Oxidation characteristics and explosion risk of 2, 5-dimethylfuran at low temperature

The thermal oxidation reaction of 2,5-dimethylfuran (DMF) was investigated using a custom-designed mini closed pressure vessel test (MCPVT) and traced by H-1 nuclear magnetic resonance(H-1 NMR). The oxidation behavior was monitored by-via temperature-time (T-t) and pressure-time (p-t) plots of MCPVT recording. Oxidation products were determined via gas chromatography-mass spectrometry (GC-MS), and the generated peroxide was examined by iodimetry and thin-layer chromatography (TLC), with the thermal decomposition hazard evaluation by differential scanning calorimeter (DSC) and MCPVT. Results show that the DMF oxidation reaction proceeded through initial oxygen absorption at 39.3 degrees C, followed by an exothermic self-accelerating oxidation at 84.5 degrees C. DMF could form high level peroxide in auto-oxidation; the decomposition of peroxides would lead to the radical oxidation that the generated center dot OH radical mainly attacks on the position 2/5 of DMF with subsequent addition of O-2 initiating ring-opening reaction, in which DMF was firstly converted to cis-3-hexene-2,5-dione, and then produced the trans-3-hexene-2,5-dione with strong photoisomerism. DMF oxidation showed a high level of residue formation, and those solid products contained considerable amount of peroxides with a high thermal hazard; its exothermic onset temperature (T0) and decomposition heat (QDSC) of 58.8 degrees C and 1982.3 J.g(-1), and the decomposition maximum temperature rising rate (dT/dt) max and maximum of pressure rising rate (dp/dt) max was 9.98 degrees C.s(-1) and 291 kPa.s(-1), respectively. Thermal decomposition of those peroxide products could give rise to thermal runaway of DMF oxidation, and further transformed into a detonation possibly.