1 / 14

Newman projection : conformational view along a carbon-carbon bond

Newman projection : conformational view along a carbon-carbon bond. Conformations : 3-D arrangements of atoms in a molecule from rotation/twisting about single bonds. qz. cp. Conformations.

ivie
Download Presentation

Newman projection : conformational view along a carbon-carbon bond

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Newman projection: conformationalview along a carbon-carbon bond Conformations: 3-D arrangements of atoms in a molecule from rotation/twisting about single bonds qz cp

  2. Conformations Staggered conformation:atoms/groups on 1 carbon are as far apart as possible from the atoms/groups on adjacent carbon  = 60o qz cp

  3. same plane = 0o Conformations Eclipsed conformation: atoms/groups on 1-C in closet approach to atoms/groups on adjacent C qz cp

  4. Conformations Torsional strain or eclipsed interaction strain strain (E) arises from nonbonded atoms rotate from staggered to eclipsed conformations qz cp

  5. Conformations Ethane as a function of dihedral angle qz cp

  6. Conformations anti conformation • a conformation about a single bond in which the groups lie at a dihedral angle of 180° qz cp

  7. Conformations Steric strain(nonbonded interaction strain): when atoms separated by 4 (more) bonds are forced closer Angle strain: when a bond angle must compressed or expanded from 109.5o calculate total strain - determine the lowest energy conformation ( molecular mechanics ) qz cp

  8. Conformations • conformations of butane as a function of dihedral angle qz cp

  9. Cyclopropane angle strain: bond angles compressed (109.5°  60°) torsional strain: all 6Hs eclipsed strain energy high qz cp

  10. Cyclobutane puckering torsional strain slight  angle strain net - puckered (butterfly) minimum energy conformation butstrain energy high qz cp

  11. Cyclopentane “envelope” -  torsional strain slightly angle strain envelope ~ 1/4th strain energy of cyclopropane qz cp

  12. Cyclohexane - chair conformation Bond bond angles - 110.9° Staggered No angle or torsional strain six Hs are axial and six equatorial qz cp

  13. cyclohexane2 equivalent chair conformations Flip converts 6 axial Hs in one chair6 equatorial Hsin other ? 6 equatorial 6 axial qz cp

  14. Methylcyclohexane Equatorial and axial methyl conformations 94 / 6 qz cp

More Related