S . E. Stein, D. M. Golden, and S. W. Benson
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Predictive Scheme for Thermochemical Properties of Polycyclic Aromatic Hydrocarbons3 S. E. Stein,+ D. M. Golden," and S. W. Benson t Department of Thermochemistry and Chemical Kinetics, Stanford Research Institute, Menlo Park, California 94025 (Received August 20, 1976) Publication costs assisted by the Stanford Research Institute
An extension of group additivity techniques has been applied to the prediction of standard gas-phase heats of formation, intrinsic entropies, and heat capacities for polycyclic aromatic hydrocarbons (PCAHs) consisting of six-memberedrings. The proposed method is easy to apply, is more accurate than previous estimation methods, and converges to known thermochemical properties of graphite for very large, highly condensed PCAHs. The for eleven PCAHs is
AH,"Z98,
Group CB-(H) CBF-(CB), (CBF) CBF-(CB)(CBF)~ C B F - ( ~ B 1F3
mol-' 3.30 4.80 3.70 1.45
K-' 11.53 -5.00 -5.00 1.82
300K 3.24 2.99 2.99 2.08
400K 4.44 3.66 3.66 2.85
500K 5.46 4.22 4.22 3.50
600K 6.30 4.64 4.64 4.03
800K 1.54 5.23 5.23 4.75
1OOOK 8.41 5.55 5.55 5.14
TABLE 11: Shto29d(gas) for PCAHs (cal mol-, K-I) AH,,,-
Compound
So,,,(solid)a
(sublim)/298
R In P,b
R lnuC
Naphthalene Phenanthrene Anthracene Pyrene
50.63 49.58 53.15
12.85e 81.54e 81.00f
- 29.51
-38.71 -31.02
1.38 2.15 2.75
Triphenylene
60.89
98.68e
-50.5
3.56
Sh
