1. Conformational Analysis

2. Conformations of Alkanes Relatively low energy barrier to rotation about C-C bonds (4 – 40 kJ/mole) Different shapes resulting from single bond rotations are called conformations

3. Conformations of Alkanes EclipsedStaggered Hash-Wedge Newman Projection

4. Conformations of Alkanes

5. Energy and Conformations Contributions to energies of conformations Steric Strain: an increase in energy due to electrons on atoms occupying the same region of space Torsional Strain: an increase in energy due to electrons in bonds overlapping in an eclipsed conformation Angle Strain: an increase in energy due to distortion of a bond angle from its optimum value

6. Eclipsed Ethane http://lightning.chem.wwu.edu/dept/vmolckit/molecule.html http://lightning.chem.wwu.edu/dept/vmolckit/ethanecl.pdb

7. ECLIPSED CONFORMER OF ETHANE

8. SPACE-FILLING REPRESENTATION

9. Staggered Ethane http://lightning.chem.wwu.edu/dept/vmolckit/ethanstg.pdb

10. STAGGERED CONFORMER OF ETHANE

11. SPACE-FILLING REPRESENTATION

12. ENERGY DIAGRAM FOR ETHANE CONFORMATIONS

13. Eclipsed Butane—0  dihedral http://lightning.chem.wwu.edu/dept/vmolckit/butecl0.pdb

14. ECLIPSED CONFORMER OF BUTANE

15. SPACE-FILLING MODEL

16. Staggered Butane—Gauche http://lightning.chem.wwu.edu/dept/vmolckit/butgauch.pdb

17. STAGGERED CONFORMER OF BUTANE—GAUCHE

18. SPACE-FILLING MODEL

19. Eclipsed Butane—120  dihedral http://lightning.chem.wwu.edu/dept/vmolckit/butec120.pdb

20. ECLIPSED CONFORMER OF BUTANE

21. SPACE-FILLING MODEL

22. Staggered Butane—Anti http://lightning.chem.wwu.edu/dept/vmolckit/butanti.pdb

23. STAGGERED CONFORMER OF BUTANE—ANTI

24. SPACE-FILLING MODEL

25. TUBE BOND REPRESENTATION OF THE ANTI CONFORMATION OF BUTANE

26. ENERGY DIAGRAM FOR BUTANE CONFORMATIONS

27. Conformations of Cyclohexane http://lightning.chem.wwu.edu/dept/vmolckit/cheqcode.pdb

28. AXIAL EQUATORIAL SIDE VIEW OF CYCLOHEXANE

29. AXIAL EQUATORIAL TOP VIEW OF CYCLOHEXANE

30. Conformations of Cyclohexane http://lightning.chem.wwu.edu/dept/vmolckit/cheqcode.pdb

31. CHAIR CONFORMER REPRESENTATION

33. Chemscape Chime http://www.bluffton.edu/~bergerd/Models/homez.html#index http://lightning.chem.wwu.edu/dept/vmolckit/molecule.html The below websites will require that you download Chemscape Chime: http://www.mdlchime.com http://www.mdlchime.com http://www.bluffton.edu/courses/TLC/BergerD/Stutzman/Morphine/model.html http://www.wellesley.edu/Chemistry/Flick/molecules/newlist.html