What is anti conformation?

Asked By: Vella Adelt | Last Updated: 8th May, 2020
Category: science chemistry
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Anti Conformation. Consider a compound that has the following structural formula. The following staggered conformation, in which the dihedral angle between X and Y is 180°, is called the anti conformation.

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Beside this, 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.

Also Know, what is anti staggered conformation? Anti-staggered: A staggered conformation in which the two largest groups are anti (i.e., have a 180o dihedral angle).

Similarly one may ask, what is the difference between gauche and anti?

Gauche is when the large atoms are staggered adjacent to each other (60 degrees) and anti is when the large atoms are opposite each other (180 degrees). Both are staggered but the names gauche and anti tell you the different energies of the conformations.

Which conformation is most 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.

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Is gauche or eclipsed more stable?

This is called the gauche conformation. 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. The other eclipsed conformation occurs at the angles of 60 and 300 degrees.

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.

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.

Is gauche and skew same?

No they aren't. In conformations of butane along C2-C3 bond,when in newmann projections we represent two methyl groups at 60. position , conformation is gauche. Skew conformations are infinite conformations in between the specific ones formed due to rotation along the bond but they are not anti,staggered, or gauche.

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.

How do you know if something is gauche?

1 Answer. When we sight down a carbon-carbon single bond and draw a Newman projection of a particular conformation, any two groups on the adjacent (vicinal) carbons that have a dihedral angle of 60° between them are said to have a gauche relationship.

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.

Why is gauche more stable?

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. The gauche form is less stable than the anti form by 0.9 kcal/mol due to steric hindrance between the two methyl groups.

What is eclipsed form?

In chemistry an eclipsed conformation is a conformation in which two substituents X and Y on adjacent atoms A, B are in closest proximity, implying that the torsion angle X–A–B–Y is 0°.

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.

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.

What makes a Newman projection stable?

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.

What is conformation in chemistry?

Definition of Conformation. What is Conformation? The spatial arrangement of the atoms affording distinction between stereoisomers which can be interconverted by rotations about formally single bonds.

What is eclipsed conformation in organic chemistry?

Eclipsed (eclipsed conformation): Two atoms and/or groups whose dihedral angle is 0o. In other words, their bonds to the axis of rotation are aligned. Also refers to a conformation which contains this arrangement.

What is steric strain in organic chemistry?


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.

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°.

What does dihedral angle mean?

A dihedral angle is the angle between two intersecting planes. In chemistry, it is the angle between planes through two sets of three atoms, having two atoms in common. In solid geometry, it is defined as the union of a line and two half-planes that have this line as a common edge.