Evaluation of axial and equatorial conformation stabilization of compounds 1, 3-dioxane by DFT

Saturated heterocyclic compounds like carbohydrates and alkaloids play a significant role in organic and inorganic chemistry. The structural parameters of compounds 1, 3- dioxane [X: F(1), Cl(2), Br(3), CN(4), CF3(5), NO2(6)] for axial and equatorial conformations with density functional theory (DFT) B3LYP/6-311+G** were surveyed. Through analyzing natural bond orbital (NBO), the stabilization energies (E2) associated with electron delocalization LP1O1→σ*C2-C5, LP2O1→ σ*C2-C5, LP1O3→σ*C2-C5 and LP2O3→σ*C2-C5 and natural bond order (nbo) and dipole moment (μ) of compounds 1 to 6 were studied. Research indicated that the bond length (r) of O1-C2, O3-C2 the axial conformation is shorter than equatorial conformation, so more electron transfers are done. Stabilization energy differences (ΔE axial – ΔE equatorial) in compounds 1 to 6 were reported to be 0.08, 0.22, 0.22, 0.51, 0.37 and 0.62 kcal/mol-1 respectively. The tendency of the stabilization energy difference associated with electron delocalization is directly related to the dipole moment difference.