caa a22 4500 463191420 CHVBK 20180406164910.0 cr unu---uuuuu 170326e20070901xx s 000 0 eng 10.1007/s10973-006-7922-6 doi (NATIONALLICENCE)springer-10.1007/s10973-006-7922-6 Polymorphism of paracetamol [Elektronische Daten] Relative stability of the monoclinic and orthorhombic phase revisited by sublimation and solution calorimetry [G. Perlovich, Tatyana Volkova, Annette Bauer-Brandl] The thermodynamic relationship between crystal modifications of paracetamol was studied by alternative methods. Temperature dependence of saturated vapor pressure for polymorphic modifications of the drug paracetamol (acetaminophen) was mea sured and thermodynamic functions of the sublimation process calculated. Solution calorimetry was carried out for the two modifications in the same solvent. Thermodynamic parameters for sublimation for form I (monoclinic) were found: ΔG sub 298 =60.0 kJ mol−1; ΔH sub 298 =117.9±0.7 kJ mol−1; ΔS sub 298 =190±2 J mol−1 K−1. For the orthorhombic modification (form II), the saturated vapor pressure could only be studied at 391 K. Phase transition enthalpy at 298 K, ΔH tr 298 (I→II)=2.0±0.4 kJ mol−1, was derived as the difference between the solution enthalpies of the noted polymorphs in the same solution (methanol). Based on ΔH tr 298 (I→II), differences between temperature dependencies of heat capacities of both modifications and the vapor pressure value of form II at 391 K, the temperature dependence of saturated vapor pressure and thermodynamic sublimation parameters for modification II were also estimated (ΔG sub 298 =56.1 kJ mol−1; ΔH sub 298 =115.9±0.9 kJ mol−1; ΔS sub 298 =200±3 J mol−1 K−1). The results indicate that the modifications are monotropically related, which is in contrast to findings recently reported found by classical thermochemical methods. Springer Science+Business Media LLC, 2007 paracetamol nationallicence phase transition nationallicence polymorphism nationallicence solution calorimetry nationallicence sublimation thermodynamics nationallicence Perlovich G. Institute of Pharmacy, University of Tromsø, Breivika, 9037, Tromsø, Norway aut Volkova Tatyana Institute of Pharmacy, University of Tromsø, Breivika, 9037, Tromsø, Norway aut Bauer-Brandl Annette Institute of Pharmacy, University of Tromsø, Breivika, 9037, Tromsø, Norway aut Journal of Thermal Analysis and Calorimetry Springer US; http://www.springer-ny.com 89/3(2007-09-01), 767-774 1388-6150 89:3<767 2007 89 10973 https://doi.org/10.1007/s10973-006-7922-6 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10973-006-7922-6 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Perlovich G. Institute of Pharmacy, University of Tromsø, Breivika, 9037, Tromsø, Norway aut NATIONALLICENCE 700 1- Volkova Tatyana Institute of Pharmacy, University of Tromsø, Breivika, 9037, Tromsø, Norway aut NATIONALLICENCE 700 1- Bauer-Brandl Annette Institute of Pharmacy, University of Tromsø, Breivika, 9037, Tromsø, Norway aut NATIONALLICENCE 773 0- Journal of Thermal Analysis and Calorimetry Springer US; http://www.springer-ny.com 89/3(2007-09-01), 767-774 1388-6150 89:3<767 2007 89 10973 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer