Why is the boat conformation less stable?

Asked By: Fathallah Dohmel | Last Updated: 14th February, 2020
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Close proximity of the flagpole hydrogens results in steric strain. Eclipsing of carbon-hydrogen bonds on adjacent carbon atoms (3) results in torsional strain. Consequently, the boat conformation of cyclohexane ring is less stable than the chair conformation.

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Correspondingly, why is the chair conformation more stable than boat?

Chair conformation of cyclohexane is more stable than boat form because in chair conformaion the C-H bonds are equally axial and equatorial, i.e., out of twelve C-H bonds, six are axial and six are equatorial and each carbon has one axial and one equatorial C-H bond.

Additionally, which conformation of cyclohexane is least stable? The half chair form is least stable due to maximum strain. It is 10kcal/mol less stable than the chair form and is least stable. The twist boat conformation has less steric and torsion strain as compared to half chair conformation and It is 5.5kcal/mol less stable than the chair form.

Similarly, you may ask, which conformation is more stable?

In terms of stability, the staggered conformation is more stable than the eclipses. This is for two reasons: 1) Steric hindrance. In the eclipsed conformation, the positioning of the atoms forces them closer together, increasing the amount of steric strain in the molecule.

Which conformation of cyclohexane is more stable?

The chair conformation is the most stable conformation of cyclohexane. A second, much less stable conformer is the boat conformation.

28 Related Question Answers Found

Which Cycloalkane is most stable?

Cyclopentane is a stable molecule with a small amount of ring strain, while cyclohexane is able to adopt the perfect geometry of a cycloalkane in which all angles are the ideal 109.5° and no hydrogens are eclipsed; it has no ring strain at all. Therefore its the most stable cycloalkane.

What is torsional strain?

Torsional strain or eclipsing strain is the increase in potential energy of a molecule due to repulsion between electrons in bonds that do not share an atom. eg: Consider two conformations of ethane: The smallest dihedral angle is 60º in 1; it is 0º in 2. Consequently, torsional strain is greater in 2 than in 1.

Is Equatorial more stable than axial?

Also note that when you have two groups and they can be either both axial or both equatorial, it is more stable when they are both equatorial. Cis means “on the same side” and trans means “on opposite sides.” When both substituents are both up or both down, they are cis to each other.

Which is more stable cyclohexane or hexane?

Hexane is linear while cyclohexane is cyclic. This is due to the fact that cyclohexane has 2 hydrogens less compared to hexane. The volume cyclohexane occupies is lower than hexane due to its cyclic structure. Hence, there's a higher number of cyclohexane molecules in a given molecule when compared with hexane.

What is steric strain?


Steric strain is the increase in potential energy of a molecule due to repulsion between electrons in atoms that are not directly bonded to each other. eg: Consider two staggered conformations of 1,2-dibromoethane: Thus, steric strain is greater in 1 than in 2.

What is boat conformation?

The definition of Boat Conformation, in organic chemistry, is a conformation of cyclohexane in which all bond angles are fairly close to 109.5° and many hydrogen atoms are eclipsing each other.

Which Stereoisomer is more stable?

A chair conformation is one of many conformations of a cyclohexane ring and it is most stable. It has equatorial and axial bonds. The equatorial bonds (e) are perpendicular to the axis of the ring, while axial bonds (a) are parallel to the axis of the ring.

Which is more stable gauche or eclipsed?

The gauche form is less stable than the anti form due to steric hindrance between the two methyl groups but still is more stable than the eclipsed formations. Such an interaction is often referred to as a gauche-butane interaction because butane is the first alkane discovered to exhibit such an effect.

Which conformation of ethane has maximum energy?

If we now rotate the front CH3 group 60° clockwise, the molecule is in the highest energy 'eclipsed' conformation, and the hydrogens on the front carbon are as close as possible to the hydrogens on the back carbon.

What is Newman projection formula?


Newman. projection. 3D structure. A Newman projection, useful in alkane stereochemistry, visualizes the conformation of a chemical bond from front to back, with the front atom represented by a dot and the back carbon as a circle. The front carbon atom is called proximal, while the back atom is called distal.

What is conformational analysis?

They are different shapes of the same molecule. Conformational analysis is the study of kinetic and thermodynamic properties of molecules that are conformation dependent such as the existence of a preferred conformation, energies and populations of different conformational arrangements, and chemical consequences of it.

What is a gauche conformation?

Illustrated Glossary of Organic Chemistry - Gauche. Gauche: The relationship between two atoms or groups whose dihedral angle is more than 0o (i.e., eclipsed) but less than 120o (i.e., the next eclipsed conformation). A conformation which has one or more gauche interactions is can be called a gauche conformation.

Which conformation of ethane is more stable and why?

In the staggered conformation, the hydrogen atoms are lined up to be equally spaced apart in the newman projection. For the eclipsed conformation, each hydrogen on the front carbon overlaps with the hydrogens on the back carbon. In terms of stability, the staggered conformation is more stable than the eclipses.

Is anti or gauche more stable?

In the study of conformational isomerism, the Gauche effect is an atypical situation where a gauche conformation (groups separated by a torsion angle of approximately 60°) is more stable than the anti conformation (180°).

What is a cyclohexane ring?


A cyclohexane conformation is any of several three-dimensional shapes adopted by a cyclohexane molecule. Therefore, the cyclohexane ring tends to assume certain non-planar (warped) conformations, which have all angles closer to 109.5° and therefore a lower strain energy than the flat hexagonal shape.

What is a chair conformation in chemistry?

Chair Conformations are the most accurate representations of how cyclohexane rings are actually oriented in space. They appropriately reflect the angles between the carbons in the ring and the positions of the groups on each carbon in the ring.

What is cyclohexane?

Cyclohexane is a colourless, flammable liquid with a distinctive detergent-like odor, reminiscent of cleaning products (in which it is sometimes used). Cyclohexane is mainly used for the industrial production of adipic acid and caprolactam, which are precursors to nylon.