Question

6. (14 points) Consider the following molecule. DH CI H2C CH3 (a) (7 points) Draw three staggered conformations of this molecule using Newman projections from the indicated perspective (one structure per box). Then, circle the lowest energy conformation. (b) (7 points) Draw three eclipsed conformations of this molecule using Newman projections from the indicated perspective (one structure per box). Then, circle the highest energy conformation. 7. (4 points) Draw a Newman projection for the following compound: C1 CH3 NOZ CI ci c3 C3

Answer 1

6.

a)

staggered bond angle = 60° and 180°

Lowest energy conformation is the one, which has least steric interactions. Accordingly, the structure is lowest energy conformation.

H3C. CH3 D H Н. I CI

H D H CH3 H CI CH3
$\Leftrightarrow$
H D H Н3С. H CI сHз
$\Leftrightarrow$
H3C. CH3 D H H H CI

b.

Eclipsed conformation = 0° and 120°

Highest energy conformation is the one, which has most steric interactions. Accordingly, the structure is the highest energy conformation.

Н3С. H D H H3C H CI

H3C -CH3 H D H I CI
$\Leftrightarrow$
H D H H CI -CH3 H3C
$\Leftrightarrow$
Н3С. H D H H3C H CI

7. Newmann projection

H CH3 I O2N. CI C3 I H IO H H2 H