Rules of the Day
2-22-2024
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: 10. A reaction mechanism describes the sequence of steps occurring during a reaction.10. A reaction mechanism describes the sequence of steps occurring during a reaction.
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.
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.
1. 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.
2. 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.
3. Base promoted ester hydrolysis is just Mechanism B followed by an acid base reaction.
Homework:
Read: Sections 18.8-18.11 in the ebook textbook. This text is part of the Longhorn Textbook access program.
There is no daily quiz due tomorrow! Go have a mechanism party instead!!! Wo hooo!!
Finish working on the Homework Problem Set 5, due at 10 PM on Monday, February 26. Click here to access the Homework Problem Set 5. Remember to do both the Aktiv learning and Gradescope portions of the homework! We will be grading the Gradescope homework for completion only, not accuracy. This is a guaranteed 100% on a homework if you turn it in complete! I promise that if you spend the time to work through all these mechanisms even before we talk about them in class you will be a mechanism wizard and will do great on these for all of the remaining exams! No joke, this is your chance, you can do this!
