382
Y. Nagano
TABLE 4. Derived molar thermodynamic quantities at T = 298.15 K
Phenanthrene
Anthracene
Naphthacene
o
−1
−1
1 H (cr)/(kJ · mol
f
)
−7048.7 ± 0.9
110.4 ± 1.0
91.3 ± 2.7
−7065.0 ± 1.1
126.7 ± 1.1
103.4 ± 2.7
230.1 ± 2.9
−9005.1 ± 1.8
206.9 ± 1.9
124.7 ± 4.0
331.6 ± 4.4
c
m
o
1 H (cr)/(kJ · mol
)
m
o
−1
1
H
/(kJ · mol
)
sub
m
o
−1
1 H (g)/(kJ · mol
)
201.7 ± 2.9
f
m
the standard molar enthalpy of formation of naphthacene in the gas phase is derived to
be (331.6 ± 4.4) kJ · mol−1. The literature values of the sublimation enthalpy scatter
from 117 kJ · mol−1 to 144 kJ · mol−1 (20)
.
The purity of the present sample has not been
confirmed yet. Therefore, an error greater than 4.4 kJ · mol−1 is possible.
In 1951, Magnus et al. reported the standard molar enthalpy of combustion of naph-
thacene to be −(8956.9 ± 1.3) kJ · mol−1 (21)
.
However, in 1969, Dewar and de Llano(6)
showed, on the basis of a semi-empirical calculation, that the atomization energy had an
error of 43 kJ · mol−1. Recently, theoretical studies(7) indicated a similar error. Naph-
thacene is known to be sensitive to oxygen in solution. In the present study, however,
no oxidation was observed in the solid state, although Dewar and de Llano suggested that
oxidation occurred in the combustion bomb before ignition.(6) Magnus et al.(21) reported
the melting temperature of naphthacene to be (608 to 610) K, which is lower than the
value of 623.2 K obtained in the present study. The sample of Magnus et al. was, possibly,
significantly oxidized before their calorimetric measurements.
The author thanks Prof. J. Aihara, Shizuoka University, for encouraging his theoretical
interest in naphthacene.
REFERENCES
1. (a) Cook, D. J.; Schlemmer, S.; Balucani, N.; Wagner, D. R.; Steiner, B.; Saykally, R. J. Nature
1996, 380, 227–229; (b) Snow, T. P.; Witt, A. N. Science 1995, 270, 1455–1460.
2. Gold, T. The Deep Hot Biosphere. Springer: New York. 1999.
3. Harvey, R. G. Polycyclic Aromatic Hydrocarbons. Wiley-VCH: New York. 1997.
4. Steele, W. V.; Chirico, R. D.; Nguyen, A.; Hossenlopp, I. A.; Smith, N. K. AIChE Symposium
Series 279. 1990, Vol. 86. 138–154.
5. Coleman, D. J.; Pilcher, G. Trans. Faraday Soc. 1966, 62, 821–827.
6. Dewar, M. J. S.; de Llano, C. J. Am. Chem. Soc. 1969, 91, 789–795.
7. Herndon, W. C. J. Org. Chem. 1998, 63, 7445–7448.
8. Nagano, Y.; Sugimoto, T. J. Therm. Anal. Calorim. 1999, 57, 867–874.
9. Nagano, Y. J. Chem. Thermodynamics 2001, 33, 377–387.
10. Hubbard, W. N.; Scott, D. W.; Wadington, G. Experimental Thermochemistry. Rossini, F. D.:
editor. Interscience: New York. 1956, Chap. 5.
11. CODATA Task Group on Key Values for Thermodynamics. J. Chem. Thermodynamics 1978,
10, 903–906.
12. Head, A. J.; Good, W. D. Combustion Calorimetry, Experimental Chemical Thermodynamics,
Vol. 1. Sunner, S.; Ma˚nsson, M.: editors. Pergamon: Oxford. 1979.