Question

I'm not even sure if I drew the structures correctly, so please double check that as well. For the first Newman projection (most stable) are there 3 CH3 gauche groups or 6? I'm confused if I only use each CH3 group once or twice. Thank you! Will rate quickly.

2. Calculate the barrier to rotation along the C2-C3 bond of 2.2,3,3-tetramethylbutane. Start by drawing the most stable and the least stable conformations. CHA Least stal mort statu CHう 1tl CtH3 CHう 2 L x 38 ctla CH3 CH3 CHi3

Answer 1

On each carbon three methyl groups are present in gauche conformation. A pair of methyl groups (methyl groups present on adjacent carbons) can cause one gauche interaction. So total we have 3 pairs of methyl groups. Therefore total 3 gauche inteteractions present. From this we have to consider only 3 methyl groups. Not 6 methyl groups.