Full band spectroscopic studies on the molecular mobility of diluted alcohols

Hanna, F. F.; Hakim, I. K.; Saad, A. L. G.; Hufnagel, F.; Drexler, Franz

doi:10.1016/0167-7322(91)80064-b

Cited by 9 publications

(5 citation statements)

References 9 publications

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“…Here we report dielectric relaxation data of four alicyclic alcohols, cyclopentanol (C 5 ) to cyclooctanol (C 8 ), as measured up to 72 GHz. In relation to the literature quoted, our results complement the hitherto known lower frequency part of the dielectric spectrum of pure cycloalcohols [5,6] and also the solution results for cyclohexanol [2].Substances obtained from Fluka and Merck were used without further purification. Residual water contents < 0.5 percent should, according to experiences with various alcohol-water systems [7], not yet significantly influence the relaxation parameters.…”

supporting

confidence: 75%

“…Our AH zl values are somewhat smaller (by 15 ... 5 percent for C 5 to C 8 , respectively) than those given in [6], which is understandable since that quantity is sensitive to fitting details (note that three fitting terms are used in both studies for the coverage of, however, quite different frequency intervals). The high frequency shoulder corresponds to the predominant feature in the dilute solution spectra of C 6 yet studied [2], which also show how the principal relaxation region develops at the expense of the high frequency one as concentration is increased. An extrapolation of the solution data to pure C 6 is again in accordance with the present results.…”

mentioning

confidence: 99%

“…Cyclohexanol has been examined in nonpolar solvents [1], which work was extended recently to some very high spot frequencies (< 670 GHz) [2], On ther other hand, the solid state dielectric properties have attracted attention. These, for example, have been measured at frequencies covering the solid state absorption region (at < 13 MHz [3,4]) over a very broad temperature and pressure range.…”

mentioning

confidence: 99%

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Dielectric Relaxation of Liquid Alicyclic Alcohols

Stockhausen

Hornhardt

1992

Zeitschrift Für Naturforschung A

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The dielectric spectra of liquid cyclopentanol, cyclohexanol, cycloheptanol and cyclooctanol are reported for frequencies up to 72 GHz and temperature 20 (cyclohexanol solid), 30 and 40 °C. The absorption spectra are peculiar in exhibiting a remarkably developed high frequency shoulder which is attributed to single molecule and internal motion, while the principal absorption is due to association as with other alcohols.Although numerous dielectric relaxation studies on different kinds of liquid alcohols have been reported, alicyclic ones have received only little attention. Cyclohexanol has been examined in nonpolar solvents [1], which work was extended recently to some very high spot frequencies (< 670 GHz) [2], On ther other hand, the solid state dielectric properties have attracted attention. These, for example, have been measured at frequencies covering the solid state absorption region (at < 13 MHz [3, 4]) over a very broad temperature and pressure range. Those studies yielded also some results on the liquid state [5], An investigation of pure liquid cycloalcohols by Shinomiya [6] was restricted to frequencies covering the principal absorption region (< 4.5 GHz). It seems therefore worthwhile to reconsider the dielectric properties of pure cycloalcohols (at normal pressure) and to extend measurements over a broader frequency band in order to gain information also on possible higher frequency relaxation contributions. Here we report dielectric relaxation data of four alicyclic alcohols, cyclopentanol (C 5 ) to cyclooctanol (C 8 ), as measured up to 72 GHz. In relation to the literature quoted, our results complement the hitherto known lower frequency part of the dielectric spectrum of pure cycloalcohols [5,6] and also the solution results for cyclohexanol [2].Substances obtained from Fluka and Merck were used without further purification. Residual water contents < 0.5 percent should, according to experiences with various alcohol-water systems [7], not yet significantly influence the relaxation parameters. The complex permittivity was determined by use of various Reprint requests to Prof. M. Stockhausen,

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confidence: 75%

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confidence: 99%

mentioning

confidence: 99%

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Dielectric Relaxation of Liquid Alicyclic Alcohols

Stockhausen

Hornhardt

1992

Zeitschrift Für Naturforschung A

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“…Despite such considerable effects in the dielectric parameters and though several alcohol/alcohol, − alcohol/water, ,,− and also alcohol/nondipolar solvent ,− mixtures have been studied by dielectric spectrometry there is still no generally accepted model of the relaxation mechanism of these liquids. An interesting finding that casts some light on the mechanism of hydrogen bond network fluctuations is the relation which empirically relates the characteristic (model-independent) relaxation time ratio τ/τ w0 of a variety of associating liquids to the normalized number density ρ of hydrogen-bonding groups and water molecules .…”

Section: Introductionmentioning

confidence: 99%

Dielectric Properties of Alkanediol/Water Mixtures

1997

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At 25 °C the complex dielectric permittivity has been measured as a function of frequency ν (1 MHz ≤ ν ≤ 56 GHz) and mole fraction x (0 ≤ x ≤ 1) for mixtures of water with 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,7-heptanediol. Some parameters like the (extrapolated) static permittivity and the characteristic relaxation time can be directly taken from the spectra. But the spectra can be also analytically represented by semiempirical relaxation spectral functions. A function containing two relaxation terms, a high-frequency Cole−Cole term and a Debye term with smaller relaxation frequency, appears to be appropriate. The relaxation parameters of the water/diol mixtures have been evaluated and compared to other water/organic solvent systems to show that (i) a high degree of permanent electric dipole orientation correlation exists in the diols that is significantly reduced on addition of water, (ii) the characteristic relaxation time reflects a substantial effect of entropy in the mechanism of dielectric relaxation but exhibits also a significant difference from monohydric alcohol/water systems, and (iii) the subdivision of the spectra into two relaxation terms seems to be due to regions of different concentration of hydrogen-bonding sites within the mixtures.

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“…We have ob served a /iapp minimum also for hexanol with n-heptane or decahydronaphthalene as solvent, and it has been reported for cyclohexane solutions as well [35]. Related monohydric alcohols (cyclohexanol, n-decanol and n-dodecanol) were found to behave similarly in cyclohexane solution [40]. Referring to as usually reported for n-alkanols in dilute solution, and it differs noticeably from the extrapolated ^app values obtained with the other solvents mentioned.…”

Section: Static Dielectric Propertiesmentioning

confidence: 84%

Dielectric Properties of 1-Hexanol in Mesitylene Solution on Admixture of Aromatic Dihydric Alcohols

Turky

Hanna

Klages

et al. 1994

Zeitschrift Für Naturforschung A

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Broadband dielectric relaxation spectra (at 20 to 40 °C) are reported for three liquid alcoh ol/non polar solvent systems: Binary hexanol/mesitylene mixtures and two corresponding ternary mixtures, where 5 percent of hexanol are replaced by a dihydric alcohol, namely resorcinol (1,3-dihydroxyben zene) or 2,2'-dihydroxydiphenyl. The concentration of the polar substance(s) ranges from dilute solutions to pure alcohol(s). The lower frequency relaxation contribution, which generally is the more dominating the higher the alcohol concentration, is additionally enhanced by the diol admix ture in the case of low and moderate concentrations. This can be understood as a hetero-association effect, the diol m olecules playing a bridging role, which also leads to an increase in the mean lifetime o f associated states.

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Full band spectroscopic studies on the molecular mobility of diluted alcohols

Cited by 9 publications

References 9 publications

Dielectric Relaxation of Liquid Alicyclic Alcohols

Dielectric Relaxation of Liquid Alicyclic Alcohols

Dielectric Properties of Alkanediol/Water Mixtures

Dielectric Properties of 1-Hexanol in Mesitylene Solution on Admixture of Aromatic Dihydric Alcohols

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