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Polymorphic Phase Transitions in Carbamazepine and 10,11‐Dihydrocarbamazepine
Author(s) -
Clout Alexander E.,
Buanz Asma B. M.,
Gaisford Simon,
Williams Gareth R.
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201802368
Subject(s) - differential scanning calorimetry , sublimation (psychology) , carbamazepine , phase transition , crystallography , chemistry , diffraction , recrystallization (geology) , phase (matter) , materials science , lattice (music) , thermodynamics , organic chemistry , physics , optics , psychology , paleontology , neuroscience , biology , acoustics , epilepsy , psychotherapist
Temperature‐induced phase transitions in carbamazepine (CBZ) and 10,11‐dihydrocarbamazepine (DHC) were studied by simultaneous differential scanning calorimetry–X‐ray diffraction in this work. The transitions generally involve a transitional melt phase which is quickly followed by recrystallisation. The expansions of the unit cell as a function of temperature could be quantified and allow us to determine a directional order of stability in relation to the lattice constants. Dihydrocarbamazepine form II undergoes a conversion to form I by a localised melt phase. Carbamazepine (CBZ) form IV converts to form I at 182 °C, again by a localised intermediate melt phase. CBZ form II converted to form I at 119 °C by a pathway that appears to have included some melting, and form III underwent a part melt‐recrystallisation and a part sublimation‐recrystallisation to form I.