Role of solvent accessible surface area in the conformational equilibrium of n-butane in liquids

Explicit computer simulations have unequivocally demonstrated that water significantly affects the conformational equilibrium of n-butane, favouring the gauche conformation with respect to the trans conformation. In this Letter, it is shown that a theoretical approach, grounded on the basic notion that the fundamental difference among the various n-butane conformations is the solvent-excluded volume they produce, is able to quantitatively reproduce the dependence of the conformational Gibbs energy upon the dihedral angle in both water and carbon tetrachloride.