Pomona College Chemistry 110a, Lecture 37
Conjugated Unsaturated Systems
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December 9, 2015
Kinetic vs. Thermodynamic Control.
The Diels-Alder Reaction.
The organic chemistry of color.
Course evaluation.
110a Teaching Fellows: Alex Chang, Emily Chang, Alice (Ah Yeon) Chung, Phillip Clayman, Colin Eckstein, Mark Zhang, Marek Zorawski. Review
session days & times: Sunday, Monday, Tuesday, Thursday, 7-10 PM, location Oldenborg Glass Room on Mondays and Tuesdays, Seaver North 202 on
Sundays and Thursdays. Join the Pomona Organic Chemistry 110A FB page!
O’Leary’s next review session: Wednesday 12/9 7:00 PM SN 111. Sunday 12/X 3:00 PM SN Aud.
Course website: http://pages.pomona.edu/~djo04747/110//
Final Exam Information: The final exam (December 18, 9:00 AM-Noon) will be “open notes,” but you will be limited to 13 pages of 8.5x11 inch paper
(front and back, i.e. 26 sides). Your notes must be hand-written or typed (no scanned images) and organized to your liking. I will take a dim view
of notes that include book problems/solutions. Remember– these notes are meant to be useful to you in the coming years. As you prepare for
the final exam, work to find common threads that permeate the material. For example and as discussed in class, there is remarkable similarity in
the chemistry of the bromonium ion, a protonated epoxide, and the mercurinium ion. Bring one copy of your notes to use during the exam; the notes
will be turned in to me at the end of the exam period and returned to you in January.
[4+2] Cycloaddition: the Diels-Alder Reaction
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Pomona College Chemistry 110a, Lecture 37
[4+2] Cycloaddition: the Diels-Alder Reaction
T-state rationalization of endo rule
Molecular Orbitals and max Values for Ethylene, Butadiene, and Hexatriene
6
4
energy
0
5

3
h
h
4
h
3



1
max
1
171 nm
217 nm
274 nm
ethylene
1,3-butadiene
1,3,5-hexatriene
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Pomona College Chemistry 110a, Lecture 37
max 242.5 nm
Here’s a little Maine chemistry to consider…
Crustacyanin-Astaxanthin
complex (blue)
Free Astaxanthin (red)
Blue lobsters have a rare mutation that causes an overexpression of crustacyanin, a protein that binds
astaxanthin to form a blue pigment. ‘Normal’ live lobsters have a muddy dark color resulting from bound and
free astaxanthin. Cooked lobsters turn bright red because the protein-pigment complex denatures, releasing its
astaxanthin.
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