Periplanar Definition in Chemistry

Definition of Periplanar

Butane Periplanar Conformations
These structures show the sawhorse and Newman projections of two periplanar conformations of butane. Todd Helmenstine

Periplanar refers to two atoms or groups of atoms in a conformation are in the same plane with respect to the reference single bond.

The image shows two conformations of butane (C4H10). The methyl groups (-CH3) are lined up in the same plane with the middle carbon-carbon single bond.

The top conformation is known as syn-periplanar and the bottom is known as anti-periplanar.


  • March, Jerry (1985). Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (3rd ed.). New York: Wiley. ISBN 0-471-85472-7.
  • Testa, Bernard; Caldwell, John (2014). Organic Stereochemistry: Guiding Principles and Biomedicinal Relevance. ISBN 390639069.
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Your Citation
Helmenstine, Anne Marie, Ph.D. "Periplanar Definition in Chemistry." ThoughtCo, Aug. 27, 2020, Helmenstine, Anne Marie, Ph.D. (2020, August 27). Periplanar Definition in Chemistry. Retrieved from Helmenstine, Anne Marie, Ph.D. "Periplanar Definition in Chemistry." ThoughtCo. (accessed June 4, 2023).