How to convert fischer and wedge dash projection to newman projection. - Class 12 PDF Download

First let me show you how to convert Fischer projection to Newman projection. The easiest way to do this is to proceed via Sawhorse projection (if you are aware of that). However you can convert the projection directly also. In Fischer projection, the crosses or the intersection represent the chiral centres of the molecule. However, we are considering 1,1-dichloroethane which has no chiral centre.

Here is the Fischer-like projection of the molecule

Now while converting a Fischer projection to Sawhorse, please remember that the resulting structure will be eclipsed in nature. This is the general rule of fischer to sawhorse conversion. However, you can skip the eclipsed structure once you are adept with the projection formulas. The horizontal bonds will remain above the plane. The lowermost carbon centre would be the one closest to you. Notice that in Sawhorse, there's no separate distinction for chiral centres. Any two adjacent carbon centres can be considered for Sawhorse projection. Let me show.

Notice that the arrangement of functional groups around each carbon centre represents a 'Y'. This is also followed in the Newman projection. Now let's convert these Sawhorse projections to Newman projections. In Newman projection formula, the front carbon is represented by a dot and the back carbon by a circle encircling the dot. The bond between the front and the back carbon is not shown due to front perspective. The other functional groups attached to these two carbons are shown by simple bonds that look like a 'Y'. An eclipsed Newman projection looks like this.

Now when converting Sawhorse to Newman projection, we need to keep in mind the direction of viewing.

So here is the Newman projection of 1,1-dichloroethane as translated from its Sawhorse projection. Notice that the red dot is carbon centre 1 or the front carbon. Likewise the blue circle is carbon centre 2 or the back carbon. Now what we have here is the eclipsed conformation of 1,1-dichloroethane, more accurately represented as

To get the most stable conformer, you need to rotate this to its staggered form. Like this.

Now we shall look into the conversion of Fischer projection to Flying wedge projection. Flying wedge is also known as the Wedge-dash projection. The main carbon chain here is represented on plane in a zigzag fashion. The functional groups are then placed appropriately on each carbon using a solid or a dashed wedge. Quite like this

Now how to carry this out? While considering the Fischer projection, consider as if it is laid down on the surface of a cylinder, much like this

(Sorry for using D-glucose as the reference molecule here, but you pretty much get the idea! Imagine the 1,1-dichloroethane in its place.) Now we come to the tricky part where you put the main carbon chain (i.e., the vertical line) on the plane of the paper. The groups on the right hand side will be represented by solid wedges (beta bond) and the groups to the left by dashed ones (alpha bond). Here's how to do it.

There, now you have your basic flying wedge. But C-2 is just plain methyl group so you could instead write down the structure as

Hope this helps! :)