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Volumn 106, Issue 42, 2002, Pages 9883-9889

S-H bond dissociation enthalpies in thiophenols: A time-resolved photoacoustic calorimetry and quantum chemistry study

Author keywords

[No Author keywords available]

Indexed keywords

CALCULATIONS; CALORIMETRY; DISSOCIATION; ENTHALPY; HYDROGEN BONDS; LASER APPLICATIONS; MOLECULES; PHOTOCHEMICAL REACTIONS; PROBABILITY DENSITY FUNCTION; QUANTUM THEORY; SPECIFIC HEAT; SULFUR;

EID: 0037168316     PISSN: 10895639     EISSN: None     Source Type: Journal    
DOI: 10.1021/jp025677i     Document Type: Article
Times cited : (75)

References (35)
  • 3
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    • Cadenas, E., Packer, L., Eds.; Marcel Dekker: New York
    • (b) Handbook of Antioxidants; Cadenas, E., Packer, L., Eds.; Marcel Dekker: New York, 1996.
    • (1996) Handbook of Antioxidants
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    • 0032085854 scopus 로고    scopus 로고
    • note
    • An important requirement of the PAC technique is that the thermoelastic properties of the solution used in the calibration and those of the sample solution, namely, their adiabatic expansion coefficient χ (eq 4), should be identical. Because the solutions used are normally very dilute, it is generally assumed that both will have χ equal to that of the pure solvent. There has been a nagging doubt as to whether this assumption is valid for the experiments based on the approach illustrated in Scheme 1, because of the fact that the sample solution contains ca. 7% (v/v) of di-tert-butylperoxide, whereas the calibration contains none. In fact, it was showed that when methanol is used as the solvent, both the amplitude and the arrival time of the acoustic wave vary between those of the reference and of the sample containing 15% peroxide, demonstrating a change in the thermoelastic properties (Autrey, T.; Foster, N. S.; Klepzig, K.; Amonette, J. E.; Daschbach, J. L. Rev. Sci. Instrum. 1998, 69, 2246).
    • (1998) Rev. Sci. Instrum. , vol.69 , pp. 2246
    • Autrey, T.1    Foster, N.S.2    Klepzig, K.3    Amonette, J.E.4    Daschbach, J.L.5
  • 17
    • 0000754425 scopus 로고
    • note
    • We are currently investigating this matter by determining experimental values of χ for the solutions involved. However, using benzene, isooctane, and carbon tetrachloride as solvents, all of the available evidence seems to corroborate the assumption above: the shape and time of arrival of the photoacoustic waveform is the same for calibration and experiment, and increasing the amount of peroxide in the sample solution does not noticeably affect the time of arrival of the photoacoustic waveform. Moreover, and which is a more rigorous test, a plot of the photoacoustic signal versus the amount of peroxide added during the experiment remains linear even beyond 12% (v/v) of peroxide in solution (see also Clark, K. B.; Griller, D. Organometallics 1991, 10, 746).
    • (1991) Organometallics , vol.10 , pp. 746
    • Clark, K.B.1    Griller, D.2
  • 20
    • 0003569570 scopus 로고
    • International Series of Monographs on Chemistry 16; Oxford University Press: Oxford, U.K.
    • Parr, R.; Yang, W. Density-Functional Theory of Atoms and Molecules; International Series of Monographs on Chemistry 16; Oxford University Press: Oxford, U.K., 1989.
    • (1989) Density-Functional Theory of Atoms and Molecules
    • Parr, R.1    Yang, W.2
  • 28
    • 0011858877 scopus 로고    scopus 로고
    • note
    • This methodology is different from the one proposed by Wayner et al. (ref 22), which is based on a comparison with an auxiliary reaction (hydrogen abstraction from cyclohexadiene) to avoid the estimation of the volume change of reaction 7 and the need for thermochemical data on di-tert-butylperoxide and tert-butyl alcohol. The drawback is that it relies on the C-H bond dissociation enthalpy of cyclohexadiene. Both methods afforded the same result for the determination of the O-H bond dissociation enthalpy of phenol, a proposed test reaction for PAC (ref 6).
  • 32
    • 0003552265 scopus 로고
    • Cox, J. D., Wagman, D. D., Medvedev, V. A., Eds.; Hemisphere: New York
    • CODATA Key Values for Thermodynamics; Cox, J. D., Wagman, D. D., Medvedev, V. A., Eds.; Hemisphere: New York, 1989.
    • (1989) CODATA Key Values for Thermodynamics
  • 34
    • 0011821572 scopus 로고    scopus 로고
    • Martinho Simões, J. A., Greenberg, A., Liebamn, J. F., Eds.; SEARCH Series; Blackie: London; Chapter 2
    • Tsang, W. In Energetics of Organic Radicals; Martinho Simões, J. A., Greenberg, A., Liebamn, J. F., Eds.; SEARCH Series; Blackie: London, 1996; Vol. 4, Chapter 2.
    • (1996) Energetics of Organic Radicals , vol.4
    • Tsang, W.1
  • 35
    • 0011888351 scopus 로고    scopus 로고
    • note
    • Note that the estimation of the solvation enthalpy of the hydrogen atom is now made redundant. The knowledge of this value is only necessary if we aim to determine the bond dissociation enthalpy in solution through eq 10, because it cancels out when eq 12 is used to derive the gas-phase value.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.