Stereochemistry and Isomerism (3) - conformation Flashcards
different spatial arrangement
rotation around bonding
how conformation is made
made different by rotation of chemical bonds
staggered conformation
substituent located far from each other
eclipse conformation
substituents located in the same plane
stability of stagger vs eclipse
staggered - more stable - chemical bonds one from each other
due to chemical bonds - compose of e- - repel
Newman molecules projection - view
along axis of bond - placing circle in middle and perpendicular to bond and project molecule
example - Newman molecules projection - ethanol
determine from RHS
projected easily - allow derivation of dihedral angle
dihedral angle
angle between 2 bonds of substituent on adjacent atom
cyclohexane
not flat ring - in order have 109 degree 28’ bond angles
chair conformation example
diamond lattice - form chair cyclohexane building block
2 types of substiuents
axial - perpendicular to plane
equatorial - along the plane
rotation in cyclohexane - ring inversion
moves one side of plane up - forming boat formation
move other side of plane down
ring inversion
axial substituent become equatorial - vice versa
v. dynamic
monosubstituted cyclohexane
thermodynamic preference for equatorial substituted chair
- H atoms - v. close - repel
chair formation stability vs boat formation
chair formation - more stable - all the bonds are staggered