The vapor pressures for 5-fluorouracil, 1-methyl-5-fluorouracil, and 1,3-dimethyl-5-fluorouracil were measured by a torsion method. The following linear equations, representative of the temperature dependence in the covered temperature ranges, were selected: 5-fluorouracil, log(p/kPa) = (15.18+- 0.20) - (7860 +-100)K/T, (421-483) K; 1-methyl-5-fluorouracil, log(p/kPa)= (12.64 +-0.20) - (6083+- 100)K/ T, (381-423) K; 1,3-dimethyl-5-fluorouracil, log(p/kPa) = (15.16+- 0.40) - (6286 +- 200)K/T, (338-473) K. From these equations the standard sublimation enthalpies and entropies, DsubH° (298 K) = 154+- 5, 116 +- 2, and 119 +- 4 kJ mol-1 and DsubS° (298 K) = 259 +- 8, 203 +- 4, and 252 +- 8 J K-1 mol-1, respectively, for 5-fluorouracil, 1-methyl-5-fluorouracil, and 1,3-dimethyl-5-fluorouracil were determined. The vaporization behavior for these compounds was compared with that for uracil and corresponding methyl derivatives.

[object Object]

Sublimation thermodynamic parameters for 5-fluorouracil and its 1-methyl and 1,3-dimethyl derivatives from vapor pressure measurements

Brunetti Bruno;
2002

Abstract

[object Object]
2002
The vapor pressures for 5-fluorouracil, 1-methyl-5-fluorouracil, and 1,3-dimethyl-5-fluorouracil were measured by a torsion method. The following linear equations, representative of the temperature dependence in the covered temperature ranges, were selected: 5-fluorouracil, log(p/kPa) = (15.18+- 0.20) - (7860 +-100)K/T, (421-483) K; 1-methyl-5-fluorouracil, log(p/kPa)= (12.64 +-0.20) - (6083+- 100)K/ T, (381-423) K; 1,3-dimethyl-5-fluorouracil, log(p/kPa) = (15.16+- 0.40) - (6286 +- 200)K/T, (338-473) K. From these equations the standard sublimation enthalpies and entropies, DsubH° (298 K) = 154+- 5, 116 +- 2, and 119 +- 4 kJ mol-1 and DsubS° (298 K) = 259 +- 8, 203 +- 4, and 252 +- 8 J K-1 mol-1, respectively, for 5-fluorouracil, 1-methyl-5-fluorouracil, and 1,3-dimethyl-5-fluorouracil were determined. The vaporization behavior for these compounds was compared with that for uracil and corresponding methyl derivatives.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.14243/275228
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