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. Substituents already on the ring influence reactivity and orientation by interacting with the partial positive charges of the arenium ion intermediate. The groups are analyzed on the basis of pi donation (resonance of lone pairs on atoms attached to ring donated into aromatic pi system), hyperconjugation (alkyl groups donate electron density into aromatic pi system), and inductive effects (electron withdrawing groups remove electron density).

2. Activating ortho,para directing groups operate by stabilizing an adjacent positive charge through resonance (for groups with lone pairs on atoms attached to the ring) or hyperconjugation (for alkyl groups). These are sometimes called electron releasing groups. THE GOOD

3. Deactivating, meta directing groups operate by destabilizing an adjacent positive charge through an inductive effect. These are sometimes called electron withdrawing groups and they usually have pi bonds to heteroatoms on the atoms attached to the ring or a highly positively-charged atom attached to the ring.THE BAD

4. Halogens are deactivators due to inductive effects, but ortho,para directors due to a resonance effect. THE UGLY

5. If there are two groups on the ring, and they predict different products, then just like in the movie, Good beats Ugly or Bad, and Ugly beats Bad. Bad always loses. Because of steric hindrance, electrophiles never add between meta substituents.

6. Amines are good bases (pKa of conjugate acid is around 10) and strong nucleophiles in SN2 and Michael reactions. Amines are protonated and positively charged at neutral pH in water.

7. Our sense of smell is tuned to detect molecules that indicate spoiled food by detecting certain characteristic molecules resulting from microbial contamination and degradation. Simple diamines indicate rotten mammal flesh, triethyl amine indicates rotten fish, thiols such as hydrogen sulfide indicate rotten eggs among other spoiled food and butyric acid indicates vomit. Our noses are capable of detecting as little as a few parts per billion of some of these molecules.

8. Because of pi delocalization, an amino group attached to a benzene ring is close to or fully sp2 hybridized. This explains why the DNA bases are planar!!

Homework:

No assigned reading

Many students have difficulty understanding how to think about "equivalents", how to balance certain equations like the Claisen condensation, what do we mean by H3O+ and knowing when to use hydroxide versus ethoxide. Here are some short videos to help you with any of these: How to think about "Equivalents" when using base in enolate reactions (7:17 minutes) Correct video for How to think about "Equivalents" when using base in enolate reactions (3:29 minutes) How to balance a Claisen reaction equation (5:06 minutes) What do we mean by H3O+ (2:52 minutes) When to use NaOH vs. NaOEt (7:35 minutes)

Take the Daily Quiz 19 before 10 PM tomorrow. Click here to access the quiz. These quizzes are designed to review the important material from today's lecture.

Finish working on Homework 9 that will be due tonight Wednesday, April 8th at 10 PM. Note, there are no Aktiv learning problem sets for the rest of the semester.

Click here for the Gradescope Homework Problem Set 9

Start working on Homework 10 that will be due Wednesday, April 15th at 10 PM. Note, there are no Aktiv learning problem sets for the rest of the semester.

Click here for the Gradescope Homework Problem Set 10