3 Conformations Flashcards
Different rotational arrangements are called
conformations
Different conformations require different amounts of _____
energy
what are the 3 types of strain
Angle strain
Torsional strain
Steric strain
what is angle strain
- Torturing a molec into a not ideal geometry (raises energy)
- Orbitals with bad overlap (because they don’t want to be in a not ideal geometry)
3 membered rings have _____ angle strain
tremendous
what is the most common reason for angle strain
unusual geometry
what is torsional strain
- e- clouds from 2 atoms that are separated by exactly 3 bonds coming too close together (negative charges are repelling)
- Like a dihedral side angle (H’s lined up exactly w each other)
torsional strain has a ____ energy cost associated with it
low
what is steric strain
- 2 atoms that are not bonded together being close in proximity
TF ATs considered non bonded if they are separated by 2 bonds (or if on diff molecs)
F , its 3 or more bonds
what is an example of massive steric strain
heavily overlapping electron clouds.
what are 5 diff types of conformations
○ Eclipsed
○ Staggered
○ Antiperiplanar
○ Gauche
○ Partially eclipsed
what does the antiperiplanar confomration look like
2 large/high priority substituents are the max distance from eachother
what does a gauche conformation look like
Staggered but large/high priority grps r close to each other
what does a partially eclipsed conformation look like
Largest/priority groups are eclipsed but with a smaller atom
what are the conformations based on lowest to highest energy
staggered
partially eclipsed
eclipsed
gauche
antiperiplanar
TF 3 membered rings must be planar
T
TF 4, 5, and 6 membered rings must be planar
F, they do not have to be planar
what are the conformations called for a 6 a rings
half chair
boat
twisted boat
chair
rate from lowest to highest energy
half chair, boat, twisted boat, chair
chair
twisted boat
boat
half chair
TF when ring inversion happens then all axial groups become equitorial and vise versa
T
What is the A value of a molecule
how much stain the molec has
