Some new energetic benzaldoximes Synthesis, structure and a comparison of theoretic and experimental results of thermal decomposition

• Published in: Journal of thermal analysis and calorimetry Vol. 112; no. 3; pp. 1587 - 1599
• Main Authors: Kunduracı, Melike, Özkaramete, Elif, Yılmaz, Nurdane, Öz, Sevi, Svoboda, Ingrid, Kübra İnal, E., Atakol, Orhan
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.06.2013; Springer
• Subjects: Aldehydes; Analytical Chemistry; Chemistry; Chemistry and Materials Science; Comparative analysis; Exact sciences and technology; Inorganic Chemistry; Measurement Science and Instrumentation; Nitriles; Noncondensed benzenic compounds; Organic chemistry; Physical Chemistry; Polymer Sciences; Preparations and properties; Oxime; TG; DSC; Thermal decomposition; CBS-4M; Differential scanning calorimetry; Nitro compound; Pyrolysis; Thermogravimetry; Theoretical study; Formation free energy; Experimental study; Reaction mechanism; Density functional method; Phenols; Thermal analysis; Thermodynamic properties; Chemical synthesis; Comparative study
• ISSN: 1388-6150; 1588-2926; 1572-8943
• DOI: 10.1007/s10973-012-2660-4

5-Nitro-2-hydroxy benzaldoxime ( I ), 3-nitro-4-hydroxy benzaldoxime ( II ), 3,5-dinitro-2-hydroxy benzaldoxime ( III ), and 3,5-dinitro-4-hydroxy benzaldoxime ( IV ) were prepared from their respective nitrated aldehydes. Prepared oximes were characterized by IR spectroscopy, elemental analysis, and mass spectrometry. Suitable crystals of compounds II and III were obtained and molecular structures were determined by means of the single crystal XRD method. All benzaldoximes were investigated by TG. At temperatures above 140 °C, it was observed that compounds II and IV lost one H 2 O and was converted to the respective benzonitriles. Only thermal analysis peaks of 3,5-dinitro-4-hydroxy benzonitrile ( V ) were found proper for both experimental and theoretic calculations; whereas, compounds I and III were converted to phenoxazines by Beckmann rearrangement along with dehydration. Beckmann product of compound III is referred as compound VI and its tautomer as compound VII . Similarly only 3,5-dinitro phenoxazine (VIII) was investigated experimentally and theoretically since its thermal analysis peaks were proper for the purpose. DFT-based structure optimizations and frequency analyses were performed at the B3LYP/cc-pVDZ level of theory. The enthalpies of formation for compounds III – VIII were calculated by means of the complete basis set (CBS-4M) method of Petersson and coworkers to obtain accurate energies. The enthalpies of decomposition for compounds III and IV were obtained from calculated enthalpies of formation according to Hess’ law and were compared with the experimental values which were available from DSC analyses and were found to be in good agreement with the theoretic values.