Rules of the Day 320N

1. Warning: Students often confuse keto-enol equilibria (these are two different species, with a proton moving between them) and the contributing structures for enolates (both structures represent one single species that is the hybrid of the contributing structures) because of structural similarities.

2. Diazomethane converts carboxylic acids into methyl esters in very high yield.

3. The haloform reaction converts methyl ketones into carboxylic acids, breaking a carbon-carbon bond in the process. The haloform reaction is important because it combines an enolate reaction with Mechanism B, both of which are important moving forward.

4. The important carboxylic acid derivatives are acid chlorides, anhydrides, esters, and amides.

5. Carboxylic acid derivatives all have leaving groups of various abilities. The more stable the anion, the better then leaving group, so relative leaving group abiilty is correlated with relative pKa of leaving group conjugate acid. The better the leaving group, the more reactive the carboxylic acid derivative.

6. Carboxylic acid derivatives react though variations of Mechanism B because they all have leaving groups of various abilities attached.

7. Acid chlorides and anhydrides are very reactive, esters are moderately reactive, and amides are unreactive.

8. You can make any of the less reactive carboxylic acid derivatives from any of the more reactive ones with the appropriate nucleophiles. You can make acid chlorides from carboxylic acids. You can make carboxylic acids from the hydrolysis of any of the carboxylic acid derivatives. Therefore, you can convert any carboxylic acid derivative into any of the other ones.

Homework:

Read: Sections 18.3-18.4 in the ebook textbook. This text is part of the Longhorn Textbook access program.

Best of luck on the exam, there are no new homeworks or Daily Quizzes this week.