Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    The description ofP, T, X-phase diagrams in systems with clathrate formation where the guest-guest interaction is taken into account. Hydroquinone-noble gas systems (1984)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 1 (1984), S. 251-262 
    Details
    ISSN: 1573-1111
    Keywords: Clathrate ; calculation of the Phase Diagram of binary systems ; the role of the guest-guest interaction ; thermodynamics ; hydroquinone-noble gas systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract We discuss phase equilibria in the binary guest-host system with clathrate formation where the guest-guest interaction is taken into account. The equations for phase equilibria in this system are derived for the general case, where the initial host α-modification can include guest molecules, and where the host molecules can form several metastable clathrate frameworks whose energies do not differ greatly from one another and from the stable form. We have applied these equations to the binary noble gas-hydroquinone systems for which the equations simplify considerably. This allowed us to calculateP, T, X-phase diagrams for these systems and to compare them with the diagrams obtained experimentally. The model employed describes experimental results not only qualitatively (e.g., the increase of the melting temperature of the hydroquinone α-modification with increasing content of the guest) but also quantitatively. It has been shown that consideration of guest-guest interaction even in the hydroquinone systems, in which this interaction is relatively small, improves the description of the phase diagrams.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00656760
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Clathrate formation and phase equilibria in the pyridine-cadmium nitrate system (1996)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 26 (1996), S. 269-280 
    Details
    ISSN: 1573-1111
    Keywords: phase diagram ; vapour pressure ; thermal analysis ; clathrate, pyridine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Preparative, thermal (DTA, TGA), solubility, strain and spectral (Raman) techniques were used to study clathrate and complex formation in the pyridine (Py)-cadmium nitrate system. Three compounds have been isolated and studied: the clathrate compound [CdPy4(NO3)2] · 2Py (I), the complex [CdPy3(NO3)2] (II) and a compound of composition ‘Cd(NO3)2·7/4Py’ (III), of unknown nature. The phase diagram of the system has been determined for the concentration and temperature range 0–66 mass-% Cd(NO3)2 and −100 to +200 °C, respectively. ClathrateI undergoes polymorphous conversion at −51.8(4) °C and melts incongruently at 106.0(5) °C, forming complexII. CompoundsII andIII melt congruently at 165.5(4) and 191(1) °C, respectively. The complexes [CdPy4(NO3)2] (the host phase) and [CdPy2(NO3)2] are not observed in the system. The nature and thermodynamic parameters of the dissociation of clathrate I have been determined. For the process 1/13[CdPy4)NO3)2] · 2Pysolid = 1/3[CdPy3(NO3)2]solid + Pygas in the range 290–360K δH o = 54.9(3) kj/mole, ΔS 298 o = 142(1) J/(mole K), ΔG 298 o = 12.5(5) kJ/mole.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01053544
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Hydroquinone clathrates and the theory of clathrate formation (1985)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 3 (1985), S. 243-260 
    Details
    ISSN: 1573-1111
    Keywords: Clathrate ; theory of clathrate formation ; hydroquinone clathrate ; the role of the guest-guest interaction ; statistical thermodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The model of a clathrate solid solution, taking into account directed and nondirected guest-guest interactions, has been obtained using statistical thermodynamic methods in the approximation of the mean-field type for the general case (the formation of cavities of several types and the inclusion of different kinds of guest molecules by the host). Consideration of this interaction has been shown to improve the quantitative agreement between theory and experiment. When the guest-guest interaction is considerable in the case of guest molecules of the same type a phase transition (of a gas-liquid type) of the guest component may occur in the clathrate matrix. In the case of guests of two different types, the phase transition of the guest subsystem of the liquid-liquid type may also occur within one framework at the expense of a preferable interaction among guest molecules of the same type. We present the isothermal (20°C) section of the phase diagram of a hydroquinone-— formic acid — acetonitrile system. Clathrates, forming in the binary systems (with hydroquinone) produce restricted solid solutions (of type IV, according to Roozeboom). These and other experimental data are discussed in terms of the proposed theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00655728
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Phase Diagram of the Benzene–Dinitratotetrapyridinecopper(II) (Guest–Host) System and Thermodynamic Parameters for the Hostβ2Guest Clathrate Dissociation (2000)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 37 (2000), S. 265-271 
    Details
    ISSN: 1573-1111
    Keywords: phase diagram ; Werner clathrate ; thermodynamic parameters ; copper(II) complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In the first part of the work, thephase diagram of the benzene -ndash;[CuPy4(NO3)2] system has beendetermined in the -100 to +200 °C temperaturerange using DTA and solubility techniques. The onlycompound found in the system is the[CuPy4(NO3)2]β 2C6H6clathrate. It is stable up to a temperature of+104.2(5) °C at which it melts incongruently togive liquid and the solid [CuPy4(NO3)2]host phase. At 146.1(5) °C exfoliation into twoliquid phases is observed, with the composition of themonotectic point being close to that of the clathrate.In the second part of the work, thermodynamicparameters of the clathrate dissociation have beendetermined from benzene vapour pressure strainmeasurements. For the process1/2 [CuPy4(NO3)2]β2C6H6(solid) = 1/2 [CuPy4(NO3)2] (solid) +C6H6 (gas) Δ H° = 45.3(3) kJ/mole;Δ S298° = 126(1) J/(mole K);Δ G298° = 7.7(5) kJ/mole.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008162514955
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Clathrate formation in water-peralkylonium salts systems (1984)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 2 (1984), S. 61-72 
    Details
    ISSN: 1573-1111
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract We discuss composition, stoichiometry and stability (phase diagrams) of peralkylonium salts and analogues (Alk3XO, where X=N,P,As) polyhydrates depending on the dimensions and the configuration of the hydrophobic part of a guest-molecule and its ability to interact in a hydrophilic way with the framework.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00663240
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    The phase diagram of the water-hydrogen system in the crystallization field of solid solutions based on ices Ih and II at high pressures (1994)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 20 (1994), S. 115-121 
    Details
    ISSN: 1573-1111
    Keywords: Hydrogen-water solid solutions ; phase diagram ; stoichiometry of clathrates ; high pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The decomposition curves of the solid solutions based on ices Ih (α-solutions) and II (β-solutions) in the water-hydrogen system were studied by the DTA technique at pressures up to 7 kbar. The α-solution is destabilized by pressure but to a lesser degree than ice Ih and is stable up to 2.3 kbar. Theβ-solution is stabilized by pressure and at 7 kbar decomposes at about 20°C. TheP, T-phase diagram of the water-hydrogen system in the crystallization range is constructed on the basis of reference [1] and our data. All possible types of stoichiometric interrelationships in the guest —host system are demonstrated by the example of the water-hydrogen system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00709335
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    The formation of solid solutions in the tetrahydrofuran-tetra(n-propyl)ammonium fluoride-water system (1994)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 17 (1994), S. 99-106 
    Details
    ISSN: 1573-1111
    Keywords: Double clathrate hydrate ; solid solutions ; tertiary system ; tetra(n-propyl)ammonium fluoride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The phase diagram of the tetrahydrofuran (THF)-tetra(n-propyl)ammonium fluoride (Prp4 NF)-water system has been studied by differential thermal analysis (DTA). Solid solutions have been detected of the general formula THF·x Prp4NF·(17−2x) H2O, wherex changes from 0.06 to 0.5. The formation of solid solutions is due to the variable degree of the filling of the fragment consisting of four D-cavities in CS-II clathrate hydrates by the tetra(n-propyl)ammonium cation. The solid solution obtained is peculiar in that its vacancies are occupied by the blocks of four D-cavities each. Besides, this kind of displacement of two water molecules by an ionic pair Prp4N++F−, where only the charges of the substituting and substituted groups are equal, takes place here. It appears that this type of solid solution has been discovered for the first time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00708004
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Phase and X-ray study of clathrate formation in the tetraisoamylammonium fluoride-water system (1994)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 17 (1994), S. 137-148 
    Details
    ISSN: 1573-1111
    Keywords: Clathrate hydrate ; phase diagram ; crystal structure ; tetraisoamylammonium fluoride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The phase diagram of the binary (i-C5H11)4NF-water system has been studied in the clathrate formation region. Three polyhydrates have been discovered, two of which (1∶38.9 and 1∶32.7) are the known orthorhombic and tetragonal phases:Pbmn,a=11.88,b=21.53,c=12.70 Å,ρ means=1.019 g cm-3 (0°C), m.p.=32.4°C andP42/m, a=23.729,c=12.466 Å,ρ means=1.062 g cm-3, (0°C), m.p.=31.2°C, respectively. A single crystal X-ray analysis of the novel clathrate hydrate (i-C5H11)4NF·27 H2O is reported. This new clathrate hydrate is tetragonal,I4I/a, witha=16.894(5),c=17.111(2) Å,Z=4, (−50°C), and m.p.=34.6°C. Each (i-C5H11)4N+ cation occupies a four-chamber cavity built of 15-hedra 71635942 (idealized description), with small vacant 5444 cavities filling the intervening space.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00711854
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Phase and structural study of clathrate formation in the [Zn(MePy)2(NCS)2]-MePy system (MePy=4-methylpyridine) (1994)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 17 (1994), S. 305-316 
    Details
    ISSN: 1573-1111
    Keywords: Phase diagram ; clathrate ; X-ray structure ; 4-methylpyridine ; Zn(II) isothiocyanate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A phase diagram of the [Zn(MePy)2(NCS)2]-MePy binary system has been studied by DTA and solubility methods. Two compounds melting incongruently (at 63 and 57°C) have been discovered in the system. They have been obtained as separate phases with crystals of different shape (needles and octahedra). Their composition has been determined by analytical methods and verified by X-ray structural analysis: [Zn(MePy)4(NCS)2]·0.67 MePy·xH2O, wherex depends on the synthesis conditions, and [Zn(MePy)4(NCS)2]·MePy, respectively. The preliminary X-ray study of the first compound (at −100°C) has shown it to be isostructural with the known clathrates of the common formula [M(MePy)4(NCS)2]·0.67MePy·xH2O, where M=Cu, Mn, Mg andx=0–0.33. The unit cell parameters are as follows:a=27.20(1),c=11.202(4) Å, space group $$R\bar 3$$ ,Z=9. The X-ray study of [Zn(MePy)4(NCS)2]·MePy (at−50°C) has shown it to be analogous to the ‘organic zeolite’ β-phase with the guest MePy molecules located in the channels formed by molecular packing of the [Zn(MePy)4(NCS)2]host. The cell is tetragonal, the space groupI41/a,a=16.845(6),c=23.496(7) Å,V=6667(4) Å3,Z=8,D calc=1.289 g cm−3,R=0.074. The zinc cation is surrounded by a slightly irregular octahedron of six nitrogen atoms of the MePy and NCS ligands. The crystallisation field of the host [Zn(MePy)4(NCS)2] complex in the temperature range concerned is absent in the phase diagram. It suggests contact stabilization of the [Zn(MePy)4(NCS)2] molecule by the guest in the clathrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00707126
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Vapour pressure of 4-methylpyridine (MePy) over [Ni(MePy)4(NCS)2]·y(MePy) and [Cu(MePy)4(NCS)2]·2/3(MePy) clathrates during their dissociation (1995)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 23 (1995), S. 23-33 
    Details
    ISSN: 1573-1111
    Keywords: Clathrate formation ; vapour pressure, 4-methylpyridine ; Ni(II) ; isothiocyanate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Strain measurement and quasiequilibrium thermogravimetry were used to study the dissociation processes of two clathrates, [Ni(MePy)4(NCS)2]·(MePy) and [Cu(MePy)4(NCS)2]·2/3(MePy), accompanied by the liberation of MePy into the gaseous phase. In the Ni clathrate dissociation process in the temperature range 298–368 K the liberated MePy was redistributed between the solid clathrate and gaseous phases; the MePy vapour pressure over the clathrate is a function of temperature and the guest contenty, which agrees with the presence in the MePy-[Ni(MePy)4(NCS)2] system of a wide range of β-clathrate solutions, [Ni(MePy)4(NCS)2]·y(MePy). The same methods used to study the Cu clathrate dissociation resulted in conclusions different from those obtained for the dissociation process of the above clathrate: the process is described by the equation [Cu(MePy)4(NCS)2]·2/3(MePy)solid =[Cu(MePy)2(NCS)2]solid+22/3(MePy)gas; the temperature dependence of the Mepy vapour pressure over the solid sample does not depend on its composition, which points to the absence from the system of solid solutions based on the clathrate. Standard changes of the enthalpy, entropy, and isobaric-isothermal reaction potential for the temperature range 292–325 K are equal to 178.6±1.7 kJ (mole of clathrate)−1, 463±5.6 J (mole of clathrate)−1 K−1, and 40.4±2.4 kJ (mole of clathrate)−1, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00706946
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...