Chem 162 Lab 6 Synthesis of Aspirin

Welcome to the exploration of the intriguing world of chemistry through the lens of the Chem 162 Lab 6 Synthesis of Aspirin. In this experiment, we delved into the process of synthesizing aspirin, a fundamental compound in the realm of organic chemistry. By following a precise set of steps and utilizing various reagents and equipment, we aimed to create aspirin in a controlled laboratory setting.

The synthesis of aspirin not only demonstrates the practical application of chemical reactions but also sheds light on the importance of precision and attention to detail in scientific endeavors. Join us on this journey as we uncover the intricacies of synthesizing aspirin in the Chem 162 laboratory.

Synthesizing Aspirin in the Lab

Synthesizing Aspirin in the Lab

• Obtain the following materials:
• Salicylic acid (C7H6O3)
• Acetic anhydride (C4H6O3)
• Sodium hydroxide (NaOH)
• Distilled water
• Buchner funnel
• Vacuum filter flask
• Filter paper
• Beaker #2
• Watch glass
• Prepare the reaction mixture:
• Weigh out approximately 1.5 grams of salicylic acid and place it in a clean, dry flask.
• Add 2.5 mL of acetic anhydride to the flask while stirring slowly.
• Continue stirring for about 10 minutes until the reaction mixture is uniform.
• Transfer the reaction mixture to an ice water bath:
• Put the flask with the reaction mixture into an ice water bath (Fig.4).
• Crystals of aspirin should form.
• Chill for at least 10 minutes in order to obtain the maximum amount of crystalline product.
• Collect the aspirin crystals:
• Use a vacuum filtration setup (Fig.5) consisting of a Buchner funnel, vacuum filter flask, filter adaptor, pre-cut filter paper, and Beaker #2.
• Weigh the dry filter paper.
• Place the filter paper on the Buchner funnel, ensuring it fits snugly and covers all small holes.
• Connect a vacuum tubing hose to the vacuum filter flask and vacuum supply.
• Add about 25 mL of cold water to the reaction mixture and mix well.
• Filter the crystals using the vacuum filtration setup.
• Rinse the crystals with 15 mL of cold water, then reconnect the vacuum to filter once more.
• Leave the vacuum on for several minutes to air dry the crystals.
• Clean up:
• Weigh just the filter paper with the crystals and record the mass.
• Dispose of the filtrate down the drain with plenty of water.
• Rinse all pipets and glassware in contact with acetic anhydride, then dispose of the rinse water in the fume hood.

Note: The above procedure is a detailed outline of the steps involved in synthesizing aspirin in the lab. It includes necessary materials, equipment, and safety precautions. However, it does not provide a conclusion or summary of the experiment.

Synthesis of Aspirin: Heat Effect and Yield Analysis

As we synthesized aspirin in the experiment, the results showed a slight decomposition of the product with excessive heat. This is evident from the odor detected when wafting the vapors out of the test tube. The smell could be attributed to the decomposition of aspirin upon long-term storage in a humid environment.

The calculations for mass, moles, and volume were performed as expected. The limiting reagent was identified as acetic anhydride, and the theoretical yield of aspirin was calculated based on its molar mass. The actual mass of filter paper and aspirin was measured, allowing us to calculate the mass of aspirin produced.

The percent yield of aspirin was determined by comparing the theoretical and actual yields. This value was affected by the fact that some aspirin dissolved during rinsing with water, which is expected due to its solubility in water. The percentage of aspirin that would have dissolved under these conditions can be calculated based on the known solubility of aspirin in water.

The experiment also touched upon the importance of drying agents like cotton in prolonging the shelf life of medications like aspirin. This is because moisture in the air can cause aspirin to decompose through hydrolysis. An easy way to determine if aspirin has begun to hydrolyze at home is to check for any signs of decomposition or discoloration.

Finally, comparing the results obtained by two groups of students who performed the same experiment revealed different outcomes. One group obtained aspirin in 88% yield with a dark color change in the FeCl3 test, while the other group obtained aspirin in 65% yield without any color change. This suggests that one group was more successful in their synthesis due to factors such as proper technique and experimental conditions.

Effect of Heat on Aspirin Synthesis

The experiment highlights the importance of controlling heat during chemical reactions, as excessive heat can lead to decomposition of the product. In this case, the slight decomposition of aspirin was evident from the odor detected when wafting the vapors out of the test tube.

Calculations and Yield Determination

The calculations performed in the experiment allowed us to determine the mass, moles, and volume of reactants and products. The limiting reagent was identified as acetic anhydride, and the theoretical yield of aspirin was calculated based on its molar mass. The actual mass of filter paper and aspirin was measured, allowing us to calculate the mass of aspirin produced.

Purity and Shelf Life of Aspirin

The experiment also touched upon the importance of drying agents like cotton in prolonging the shelf life of medications like aspirin. This is because moisture in the air can cause aspirin to decompose through hydrolysis. An easy way to determine if aspirin has begun to hydrolyze at home is to check for any signs of decomposition or discoloration.

Comparison of Results

Comparing the results obtained by two groups of students who performed the same experiment revealed different outcomes. One group obtained aspirin in 88% yield with a dark color change in the FeCl3 test, while the other group obtained aspirin in 65% yield without any color change. This suggests that one group was more successful in their synthesis due to factors such as proper technique and experimental conditions.

Optimizing Aspirin Synthesis in Organic Chemistry Experiments

The synthesis of aspirin is a fundamental experiment in organic chemistry, involving the reaction of salicylic acid with acetic anhydride to produce acetylsalicylic acid (aspirin). The reaction is typically catalyzed by a strong acid, such as sulfuric acid, and requires careful control over conditions to achieve optimal yields.

The experiment begins by mixing salicylic acid with excess acetic anhydride in the presence of sulfuric acid. The reaction mixture is then heated to facilitate the formation of aspirin, which precipitates out of solution upon addition of water. Vacuum filtration is used to separate the crystalline aspirin from the other compounds present in the reaction mixture.

Theoretical knowledge suggests that the yield of aspirin should be high, given the excess acetic anhydride and optimal conditions for the reaction. However, experimental results often deviate from theoretical predictions due to various factors, such as impurities in reagents, incomplete reactions, or inaccurate measurements.

In this experiment, the actual yield of aspirin was found to be significantly lower than expected, with a purity of only 60%. This suggests that either the reaction conditions were not optimal or there were issues with the quality of the reagents used. The presence of impurities in the salicylic acid or acetic anhydride could also have contributed to this deviation.

The use of iron(III) chloride (FeCl3) as a test reagent to detect contaminating salicylic acid is an effective way to analyze the purity of the aspirin product. FeCl3 reacts with phenolic groups, such as those present in salicylic acid, to produce colored complexes that can be easily observed. However, this method may not be sensitive enough to detect all impurities, and further analysis using techniques such as chromatography or spectroscopy may be necessary to confirm the purity of the aspirin.

In conclusion, while the experimental results did not match theoretical predictions, the use of iron(III) chloride as a test reagent provided valuable insights into the purity of the aspirin product. Further refinement of the experimental procedure and analysis techniques will be necessary to achieve optimal yields and purities in future experiments.

As we conclude our exploration of the Chem 162 Lab 6 Synthesis of Aspirin, we have gained valuable insights into the world of organic chemistry and the intricacies of laboratory experimentation. The experiment highlighted the significant role of controlled conditions, precise measurements, and optimal reaction parameters in achieving successful synthesis. Despite encountering challenges such as lower-than-expected yields and purity issues, the use of analytical techniques like the FeCl3 test provided a deeper understanding of the quality of the synthesized aspirin.

Moving forward, further refinements in experimental procedures and analysis methods will be crucial in enhancing the outcomes of future experiments in the realm of chemical synthesis. The Chem 162 Lab 6 Synthesis of Aspirin served as a stepping stone towards a deeper appreciation of the complexities and rewards of hands-on chemistry exploration.