separate the p-t-butylphenol crystals from the solution by vacuum filtration with the Buchner funnel. The paper along with the crystals were placed on a watch glass and allowed to air dry.

The ether-acetanilide solution was supposed to be transferred into a clean 125 mL Erlenmeyer flask and then mixed with approximately 1 gram of anhydrous Na2SO4. In the experiment, NaOH was added to the mixture instead of Na2SO4 producing no visible reaction. As a result, acetanilide was unable to be isolated ultimately ruining the experiment.

There are a few measures that should have been implemented to complete the extraction process. During separation, the NaOH layer within the separatory funnel was not extracted carefully and precisely, leaving a considerable amount within the funnel. Most importantly, human negligence accounted for most of the shortcomings during the experiment. The inability to properly follow directions resulted in the incompletion of the extraction process.

Conclusion

The extraction process was ultimately a failure. Human error was the predominant factor which led to the incompletion of the extraction process. Consequently, the desired result was not achieved and the experiment was deemed a failure. Since the experiment was a failure, the analysis of any substitutes was impossible.