H₂O, HDO, and CH₃OH Infrared Spectra and Correlation with Solvent Basicity and Hydrogen Bonding

Abstract

A study has been made of the infrared 0-H bands for CH30H, DOH, and H z O in solution and of their correlation with hydrogen bonding and solvent basicity. Infrared bands for the three fundamentals and the first bending overtone of HzO and for the 0-H stretching fundamentals of DOH and C H 3 0 H have been measured between 30 and -40°C in a solvent range extending from weakly interacting fluorocarbons to strongly hydrogen-bonding organic amines. The 0-H stretching bands for the weakly acidic solutes CH30H, DOH, and H z O are mostly Lorentzian in shape and move to lower frequencies with higher extinctions in the more basic solvents. Many correlations are found between the stretching frequencies and band areas, and between the frequencies and solvent basicity. Monofunctional C H 3 0 H is found to be a stronger acid and forms stronger hydrogen-bonds with a given base than do the doubly bonded DOH and HOH which show equal dibasic acid strengths.The wide, overlapped, fundamental stretching bands for H 2 0 strongly hydrogen-bonded to the tertiary amines and for ice have been partially resolved and unequivocally assigned, showing that there is no cross-over of the v3 and v, bands despite the strong hydrogen-bonding.At higher temperatures in solvents containing both hydrophobic and strongly basic groups water was found with the lower C, type symmetry, in which unbonded 0-H groups gave sharp bands in the 3680-3650 cnl-' region in addition to the wide hydrogen-bonded bands at lower frequencies. Aux temperatures superieures dans les solvants contenant des groupes hydrophobes et fortement basiques I'eau possede la symetrie inferieure de type C, suivant laquelle des groupes 0-H non-lies procurent des bandes fines dans la region 3680-3650 cm-' en plus des bandes larges causees par les liaisons hydrogenes aux frkquences inferieures.

Aqueous nonelectrolyte solutions. Part XIV. D-ice and D-hydrate freezing points of deuterium oxide – ethylene oxide solutions and the formula of congruent ethylene oxide D-hydrate

“…This work was part of earlier studies on aqueous nonelectrolyte solutions and the gas hydrates (1) and was a direct exten- sion of work on EO hydrate reported recently (2). Deuterium oxide and EO liquids were miscible in all proportions, as in the water-EO system, and the enthalpies of mixing of deuterium oxide or water with EO were quantitatively similar (3).…”

“…All materials were as described earlier (1,2). EO was selected from the production of Dow Chemical Canada, Limited, and had impurities 4 0 ppm by wt.…”

“…The method of use of the freezing point cell has already been described (2). Some D-ice freezing points of EO solutions were earlier reported and analysed in a different manner (1).…”

“…EO D-hydrate formation temperatures listed in Table 2D were extrapolated to zero supercooling (2). In contrast to work on EO hydrate, many fewer runs were made on the formation of EO D-hydrate and very few measurements were repeated.…”

“…The temperature for formation of EO D-hydrate, TFDH, is best represented by the five-parameter equation, The congruent composition 12.604 mol% EO, with SE 0.071 mol% EO, is determined as the composition for zero slope of eq. [2], and the SE from the error on that slope. Formula for the congruent EO D-hydrate is E0.6.93D20 with SE 0.045 mol D20/mol EO.…”