Organic Chemistry Semester II 1st unit specialty reactions (mechanisms not emphasized)

Transcription

1 rganic Chemistry Semester II 1st unit specialty reactions (mechanisms not emphasized) 1. X addition to an alkyne powerful method to add halogens (Cl,, I) to an alkyne to create geminal dihalides (pages ) 2. Addition of X 2 to alkynes (Section 10.7) 3. pening epoxides with various reagents in particular with Grignard, organolithium, and organocuprate reagents (pages ; ) 4. Different work-up conditions following ozonolysis lead to different types of carbonyl-containing products (pages ) 5. Diols from alkenes using S 4 or KMn 4 (pages ) 6. Williamson ether synthesis (pages ) 7. Alkynes, amines, sulfides, etc as nucleophiles (page 328) 8. Benzylic oxidation (page 661) again, using KMn 4 (or alternatively, Na 2 Cr 2 7 ), you can chew down alkyl side chains to produce the corresponding benzoic acid. Be careful, there are a lot of variations on using oxidizing agents! I d recommend that you build your Synthetic Toolbox using reaction flash cards (as recommended on page 337 of the text). These can also be used for nomenclature, spectroscopy, etc. You should review your flash cards with paper and pencil in hand. Writing reactions, mechanisms, structures, reagents, etc helps most people learn much faster and in greater detail than a cursory visual review of the card. And, you can take them anywhere and practice as many or as few as the moment permits. The first reaction cards you should make are from the initial chapters of the text. These should help you learn functional groups, conformational analysis, stereochemistry, and if you leave enough room on the back of the card you can add information to identify the functional groups from their spectroscopic data. For studying reactions and their mechanisms there are three ways we recommend you make cards. All three give some information on the front of the card with a question to stimulate thought. ne type gives starting materials and reagents and asks you to predict products (see reaction cards 2, 3). The second gives the reagent and the product and asks you to predict the starting compound (see reaction card 4) and the third type gives the starting material and the product and asks you to provide the proper reagents to make the chemical transformation (see reaction card 5). You should make two to three reactions cards for each reaction we cover throughout the year. The text book problems and chapter reviews at the end of the chapter are a good place to start. They are ready-made reaction cards. You may find ways to make reaction cards better suited for you. owever, if you are to be successful throughout the year you will have to know and understand many of the reactions. If you wait to study until the night before an exam you will get many of the reactions mixed up and feel like you got a poorer grade than your understanding of the information. If you study reaction cards on a daily basis you will find you can retain a lot of information. Good luck comes to those who work hard.

2 Example Reaction Card 1 Name the Functional Group R IR and NMR information Aldehyde Example: Ca b b Pentanal a IR-- Ca-a stretch cm-1 Ca= stretch 1710 cm-1 NMR-- a 9-10 ppm b 2.4 ppm Ca ppm p

3 Example Reaction Card 2 2 C 3 C 3 CCl 4 pp337 Mechanism C 3 C 3 alogenation of alkenes omonium Ion + C 3 C 3 - Backside attack -Anti Addition -alonium Ion Intermediate

4 Example Reaction Card K +? Williamson Syn. of ethers + K+ - S N 2 mechanism -must be 1o halide R - p.432

5 Example Reaction Card 4? Williamson Syn. of ethers - K + S - N 2 mechanism R -must be 1o halide -alcohol may be 1o, 2o, or 3o + p.432

6 Example Reaction Card 5? P 3 ---for 1o, and 2o alcohols P R - R P + R + P For 3o alcohols use (S N 1 Mech.) p.419