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.

2. Constitutional isomers
Isomerism : Compounds with the same molecular formula but different structures
Stereochemistry
Stereoisomer
Constitutional isomers
Conformation
Configuration
Geometrical
Diastereomer
Enantiomer
Trans
Cis

3. Stereochemistry of Tetrahedral Carbons
Is the chemistry of the molecules in three dimensions 3

4. Definitions
Configuration isomers - differ from each other only in arrangement of their atoms in space
Chiral compounds( asymmetric carbon) (stereogenic center or stereo center) – sp3 carbon with 4 different atoms or groups attached & don’t have plane of symmetry (that is optically active and are called optical isomers) .
achiral compound – a compounds have two or more atoms or groups that are the same (that is optically inactive)
Optical activity – the ability to rotate the plane of plane –polarized light
Polarimeter – device that measures the optical rotation of the chiral compound

6. More 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
Racemic mixtures – a mixture of enanatiomers with the same amount of each ( are optically inactive and donated by +/-)

8. Plane-Polarized Light through an Achiral Compound

9. Plane-Polarized Light through a Chiral Compound

10. 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

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

12. Chirality Center Carbon has four different groups attached

13. Enantiomers nonsuperimposible mirror images

14. NAMING ENANTIOMERS
Since two enantiomers are different compounds, we will need to have nomenclature which distinguishes them from each other.
The convention which is used is called the (R,S) system (absolute configuration)
because one enantiomer is assinged as the R enantiomer and the other as the S enantiomer. What are the rules which govern which is which?
The conversion of a perspective drawing to a Fischer projection requires rotating the molecule so that the "top" and "bottom" groups are oriented back, away from you. This places the "right" and "left" groups in a position where they are projecting outward towards you, as in a "bow-tie"

15. These rules are restated below, with examples:
1.Examine the four atoms directly attached to the chiral center in question. Assign priorities in order of decreasing atomic number; the atom with the highest atomic number is #1, the next is #2, etc.
2. If a decision regarding priority cannot be reached using Rule #1, compare the atomic numbers of the second atoms
in each substituent, then the third, etc., until a difference is found.Example:
3-Ethoxy-2-chlorohexane

16. 3. Multiple bonds count twice (or three times) when examining substituents.
3-Ethyl-4-chloro-pentene

17. C.I.P. Priorities

18. Enantiomeric Excess (Optical Purity)

20. Diastereomers
Molecules with more than one chirality center have mirror image stereoisomers that are enantiomers . In addition they can have stereoisomeric forms that are not mirror images

31. Fischer Projections with 2 Chiral Centers

32. Identical, Enantiomers or Diastereomers?

33. Tartaric Acids

34. Racemic Mixture

35. Meso Compound Internal Plane of Symmetry Optically Inactive

36. 2,3,4-trichlorohexane How many stereoisomers?

37. n = 3; 2n = 8

38. A Carbohydrate

39. Internal Planes of Symmetry

40. Asymmetric Centers on Rings

41. Allenes can be Chiral

42. Mycomycin, an antibiotic

43. Reactions that Generate Chirality Centers Hydrogenation, syn

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

45. Bromonium Ion is Opened Equally from Both Sides

46. trans alkene + anti addition = MESO

47. cis Alkene + anti addition = racemic mixture

48. Brominations Often Generate Asymmetric Centers

49. Asymmetric Center is Generated Racemic Mixture Formed

50. Asymmetric Induction

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

52. Relevance of Stereochemistry

53. One-step synthesis

54. a-(p-isobutylphenyl)propionic acid

55. Model of Thalidomide

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

57. Sildenafil (Viagra) and Caffeine

58. Radiosensitizer of Choice Until 2004