Aqueous Nonelectrolyte Solutions. Part XII. Enthalpies of Mixing of Water and Deuterium Oxide with Tetrahydrofuran

1973 ◽  
Vol 51 (12) ◽  
pp. 1933-1940 ◽  
Author(s):  
David N. Glew ◽  
Harry Watts
Keyword(s):  
Hydrogen Bonding ◽  
Proton Magnetic Resonance ◽  
Composition Range ◽  
Deuterium Oxide ◽  
Enthalpy Of Mixing ◽  
Water Systems ◽  
Water Proton ◽  
Oxide Systems ◽  
Enthalpies Of Mixing ◽  
Water Hydrogen

Calorimetric enthalpies of mixing have been measured over the whole composition range for the water–tetrahydrofuran and the deuterium oxide – tetrahydrofuran systems at 10.00 and 25.00 °C. The experimental S-shaped, enthalpy of mixing –composition curves are interpreted in terms of changes of the water hydrogen bonding in solution. At low tetrahydrofuran mole fractions the deuterium oxide systems are more exothermal and at high tetrahydrofuran mole fractions more endothermal than the corresponding water systems. A good correlation is found between the enthalpy of mixing and the water proton magnetic resonance chemical shift for solutions with greater than 0.55 mole fraction of tetrahydrofuran.

Aqueous Nonelectrolyte Solutions. Part IX. Enthalpies of Mixing of Water and Deuterium Oxide with Ethylene Oxide

1971 ◽  
Vol 49 (11) ◽  
pp. 1830-1840 ◽  
Author(s):  
D. N. Glew ◽  
Harry Watts
Keyword(s):  
Hydrogen Bonding ◽  
Ethylene Oxide ◽  
Composition Range ◽  
Deuterium Oxide ◽  
Enthalpy Of Mixing ◽  
Water Systems ◽  
Oxide System ◽  
Water Proton ◽  
Oxide Systems ◽  
Enthalpies Of Mixing

Calorimetric enthalpies of mixing have been measured over the whole composition range for the water – ethylene oxide system at 10.75 and 20.00 °C and for the deuterium oxide – ethylene oxide system at 13.45 and 20.00 °C. Less extensive measurements have been made for dilute ethylene oxide solutions in water at 0.6 °C and in deuterium oxide at 4.1 and 7.3 °C. The experimental S-shaped, enthalpy of mixing – composition curves are interpreted in terms of solution hydrogen bonding changes, with particular reference to the hydrogen bonding of water. At low ethylene oxide mole fractions the deuterium oxide systems are more exothermal and at high ethylene oxide mole fractions more endothermal than the corresponding water systems. A good correlation is found between the enthalpy of mixing and the water proton magnetic resonance chemical shift for solutions with greater than 0.55 mol fraction of ethylene oxide.

Calorimetric Investigation of MCI-EuCI2 Melts (M = Na, K, Rb)

2001 ◽  
Vol 56 (9-10) ◽  
pp. 653-657
Author(s):  
F. Da Silva ◽  
L. Rycerz ◽  
M. Gaune-Escard
Keyword(s):  
Least Squares ◽  
Interaction Parameter ◽  
Atmospheric Pressure ◽  
Binary Systems ◽  
Composition Range ◽  
Enthalpy Of Mixing ◽  
Mixing Enthalpy ◽  
Calorimetric Investigation ◽  
Direct Calorimetry ◽  
Enthalpies Of Mixing

Abstract The molar enthalpies of mixing (ΔmixHm) of MCl-EuCl2 (M = Na, K, Rb) liquid binary systems were measured at 1138 K over the whole composition range by direct calorimetry. A Calvet type calorimeter was used, and mixing of the two liquid components was achieved by the ampoule break-off technique under argon at atmospheric pressure. The enthalpy of mixing of these systems is negative over the whole composition range with a minimum of approximately -0.5, -3.5 and -4.5 kJ mol-1 for M = Na, K, Rb, respectively. The least-squares coefficients A, B, C in the equation A (kJ mol-1) = A + B x + C x2, where λ is an interaction parameter, are reported. From the trend observed in these MCl-EuCl2 systems it was possible to estimate the mixing enthalpy of the CsCl-EuCl2 system.

Solvent effects in ultraviolet spectral studies of hydrogen bonding between phenol and N,N-dimethylacetamide

1967 ◽  
Vol 45 (18) ◽  
pp. 2033-2038 ◽  
Author(s):  
F. Takahashi ◽  
W. J. Karoly ◽  
J. B. Greenshields ◽  
N. C. Li
Keyword(s):  
Hydrogen Bonding ◽  
Magnetic Resonance ◽  
Complex Formation ◽  
Equilibrium Constant ◽  
Proton Magnetic Resonance ◽  
Mixed Solvent ◽  
Resonance Method ◽  
Spectral Studies ◽  
Magnetic Resonance Method ◽  
Hydrogen Bonded

Ultraviolet spectral studies of hydrogen bonding between phenol and N,N-dimethylacetamide (DMA) in several media are reported. The equilibrium constant for the formation of the phenol–DMA complex is strongly solvent dependent, varying from 295 1/mole in cyclohexane to 130 in CCl4 and 16 in CHCl3, all at 28°. The greatly reduced value in CHCl3 indicates that the measured equilibrium constant is only an apparent one which does not take into account the decrease in free DMA concentration resulting from hydrogen-bonded complex formation with the solvent acting as hydrogen donor. In CCl4/CHCl3 mixed solvent, in the range of [chloroform] = 0 to 1.227 M, the measured equilibrium constant, K′, varies linearly with K′ [chloroform]. The slope of the line corresponds to the equilibrium constant for the formation of the hydrogen-bonded complex between CHCl3 and DMA in CCl4. The value, 0.9 1/mole, agrees with that obtained from a proton magnetic resonance method. The agreement is particularly noteworthy when we consider that the concentrations of phenol used in the proton magnetic resonance and ultraviolet spectral methods differ by a factor of 200, which leads definitely to the conclusion that the hydrogen-bonded CHCl3–DMA complex formed is 1:1. In cyclohexane/CHCl3 mixed solvent, similar results are obtained.

Selective deshielding of aromatic protons in some ortho-substituted acetanilides

1968 ◽  
Vol 46 (15) ◽  
pp. 2593-2600 ◽  
Author(s):  
James R. Bartels-Keith ◽  
Ronald F. W. Cieciuch
Keyword(s):  
Hydrogen Bonding ◽  
Magnetic Resonance ◽  
Solvent Effects ◽  
Proton Magnetic Resonance ◽  
Aromatic Proton ◽  
Intramolecular Hydrogen Bonding ◽  
Low Field ◽  
Intramolecular Hydrogen

Certain ortho-substituted acetanilides exhibit proton magnetic resonance signals at unusually low field for the amido proton and the aromatic proton adjacent to the acetamido group. This effect, explicable in terms of intramolecular hydrogen-bonding, has been observed for nitro, carbonyl, sulfamoyl, and sulfonyl substituents. Solvent effects are discussed.

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