Thermal investigation on polymorphism in sodium saccharine

• Published in: Journal of thermal analysis and calorimetry 2014-07, Vol.117 (1), p.361-367
• Main Authors: Medina, Deyber Arley Vargas, Ferreira, Ana Paula Garcia, Cavalheiro, Eder Tadeu Gomes
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Calorimetry; Chemistry; Chemistry and Materials Science; Differential scanning calorimetry; Diffraction; Hydrates; Hydration; Inorganic Chemistry; Investigations; Measurement Science and Instrumentation; Physical Chemistry; Polymer Sciences; Sodium; Solidification; Spontaneous; Thermodynamics; X-rays
• ISSN: 1388-6150; 1588-2926; 1572-8943
• DOI: 10.1007/s10973-014-3733-3

The thermal behavior of sodium saccharin polymorphic forms was investigated using thermogravimetry and differential scanning calorimetry, while structural changes during the dehydration processes were monitored by X-ray powder diffraction. In solid state, sodium saccharine may exhibit three forms: anhydrate, 2/3 hydrate (triclinic), and 15/8 hydrate (monoclinic) ones. In this investigation, it was established that monoclinic and triclinic forms compose an entantiotropically related polymorphs system. At 82 °C, the 15/8 hydrated monoclinic form is converted to 2/3 hydrated triclinic form, which showed to be the more thermodynamically stable form at room temperature. Spontaneous solidification leads to the formation of triclinic cell setting, and additionally, spontaneous hydration of the anhydrous form leads to formation of 2/3 hydrated triclinic form.