Question

For each of the following compounds, predict the energy barrier to rotation (looking down any one of the C—C bonds). Draw a Newman projection and then compare the staggered and eclipsed conformations. Remember that we assigned 4 kJ/mol to each pair of eclipsing H’s and 6 kJ/mol to an H eclipsing a methyl group:

1. (a) 2,2-Dimethylpropane
2. (b) 2-Methylpropane

Answer 1

Piimety Lpropne 2,2 Ylar CHS H 60 ul H stagrad Eclipsed 0 6X3 18 KT/m H-l4 b 2- Mtky opan CH2 H H CH A H sta Blurn'r 16 /mo 4 X1 + 6X2