Rules of the Day
Click here for a copy of my lecture notes from today's lecture
Click here for a copy of the handout used in class today
Click here for a helpful video that reviews mechanisms for the exam next week
Click here for the notes I used in the above video
Featured Golden Rules of Chemistry: Nothing today
1. For each reaction of an alkene we have covered you need to remember to call a NIRRS:
Nature of the reaction; what is the starting material/product? (i.e. alkene converted to an alcohol)
Intermediate (or "Important transition state" if applicable) of the reaction, the key to the mechanism (carbocation, halonium ion, etc.)
Reagents Learn the exact way to designate the reagents for each reaction
Regiochemistry What is the regiochemistry of addition? (Markovnikov, non-Markovinikov, etc.)
Stereochemistry of addition (anti, syn or mixed)
2. When studying for the exam, remember this material is very different then the first midterm material. You CAN do this. I suggest you follow these steps before looking through old exams: 1) Read each Rule of the Day so you can identify those things you are not familiar with. 2) Binge-watch the lectures recordings, skipping the things you undersrtand and spending time watching the things you do not yet understand (last year's class used this study method and they did great!) 3) Consult the Missed the Wave topics to see if you can get help from those recordings 4) Ask questions at office hours and the Review Session on Tuesday night 5) Start working through the old exams.
3. Alkenes react with 1) BH3, 2) H2O2/HO- to give an alcohol. The reaction involves a four-membered ring transition state in which the H ends up on the more highly substituted carbon, largely for steric reasons, so the reaction shows non-Markovnikov regiochemistry. Note the BH3 reacts three times, so one BH3 molecule reacts with three alkenes. The last step does not mix the stereochemistry, so overall it is syn stereochemistry.
4. An oxidation reaction involves a net loss of electrons and replaces C-H bonds with C-O bonds or pi bonds. A reduction reaction involves a net gain of electrons and replaces C-O or pi bonds with C-H bonds.
5. Alkenes are oxidized with 1) OsO4, 2) NaHSO3/H2O to give vicinal diols (glycols) . You are not responsible for Ozzy Osbourne mechanism because it involves metal species, but you should know about the key cyclic osmate intermediate because this explains the syn addition stereochemistry. Regiochemistry isnot important because OH adds to both atoms.6. Alkenes react with O3 (ozone) followed by (CH3)2S to give C=C bond cleavage and two new C=O bonds. You are not responsible for entire mechanism but you should be familiar with malozonide and ozonide intermediates. Regiochemistry and stereochemistry do not apply. THIS IS THE ONLY WAY TO BREAK CARBON-CARBON BONDS that you will see this semester so this is a very important chemical reaction for synthesis!
HOMEWORK:
Read: Study for the exam next week.
Take the Daily Quiz 14 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 5% of your final grade.