A dynamic light scattering study of the tert-butyl alcohol-water system

Bender, Thomas M.; Pecora, R.

doi:10.1021/j100399a048

Cited by 65 publications

(69 citation statements)

References 4 publications

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“…This suggests association of TBA molecules and hence the possible existence of a lower critical solution temperature above the boiling point (10). This is a very probable explanation on the abnormal enhancement in the concentration fluctuations (1 1 -14) and the maxima in the correlation lengths (2,10,14) in the middle range 0fXmA.…”

Section: Resultsmentioning

confidence: 90%

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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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Section: Resultsmentioning

confidence: 90%

“…The remaining -10.1 kJ mol-' in HmE(TBA, XTBA = 0) should therefore be attributed to some structural enhancement, i.e. formation of extra hydrogen bonds, in the solvent H 2 0 caused by a TBA molecule (2,20). The temperature dependence of the energies of hydrogen bonds is small.…”

Section: Resultsmentioning

confidence: 94%

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

Koga¹

1988

Can. J. Chem.

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“…The values of HmE(TBA) at XTBA = 0 and the temperature dependence showed that TBA molecules not only form hydrogen bonds towards H 2 0 molecules for an enthalpy gain but also induce more hydrogen bondings among the solvent H 2 0 molecules for an equally, if not more, substantial enthalpy gain. The latter effect has been termed "iceberg formation", or in a more recent terminology, "structure enhancement of the solvent" (5)(6)(7)(8). It was pointed out in paper I1 that such an effect was long range.…”

Section: Introductionmentioning

confidence: 99%

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

Koga¹

1988

Can. J. Chem.

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The excess partial molar enthalpies of H20, H,,,~(H~O), in water-tert-butanol mixtures were measured at 30.00, 36.75, and 40.45". Using the values of H,~(TBA) of the previous work (Y. Koga, Can. J. Chem. 66, 1187(1988), the excess (integral) molar enthalpies of the solution, H,,~, were calculated at 30.00°C, and compared with the literature values. The comparison was satisfactory. From the literature values of the excess free energy, the chemical potentials of each component were evaluated for the range, XTBA > 0.1. With the measured values of the excess partial molar enthalpies, the excess partial molar entropies were also calculated. These partial molar thermodynamic quantities and their dependence on temperature and composition clearly support the following views: (1 ) in the intermediate region, 0.1 < XTBA < 0.5, the system is very close to a critical demixing, and (2) in the TBA-rich region, XTBA > 0.6, TBA molecules in the solution are in almost the same environment as in the pure liquid, while H20 molecules lose the hydrogen bond network completely and are dispersed in the TBA liquid structure.YOSHIKATA KOGA. Can. J . Chem. 66, 317 1 (1988).On a mesurC les enthalpies molaires partielles en excks du H20, HmE(~,O), dans des melanges eau-tert-butanol 2 30,00, 36,75 et 40,45"C. Utilisant les valeurs du H,:(TBA)de travaux antirieurs (Y. Koga, J . Can. Chem. 66, 1187(1988), on a calculC les enthalpies molaires (integral) en excks 2 30,0OoC, du HmE en solution et on les a comparCes aux valeurs existantes. La comparaison s'est rkvklke satisfaisante. A partir des valeurs d'knergie libre rCpertoriCes dans la littkrature, on a kvaluk les potentiels chimiques de chaque composante dans l'intervalle de xT,, > 0 , l . On a Cgalement calculk les entropies molaires en excks 2 partir des valeurs mesurCes des enthalpies molaires partielles en excks. Ces quantitks thermodynamiques partielles en excks, leurs relations avec la tempkrature i t la composit~on confirment nettement les faits suivants : (1 ) dans la rkgion intermkdiaire, 0,1 < XTBA < 0,5, le systemeest trks prks de ladkmixion critique, et (2) dans larCgion richeenTBA, XTBA > 0,6, les molCcules de TBA en solution sont 2 peu prks dans le mCme environnement que dans le liquide pur; par ailleurs, les molkcules de H 2 0 perdent complktement le reseau de liaisons hydrogknes et se dispersent dans la structure du TBA.[Traduit par la revue] Introduction solute-solute interaction is apparently repulsive. This suggests In the previous papers (called paper I (1) and I1 (2) that already at this concentration TBA molecules have more hereinafter), results were reported on the excess partial molar enthalpic difficulty in settling into the solution, i.e. the structure enthalpies of tert-butanol (TBA) in TBA-H20 mixtures, enhancement by a previously settled TBA molecule spans a H,~(TBA). While this system had been investigated previously long range. If TBA molecules are distributed randomly among (3,4), it was the first time that the partial molar enthalpies were H 2 0 molecules wit...

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“…3). The relaxation time which is order of 10 -10 sec is due to structural relaxation [18][19] process in such a case it is suggested that molecules get rearranged due to co-operative process [20][21][22][23][24][25][26]. …”

Section: Resultsmentioning

confidence: 99%