Rules of the Day
2-1-2024
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: 9. Functional groups react the same in different molecules.
1. Cyclic hemiacetals that form five- or six-membered rings are stable (as opposed to non-cyclic hemiacetals which are not stable species). Carbohydrate monomers like D-Glucose are actually found in the cyclic hemiacetal state in solution (SWEET!). In carbohydrates, the new C-O bond is formed to the so-called anomeric carbon, and for D-glucose, alpha means the new OH group is axial, and beta means it is equatorial.
2. Water behaves the same as alcohols to generate geminal diol products, which are not stable except for the case of formaldehyde (a gas), which predominantly forms the liquid formalin (a geminal diol) in water.
3. Protecting groups are chemical functions that can reversibly mask a reactive functional group to prevent an unwanted reaction. The protecting group is added prior to the reaction in question, then removed following the reaction in question.
4. 5- or 6-membered ring cyclic acetals are good protecting groups for use with Grignard reagents, since the cyclic acetals can be reversibly attached, and they have an sp3 carbon atom that won't react with nucleophiles like carbonyls do.
5. Imines are formed when a primary amine or ammonia reacts with an aldehyde or ketone with some acid around. The mechanism involves mechanism C to make an aminal, followed by protonation of the OH group then loss of water at the same time a proton is lost from the nitrogen atom. Like acetal formation, this process is reversible and can be run in either direction depending on the ratio of amine (ammonia) to water in the solution.
Homework:
Read: Sections 16.9, 16.12 in the ebook textbook. This text is part of the Longhorn Textbook access program.
Take the Daily Quiz 6 before 10 PM tomorrow. Click here to access the quiz. These quizzes are designed to review the important material from today's lecture. Together, they will count as 3% of your final grade..
Continue working on the Homework Problem Set 3, due at 10 PM on Monday, February . Click here to access the Homework Problem Set 3. Note there are Aktiv Learning and Gradescope Questions, and you MUST DO BOTH. Homeworks will be worth 10% of your final grade (20% from the Aktiv Learning and 80% from the Gradescope portions of the homework.
