Conformational behavior of polar endgroup substituted alkanes explored by simulation methods

Results from the Monte Carlo computational simulation of the equilibrium thermodynamics of terminally substituted linear alkanes are described. The molecules modeled have a linear alkyl backbone of the form -(CH₂)_n-, where n=10, 12, or 14, bearing identical polar chain termini. The range of endgroup dipole moments investigated is 0.1 to 10 D. The analytical basis of the model and the assumptions and limitations inherent in it are fully discussed. For the purposes of comparison with the available experimental observations on 1,12-dinitrododecane, O₂N-(CH₂) ₁₂-NO₂, which is a typical member of this class of molecules, the parameters of interest are the net dipole moment and the mean-square end-to-end separation. The temperature dependencies of these parameters with varying chain length and endgroup dipole moment are described and evaluated