About Us
About Site
Fascinating Facts
Contact Us
StereoChemistry Conformational Isomerism - Level 2

Rotation about the C-C single bond

Rotation About C-C single bond

In a simple molecule like ethane, the conformation in which the atoms are closest to each other is called the eclipsed form, and the one in which they are farthest apart is the staggered conformation. Inter atomic repulsions are maximum in the eclipsed and minimum in the staggered form thereby making the former less stable than the later.

Representation of the 3D structures of conformations for simple molecules.
The Newmann projection

Ethane has two carbons and three hydrogens attached to each carbon, the two carbons are joined by a single bond about which rotation is possible. First a circle is drawn and the center of the circle represents the carbon in front when you are looking at the molecule (see the diagram). That carbon has three hydrogens attached, the carbon in the back also has three hydrogens attached but they are not visible because they are exactly behind the ones in front looking in that specific direction, this is the eclipsed form. In the diagram for the carbon in front the bonds start in the middle of the circle and the one in the back they are drawn starting from the edge of the circle. In the eclipsed form the hydrogens in the back are drawn with a dotted line close to the one in front indicating they are eclipsed.

Conformationsof ethane "The Sawhorse form"

conformation of Ethane
Copyrights: 2005 All Rights Reserved
Tutorial topics| Home | Recent Articles