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Carey Chapter 3 – Conformations of Alkanes and Cycloalkanes

Carey Chapter 3 – Conformations of Alkanes and Cycloalkanes. Figure 3.5. YSU. Conformational Analysis. Cytosine (C) (from TGCA alphabet in DNA. YSU. Conformational Analysis. Hemoglobin. YSU. Conformational Analysis. Thymidine – incorporated into DNA as “T”.

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Carey Chapter 3 – Conformations of Alkanes and Cycloalkanes

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  1. Carey Chapter 3 – Conformations of Alkanes and Cycloalkanes Figure 3.5 YSU

  2. Conformational Analysis Cytosine (C) (from TGCA alphabet in DNA YSU

  3. Conformational Analysis Hemoglobin YSU

  4. Conformational Analysis Thymidine – incorporated into DNA as “T” Zidovudine (AZT) – incorporated into DNA instead of T – stops chain growth YSU

  5. Conformational Analysis YSU

  6. 3.1 Conformational analysis of Ethane Since single bonds can rotate around the bond axis, different conformations are possible -conformational analysis Figure 3.1 - (use SpartanModel) YSU

  7. 3.1 Conformational analysis Different 3-D depictions of Ethane Wedge/dash Newman Projection Sawhorse Rotation around the central C-C bond will cause the hydrogens to interact -rotamers or conformers YSU

  8. Definitions Gauche torsion angle 60o Eclipsed torsion angle 0o Anti torsion angle 180o Both gauche and anti conformers arestaggered Eclipsed conformers are destabilized bytorsional strain YSU

  9. 3.1 Conformational analysis of Ethane Figure 3.4 YSU

  10. 3.2 Conformational analysis of Butane Figure 3.7 YSU

  11. 3.3 Conformations of higher alkanes eclipsed eclipsed Anti (staggered) Gauche (staggered) Applicable for any acyclic molecule YSU

  12. 3.4 Cycloalkanes – not planar YSU

  13. 3.5 Cyclopropane and Cyclobutane Figure 3.10 YSU

  14. 3.6 Cyclopentane Figure 3.12 YSU

  15. 3.7 Conformations of Cyclohexane YSU Conformationally flexible (without breaking bonds) Chair Boat Chair

  16. 3.7-3.8 Cyclohexane – axial and equatorial positions Figures 3.13-3.14 YSU

  17. 3.9 Conformational inversion – ring flipping Figure 3.18 YSU

  18. 3.10 Analysis of monosubstituted cyclohexanes Based on unfavourable1,3-diaxialinteractions YSU

  19. 3.11 Disubstituted cycloalkanes - Stereoisomers Cis-1,2-dimethylcyclopropane is less stable than the trans isomer Cis-1,2-dimethylcyclohexane is less stable than the trans isomer Cis-1,3-dimethylcyclohexane is more stable than the trans isomer Cis-1,4-dimethylcyclohexane is less stable than the trans isomer All based on interactions between substituents and other groups on the ring YSU

  20. 3.11 Disubstituted Cyclopropanes – Energy Differences Figure 3.20 YSU

  21. 3.12 Disubstituted Cyclohexanes – Energy Differences YSU

  22. 3.13 Medium and large rings – not covered 3.14 – Polycyclic compounds – covering bicyclics Bicyclobutane Bicyclo[3.2.0]heptane Bicyclo[2.2.2]octane YSU

  23. 3.15 Heterocyclic compounds tetrahydrofuran pyrrolidine piperidine YSU

  24. 3.15 Heterocyclic compounds morphine ritilin librium YSU

  25. 3.15 Heterocyclic compounds D-Glucose (dextrose, blood sugar) YSU

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