Related Experiment Video
Updated: Oct 13, 2026

High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
Published on: October 31, 2019
Conformational transformation coupled with the order-disorder phase transition in 2-methyl-1,3-cyclohexanedione
1Department of Crystal Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznań, Poland. katran@amu.edu.pl
Abstract:
The half-chair conformation of the dynamically disordered molecular ring of 2-methyl-1,3-cyclohexanedione, C(7)H(10)O(2), transforms to a sofa below Tc = 244 K, when the crystal undergoes a continuous phase transition induced by the onset of halting large-amplitude vibrations of methylene groups C(4)H(2) and C(5)H(2). The temperature dependence of the crystal structure has been investigated by X-ray diffraction. The Ibam symmetry of the crystal reduces below Tc to space group Pccn. The mechanism of the phase transition and of the conversion of the ring conformation is discussed.
Related Concept Videos
Chair Conformation of Cyclohexane
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this staggered...
Conformations of Cyclohexane
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal tetrahedral value,...
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
Stability of Substituted Cyclohexanes
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
Disubstituted Cyclohexanes: cis-trans Isomerism
In cyclohexane, the substituents can occupy different positions generating distinct isomers.
Stereoisomerism of Cyclic Compounds

