Rules of the Day
2-18-2026
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
Featured Golden Rule of Chemistry:7. Delocalization of pi electron density over a larger area is stabilizing.
1. 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.
2. All of the carboxylic acid derivative mechanisms involve the four mechanistic elements: Make a bond, Break a bond, Add a proton, Take a proton away.
3. When learning mechanisms, the key to "catching the wave" is to always ask yourself WHY each step happens the way it does. When you start understanding the answers to that question at each step, the whole thing will make sense.
4. You should keep a few things in mind when writing these complex mechanisms to make sure you are not making any mistakes: 1) Identify the bonds to be made and broken 2) Avoid "mixed media errores". In acid all intermediates are positively-charged/neutral, in base all intermediates are negatively-charged/neutral, in neutral solution the intermediates can be positvely-charged or negatively-charged 3) Proton transfers are fast 4) Evaluate properties of intermediates to predict next step.
5. The characteristic reaction of carboxylic acid derivatives is Mechanism B. If the attacking nucleophile is an alkyl group or hydride, a ketone or aldehyde is produced as an intermediate that then continues to react via Mechanism A to give the alcohol product.
6 Anhydrides react with water to produce two molecules of carboxylic acid and this process is catalyzed by acid.
7. Esters require acid catalysis or base promotion to hydrolyze. The acid catalyzed ester hydrolysis mechanism is the functional reverse of the Fischer esterification mechanism, illustrating the concept of microscopic reversibility.
8. Microscopic reversibility predicts that you encounter the same intermediates in either direction of a reversible reaction. You will also see the complement mechanistic elements (make a bond vs. break a bond and add a proton vs. take a proton away) at each step in either direction. Is it really true? Can mechanisms really make that much sense? Mind officially blown.
9. Reactions with rings are harder to keep track of, so I suggest that you number the ring atoms and use the following for practice.
Microscopic Reversibility Practice Sheet 3: Lactone Hydrolysis
Microscopic Reversibility Practice Sheet 4: Lactone Formation
10. Heating in very strong aqueous acid hydrolyzes amides in a mechanism analogous to the acid catalyzed ester hydrolysis reaction except for amides the reaction is only promoted by acid, not catalyzed by it, because the last step involves transfer of a proton to the amine group that departed.
11. Nitriles are hydrolyzed in strong acid to give carboxylic acids, a mechanism that involves formation of amides.
Homework:
Read: Sections 18.5-18.7 in the ebook textbook. This text is part of the Longhorn Textbook access program.
Take the Daily Quiz 9 before 10 PM tomorrow. Click here to access the quiz. These quizzes are designed to review the important material from today's lecture.
Start working on Homework 5, that will be due Wednesday, February 25 at 10 PM. There are both Aktiv learning and Gradescope problem sets.
Click here to get the Aktiv Homework Problem Set 5
Click here for the Gradescope Homework Problem Set 5
To submit your homework log onto "Gradescope" on the menu bar of the class Canvas page, or you can Click here to get there directly.