Studies on thermal decomposition behaviour of N,N-dialkyl octanamides

• Thermal stability of DBOA and DHOA were studied in presence and absence of HNO3.
• DBOA and DHOA are stable up to 500 K and 525 K respectively.
• DBOA and DHOA showed exothermic decomposition at 375 K in presence of HNO3.
• High rise in T and P due to decomposition of amide-HNO3 may lead to explosion.

Thermal decomposition behaviour of neat N,N-dibutyl octanamide (DBOA) and N,N-dihexyl octanamide (DHOA) was investigated in closed air ambience, using an adiabatic calorimeter. Neat DBOA and DHOA were found to be thermally stable up to 500 K and 525 K respectively and exhibited an exothermic decomposition thereafter. In the presence of nitric acid, both DBOA and DHOA decomposed at a lower temperature, 375–390 K. These samples on decomposition form incompressible gases and viscous black solutions. FTIR and NMR techniques were used for analyzing decomposition products. The exothermic nature of decomposition reaction exhibits a strong dependency on nitric acid contents of the system. Thermo-kinetic parameters for the decomposition reaction were derived and reported for the first time. The results also indicate that amides such as DBOA and DHOA are thermally less stable compared to tri-n-butyl phosphate.