Conformations: Ethane and Cyclohexane

Also called

conformations · conformational isomers · ethane rotation · staggered conformation · eclipsed conformation · Newman projection · sawhorse projection · torsional strain · dihedral angle · cyclohexane chair · boat conformation · ring flip · axial hydrogen · equatorial hydrogen · rotation about C-C bond · संरूपण · कुर्सी संरूपण · नाव संरूपण

Topics

• Rotation about a C–C single bond gives different spatial arrangements of the same molecule: conformations.
• In staggered ethane the hydrogens on the two carbons are 60° apart; in eclipsed ethane they line up behind each other.
• The staggered form is lower in energy; the eclipsed form lies about 12.5 kJ/mol higher because of torsional strain.
• A Newman projection looks down the C–C bond: the front carbon is a dot with three bonds, the back carbon a circle.
• The energy barrier is so small that at room temperature ethane's CH₃ groups spin freely through all conformations.
• Cyclohexane is not flat: in the chair form all C–C–C angles are 109.5° and every C–H bond is staggered.
• The boat form is about 29 kJ/mol higher than the chair, so almost all molecules are chairs at room temperature.
• Each chair carbon has one axial hydrogen (up or down) and one equatorial (outwards); a ring flip swaps the two sets.

About this model

A GLB file of about 497 KB, shown in Lably's 3D viewer and, on a phone, placed in your room with AR. Credit: Model, science and animation: Lably (built procedurally with three.js; no downloaded meshes). | CC BY 4.0. Original geometry and animation made for Lably.

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