• Sawhorse projection formula. Sawhorse projection formulas are used to denote two principal stereocentres. It is a view of a molecule down a particular carbon-carbon bond, with the groups connected to both the front and back carbons are drawn using sticks at 120° angles. Sawhorse Projections can also be drawn so that the groups on the front carbon are staggered (60 ° apart) or eclipsed (directly overlapping) with the groups on the back carbon. The overall representation is given below (Figure 10).

Figure 10

Newmann projection formula. In this notion, the molecule is again viewed by looking down a particular carbon-carbon bond. The front carbon of this bond is represented by a dot, and the back carbon is represented by a large circle. The three remaining bonds are drawn as sticks coming off the dot (or circle), separated by one another by 120°. Just like Sawhorse projection formula, Newman Projection can be drawn such that the groups on the front carbon are staggered (60° apart) or eclipsed (directly overlapping) with the groups on the back carbon (Fig 11).

Figure 11