What is the most stable Newman projection?

Asked By: Dida Kollmannthaler | Last Updated: 27th May, 2020
Category: science chemistry
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The most stable one would have the rear hydrogen in between the front methyl and bromine in a staggered conformation to minimize [lone-pair]-[bonding-electron] repulsions. 4) Rotate the rear groups on the C2−C3 bond 120∘ counterclockwise from the Newman projection shown, and you'll have it.

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Accordingly, which is more stable anti or gauche?

In the most stable conformation, the two methyl groups lie as far apart from each other as possible with a dihedral angle of 180 degrees. This particular staggered conformation is called anti. The gauche form is less stable than the anti form by 0.9 kcal/mol due to steric hindrance between the two methyl groups.

Also, which is more stable staggered or eclipsed? 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.

Similarly, you may ask, which Newman projection has the highest energy?

If we now rotate the front CH3 group 60° clockwise, the molecule is in the highest energy 'eclipsed' conformation, where the dihedral angles are all 0o (we stagger the bonds slightly in our Newman projection drawing so that we can see them all).

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.

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What is gauche Newman projection?

If there is a chain of carbon as an attachment in both the front and back carbon, and the attachments are 60 degrees apart, this is considered a gauche conformation. If the carbon attachments are on opposite ends, 180 degrees apart, this is considered an anti conformation.

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.

Which is the most stable conformation of 2 Methylbutane?

Comparing 1, 3 and 5, we see that 1 has two “bad” gauche interactions, whereas 3 and 5 have only one gauche interaction; thus 3 and 5 are both equally stable, and they are the most stable conformations for 2-methylbutane.

Is axial or equatorial more stable?

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 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.

Why is half chair so unstable?

The half chair form is least stable due to maximum strain. Due to interaction between two flagpole hydrogens, there is steric strain in boat form and also torsional strain is present. It is 6.5kcal/mol less stable than the chair form.

Which cyclohexane is more stable?

The most stable conformation of cyclohexane is the chair form shown to the right. The C-C-C bonds are very close to 109.5o, so it is almost free of angle strain. It is also a fully staggered conformation and so is free of torsional strain.

What is the most stable conformer?

The trans-1,2-dimethylcyclohexane has the most stable conformer, so it is the more stable isomer.

What makes a chair conformation more stable?

The transition state structure is called a half chair. This energy diagram shows that the chair conformation is lower in energy; therefore, it is more stable. The chair conformation is more stable because it does not have any steric hindrance or steric repulsion between the hydrogen bonds.

What is the lowest energy conformation?

The lowest energy conformation of ethane, shown in the figure above, is called the 'staggered' conformation, in which all of the C-H bonds on the front carbon are positioned at dihedral angles of 60°relative to the C-H bonds on the back carbon.

What is the least stable conformation of cyclohexane?

Boat conformation is the least stable, with the highest energy, has steric hindrance between the two equatorial hydrogens on carbon 1 and carbon 4, and has torsional tension because each bond almost completely ellipses other bonds in the Newman projection.

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.

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.

Which conformation of butane is most stable?

The most stable conformation of butane is the one in which the two terminal methyl groups are the farthest removed from each other, i.e. the anti conformation. Somewhat less favorable is the gauche conformation in which the methyl groups assume a dihedral angle of 60°.

Which conformation of ethane is more stable?

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.

What is 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.

Are gauche and staggered the same?

In Staggered Conformation, no group lies parallel to another one in a compound. In Gauche form, More bulky and less bulky groups lie parallel to each other. Thus one can say Staggeres form is the most stable Conformer. BUT in few cases, Gauche form is more stable due to intermolecular hydrogen bonding, etc.