Which one of the following statements is not correct?a)Fischer projection represents the molecule in an eclipsed conformationb)Newman projection can be represented in eclipsed, staggered and skew conformationsc)Fischer projection of the molecule is its most stable conformationd)In Sawhorse projections, the lines are inclined at an angle of 120o to each other.Correct answer is option 'C'. Can you explain this answer?

Question

Answer

Fischer projection represents the molecule in an eclipsed conformation:
The Fischer projection is a two-dimensional representation of a three-dimensional molecule. It is commonly used to depict organic molecules, especially carbohydrates. In a Fischer projection, the horizontal lines represent bonds that project out of the plane of the paper, while the vertical lines represent bonds that project into the plane of the paper. The Fischer projection does not provide information about the conformation of the molecule, such as whether it is eclipsed or staggered.

Newman projection can be represented in eclipsed, staggered and skew conformations:
The Newman projection is another way to represent the three-dimensional conformation of a molecule. It provides a view along a specific bond axis. In a Newman projection, the front carbon atom is represented by a dot, and the rear carbon atom is represented by a circle. The lines connecting the two atoms represent the bonds. The Newman projection can be represented in three different conformations: eclipsed, staggered, and skew. In the eclipsed conformation, the two largest groups on each carbon are directly in line with each other, resulting in high steric strain. In the staggered conformation, the two largest groups are as far apart as possible, resulting in low steric strain. In the skew conformation, the two largest groups are neither eclipsed nor staggered, resulting in intermediate steric strain.

Fischer projection of the molecule is its most stable conformation:
This statement is not correct. The Fischer projection does not represent the conformation or stability of the molecule. It is simply a way to depict the connectivity of the atoms in a two-dimensional format. The stability of a molecule is determined by its conformation, which can be represented using other projections such as Newman or Sawhorse projections.

In Sawhorse projections, the lines are inclined at an angle of 120o to each other:
This statement is correct. In a Sawhorse projection, the molecule is viewed at an angle, and the lines representing the bonds are inclined at an angle of 120 degrees to each other. This projection provides a three-dimensional view of the molecule, allowing for the visualization of the dihedral angles between different groups.

In conclusion, the correct statement is option 'C' - the Fischer projection of the molecule is not its most stable conformation. The Fischer projection does not provide information about the conformation or stability of the molecule, but rather represents the connectivity of the atoms in a two-dimensional format.

Answer

Fischer projections were originally proposed for the depiction of carbohydrates and used by chemists, particularly in organic chemistry and biochemistry.
A Fischer projection always uses an eclipsed conformation. A Newman diagram can represent either an eclipsed confirmation or a staggering confirmation or a skew conformation.
Just as with Newman projections, you can draw sawhorse projections in eclipsed and staggered conformations.
Since staggered conformation is more stable than eclipsed one, Fischer projection being in eclipsed projection represents least stable conformation.

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