Sublimation Enthalpies of Some Methyl Derivatives of Uracil from Vapor Pressure Measurements

The standard sublimation enthalpies for uracil, 1-methyluracil, 3-methyluracil, and 1,3-dimethyluracil, Δsub H°(298 K) = (128 ± 2), (124 ± 5), (121 ± 4), and (118 ± 4) kJ mol-1, respectively, were determined from their vapor pressures measured by the torsion method. The results of vapor pressure mea...

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Bibliographic Details
Published in:Journal of chemical and engineering data 2000-03, Vol.45 (2), p.242-246
Main Authors: Brunetti, Bruno, Piacente, Vincenzo, Portalone, Gustavo
Format: Article
Language:English
Subjects:
Chemical thermodynamics
Chemistry
Elements, mineral and organic compounds
Exact sciences and technology
General and physical chemistry
Thermodynamic properties
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Summary:The standard sublimation enthalpies for uracil, 1-methyluracil, 3-methyluracil, and 1,3-dimethyluracil, Δsub H°(298 K) = (128 ± 2), (124 ± 5), (121 ± 4), and (118 ± 4) kJ mol-1, respectively, were determined from their vapor pressures measured by the torsion method. The results of vapor pressure measurements were fit to the following linear equations:  uracil, log(p/kPa) = (12.29 ± 0.15) − (6634 ± 100) K/T (from 384 K to 494 K); 1-methyluracil, log(p/kPa) = (13.75 ± 0.15) − (6357 ± 150) K/T (from 343 K to 428 K); 3-methyluracil, log(p/kPa) = (13.59 ± 0.10) − (6210 ± 100) K/T (from 344 K to 419 K); 1,3-dimethyluracil, log(p/kPa) = (15.10 ± 0.10) − (6049 ± 100) K/T (from 311 K to 364 K). The different sublimation behavior of some compounds can be due to the presence of hydrogen bonds in their solid state.
ISSN:0021-9568
1520-5134
DOI:10.1021/je9902802