What is the Difference Between Staggered and Eclipsed Conformation?

Staggered and eclipsed conformations are two different arrangements of atoms in a molecule, particularly in alkanes like ethane. The main differences between these two conformations are:

Steric hindrance: In an eclipsed conformation, the carbons are aligned so that the hydrogens are lined up with each other, creating steric hindrance between them. In a staggered conformation, the atoms are all equally spaced from each other, minimizing steric hindrance.
Energy: The staggered conformation is lower in energy than the eclipsed conformation, meaning there is a small barrier to rotation of about 3.0 kcal/mol. The staggered conformation is the most stable of all possible conformations of ethane, since the angles between C-H bonds on the front and rear carbons are maximized, which minimizes the energy.
Dihedral angles: Staggered and eclipsed conformations differ in the relative orientation of all the bonds on the front carbon versus the back carbon. The dihedral angle refers to the relationship between one individual bond on the front carbon versus one on the back carbon.

In summary, staggered conformations are more stable and have less steric hindrance than eclipsed conformations. This stability difference is due to the maximized angles between C-H bonds on the front and rear carbons in staggered conformations, which minimizes the energy of the molecule.

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What is the Difference Between Staggered and Eclipsed Conformation?

Comparative Table: Staggered vs Eclipsed Conformation

Staggered and eclipsed conformations refer to the relative orientation of the bonds in a molecule, specifically in alkanes like ethane and propane. The differences between these conformations are summarized in the table below:

Feature	Staggered Conformation	Eclipsed Conformation
Description	In this conformation, the C-H bonds are arranged as far apart as possible, minimizing repulsion between the electrons of C-H bonds of the two carbons.	In this conformation, the dihedral angle is 0°, and the H atoms on the front carbon are overlapping with the H atoms on the rear carbon. This arrangement causes electrons of C-H bonds of the two carbons to repel each other, resulting in torsional strain or eclipsing strain.
Energy Level	Lower in energy than the eclipsed conformation.	Higher in energy than the staggered conformation.
Barrier to Rotation	There is a small barrier to rotation of about 3.0 kcal/mol.	There is a greater barrier to rotation due to the torsional strain or eclipsing strain.
Stability	More stable due to the minimized repulsion between the electrons of C-H bonds of the two carbons.	Less stable due to the increased repulsion between the electrons of C-H bonds of the two carbons.
Percentage of Ethane Molecules	At any given moment, about 99% of the ethane molecules will be in a staggered conformation.	Due to the continuous interconversions between staggered and eclipsed conformers, these two conformers cannot be separated from each other.

In higher alkanes like butane and propane, the same concept of staggered and eclipsed conformations applies, but the analysis becomes more complex due to the presence of more carbons and thus more possible conformations.

Guilherme Mazui

Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.