McMurry (Kap.5,5)

Question 1

The written method for indicating the 3D arrangement/conformation of substituents at a chirality center is needed.

what 2 conformations are used?

Answer 1

S = counterclockwise.

R = clockwise.

Question 2

How do you determine whether is is R or S conformation?

Answer 2

1) Look at the 4 atoms directly bonded to the c atom, and rank them based on atomic number.

2) if the atoms are the same, look at the second, third and so on, until a difference can be found.

3) Multiple bonded atoms are equivalent to the same atom twice.

Question 3

is the direction of optical rotation (+) and (-) related to the R and S conformations?

Answer 3

No, there is no simple correlation between these two.

R can sometimes be both (-) and (+) and the same goes for S.