Interactions in 1-Propanol−(1,2- and 1,3-)Propanediol−H₂O:  The Effect of Hydrophobic vs Hydrophilic Moiety on the Molecular Organization of H₂O

Abstract

The excess partial molar enthalpy and the excess chemical potential of 1-propanol in ternary systems 1-propanol-(1,2-and 1,3-)propanediols-H 2 O were determined. The enthalpic interaction function between 1-propanol molecules was evaluated. The mole fraction dependence of the 1-propanol-1-propanol interaction function was used as a probe to elucidate the effect of 1,2-and 1,3-propanediols on the molecular organization of H 2 O. Together with the earlier similar works on 2-propanol and glycerol, we conclude that the hydrophobic moiety diminishes the hydrogen bond connectivity of H 2 O by reducing the hydrogen bond probability of bulk H 2 O, while the effect of the hydrophilic moiety is primarily to reduce the degree of fluctuation inherent in liquid H 2 O.

Toward Understanding the Hofmeister Series. 3. Effects of Sodium Halides on the Molecular Organization of H2O As Probed by 1-Propanol

“…We stress that in mixing scheme 1 the solute−solute interaction is bulk H 2 O mediated. ,,− It is the somewhat modified but still hydrogen-bond percolated H 2 O that dictates the solute−solute interaction. This is true between different solute molecules for multicomponent aqueous solutions 24,25 as well as the same solutes.…”

“…Our methodology has been described earlier. ,,− Briefly, we experimentally determine the excess partial molar enthalpy of 1P, , in ternary 1P−a salt−H 2 O, by perturbing the amount of 1P, n 1P , keeping all the other variables constant. Namely, which signifies the actual enthalpic contribution of 1P toward the entire system, or the actual enthalpic situation of 1P in the mixture.…”

Toward Understanding the Hofmeister Series. 1. Effects of Sodium Salts of Some Anions on the Molecular Organization of H2O

“…Our methodology has been described at some length earlier for binary 6-8 and ternary aqueous solutions. − Briefly, we measure the excess partial molar enthalpy of 1P, H 1P E , in the 1P−cosolute−H 2 O system. Namely, where H E is the excess enthalpy of the system and n 1P is the amount of 1P.…”

Hydrophobicity vs Hydrophilicity: Effects of Poly(ethylene glycol) and tert-Butyl Alcohol on H2O as Probed by 1-Propanol

“…On the other hand, we conducted similar thermodynamic studies on aqueous ethylene glycol (2C/2OH, meaning an alkyl group with two carbons and two hydroxyl groups), glycerol (3C/3OH), , and 1,2- and 1,3-propanediols (3C/2OH) , to learn the effect of the hydrophilic moiety, −OH. A general picture has emerged that in the H 2 O-rich region −OH forms hydrogen bonds with the existing network of H 2 O.…”

“…In studying the effect of poly-ols, we used the detailed thermodynamic behavior of 1-propanol (1P) as a probe to elucidate the effect of a third component (a poly-ol) in 1P−a third component−H 2 O systems. ,,− This three-component method has been proved to be useful in elucidating effects of salts, , an ionic liquid, and other compounds 10,12,14-18 in addition to the poly-ols mentioned above. Here we apply the same methodology for studying the effect of poly(ethylene glycol) (PEG) on H 2 O. PEG's are known to have a strong favorable interaction with H 2 O and is often attributed to a good match of the inter-oxygen distance in liquid H 2 O and that between the neighboring ether oxygens in the PEG helicoidal chain .…”