Entropy contribution to the axial–equatorial energy difference of isopropylcyclohexane

Abstract

Use of a cryogenic high temperature equilibrium trapping technique in conjunction with dynamic ¹³C n.m.r. spectroscopy shows that the entropic term for the free energy difference of isopropylcyclohexane is 2.2 cal K^–1 mol^–1 based on our determination of a statistical average of the anti and gauche rotamers of the equatorial isomer with a free energy of activation for the conversion of these two isomers found to be 4.1 ± 0.1 kcal mol^–1(1 kcal = 4.184 kJ).