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 to see a special video intended to help you with the reaction to products questions on the next exam (recorded Oct. 12, 2022)

Click here for the notes I used in the above video

Filled-in Mechanism Sheets for the 2nd Midterm

Link to register for the Run for the Water: https://www.runforthewater.com/register

Code: (If you register for the race, be sure to use the following code to get a discount)

Link to the Camp Kesem Texas website

Featured Golden Rules of Chemistry: Nothing today

1. The chemistry of alkynes is predictable based on where the electrons are located: In two orthogonal pi bonds. Like alkenes, alkynes have the chemical personality of being a weak nucleophile, weak base.

2. Alkynes react with 2 equivalents of X2 and HX to give vicinal tetrahaloalkanes and dihaloalkanes, respectively. The HX reaction follows Markovnikov regiochemistry with terminal alkynes.

3. Alkynes are prepared from the base (NaNH2) promoted double elimination of a vicinal dihalide. For making an internal alkynes you need two equivalents of NaNH2, but for making terminal alkynes you need to 1. Add 3 equivalents of NaNH2 followed by 2. HCl/H2O to protonate the alkyne product. This provides a way to produce an alkyne from an alkene via the vicinal dihalide produced from an alkene and X2.

4.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.

5. 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")

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.

There are no quizzes during exam week. These quizzes are designed to review the important material from today's lecture. Together, they will count as 5% of your final grade.

Keep working on the Exam 2 Practice Homework. It is not graded, you will not turn it in, and the answers have already been posted. Click here to access the Exam 2 Practice. Note there are Aktiv Learning and Gradescope Questions, and you should do both. Access the Aktiv Learning questions in the "Practice" folder on the Aktiv Learning site.