MOLECULAR SPECTROSCOPIC STUDIES AND AB-INITIO CALCULATIONS OF 4 ALCOHOLS DERIVED FROM 2,2-DIMETHYLPROPANE

Four alcohols with the formulas C(CH2OH)(x)(CH3)(4-x), (x=1,2,3,4) hav e been investigated by IR and Raman spectroscopy at different temperat ures from the crystalline phases to the plastic phases and the melts. Solution spectra in different solvents have also been obtained. The al cohols with the highest vapour pressures, 2,2-dimethyl-1-propanol and 2,2-dimethyl-1,3-propanediol were studied in argon and nitrogen matric es at 4.5 K using the hot nozzle technique. As observed for the corres ponding halogenated compounds, the alcohols are expected to have confo rmational equilibria due to restricted rotations around the C-C bonds in the plastic phases, the melts and in solution. Additional conformer s from rotations around the C-O bonds cannot be excluded. The energies and frequencies of the expected conformations were determined by ab i nitio calculations using a 3-21 G basis set and compared with the exp erimental values. The data reveal that the G/G (C-2) conformer is the most stable in 2,2-dimethyl-1,3-propanediol, while in 2-hydroxymethyl- 2-methyl-1,3-propanediol the C-1 conformer is more stable than both C- 3 and C-s with enthalpy differences of 2.9 and 3.7 kJ mol(-1), respect ively.