Newman Projections Flashcards
What does it mean to say a conformation is anti? Is it present in staggered or eclipsed?
Methyl groups are directly opposite each other, i.e 180 degrees apart. It is present in staggered ONLY.
What is a gauche conformation? Is it present in staggered or eclipsed?
Two adjacent methyl groups are present 60 degrees from each other. It is possible in a staggered conformation ONLY.
What it torsional strain?
Torsional strain is electron-cloud repulsion between atoms that are not optimally positioned due to rotation around a bond. It is only present when atoms are in an eclipsed formation. It is present between atoms that are 3 bonds apart.
Are eclipsed or staggered conformations less stable and why?
Eclipsed conformations are less stable because they have more torsional strain.
What is steric strain?
Steric strain is electron-cloud repulsion between groups (atoms/molecules) not directly bonded to each other. It is present in both staggered and eclipsed conformations. Found in atoms that are more than three bonds apart.
What is a gauche interaction?
2 bulky groups positioned 60 degrees apart, leading to steric strain.
When does steric strain exist in a staggered conformation?
When 2 bulky groups are positioned 60 degrees apart (gauche interaction).
If bulky groups are next to each other in an eclipsed formation, what type of strain does it have?
It has both torsional AND steric strain.
Is torsional or steric strain generally stronger and why?
Steric strain is generally stronger. Steric strain happens between molecules not directly bonded to each other. However, torsional strain can be minimized simply by rotating molecule.
What types of strain do eclipsed conformations have?
Torsional and steric
What types of strain can staggered conformations have?
Staggered conformations can only have steric strain. They have no torsional strain since they are at the maximum angle relative to each other.
