Experimental and theoretical studies on the thermal decomposition of metformin

• Published in: Journal of thermal analysis and calorimetry Vol. 138; no. 1; pp. 433 - 441
• Main Authors: Badran, Ismail, Hassan, Azfar, Manasrah, Abdallah D., Nassar, Nashaat N.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01-10-2019; Springer; Springer Nature B.V
• Subjects: Ammonia; Analytical Chemistry; Chemistry; Chemistry and Materials Science; Commodities; Decomposition; Decomposition reactions; Density functional theory; Formulations; Gravimetric analysis; Inorganic Chemistry; Mass spectrometry; Measurement Science and Instrumentation; Metformin; Methyl radicals; Perturbation methods; Physical Chemistry; Polymer Sciences; Reaction mechanisms; Thermal decomposition; Thermal degradation; Wastewater treatment; DFT; Reaction mechanism; Decomposition; Metformin; Thermal analysis; Evolved gas analysis; Mass spectrometry; MP2
• ISSN: 1388-6150; 1588-2926
• DOI: 10.1007/s10973-019-08213-9

This work is a first attempt to understand the mechanism of metformin thermal decomposition under inert conditions. Thermal gravimetric analysis coupled with mass spectrometry was used to probe the thermal degradation reactions. Density functional theory and second-order perturbation (MP2) theoretical calculations were used to construct a reaction mechanism for metformin decomposition. It was evident that the reactions are initiated via formation of methyl radicals, and ammonia via 1.3-H shift, followed by a series of different secondary reaction pathways. The formation of cyanamide, dimethylamine and HCN were among the main secondary products. The proposed mechanism is important for future treatment of wastewater containing metformin and similar drugs formulations, and their possible conversion to useful commodities.