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

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Featured Golden Rules of Chemistry: Nothing today

1.The enol form of a compound rapidly tautomerizes to the more stable keto form. The keto form is more stable because the C=O pi bond is stronger than the C=C pi bond.

2. Alkynes give enols that rapidly tautomerize to ketones or aldehydes when reacted with 1. BH3 2. H2O2/NaOH. To see a strong preference for the terminal side of an alkyne (non-Markovnikov), use the bulkier (sia)2BH.("borane with antlers")

3. Alkynes add water in the presence HgSO4/H2SO4 to give enols that tautomerize to ketones. For terminal alkynes, the oxygen atom ends up on the internal carbon atom as Markovnikov would predict. You are not responsible for the really long mechanism that involves a mercurinium ion intermediate and eventually loss of Hg2+ to give the enol that tautomerizes to the keto form.

4. Catalytic reduction using H2 takes an alkyne all the way to an alkane when elemental catalyst such as Pd is used. When a kinder/gentler catalyst called Lindlar's catalyst is used, the reaction stops at the alkene stage, stereochemistry of addition is syn, leading to cis products.

5. Flashback Rule of the Day: Trans alkenes are more stable thatn cis alkenes because cis alkenes have some steric strain (non-bonded intereatction strain). In addition, more highly substituted alkenes are more stable than less substituted alkenes (we don't really tell you why, just learn it please.)

6. Chemical reduction using sodium (Na) in liquid ammonia (NH3) gives a trans alkene. The mechanism involves single electron transfers and radical/anion intermediates, resulting from sequential electron and proton transfers, repeated a second time.

HOMEWORK:

Read: Sections 7.1 - 7.10, 8.1 - 8.4 to catch up with the reading so you are ready for next week's material. This is a lot but it will really help as we move into some very different chemistry.

Take the Daily Quiz 15 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.