205 Warren Place
Campbellsville, KY 42718
February 23, 2011
Mrs. Peggy Monson
112 Lane Way
Campbellsville, KY 42718
Dear Granny,
I’m going to explain the lay out of aromaticity, which is another word for fragrance. The structures of these compounds have double bonds regularly, but they don’t in fact behave like a double bond. Reagents such as bromine for example react with benzene by substitution instead of addition. Benzene and its derivatives are referred to as aromatic because of there unique odors. The aromaticity of the benzene ring can be assessed by measuring its resonance energy. A way to this is by measuring its heat of hydrogenation which is a Kekule formula. Both the heat of hydrogenation and combustion will have double bonds present, along with its bond distances being uniform, which is measured by spectroscopy. Also it will have longer wavelengths absorption bands in the ultraviolet region of the spectrum.
Huckel’s rule determines the number of π electrons that provide stability to an unsaturated planar ring. Huckel’s rule uses the formula 4n + 2. Although most polycyclic aromatic molecules follow Huckel’s rule some don’t, like pyrene, which has sixteen π electrons and is aromatic. For benzene, n = 1 and when put in the formula equals six (4n + 2 = 6), which is an aromatic sextet. The rule was calculated for single ring molecules and generally doesn’t apply to multiring systems. Also NMR can be used to measure the degree of aromaticity in a molecule by how well its ring of π electrons can maintain an induced ring current. In other words, it can be diatrophic which is were π electrons are delocalized and proteins are attached to the ring and it is shifted downfield in the nuclear magnetic resonance spectrum or NMR, where double bonds are present.
Overall, I hope I helped you understand the concept of aromaticity and I hope to see you soon.
Sincerely you’re favorite,
Alexia
Overall, I liked the format of your letter! You addressed it and everything, which I thought was nice. I also liked that you pointed out that compounds that were aromatic, were odorous. The only comment I would make, however, is that the vocabulary still seemed too advanced to be talking to you grandmother. While to me the letter seemed to be simple explainations of aromaticity and its properties, your grandmother would still, most likely, have trouble understanding terms such as double bonds, heat of hydrogenation, unsaturated, planar, etc.
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