Rank the conformers of 1,2,4-trimethylcyclohexane in order of decreasing stability, putting the most stable first.

Question

Quizplus · Accepted Answer

The most stable conformer of 1,2,4-trimethylcyclohexane is the equatorial conformation which places all methyl groups in the equatorial positions to minimize steric hindrance. Therefore, conformer III with all methyl groups equatorial is the most stable. Conformers IV and II both have one axial methyl group, resulting in some steric hindrance, but since the axial methyl group in conformer IV is on C1 (next to the C2-C3 bond), it experiences less steric hindrance than the axial methyl group in conformer II which is on C4 (next to the C3-C4 bond). Therefore, conformer IV is more stable than II. Conformer I has two axial methyl groups, resulting in significant steric hindrance and is therefore the least stable. Thus, the correct order of decreasing stability is III > IV > II > I, which matches choice C.

Rank the Conformers of 1,2,4-Trimethylcyclohexane in Order of Decreasing Stability