Rules of the Day 320N

Click here for a copy of the lectures notes I wrote in class

Click here for a copy of the handouts I used in class today

1. The energy absorbed by molecules when they absorb a photon is usually converted to vibrational energy (they heat up). Fluorescence occurs when there are not vibrations possible (a rigid molecule) so the photon is emited as the electron goes back to ground state. Phosphorescence (glow in the dark) happens when the excited electron has flipped spins, and must reflip back before entering the original filled orbital while emitting a photon. Chemiluminescence (firefly light, "light sticks") happens when a chemical reaction produces an excited electron in a rigid molecule.

2. The Diels-Alder reaction works in part because the transition state can be viewed as being stabilized by the same considerations that make aromatic pi systems more stable (by 36 kcals/mol).

3. Because the Diels-Alder reaction is concerted: 1) the orientation of groups originating on the diene are determined by the s-cis conformation and 2) the configuration of the alkene (dienophile), either cis or trans, is maintained in the product. In addition (excuse the pun), carbonyl groups react in the so-called endo position "underneath" the double bonds of the diene. Click here to see a movie of a smiple Diels-Alder reaction. There are three more Diels-Alder movies, showing alternative views of a more complicate Diels-Alder reaction. Click here for a side view. Click here for an alternative view of the same reaction. Click here so see both views simultaneiously.

Homework:

Read: Section 22.1 in the ebook textbook. This text is part of the Longhorn Textbook access program.

Take the Daily Quiz 18 before 10 PM tomorrow. Click here to access the quiz.

Finish working on the Homework Problem Set 9, due at 10 PM on Monday, April 8. Click here to access the Homework Problem Set 8. This IS ALSO AN IMPORTANT ONE!! We will be grade it for completion only. It will teach you how to use KRE's to solve synthesis problems! Like last week, there is no Aktiv learning portion of this homework, just Gradescope.