Question

1. Ethane. Construct two models of ethane and arrange one in a fully staggered conformation and the other in a fully eclipsed conformation.

a) Draw both of these conformations using the Newman, “sawhorse” and dash-wedge drawing conventions.

b) Locate all the planes of symmetry in the two conformations.

c) By how many degrees must one rotate one carbon atom with respect to the other to carry a staggered conformation into an eclipsed conformation (or vice versa).

d) By how many degrees must one rotate one carbon atom with respect to the other to carry one staggered conformation into another staggered conformation (or one eclipsed conformation into another eclipsed conformation).

e) What are the H-C-C-H dihedral angles in the two conformations.

2. Propane.

Replace one of the hydrogens in an ethane model with a methyl group to make a model of propane.

a) Arrange the model in a fully staggered conformation and draw a Newman Projection of the conformation.

b) Arrange the model in a fully eclipsed conformation and draw a Newman Projection of the conformation.

c) Locate all the planes of symmetry in the two conformations

Answer 1

Answer:

a) Newman:

Eclipsed Staggered

Sawhorse projection:

Dash wedge:

b) It containes the plane of symmetry

c) 45⁰

Explanation:

For the Ethane molecule two carbon atoms containes the Hydrogens, These are separated by only 45⁰.

d) 180⁰

e) 45⁰