The isolation process of aspirin was stopped after the filtration step with alumina and one week later the methanol was evaporated and the experiment was completed. The melting point of the aspirin was found to be 110-115 Celsius. explain why the meltingpoint was low and why the melting range was so wide.
can you please help
also if the process would be completed on time what are the reasons that the % of recovery is less than 100% ?
The low and wide melting point could be low due to the sample being impure. Reasons include:
incomplete drying so that the sample still ocntains some methanol and/or water.
the sample may still contain some of the starting materials.
another possibility is did the sample smell of oil of wintergreen? If the aspiring is left standing in methanol some of the COOH group will be esterified to the methyl ester.
Any manipulation of a sample will result in small losses. You need to look at the steps you took to see where sample may have been 'lost'.
thank you
The low melting point and wide melting range of aspirin could be explained by potential impurities remaining in the final product.
1. Low melting point: Aspirin is expected to have a melting point of around 135-136 degrees Celsius. The fact that the observed melting point is lower suggests the presence of impurities, such as unreacted starting materials or side products from incomplete reactions. These impurities can lower the overall melting point of the sample.
2. Wide melting range: The presence of impurities can also result in a wide melting range. Different impurities may have different melting points, so when the impurities mix with the aspirin, the overall melting behavior of the sample can change. This leads to a broader temperature range over which the sample appears to be melting.
If the isolation process had been completed on time and the recovery of aspirin was less than 100%, there could be several reasons for this:
1. Incomplete reaction: The synthesis of aspirin might not have gone to completion, resulting in unreacted starting materials remaining in the mixture. This would lead to a lower yield of aspirin.
2. Loss during filtration: It is possible that some aspirin was lost during the filtration step, either due to insufficient washing or improper handling.
3. Loss during evaporation: If the methanol was not completely evaporated or if there was accidental spillage, some aspirin may have been lost in this step.
4. Impurities: The presence of impurities, as mentioned earlier, can affect the overall yield of aspirin. Impurities might have formed during the synthesis or carried over throughout the isolation process.
To optimize the yield and purity of aspirin, it is important to follow precise procedures, monitor reaction progression, perform thorough filtrations, and ensure complete drying of the final product.