scholarly journals Thermoanalytical studies of carbamazepine: hydration/dehydration, thermal decomposition, and solid phase transitions

2014 ◽  
Vol 50 (4) ◽  
pp. 877-884 ◽  
Author(s):  
Mônia Aparecida Lemos Pinto ◽  
Beatriz Ambrozini ◽  
Ana Paula Garcia Ferreira ◽  
Éder Tadeu Gomes Cavalheiro
Keyword(s):  
Solid Phase ◽  
Evolved Gas Analysis ◽  
Anticonvulsant Drug ◽  
Kinetic Studies ◽  
Gas Analysis ◽  
Scanning Calorimetry ◽  
Evolved Gas ◽  
Solid State Decomposition ◽  
Thermoanalytical Studies ◽  
Polymorphic Forms

Carbamazepine (CBZ), a widely used anticonvulsant drug, can crystallize and exhibits four polymorphic forms and one dihydrate. Anhydrous CBZ can spontaneously absorb water and convert to the hydrate form whose different crystallinity leads to lower biological activity. The present study was concerned to the possibility of recovering the hydrated form by heating. The thermal behavior of spontaneously hydrated carbamazepine was investigated by TG/DTG-DTA and DSC in dynamic atmospheres of air and nitrogen, which revealed that the spontaneous hydration of this pharmaceutical resulted in a Form III hydrate with 1.5 water molecules. After dehydration, this anhydrous Form III converted to Form I, which melted and decomposed in a single event, releasing isocyanic acid, as shown by evolved gas analysis using TG-FTIR. Differential scanning calorimetry analyses revealed that Form III melted and crystallized as Form I, and that subsequent cooling cycles only generated Form I by crystallization. Solid state decomposition kinetic studies showed that there was no change in the substance after the elimination of water by heating to 120 °C. Activation energies of 98 ± 2 and 93 ± 2 kJ mol-1 were found for the hydrated and dried samples, respectively, and similar profiles of activation energy as a function of conversion factor were observed for these samples.

The Pyrolytic Decomposition of Owens-Illinois Resin Gr650, an Organosilicon Compound

1984 ◽  
Vol 32 ◽  
Author(s):  
B. G. Bagley ◽  
P. K. Gallagher ◽  
W. E. Quinn ◽  
L. J. Amos
Keyword(s):  
Room Temperature ◽  
Evolved Gas Analysis ◽  
Condensation Reaction ◽  
Gas Analysis ◽  
Weight Loss Curve ◽  
Reaction Products ◽  
Scanning Calorimetry ◽  
Evolved Gas ◽  
Temperature Range ◽  
Pyrolytic Decomposition

ABSTRACTThe pyrolytic conversion of an organosilsesquioxane (Owens-Illinois resin GR650) to SiO2 is characterized by ir spectroscopy, thermogravimetry and evolved gas analysis (line-of-sight mass spectroscopy). Scanning calorimetry, ramping at 10°C/min, on the as-received (room temperature annealed) resin indicates a glass transition temperature of 67°C which decreases to 58°C for an unrelaxed sample. The ir spectra have bands which can be assigned to Si-CH3 and Si-O-Si modes. For 30 minute isothermal anneals at temperatures above 420°C there is a continuous decrease in the bands associated with the Si-CH3 groups such that after 30 minutes at 650°C the ir spectrum has evolved to that for SiO2. Evolved gas analysis indicates that there are four major components evolving. Over the temperature range (ramping at 10°C/min) ∼180 to ∼500°C we observe C2H5OH and H2O, both of which are condensation reaction products from the curing reaction. Methane is a major evolving species over the temperature range ∼500 to ∼800°C and the thermal spectrum is double peaked which we attribute to CH3+ bound to the inside and outside of the polymer cage structures. The final major component detected was H2, over the temperature range ∼600 to ∼1100°C, which was attributed to pyrolysis of the organic components, both trapped and evolving. The features of the weight loss curve can be accounted for by the measured evolving species spectra.

Thermoanalytical studies of titanium(IV) acetylacetonate xerogels with emphasis on evolved gas analysis

2007 ◽  
Vol 88 (2) ◽  
pp. 557-563 ◽  
Author(s):  
I. Oja Açik ◽  
J. Madarász ◽  
M. Krunks ◽  
K. Tõnsuaadu ◽  
D. Janke ◽  
...  
Keyword(s):  
Evolved Gas Analysis ◽  
Gas Analysis ◽  
Evolved Gas ◽  
Thermoanalytical Studies

scholarly journals Thermal decomposition of tris(O-ethyldithiocarbonato)-antimony(III)—a single-source precursor for antimony sulfide thin films

2021 ◽  
Author(s):  
Jako S. Eensalu ◽  
Kaia Tõnsuaadu ◽  
Jasper Adamson ◽  
Ilona Oja Acik ◽  
Malle Krunks
Keyword(s):  
Thin Films ◽  
Thermal Decomposition ◽  
Mass Loss ◽  
Solid Phase ◽  
Evolved Gas Analysis ◽  
Gas Analysis ◽  
Thermal Decomposition Mechanism ◽  
Product Analysis ◽  
Gaseous Species ◽  
Single Source Precursor

AbstractThermal decomposition of tris(O-ethyldithiocarbonato)-antimony(III) (1), a precursor for Sb2S3 thin films synthesized from an acidified aqueous solution of SbCl3 and KS2COCH2CH3, was monitored by simultaneous thermogravimetry, differential thermal analysis and evolved gas analysis via mass spectroscopy (TG/DTA-EGA-MS) measurements in dynamic Ar, and synthetic air atmospheres. 1 was identified by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) measurements, and quantified by NMR and elemental analysis. Solid intermediates and final decomposition products of 1 prepared in both atmospheres were determined by X-ray diffraction (XRD), Raman spectroscopy, and FTIR. 1 is a complex compound, where Sb is coordinated by three ethyldithiocarbonate ligands via the S atoms. The thermal degradation of 1 in Ar consists of three mass loss steps, and four mass loss steps in synthetic air. The total mass losses are 100% at 800 °C in Ar, and 66.8% at 600 °C in synthetic air, where the final product is Sb2O4. 1 melts at 85 °C, and decomposes at 90–170 °C into mainly Sb2S3, as confirmed by Raman, and an impurity phase consisting mostly of CSO 2 2− ligands. The solid-phase mineralizes fully at ≈240 °C, which permits Sb2S3 to crystallize at around 250 °C in both atmospheres. The gaseous species evolved include CS2, C2H5OH, CO, CO2, COS, H2O, SO2, and minor quantities of C2H5SH, (C2H5)2S, (C2H5)2O, and (S2COCH2CH3)2. The thermal decomposition mechanism of 1 is described with chemical reactions based on EGA-MS and solid intermediate decomposition product analysis.

Evolved Gas Analysis by Infrared Spectroscopy

2010 ◽  
Vol 45 (4) ◽  
pp. 241-273 ◽  
Author(s):  
S. Materazzi ◽  
S. Vecchio
Keyword(s):  
Infrared Spectroscopy ◽  
Evolved Gas Analysis ◽  
Gas Analysis ◽  
Evolved Gas
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