Benzocaine Testing Experiment

Discussion: Based on the TLC results that were obtained through the experiment, the benzocaine seems to be relatively pure. There was only one spot in the benzocaine lane and one spot in the p-aminobenzoic acid lane, while there were two spots in the lane with both chemicals. The benzocaine had an Rf value of 0. 40 and the p-aminobenzoic acid had an Rf value of 0. 21. These results show that there is no evidence for the presence of p-aminobenzoic acid in the reaction product.

The percent yield that we obtained for the benzocaine was relatively low. The theoretical yield for our product was 1. grams but we collected only 0. 612 grams of product. At only 43. 70%, less than half of the theoretical yield was obtained. This low to average percent yield could have been caused by not getting all of the product from the reaction flask into the vacuum filtration apparatus. Also, some product was probably lost from checking the pH of the solution multiple times while adding the Na2CO3.

The melting range that we obtained for the benzocaine was 88. 7-89. 9 degrees Celsius. This melting range tells us that the benzocaine could be quite pure because there is only a 1. 2 degree differential between the temperatures.

This experimental melting point is also spot on with the known melting point of 89. 7 degrees Celsius. This tells us that our product was indeed very pure and contained very few impurities. The IR spectrum for the p-aminobenzoic acid does not contain a CH3 peak at 1375nm or a CH2 peak at 1450nm.

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The benzocaine spectrum does contain these peak though. The p-aminobenzoic acid spectrum does contain a carboxylic acid peak while the benzocaine spectrum does not. These differences in the spectrums show that the benzocaine is quite pure and doesn’t contain any p-aminobenzoic acid.

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