PART I: The Newman Projections of Butane

The illustration of butane above is represented by the Newman Projections below by designating the two middle carbons, one as the "front" and one as the "behind" carbon, and connecting the two end methyl groups accordingly.

PART II: Comparing Potential Energies Based on the DIHEDRAL ANGLE

Dihedral Angle(in degrees)Conformationkcal/mol difference from 0°
0 and 360syn (eclipsed) none
30no name-2.0
60gauche (staggered)-4.1
90no name-2.8
150no name-3.3
180anti (staggered)-5.0
210no name-3.3
270no name-2.8
300gauche (staggered)-4.1
330no name-2.0

GRAPH: The Potential Energy of Butane as a Function of the Dihedral Angle

MOVIE: The Relationship of the Dihedral Angle and the Potential Energy of Butane Reprised

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The Conformation of Ethane Tutorial
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Bryan Modders
with Dr. Abby Parrill 
Department of Chemistry
Michigan State University
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