Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2485615 | Journal of Pharmaceutical Sciences | 2011 | 9 Pages |
Abstract
The vaporization, fusion, and sublimation enthalpies of methyl, ethyl, propyl, and butyl paraben are reported and compared with literature values. The vaporization enthalpies were measured by correlation gas chromatography and the fusion enthalpies by differential scanning calorimetry. Adjusted to T = 298.15 K, these enthalpies were combined to yield the sublimation enthalpy. The results compare favorably to some of the literature values but do not support the reversal in magnitude of both the vaporization and sublimation enthalpy previously reported for propyl and butyl paraben. The following fusion and vaporization enthalpies were measured for methyl through to butyl paraben, respectively: ÎHfus(Tfus) 26.3 ± 0.1 (398.6 K), 26.5 ± 0.1 (388.5 K), 27.3 ± 0.1 (368.8), and 25.9 ± 0.3 (340.7 K) kJ·molâ1; ÎHvap (298.15 K) 79.5 ± 0.5, 84.0 ± 0.5, 89.7 ± 0.6, and 95.8 ± 0.6 kJ·molâ1. The results are believed to be accurate to ±4 kJ·molâ1. © 2011 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 100:1847-1855, 2011
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Authors
Patamaporn Umnahanant, James Chickos,