Rules of the Day CH320M/328M

Featured Golden Rules of Chemistry: Nothing today

1. When trying to predict reaction products, first recognize the chemistry based on the reagents (HBr, H2O/H2SO4, Br2/H2O, etc.), then work out the regiochemistry (which carbon gets what new bond, Markovnikov, etc.) then see if any chiral centers are created. If they chiral centers are formed, focus on the stereochemistry of the reaction (anti, mixed, etc.) to determine which of the possible stereoisomers are made ON A CASE BY CASE BASIS. DO NOT LOOK FOR ONE-SIZE-FITS-ALL SHORT CUTS OR HACKS THAT DO NOT EXIST. CASE BY CASE IS THE ONLY WAY TO GO.

2. 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)

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. 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!

5.Alkenes react with H2 in the presence of metals such as Pd, Pt, Ni to give alkanes. Reaction occurs on metal surface, and both H atoms add to same face of double bond leading to syn stereochemistry. Regiochemistry does not apply.

HOMEWORK:

If you have not already, you must Watch the Terpene video. You are responsible for this information for the next midterm! Last time we will mention it!

Read: Sections 6.5 and 6.6 in the eBook.

Take the Daily Quiz 13 before 10 PM tomorrow. Click here to access the quiz .These quizzes are designed to review the important material from today's lecture.

Finish Working on Homework Problem Set 6, due at 10 PM tonight on Wednesday, October 14.

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Start Working on Homework Problem Set 7, due at 10 PM on Wednesday, October 21.

Click here to go to the Aktive Homework Problem Set 7

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