Newman Projections: Identify
Common Questions
What is a Newman projection?
A Newman projection shows the conformation of a molecule by looking straight down the axis of a carbon-carbon bond. The front carbon is a dot, the back carbon is a circle, and each carbon's three substituents radiate outward at 120-degree angles.
What is the difference between eclipsed and staggered conformations?
In a staggered conformation, substituents on the front and back carbons are 60 degrees apart (maximally separated). In an eclipsed conformation, they line up directly behind each other (0-degree dihedral). Staggered is lower energy because it minimizes electron repulsion.
What is the difference between anti and gauche conformations?
Both are staggered. Anti has the two largest substituents 180 degrees apart (lowest energy). Gauche has them 60 degrees apart (slightly higher energy due to steric strain). For butane, anti is about 3.8 kJ/mol more stable than gauche.
How do you convert a Newman projection to a line-angle structure?
Identify which substituents are on the front vs. back carbon. The dihedral angle in the Newman becomes the torsion angle in the line structure. Wedge/dash bonds show whether groups point toward or away from the viewer.