Why is biphenyl not planar

Show 3 more comments. Active Oldest Votes. Otto Bastiansen, Svein Samdal, "Structure and barrier of internal rotation of biphenyl derivatives in the gaseous state: Part 4. Barrier of internal rotation in biphenyl, perdeuterated biphenyl and seven non- ortho -substituted halogen derivatives," J. Improve this answer. Mathew Mahindaratne Mathew Mahindaratne Add a comment. Divyansh Verma Divyansh Verma 3 3 silver badges 14 14 bronze badges. Featured on Meta.

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Chemistry - Why is biphenyl not planar? Otto Bastiansen, Svein Samdal, "Structure and barrier of internal rotation of biphenyl derivatives in the gaseous state: Part 4. As shown in the following diagram, biphenyl itself is not planar, one benzene ring being slightly twisted or canted in relation to the other as a consequence of steric crowding.

This crowding will be demonstrated by clicking on the diagram. In order to interconvert such conformers with their mirror image structures, a rotation through the higher energy coplanar form must be made. The ease with which this interconversion occurs will depend on the size of the ortho substituents, since these groups must slide past each other. The 2,2'-dicarboxylic acid on the left below cannot be resolved at room temperature, since thermal kinetic energy is sufficient to provide the necessary activation energy for racemization.

The two additionally substituted diacids to its right have a higher activation energy for racemization, and can be resolved if care is taken to avoid heating them.