Which cyclohexane conformation is more stable? Detailed analysis of the stability of cyclohexane

cyclohexane (C6H12) is a common hydrocarbon compound in chemical industry, which is widely used in solvent, petrochemical and synthetic chemistry. The stability of cyclohexane is a key topic because there are many possible conformations of the cyclohexane molecule, and the stability of different conformations varies greatly. Which conformation of cyclohexane is more stable? This article will analyze the different conformations of cyclohexane and the reasons for its stability in detail.

Overview of the conformation of cyclohexane

cyclohexane is a six-membered ring molecule consisting of six carbon atoms and twelve hydrogen atoms. Since the conformation of cyclohexane exhibits a strong bending nature when the carbon atom is located on a plane, cyclohexane reduces the intramolecular stress through different conformational forms. The common conformation of cyclohexane includes chair conformation, boat conformation and torsion conformation.

chair conformation

the chair conformation is the most stable conformational form of cyclohexane. In this conformation, five of the six carbon atoms are in a plane, while the sixth carbon atom is bent to form the shape of a "chair. The stability of chair conformation mainly comes from the following factors:

1. minimum angular stress: In the chair conformation, the bond angle around each carbon atom is close to the ideal 109.5 °, that is, close to the regular tetrahedral angle, which reduces the angular stress.
2. Minimal stereo obstruction: Because the hydrogen atoms in the molecule are in the axial and equatorial directions, a symmetrical structure is formed, and the three-dimensional repulsion between hydrogen atoms is relatively small.

Therefore, the chair conformation becomes the most common and stable conformation of cyclohexane.

ship conformation

the boat conformation is another common conformation of cyclohexane. In the boat conformation, the six carbon atoms show a boat-like structure, which causes some carbon atoms to bend and some atoms form an approximate "scissors" structure. The stability of the ship conformation is poor, mainly has the following problems:

1. large angular stress: Due to the deviation of the bond angle between carbon atoms, the ship conformation has a larger angular stress than the chair conformation.
2. Strong three-dimensional rejection: In the boat conformation, the hydrogen atoms at both ends of the ring are in axial positions, which makes the repulsive force between these hydrogen atoms larger, thereby reducing stability.

Although the boat conformation can exist under certain conditions, its stability is significantly lower than that of the chair conformation.

torsion conformation

the twisted conformation is another extremely unstable conformation of cyclohexane, which mainly exists in an intermediate form of the cyclohexane molecule in the transition state. In the twisted conformation, the steric repulsion between carbon and hydrogen atoms is severe, so its stability is very poor. The twisted conformation does not generally exist as a long-term conformation of cyclohexane, which is usually a transition state in which cyclohexane transitions from one conformation to another.

Which cyclohexane conformation is more stable?

According to the above analysis, the chair conformation is more stable, mainly due to its minimal angular stress and three-dimensional repulsion. Although the ship conformation and the twisted conformation may exist in some special cases, their stability is obviously lower than that of the chair conformation. Therefore, if you care about the stability of cyclohexane, then the chair conformation is undoubtedly the best choice.

Summary

the conformational stability of cyclohexane was significantly different, and the chair conformation became the most stable conformation due to its minimal angular stress and minimal steric hindrance. The boat and twisted conformations are relatively unstable due to greater steric repulsion and angular stress. Therefore, when analyzing which cyclohexane conformation is more stable, the chair conformation is undoubtedly the most advantageous choice.