McMurry (Kap.3,6)

Question 1

What is the stereochemistry?

Answer 1

It is the branch of chemistry concerned with the three dimensional aspect of molecules.

Question 2

Is the stereochemistry important for the molecule?

Answer 2

Yes, it is crucial for determining the properties and biological behaviors of chemical molecules.

Question 3

In sigma bonds, free rotation around the C-C are possible. Therefore different arrangements of atoms can result from bond rotation. What are the different arrangements called?

Answer 3

The different arrangements of atoms that result from bond rotation are called conformations.

Don’t confuse with conformational isomers/or isomers, which is the different arrangements of molecule with same formula.

Question 4

Which two ways can conformational isomers be illustrated?

Answer 4

By a sawhorse representation (viewing the molecule from an obliqued angle)

or

A Newman projection (representing the two carbons as a circle, bonds attached to first carbon by lines to the center of the circle, and bonds attached to the rear carbon, are represented by lines attached to the edge of the circle.).

Question 5

Which is the most stabil and least stable conformation of the Newman Projection?

Answer 5

Most stable = staggered.
Least stable = Eclipsed.

Question 6

Does the molecule always excist in the staggered conformation?

Answer 6

No, 99% yes, but 1% of the time it is in the eclipsed conformation.

Question 7

What is the torsional strain?

Answer 7

The energy that arises from the conformation being in the eclipsed position.