Lab 14: Create a Smell Lab: Ester Synthesis

Summary: In this lab, we combined different acids with alcohol in order to synthesize, or produce, three esters with various smells. Our goal was to produce a sweet-smelling molecule from a putrid, foul smell. What we added and what we ended up with are shown in the table below:

Microcentri- fuge Tube	Alcohol	Acid	Odor of Ester
I	Isopentyl Alcohol	Sulfuric Acid	Artificial Banana Flavor
E	Ethyl Alcohol	Glacial Acetic Acid and Sulfuric Acid	Nail Polish
M	Methyl Alcohol	Salicylic Acid and Sulfuric Acid	Mint / Peppermint Gum

 Analysis Questions:

1. Compare the odors of the three esters produced to the odors of the starting materials. How are they different?

The starting materials either smelled like nothing or were very pungent-- in a bad way. The alcohols smelled like alcohol or like medicine, and the acids were somewhat strong and putrid. On the other hand, the produced esters all had a kind of sweet smell, other than the nail polish. The one produced in tube M smelled like mint gum while the one in tube I was similar to the banana flavor in, for example, laffy taffy. Even the nail polish smell in tube E was better than other scents from the starting materials.

2. Based on the smell of the mixtures after heating, what functional group must be present in the final molecules that were produced? Draw it.

The functional group that was definitely in the final molecules was the esters. The prelab states that "in order to transform a putrid smelling molecule into a sweet-smelling molecule, it is necessary to transform a carboxylic acid into an ester molecule..." As the end result was sweet, we can safely say that there was ester in the final product.

3. Were the esters easily identified as a specific fragrance, i.e., apple or banana? In the case where a specific fragrance was detected, how does the odor compare to the natural fragrance?

The smells detected were definitely things smelled before, though they also resembled things I had never smelled before (my partner Daniel stated that the ester produced in tube M smelled like root beer, which I'd never had before, while I immediately stated that it was similar to peppermint gum). At some points it took some thinking to recall what the fragrance was, but in th end we were able to identify the smells. The smells all resembled the natural fragrances very closely. Had I closed my eyes, I could've imagined being at home with my sister painting her nails as I opened tube E. However, tube M was not exactly the same smell as mint gum, and the banana artificial flavor was not very similar, especially as I had to look for it (aka someone had to say that it resembed the fragrance) to find it. Admittedly, it was pretty similar once I had found it. All esters definitely smelled much better than the starting materials, however.