Author Archives: alan

Huckel's rule, aromatic character, and molecular orbitals

Today's lecture tried to tie Huckel's rule to a number of topics, including:aromatic character, a more nuanced way of talking about aromaticitycharge distributions and geometryevaluation of "minor" resonance structuresmolecular orbital theoryYou can see all of the slides that were used… Continue reading

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Supersized ferrocene impossible?

Ferrocene and acetylferrocene, the compounds featured in our current lab experiment, are examples of sandwich compounds or metallocenes. A metallocene of some sort has been made with every transition metal in existence, but double metallocenes in which two organic rings… Continue reading

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Alkene pi orbital energies

A question on today's conference problem set asked you to predict how the energies of the pi and pi* orbitals of a typical alkene would respond to twisting the alkene.Valence bond fans: The VB model doesn't contain "pi" or "pi*"… Continue reading

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Models of Chemical Bonding

Today I decided to re-trace my steps on Monday and provide a more complete description of chemical bonds through the eyes of molecular orbital theory. A list of take-home lessons from this presentation:MO models contain new orbitals (molecular orbitals), while… Continue reading

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Halloween Pumpkins

Halloween fell on Friday this year so I should have been expecting a "trick" or "treat" when I arrived at lecture. Little did I know that I would get both.Everyone was seated in the dark when I arrived and two… Continue reading

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Bromonium ions

Here are pictures of the models that I shared with you in class on Monday. They address different issues.Model #1 – A Stable Bromonium Ion. A bromonium can be stabilized by placing large groups around the alkene. These groups offer… Continue reading

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Back side attack & HOMO-LUMO overlap

I made two points about the 3-D aspects of nucleophilic substitution today in lecture:the bimolecular reaction that I described (aka SN2) occurs by "backside attack". This is an experimental observation that has been made hundreds (probably tens of thousands) of… Continue reading

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C7 H10 O3 contest – Week #3 Results

The final week of the C7 H10 O3 contest brought in two entries. Gabe Holt and Patrick Fink had submitted an entry during week #1, but all of the other participants were brand new, bringing the total number of participating… Continue reading

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C7 H10 O3 contest – Week #2 Results

The C7 H10 O3 contest continues with three new entries. The winning team nearly hit the jackpot: 140 references. Congratulations Orissa and Rachel !!The other teams submitted molecules that looked pretty interesting to me, but I guess organic chemists haven't… Continue reading

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Mnemonic = memory aid

Several years ago I came across a Chem 201 exam with the following written in the margin: "Albert is sick and in pain, so I brought clean forks". Afterward I asked the student what that was all about and she… Continue reading

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