What is the most stable Newman projection?

The most stable one would have the rear hydrogen in between the front methyl and bromine in a staggered conformation to minimize [lone-pair]-[bonding-electron] repulsions. 4) Rotate the rear groups on the C2−C3 bond 120∘ counterclockwise from the Newman projection shown, and you’ll have it.

What is sawhorse projection with example?

In a sawhorse projection, a molecule is viewed from an angle, rather than side-on. For example, imagine looking at model 1 of ethane below at an angle so that the carbon atom highlighted in red is further from you, and the carbon atom in grey is closer to you.

Is a sawhorse a projection?

Sawhorse projection: A representation of molecular structure, from an oblique angle. Somewhat similar to Newman and zig-zag (Natta) projections. The sawhorse projection is named after its similar appearance to a carpenter’s sawhorse.

Which Newman projection has the lowest energy?

The lowest energy conformation of ethane, shown in the figure above, is called the ‘staggered’ conformation: all of the dihedral angles are 60o, and the distance between the front and back C-H bonds is maximized.

What is the most stable conformer?

The trans-1,2-dimethylcyclohexane has the most stable conformer, so it is the more stable isomer.

What is the most stable conformation?

The most stable conformation is anti at both bonds, whereas less stable conformations contain gauche interactions. One gauche-gauche conformer is particularly unfavorable because methyl groups are aligned with parallel bonds in close proximity. This conformation is called syn.

What is the difference between sawhorse projection and Newman projection?

A sawhorse projection is similar to a Newman projection, but it shows the carbon-carbon bond that is hidden in a Newman projection. Just as with Newman projections, you can draw sawhorse projections in eclipsed and staggered conformations. Below is a sawhorse projection of the gauche conformation of butane.

What’s the difference between a sawhorse and a Newman projection?

The only difference is a slightly different perspective: the Newman projection looking straight down the bond of interest, the sawhorse projection looking at the same bond but from a somewhat oblique vantage point.

How are the backbone carbons represented in a sawhorse projection?

In a sawhorse projection, the backbone carbons are represented by a diagonal line, and the terminal carbons are shown in groups, just as in the Fischer projection. You can see in the next illustration that the top carbon group of the Fischer projection of 2‐bromo‐3‐chlorobutane has become the back carbon group of the sawhorse projection.

How are Fischer and sawhorse projection used in chemistry?

Compare the structural formula and Fischer projection of 2‐bromo‐3‐chlorobutane. A second type of projection, a sawhorse projection, allows better visualization of the three‐dimensional geometry between adjacent carbon atoms. This projection is customarily used to show interactions between groups on adjacent carbon atoms in mechanisms.

How to draw the Newman projections for pentane?

Draw the Newman projections for pentane looking down the C2-C3 bond through a full 360 degree rotation. Start with the anti-staggered Newman projection then draw and label each Newman projection (staggered, eclipsed, gauche, anti-staggered, fully-eclipsed) for every 60 degrees of rotation: