Question

What are sawhorse projections in organic chemistry ?

Answer 1

Hint : A sawhorse projection unlike the molecular formula and other molecular representations views the molecule down in a particular angle around a carbon-carbon bond. It has both staggered and eclipsed conformation like the Newman projection.

Complete Step By Step Answer:
Given the hint, a sawhorse projection is a representation of a molecule when viewed from a particular angle around a carbon-carbon bond. Unlike the Newman projection, the adjacent carbon atoms are not crushed into a single center, instead, the C-C bond is drawn and the other three groups attached to the carbon atom are separated by $ {120^ \circ } $ . It can be better explained by an example.
Take the case of n-butane $ C{H_3}C{H_2}C{H_2}C{H_3} $ ,

The first image is the eclipsed conformation of butane while the second one is its staggered conformation (anti) . Two carbon atoms are joined by a solid line and the other three functional groups attached to it have $ {120^ \circ } $ separation. Anti and gauche conformations are the different staggered conformations. Rotations around the C-C single bond gives rise to conformers. Among these, eclipsed conformation seems to be least stable due to torsional strain between two methyl groups and the anti ( staggered) more stable due to large separation between the two methyl groups.

Note :
A sawhorse projection helps in a better visualization of conformation of a molecule. It clearly depicts the three dimensional geometry and interaction between the groups of adjacent carbon atoms. This can help us to identify the characteristic properties of the molecules easier like its mirror image, stereo selectivity, reaction mechanism etc.