Chemistry 250-02

1. 0 Chemistry 250-02 Organic Chemistry I Fall, 2014 Day 9,10 9/24,26/14 Chapter 4 Cyclohexane and its Stereochemistry Chem Act 7B

2. 0 Cyclohexane C6H12 and Analogs

3. 0 Axial and Equatorial

4. Cyclohexane Ring FlipHow do you know it occurs ?

5. 0 Visualizing CyclohexaneThe Chair – Chem Act 7B Model 3

6. http://www.youtube.com/watch?v=DuX32urvZvQ&feature=channel&list=ULhttp://www.youtube.com/watch?v=DuX32urvZvQ&feature=channel&list=UL

7. 0 What kind of strain is there andWhich cycloalkane is most strain free ? Chem Act 7B Model 4

10. 0 Strain in Substituted Cyclohexanes ΔG = - RT ln K ΔG (in kcal/mole) = - 1.36 log K Klog KΔG .1 -1 1.36 1 0 0 10 1 - 1.36 1002 -2.76 Why so large ? Why so small ?

12. 0 Chemistry 250-02 Organic Chemistry I Fall, 2014 Day 10 9/24/14 Chapter 5 Stereochemistry at Tetrahedral Centers ChemAct 12A Chirality

13. Venlafaxine = EffexorChem Act 12A Model 1

14. Which of the following molecules possesses a plane of symmetry? • A only • B only • C only • A and C • B and C

15. 0 Chirality and Objects in the WorldChem Act 12A Model 2

16. Chem Act 12A Model 2 CTQ 6 6. Example of a molecule that is a. not chiral (achiral) b. chiral

17. Chem Act 12A Model 2 CTQ 7 7. Example of an everyday object that is a. not chiral (achiral) b. chiral

18. Which of the above molecules are achiral? • A and C • A and E • B and C • B and D • D and E

20. 0 Tetrahedra with 2, 3 or 4 different groups

21. Chiral Compounds

22. 0 Consequences of Chirality

23. 0 Tetrahedra with 4 different groups

24. Problems 5.1, 5.2, 5.3, 5.4, 5.5 5.1) Which objects are chiral ? (a) soda can (b) screwdriver (c) screw (d) shoe 5.2) Which molecules are chiral ?

25. What is the relationship between the two compounds shown below? • they are identical • they are constitutional isomers • they are nonsuperimposable mirror images of each other • they are different conformations of the same compound • they have different atom connectivity

26. What do you call a 1:1 mixture of the two compounds below? • a 1 M solution • a racemic mixture • a non racemic solution • an optically active solution • a mixture of diastereomers

27. 0 Stereoisomers conformers Fig. 9-14, p. 341

28. 0 Stereoisomers

29. Enantiomers have identical chemical and physical propertiesin achiral environments. Diastereomers have different properties in chiral and achiral surroundings. What can be deduced based on the observation that A smells like citrus fruits, while B has an odor of pine trees? • A and B are diastereomers. • A and B are an exception to the rule and do not have the same properties. • The sense of smell cannot be used to deduce anything about the stereochemistry of A and B. • The olefactory receptors responsible for smell are chiral. • As can be observed by looking into a mirror, our noses are chiral.

30. Enantiomer Recognition

31. 0 Q: How do you detect chirality ? A: Polarimetry !Chem Act 12A Model 3

32. Which statement about chirality and optical activity is false? • If a solution shows optical activity, it must have a compound present whose mirror image is not superimposable on the compound itself. • Molecules with plane of symmetry will show no optical activity. • The angle of rotation of plane-polarized light depends on how many chiral molecules does the light interact with while passing through the sample. • Enantiomers will always have opposite signs of optical rotation. • All enantiomers are dextrorotatory.

33. Chem Act 12AModels 4, 5 and 6

35. 0 How to specify chiralityThe Cahn-Ingold-Prelog Rules (R) and (S)

36. 0 (R) and (S)

37. 0 Absolute Configuration (R), (S)and Optical Rotation (d)(+), (l)(-)

38. 0 Assign (R) or (S) Problem 5.10, 5.12 see page 156 S N

39. 0 Problem 5-37Assign (R) or (S) and what is the relationship of these pairs of molecules ?

40. 0 2 Stereogenic Centers (C*)

41. 0 2 Stereogenic Centers and a plane of symmetry