Newman Projection [Quick Questions]

[kuckikirukia]

I got to the step where there is the circle with the 6 bonds.

1. Now, to get the types of conformations, I only need to rotate the 'back' carbon, right (never the front)?
2. And does it really matter which way I rotate the 'back' carbon?


Thanks~~!!

[bhavna]

Fristly, u need to understand Projection Formula, it states tat:

The configurational strutures by which the stereoisomers of a compound are distinguished, are characterised by three dimensional arrangement of atoms/groups in their molecules in space. It is very difficult to write down 3-D structures of these stereoisomers of compound in terms of 2-D dimensions on paper, since paper is 2 dimensional. Therefore different ways are used to draw the 3 dimensional figures, by using the projection formula.
Thus the Projection formula of a molecule may be defined as the Projection or shadow of the molecule, suitably altered on paper.

Newman Projection: According to this formula, the projection of the molecule is taken by holding the molecule with its central C-C bond perpendicular to the plane of the paper. In this case, the molecule is viewed along the axis ie from front to back. The two carbon atoms of the central C-C bond are covered by each other ie they are in Eclipsed position represented by a front circle which is superimposed on rear circle. In the centre of the circle there is point which is known as Frontal Carbon atom from which three bonds are given out (at an angle of 120 degree fr each other) where as Rear Carbon atom is represented as the periphery of the circle from which again three bonds, each at an angle of 120 degree, are given out.
I'm sure after reading this it help u understand & answer ur query.