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Stereochemistry

Stereochemistry. Source: http://biochemistry.utoronto.ca/steipe/. Childish Fantasy.

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Stereochemistry

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  1. Stereochemistry Source: http://biochemistry.utoronto.ca/steipe/

  2. Childish Fantasy “Not long ago, I expressed the view that the lack of general education and of thorough training in chemistry was one of the causes of the deterioration of chemistry research in Germany …. Will anyone to whom my worries seem exaggerated please read, if he can, a recent memoir by a Herr Van’t Hoff on “The arrangement of Atoms in Space”, a document crammed to the hilt by the outpourings of a childish fantasy…..” Written by Hermann Kolbe in 1877 Source: Solomons Organic Chemistry chapter 5

  3. Significants Source: http://nobelprize.org/chemistry/laureates/2001/public.html

  4. Constitutional Isomers Same Molecular Formula but different Structural Formula. (Different Connectivity)

  5. Diastereomers Stereoisomers that are not mirror images of each other. Cis/Trans isomers are a type of diastereomer.

  6. Diastereomers Stereoisomers that are not mirror images of each other. Cis/Trans isomers are a type of diastereomer.

  7. Enantiomers Stereoisomers that are nonsuperposable mirror images of each other.

  8. Enantiomers Enantiomers occur with chiral molecules. Chiral from the Greek cheir meaning “Hand”.

  9. Chiral Enantiomers occur with chiral molecules. Chiral from the Greek cheir meaning “Hand”.

  10. Diastereomers vs. Enantiomers • Diastereomers • Nonsuperposable • Not Mirror Images • Differ in physical properties • Enantiomers • Nonsuperposable • Mirror Images • Same physical properties

  11. Existence • Interaction with Enzymes and Receptor Sites • Stereospecific • Stereoselective • Rotation of Light • Dextrorotatory (Clockwise rotation) • Levorotatory (Counterclockwise rotation) • Louis Pasteur • Visual • Separated with tweezers

  12. Nomenclature Systems • Right Handed / Left Handed Helix (Hand) • +/- (Rotation of Light) • D/L (Base Molecule ) • R/S (Periodic Table) • Anomers (Functional Group Location)

  13. Right Handed / Left Handed Helix Right Hand Rule Left Hand Rule

  14. +/- System

  15. D/L System

  16. D/L System

  17. D/L System

  18. Anomers

  19. Glycosidic Bonds

  20. Glycosidic Bonds

  21. Polysaccharides • Glycogen • Storage form of glucose in Animals • Branches every 6 to 10 glucose residues • Starch (amylose or amylopectin) • Storage form of glucose in plants • Branches every 20 glucose residues • Cellulose (Fiber) • Structural component of plant cell walls • Contains β-1,4-glycosidic bonds

  22. R/S System First assign priority based on Periodic Table Second rotate lowest priority to the back

  23. R/S System Third connect three highest priorities in order

  24. R/S System If clockwise assign R for Rectus If counterclockwise assign S for Sinister

  25. R/S System Assign R and S designations to the structures

  26. R/S System

  27. R/S System Assign R and S designations to each stereocenter

  28. Meso

  29. Meso

  30. Meso

  31. Structural Relationships Same MF NO Yes Same Connectivity Different NO Yes Superposable NO Yes Structural Isomers Mirror Image & Stereocenter Mirror Image NO Yes Yes NO Diastereomers Enantiomers Identical Meso

  32. Problems (p. 235) • 5.39 • 5.40 • 5.43 • 5.52

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