Basic Interactions of Water with Organic Compounds

Abstract

In the present report we have studied the interactions of water with organic molecules possessing a functional group of an ether or a carbonyl group in solution in a hydrophobic medium or n-heptane at various concentrations. The infrared spectrum of the water in the water-organic molecule complex, which was clearly separated by a skillful subtraction method, drastically changed depending on the concentration of the solution. Analysis of the infrared spectrum has made clear the following. Water is hydrogen-bonded, by one OH only, to a functional group, with the other OH free, to form a one-bonded complex, when a functional group is isolated from the other in the hydrophobic medium. On the other hand, each OH of a water molecule is hydrogen-bonded to a functional group to form a two-bonded complex, when two or more of the group are within the interactive vicinity via water. The hydrogen-bonding structure of the complex was supported by the normal frequencies calculated by the ab initio quantum mechanical method. The present study has demonstrated that the hydrophobic isolation method combined with infrared spectroscopy (HIIR) is useful to study basic interactions of water with organic molecules under soft conditions.

Infrared and Near-Infrared Study of the Interaction of Amide C═O with Water in Ideally Inert Medium

“…30,31 The original nonhydrated solutions were prepared from dehydrated liquid of DEDA or MD and dehydrated heptane at concentrations from 2% (v/v) to 100% (or neat) in vials of 5 mL capacity. A spectrum of the nonhydrated solution (Sd) at a concentration was measured in an OH-free quartz cell of 1 or 2 mm path length.…”

“…26,30 In the 1:1 hydrate, one CdO is hydrogenbonded to one OH only of the water as in eq 1 where the subscripts b and f mean "bonded" and "free", respectively. The water in this hydrate is denoted as "one-bonded water", for convenience, hereafter.…”

“…the one-bonded water that is hydrogen-bonded to amide CdO, ester CdO, ether O, 30 ketone CdO, 30 and nitrile CtN 39 in Table 6. The ∆ν fb value for amide CdO (205 cm -1 ) is significantly larger than those for the other, indicating that the hydrogenbonding ability of amide CdO is significantly higher than those of the other groups.…”

“…Thus, we tried to determine the coefficient from the intensity of the band of the one-bonded water and the total water content at 2 and 5% concentrations, where the 1:1 hydrate CdO 3692 14 3487 106 205 this work ether O b 3694 16 3509 57 185 ref 30 ester CdO 3698 21 3564 55 134 this work ketone CdO b 3697 19 3563 67 134 ref 30 nitrile CtN c 3696 32 3565 51 131 a The w f and w b are the bandwidths of the ν 1 (OH f ) and ν 1 (OH b ) bands, respectively. b Bandwidths are added to the data published in ref 30. c Iwamoto, R. Unpublished work.…”

Consideration on the Relationship Between Dielectric Breakdown Voltage and Water Content in Fatty Acid Esters

“…To elucidate the status of a small amount of water molecules in liquid esters, we measured the infrared spectroscopy of water in the fatty acid esters using difference spectra of fatty acid ester samples having various moisture contents [11][12][13][14][15][16]. Figure 3, as a typical example, shows the IR spectra for samples of C12-2EH containing 930-ppm water (solid line) and 15-ppm water (dotted line) at room temperature.…”