How many different staggered conformations are there for 2-methylpropane? How many different eclipsed conformations are there?

Begin by drawing the Newman projection for 2-methylpropane along the C2-C3 bond. This will help visualize the different staggered and eclipsed conformations that the molecule can adopt. Consider the front carbon (C2) and the back carbon (C3), with the bond connecting the two carbons as the line of sight.

To create all possible conformations, first take note of the groups attached to each carbon atom. On the front carbon (C2), there are three groups: an H atom, a CH3 group (methyl), and a CH2-CH3 group (ethyl). On the back carbon (C3), there are 3 H atoms.

For staggered conformations, each group on the front carbon must have a dihedral angle of 60 degrees from its nearest group on the back carbon. The most effective way to achieve this is by arranging the groups of both carbons in a 60-degree increment. For C2, the order can be H-CH3-CH2-CH3, and for C3, it can be H-H-H. There are only two possible arrangements for staggered conformations in this case: 1. Front carbon: H-CH3-CH2-CH3, Back carbon: H-H-H (with H on the front carbon opposite to the H on the back carbon). 2. Front carbon: H-CH3-CH2-CH3, Back carbon: H-H-H (with CH3 on the front carbon opposite to the H on the back carbon). So, there are 2 different staggered conformations.

For eclipsed conformations, each group on the front carbon must have a dihedral angle of 0 degrees or 120 degrees from its nearest group on the back carbon. For C2, the order can still be H-CH3-CH2-CH3, and for C3, it can be H-H-H. There are 3 possible arrangements for eclipsed conformations in this case: 1. Front carbon: H-CH3-CH2-CH3, Back carbon: H-H-H (with H on the front carbon overlapping the H on the back carbon). 2. Front carbon: H-CH3-CH2-CH3, Back carbon: H-H-H (with CH3 on the front carbon overlapping the H on the back carbon). 3. Front carbon: H-CH3-CH2-CH3, Back carbon: H-H-H (with CH2-CH3 on the front carbon overlapping the H on the back carbon). So, there are 3 different eclipsed conformations. In conclusion, there are 2 different staggered conformations and 3 different eclipsed conformations for 2-methylpropane.