Conformations Flashcards
Are bonds free to rotate?
Yes and its free, heat in the atmosphere is enough
What is staggered conformation?
When atoms are positioned far apart
What is eclipsed conformation?
When atoms are positions so they look like they overlap.
What is more stable staggered or eclipsed conformation?
Staggered since atoms are further apart electrons face less repulsion
What does a wedged line mean>
Coming towards you
What does a dashed line mean?
Going away from you
What is the anti conformation?
When atoms are positioned as far apart as posible
What Is the gauche conformation?
When atoms are staggered but not as staggered as anti
What does adding a bulky group do to movement of a molecule about a bond?
It hinders movement by increasing steric hinderance. The energy needed to rotate this bond is increased
What’s more rigid an alkane or a cycloalkane?
Cycloalkane as bonds don’t rotate
what are the most common rings?
5 and 6 membered since they don’t have as much angle strain as other rings that deviate more from the preferred 109degrees
What his higher energy linear alkane or equivalent cycloalkane
the cycloalkane since it faces ring strain, unless its 6 membered
What effect increases energy of cycloalkanes above 6 membered rings
steric hinderance
What is angle strain? (Cycloalkanes)
When the angle deviates from the desired 109.5 degrees of an sp3 hybridised carbon
What is torsional strain? (Cycloalkanes)
The molecule trying to rotate to stop eclipsing making a strain on the bond (the molecule puckers)
What is steric strain? (Cycloalkanes)
Methyl groups forced to share space, repulsion between groups
What types of strain are there in ring strain?
Steric strain
Angle strain
Torsional strain
In rings of 3-4 carbons what type of ring strain is happening?
Angle and torsional
in rings of 7-13 what type of ring strain is happening?
steric and torsional
What’s more stable boat or chair?
Chair (groups further apart(staggered))
What has higher energy boat or chair?
Boat, its more unstable
What is more common in nature chair or boat conformation?
Chair since its lower in energy there isn’t a big energy barrier like there is to make boat
What is the position called in a ring when the group is pointing up or down?
Axial (higher in energy)
What is the position called in a ring when the group pointing outwards?
Equatorial (lower in energy)
What has higher energy axial or equatorial?
Axial (groups closer together)
Can rings flip?
Yes so axial and equatorial groups are swapped
How to work out equilibrium constant for axial and equatorial positions?
Conc of equatorial/ conc of axial
