Recommended
More Related Content
What's hot
What's hot (20)
Similar to Chapter 7 wiley version
Similar to Chapter 7 wiley version (20)
Recently uploaded
Recently uploaded (20)
Chapter 7 wiley version
- 2. What will nucleophilic substitutions work with • Need a leaving group that is connected to sp^3 carbon • Or a leaving group that is allylic
- 3. Nomenclature • Same steps as last time • Take your halogen • Take off suffix –ine • Add suffix –o • This will give you the name of the substituent
- 4. Practice
- 5. Alkyl halide properties • Very polar C-X bond • Takes electrons away from Carbon • Due to polar C-X bond: molecule has dipole-dipole IMFs
- 6. General substitution reaction • What you need • Nucleophile • C-X bond • General feature: nucleophile replaces leaving group
- 7. Leaving groups • Bigger is better • The bigger it is, the better it can accept a negative charge • The better the leaving group, the faster the reaction • Trend opposes that of basicity and follows acidity • Think in terms of its conjugate acid Electronegativity increase Increase in size
- 9. practice
- 10. Bases and nucleophiles • Bases attack protons : symbol is B: • Nucleophiles attack carbons : symbol is Nu: • In general nucleophilicity increases with basicity: opposite if solvent is protic (if I DO NOT FIX THIS; IT IS WRONG. WRONG. WRONG. WrOnG • Does charge matter? Yes, negative means stronger • Nucleophiles are Dependent on sterics
- 11. practice
- 12. Solvents • Right now we are really only worried about polar solvents • Two types: protic and aprotic • Protic solvents Hydrogen bond • Aprotic solvents: have no hydrogen bonds but do have dipole-dipoles • Acetone, DMSO, acetonitrile, DMF all are aprotic solvents • Protic favors Sn1 • Aprotic favors Sn2
- 13. practice
- 14. Relationship between Nu: and solvents
- 15. Sn2 • Bimolecular • Concerted • Stereochemistry is inversion always • Mechanism • Rate= k[substrate][Nu:] • Favors lower substitution due to steric hinderance
- 16. practice
- 17. practice
- 18. Sn1 • Unimolecular • Stepwise reaction • Carbocation intermediate • Racemization • Rate= k[substrate] • Favors higher substitution due to hyperconjugation and induction • Mechanism
- 19. practice
- 20. Stability of carbocations • In order of increasing stability • Methyl, primary, secondary, tertiary
- 21. practice
- 22. Hammond postulate • Tells us what the intermediate looks like • If closer in energy to products, it will look like the products • If it is closer in energy to the reactants it will look like the reactants
- 23. practice
- 24. Did we do synthesis today? • Yuppy Puppy? Lets yabba dabba do this thing • No? I cant wait til we do
- 25. In summary Sn1 Sn2 Stepwise Concerted Carbocation intermediate Only has a transition state Racemic products Always inverted Favored by polar protic Favored by polar aprotic Weak nucleophile Strong nucleophile Rate=k[substrate] Rate=k[substrate][Nu:] Favored by tertiary and secondary halides Favored by methyl, primary, secondary halides Unimolecular Bimolecular
- 26. Are you SN1 or SN2 • Step 1: How many R groups • Methyl, 1= Sn2 • 3= Sn1 • 2= next step • Step 2: strength of nucleophile: strong or weak? • Step 3: Is solvent protic or aprotic?
- 27. practice
- 28. practice
- 29. Exam 4 review: Ch.8 GO TO SLIDESHARE POWERED BY LINKEDIN AND SEARCH “DANIELEISENSTEIN1”
- 30. Alkene Fun Facts C=C bond Sp2 hybridized = trigonal planar Pi and sigma bond Don’t conform = What a rebel
- 31. Alkene Stability
- 32. Practice
- 34. Beta carbons Beta carbons are secondarily adjacent to the functional group Immediately adjacent to the alpha carbon Finding beta carbons is the first step in predicting products for eliminations Find Beta carbons and draw all Elimination products This is 8.1 in solution manual
- 35. Its all about that base! Basicity increases as the formal charge gets more negative Basicity is not as dependent on steric hinderance as nucleophiles A sterically hindered base is called a nonnucleophilic base B: is the symbol for a base
- 37. Elimination reaction Forms alkene We need a base We need a Leaving Group As number of R groups increase, rate of reaction increases This Photo by Unknown Author is licensed under CC BY-SA-NC
- 38. E2 reaction Rate= k[substrate][base] Bimolecular Concerted Strong base Requires anti periplanar geometry Trans-diaxial on a ring This Photo by Unknown Author is licensed under CC BY-SA-NC
- 39. E2 Mechanism
- 40. Practice
- 41. practice
- 42. practice
- 43. Major vs. Minor products We want the most stable product Follows Zaitsev’s rule The less stable product can be favored Hoffmann product Due to steric effects This Photo by Unknown Author is licensed under CC BY-SA-NC
- 44. Practice (8.12) What alkenes are formed? Follow zaittsev rule
- 45. E1 reaction Weak base Unimolecular Involves carbocation intermediate Two-step reaction Rate= k[substrate] This Photo by Unknown Author is licensed under CC BY-NC
- 47. E1 vs. E2
- 48. E1 vs. E2 vs. Sn1 vs. Sn2 BIG DADDY FLOW CHART This is not mine This is the work of clutchprep If you are having trouble in this course or in organic chemistry 2, I highly recommend them This Photo by Unknown Author is licensed under CC BY-NC-ND
- 49. Practice (8.16)
- 50. Questions I like 8.1, 8.3, 8.5, 8.6, 8.7, 8.8, 8.9, 8.10, 8.11, 8.12, 8.13, 8.14, 8.15, 8.18, 8.19 You know what, I Iike all of them
Editor's Notes
- Experimentally from hydrogenation So carbocation is formed in hydrogenation reaction, so stability of carbocation decides amount of energy released in hydrogenation and therefore alkene stability Alkene stability increases= hydrogenation energy decreases = carbocation stability increases= increased Rs
- Leaving group= college student More stable = the easier they leave Across because: increasing electronegativity Down because of increasing size Increased electronegativity means that they are more likely to “Steal” the e- in their bond and more able to keep those e- once they are taken. The increased size means that the atom has more space to spread out the increased number of e-
- In powerpoint there is DBN and DBU. Do we need to teach this? Check second line
- Across: electronegativity; more likely to share electrons to form a bond with hydrogen Up: less real estate
- Find this