1. Stereochemistry
Stereochemistry refers to the
3-dimensional properties and reactions of molecules. It has its own language and terms that need to be learned in order to fully communicate and understand the concepts.

3. Definitions
Stereoisomers – compounds with the same connectivity, different arrangement in space
Enantiomers – stereoisomers that are non- superimposible mirror images; only properties that differ are direction (+ or -) of optical rotation
Diastereomers – stereoisomers that are not mirror images; different compounds with different physical properties

4. More Definitions
Asymmetric center – sp3 carbon with 4 different groups attached
Optical activity – the ability to rotate the plane of plane –polarized light
Chiral compound – a compound that is optically active (achiral compound will not rotate light)
Polarimeter – device that measures the optical rotation of the chiral compound

5. Plane-Polarized Light

6. Plane-Polarized Light through an Achiral Compound

7. Plane-Polarized Light through a Chiral Compound

8. Polarimeter Measures Optical Rotation

9. c = concentration in g/mL
Specific Rotation, [α]
[α] = α / cl
a = observed rotation
c = concentration in g/mL
l = length of tube in dm
Dextrorotary designated as d or (+), clockwise rotation Levorotary designated as l or (-), counter- clockwise rotation

10. Specific Rotations of some Common Organic Compounds
Compound [a] # * centers Penicillin V Sucrose Camphor MSG Cholesterol Morphine

11. Chirality Center Carbon has four different groups attached

12. Enantiomers nonsuperimposible mirror images

13. Enantiomeric Excess (Optical Purity)

15. Biological Activity

16. SSRI Efficacy depends on Stereochemistry

17. Absolute Configuration

18. Assign Priority to each Group on Asymmetric Center

19. Lactic Acid

20. C.I.P. Priorities

21. Fischer Projections

22. Assigning Absolute Configuration to Fischer Projections

23. Rotation of the Projection 90o Reverses Absolute Configuration

24. Diastereomers Stereoisomers That Are Not Mirror Images

25. Fischer Projections with 2 Chiral Centers

26. 2 Chiral Centers 4 Stereoisomers

27. Identical, Enantiomers or Diastereomers?

28. Tartaric Acids

29. Racemic Mixture

30. Meso Compound Internal Plane of Symmetry Optically Inactive

31. 2,3,4-trichlorohexane How many stereoisomers?

32. n = 3; 2n = 8

33. A Carbohydrate

34. Internal Planes of Symmetry

35. Asymmetric Centers on Rings

36. Allenes can be Chiral

37. Mycomycin, an antibiotic

38. Reactions that Generate Chirality Centers Hydrogenation, syn

39. Bromination Trans is formed exclusively No Meso is formed (cis)

40. Bromonium Ion is Opened Equally from Both Sides

41. trans alkene + anti addition = MESO

42. cis Alkene + anti addition = racemic mixture

43. Brominations Often Generate Asymmetric Centers

44. Asymmetric Center is Generated Racemic Mixture Formed

45. Asymmetric Induction

46. Preparation of (L)-Dopa for Treatment of Parkinson’s

47. Relevance of Stereochemistry

48. One-step synthesis

49. a-(p-isobutylphenyl)propionic acid

50. Model of Thalidomide

51. How Sweet it is!
Sucralose is 600 times sweeter and does not get metabolized.

52. Sildenafil (Viagra) and Caffeine

53. Radiosensitizer of Choice Until 2004