The solubility limit of a solid solutions for the systems of long-chain symmetrical ketones in ann-alkane matrix

Takamizawa, Kanichiro; Nakasone, Keiko; Urabe, Yoshiko

doi:10.1007/bf00655500

Cited by 7 publications

(14 citation statements)

References 13 publications

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“…It is to be noted that they are not directly proportional to f m . The phase diagram was also constructed for bulk-crystallized C39/K39 samples from DSC measurements, and the results are shown as filled circles in Figure 5 where earlier data 25 obtained for f m < 0.50 are also reproduced as unfilled symbols for comparison. In the figure, the solid curve is the theoretical prediction and dashed ones are empirically drawn for guidance of the eye.…”

Section: Resultsmentioning

confidence: 99%

“…To the sample with f m ) 0.755, we still observe the hexagonal transition at T ) 319 K characteristic of pure C25, which indicates that the crystal structure, quite same as that of pure C25, is formed to some extent even in the high-f m region. Peak temperatures are plotted against f m as filled circles in Figure 7 where unfilled circles are earlier data 25 which were obtained for bulk-crystallized K25/C25 samples. As is evident from the figure, those two sets of data are in good agreement with each other despite a difference in crystallization method of the samples.…”

Section: Resultsmentioning

confidence: 99%

“…A characteristic feature of Kn crystals is that they generally melt, without showing any solid-solid phase transition, to the liquid phase at a temperature higher than the melting temperature of Cn with the same n. [15][16][17][18][19] Binary systems of symmetrical long-chain ketones and n-alkanes with the latter as a matrix have been studied with a dielectric relaxation technique to examine molecular motions of long-chain polar ketones in nonpolar n-alkane crystals. [20][21][22][23][24] A fruitful result is that the motion of Kn mainly occurs along its chain axis in this nonpolar field, and its activation energy increases with increas-ing n. In a previous differential scanning calorimetry (DSC) measurement on the same Kn/Cn system crystallized from melts with n ranging from 25 to 39, 25 we found that solid solutions could be formed in a limited low range of the molar fraction f m of Kn if n of a ketone molecule is either equal to or slightly lower than that of Cn. Above the solubility limit f m,c eutectic mixtures were obtained, which indicates that the enthalpy of mixing is positive to this system.…”

Section: Introductionmentioning

confidence: 99%

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Symmetrical Ketone/n-Alkane Systems. 1. Phase Diagrams from DSC

et al. 2000

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Binary phase diagrams have been determined for solution-crystallized samples of two long-chain symmetrical ketones (Kn) and n-alkanes (Cn) with the same carbon numbers of n ) 25 and 39 from differential scanning calorimetry (DSC) measurements. Toluene was used as the solvent for crystallization of K39/C39 samples and hexane for K25/C25. They are found to form a solid solution which exhibits the solid-solid phase transition behaviors characteristic of a crystal of the pure n-alkane component, when the molar fraction f m of Kn is lower than a critical value f m,c , being dependent on n. For f m > f m,c , K39/C39 samples have formed another type of solid solution which melts after a rather broad solid-liquid equilibrium at elevated temperatures. On the other hand, K25/C25 samples have given eutectic mixtures for f m > f m,c , and the phase diagram is found to agree with that of the same samples crystallized from melt. We apply the Flory-Huggins theory for reproducing the phase diagrams using the interaction parameter 12 between Kn and Cn molecules and discuss effects of solvent which gave rise to these anomalous phase behaviors in terms of 12 and 0i (i ) 1, 2) between solvent and Kn (or Cn) estimated from their solubility curves.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Symmetrical Ketone/n-Alkane Systems. 1. Phase Diagrams from DSC

et al. 2000

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“…Center-Branched Alkanes. Introduction of small functional groups such as carbonyl or hydroxyl group at the middle point of the linear chains, H 3 C(CH 2 ) n –CO–(CH 2 ) n CH 3 or H 3 C(CH 2 ) n –CHOH–(CH 2 ) n CH 3 , modifies the regular packing structure of the original linear n -alkane homologues. − The subcell structure of the methylene parts is essentially the same as that of linear homologues. The melting temperature becomes higher than that of the corresponding linear n -alkane because of the existence of strong dipole–dipole interactions between the neighboring CO bonds or relatively strong intermolecular hydrogen bonds between the OH groups.…”

Section: Introductionmentioning

confidence: 99%

“…The melting temperature becomes higher than that of the corresponding linear n -alkane because of the existence of strong dipole–dipole interactions between the neighboring CO bonds or relatively strong intermolecular hydrogen bonds between the OH groups. The solid-state phase transitions detected for linear alkanes are not observed for the center-substituted alkane derivatives due to these additional interactions. − …”

Section: Introductionmentioning

confidence: 99%

Systematic Study of Aggregation Structure and Thermal Behavior of a Series of Unique H-Shape Alkane Molecules

et al. 2011

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The H-shape alkanes of various arm lengths have been synthesized successfully through the Grignard reaction. The detailed investigation of these novel compounds may allow us to widen the topological chemistry field furthermore. The molecular form and molecular packing structure in the crystal lattice have been revealed successfully on the basis of X-ray structure analysis as well as the analysis of Raman longitudinal acoustic modes (LAM) sensitive to the alkyl zigzag chain segments. The molecular conformation in the crystal lattice is deformed markedly from the originally imagined H-shape. In the cases of C3HOH to C6HOH, for example, the molecules are packed in a complicated manner and the OH···O hydrogen bonds govern the whole intermolecular interactions mainly. Since the alkyl segmental length is not very long, the conformational change is not very drastic, i.e., the small configurational entropy. Synergic effect of the hydrogen bonds and the small configurational entropy gives the higher melting point as known from the thermal data. On the other hand, in the cases of C10HOH and C12HOH, one of the long alkyl chain arms is found to be bent by 90° so that all of the alky chain segments of planar-zigzag conformation can be packed as closely as possible, and the intermolecular OH···O hydrogen bonds are also formed effectively without any mistake. As a result, the contribution of nonbonded intra- and intermolecular van der Waals interactions between the trans-zigzag alkyl chain segments become major, and the coupling of this enthalpy effect with the larger configurational entropy effect of the molecular shape results in the decrement of the melting point which approaches gradually that of longer n-alkane compound. In this way a sensitive balance between the nonbonded van der Waals interactions, the OH···O hydrogen bonds, as well as the configurational entropy effect gives the characteristic thermal behavior of the H-shape compounds. The thus-newly synthesized H-shape alkane compounds should give us new insight into the packing topology of complicated molecules, leading to the development of new functionality unexpected for normal linear alkane compounds.

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