AB INITIO STUDY ON THE CONFORMATIONAL BEHAVIOUR OF ETHANE-1,1-DIOL and ETHANE-1,1,2-TRIOL IN SOLUTION

Abstract

Ab initio optimizations at the HF/6-31G level and single-point calculations at the MP2/6-31G**//6-31G level were performed on ethane-1,1-diol and ethane-1,1,2-triol. Their conformational properties are discussed in terms of the anomeric effect, gauche effect and internal O-H interactions. The results showed a parallel behaviour with ethane-1,2-diol. The solvent effect was taken into account using the SCRF theory with a general cavity shape which is defined by the molecular surface.

The preferred all-gauche conformations in 3-fluoro-1,2-propanediol

“…The absence of H-bonds in 1 had already been observed earlier. 13 Moreover, protonation of 1 and 2-fluoroethylamine was found to increase strongly the gauche predominance, and this gauche effect was concluded to be due to a mix of F⋯H(O/ N) H-bonds and electrostatic attraction between F and the positively charged heteroatom (O and N). 8,9 The role of vicinal fluorination in alcohols on the acidity and H-bonding ability of fluorohydrins was studied and, surprisingly, fluorination was found to attenuate the alcohol H-bond acidity due to F⋯HO interactions; these weak interactions outcompete the fluorine electron-withdrawing effect.…”