Polymorphic Phase Transitions in Carbamazepine and 10,11-Dihydrocarbamazepine.

Chemistry

UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London, WC1N 1AX, UK.

Published: September 2018

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.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6175174PMC
http://dx.doi.org/10.1002/chem.201802368DOI Listing

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