Differential heats of dilution of <i>tert</i>-butanol into water-<i>tert</i>-butanol mixtures at 26.90 °C

Koga, Yoshikata

doi:10.1139/v86-035

Cited by 28 publications

(27 citation statements)

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“…Thus, the slopes of the smooth curves in Fig. 1 were obtained graphically as (~H ,~( T B A ) /~x~~~) with (1) axTBA = 0.002 and shown in Fig. 4.…”

Section: Resultsmentioning

confidence: 99%

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Excess partial molar enthalpies of tert-butanol in water–tert-butanol mixtures

Koga¹

1988

Can. J. Chem.

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This paper is dedicated to the late Professor J. A. Morrison YOSH~KATA KOGA. Can. J. Chem. 66, 1187Chem. 66, (1988. Excess partial molar enthalpies of tert-butanol (TBA) in water-tert-butanol mixtures were measured at 20. 00, 26.90, 45.17, and 59.49"C in the water-rich region, and at 30.00°C for the entire range. The results together with those of the previous work, (Y. Koga. Can. J. Chem. 64,206 (1986)), appear to support the following views: At XTBA --0, TBA molecules form hydrogen bonds with H20 molecules, and they enhance the structure of the hydrogen bond network of H20. The latter effect is of very long range; the enthalpic repulsion between solutes is already operative via enhancement of hydrogen bond network when two TBA molecules are separated by 12 H20 molecules. This enthalpic repulsion becomes stronger as the concentration of TBA increases. At a certain threshold, XTBA = 0.03 at 30.00°C for example, the new scheme in which solutes tend to associate sets in, and for XTBA > 0.06 this scheme becomes predominant. The effect of higher temperature is to shift this threshold to the lower values of XTBA Therefore, it is probable that a lower critical solution temperature may exist at a temperature higher than the boiling points of the solution. It was also shown that if species of TBA(H20)k type persist, they exhibit a hard-sphere nature in terms of enthalpic interaction among themselves.YOSH~KATA KOGA. Can. J. Chem. 66, 1187Chem. 66, (1988. 11 est donc probable qu'une temperature de solution critique plus faible puisse exister lorsque les temperatures d'ibullition de la solution sont plus elevees. On a aussi dkmontre que, si les espkces du type ATB(H20)k persistent, elles presentent une nature de sphere dure en termes d'interaction enthalpiques entre elles.[Traduit par la revue]

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“…Thus, the slopes of the smooth curves in Fig. 1 were obtained graphically as (~H ,~( T B A ) /~x~~~) with (1) axTBA = 0.002 and shown in Fig. 4.…”

Section: Resultsmentioning

confidence: 99%

“…However, the applicability of such expression is limited to the very water-rich region only. Thus, it was elected to measure the excess partial molar enthalpies directly for the entire range of mole fraction in paper I (1). The present paper is an extention thereof.…”

Section: Introductionmentioning

confidence: 99%

Excess partial molar enthalpies of tert-butanol in water–tert-butanol mixtures

Koga¹

1988

Can. J. Chem.

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“…The buret method as described in a previous paper (2) was employed. The values of ~; ( i ) (i = BE or H20) were calculated as described previously (1)(2)(3)16). The errors were estimated to be 1% with an upperbound error of k0.1 kJ mol-' and a lower bound error of k0.03 kJ mol-'.…”

Section: Methodsmentioning

confidence: 99%

“…In the previous papers from this laboratory (1)(2)(3), the measured values of excess partial molar enthalpies, Hz(i) (i = TBA or H20), of tert-butanol (TBA) and water in the TBA-water mixtures were reported. The results have provided more direct information than hitherto available on the nature of the solute-solvent and solute-solute interactions, and hence provided more insight into the mode of molecular aggregation.…”

Section: Introductionmentioning

confidence: 99%

Excess partial molar enthalpies of 2-butoxyethanol and water in 2-butoxyethanol–water mixtures

Siu¹,

Koga²

1989

Can. J. Chem.

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WILLIAM SIU and YOSHIKATA KOGA. Can. J. Chem. 67, 671 (1989).Excess partial molarenthalpies of 2-butoxyethanol (BE) and water, H:(i) (i = BE or H20), were measured from 25 to 35OC in the entire concentration range. The results indicated that there are three concentration regions bounded at about xB = 0.02 and XB = 0.5, XB being the mole fraction of BE. In each region, the concentration and temperature dependence of H:(i) (i = BE or H20), is distinctively different from those in the other regions, and appears to support the following views: In the water-rich region, XB < 0.02, BE molecules cause an enhancement in the structure of water, and this effect spans a long range via a structurally enhanced network of water. The solute-solute (BE-BE) interaction is repulsive and of a long range character in terms of enthalpy. As XB increases, the repulsive solute-solute interaction becomes stronger sharply to the threshold value, XB = 0.017, whereupon the mode of such mixing no longer becomes possible. In the intermediate range, 0.02 < xB < 0.5, a new scheme whereby BE molecules tend to associate is predominant. Two clathrate-like aggregates of the types h[BE(H20)k] with k = 55 and 4 may exist together with BE clusters (BE),. In the third region, 0.5 < XB, BE molecules are exactly in the same environment as in pure liquid, while water molecules are almost in the same environment as in pure water. The solution consists of BE and water clusters.Key words: excess partial molar enthalpy, 2-butoxyethanol-water.WILLIAM SIU et YOSHIKATA KOGA. Can. J. Chem. 67, 671 (1989).Optrant h des temptratures allant de 25 h 35°C et sur l'ensemble des concentrations, on a mesurt les enthalpies molaires partielles en excks du butoxy-2 ethanol (BE) et de l'eau, H;(i) (i = BE ou H20). Les rtsultats indiquent qu'il existe trois regions de concentrations dont les limites sont XB = 0,02 et xB = 0,5 (xB correspond A la fraction molaire de BE). La relation qu'on peut observer dans une region entre H:(i) (i = BE ou H20) et la concentration ainsi que la temptrature differe beaucoup de celle que l'on peut dans les autres regions; cette observation supporte les hypothkses suivantes: dans la region riche en eau, XB < 0,02, les Mots clis : enthalpie molaire partielle en excks, butoxy-2 tthanolleau.[Traduit par la revue] Introduction In the previous papers from this laboratory (1-3), the measured values of excess partial molar enthalpies, Hz(i) (i = TBA or H20), of tert-butanol (TBA) and water in the TBA-water mixtures were reported. The results have provided more direct information than hitherto available on the nature of the solute-solvent and solute-solute interactions, and hence provided more insight into the mode of molecular aggregation.The present paper reports the directly measured values of excess partial molar enthalpies of BE and water, H~( B E ) and H~( H~O ) , in the BE-water mixtures from 25 to 35OC in the entire concentration range. This system has been studied extensively together with the TBA-water system, since anomalies in various physic...

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“…Micelle-like structural fluctuations lead to anomalies in the thermodynamic properties of TBA-water solutions [7]. Thermodynamic properties such as activity coefficients, chemical potentials, and heat capacity, show extrema in this concentration range and at temperatures below room temperature [21][22][23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Phase behavior and mesoscale solubilization in aqueous solutions of hydrotropes

Subramanian

Анисимов

2014

Fluid Phase Equilibria

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Hydrotropes are amphiphilic molecules that are too small to spontaneously form equilibrium structures in aqueous solutions, but form dynamic, non-covalent assemblies, referred to as clusters. In the presence of a hydrophobic compound, these clusters seem to get stabilized leading to the formation of long-lived, highly stable mesoscopic droplets, a phenomenon that we call "mesoscale solubilization". In this work, we focus on the unusual mesoscopic properties of aqueous solutions of a nonionic hydrotrope, namely tertiary butyl alcohol (TBA), on addition of various hydrophobic compounds. Aqueous TBA solutions, in about 3 mol % to 8 mol % TBA concentration range and about 0 °C to 25 °C temperature range, show the presence of short-ranged (~ 0.5 nm), short-lived (tens of picoseconds) molecular clusters which result in anomalies of the thermodynamic properties. These clusters are transient but do not relax by diffusion, thus distinctly different from conventional concentration fluctuations. In this concentration and temperature range, upon the addition of a third (more hydrophobic) component to TBA-water solutions, long-lived mesoscopic droplets of about 100 nm size are observed. In this work, we clarify the ambiguity behind the definition of solubility and elucidate the phenomenon of mesoscale solubilization. A systematic study of the macroscopic and mesoscopic phase behavior of three ternary systems TBA-water-propylene oxide, TBA-water-isobutyl alcohol, and TBA-water-cyclohexane has been carried out. We differentiate between molecular solubility, mesoscale solubilization, and macroscopic phase separation. We have confirmed that practically stable aqueous colloids can be created from small molecules, without addition of surfactants or polymers. Such kind of novel materials may find applications in the design of various processes and products, ranging from pharmaceuticals to cosmetics and agrochemicals.

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Differential heats of dilution of tert-butanol into water-tert-butanol mixtures at 26.90 °C

Cited by 28 publications

References 13 publications

Excess partial molar enthalpies of tert-butanol in water–tert-butanol mixtures

Excess partial molar enthalpies of tert-butanol in water–tert-butanol mixtures

Excess partial molar enthalpies of 2-butoxyethanol and water in 2-butoxyethanol–water mixtures

Phase behavior and mesoscale solubilization in aqueous solutions of hydrotropes

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