Thermal decomposition of 2‐ethylhexyl nitrate (2‐EHN)

The decomposition mechanism of 2‐ethyl‐hexylnitrate (2‐EHN), an important additive to diesel fuel to improve the cetane number, was investigated in solution and in the gas phase. In trans‐decalin as solvent, an activation barrier for the thermal decomposition of 39 kcal/mol was determined, and thus the decomposition is slow at temperatures below 100°C. Under high pressure conditions (2.4 kbar) the decomposition rates decrease, in accordance with a radical mechanism. Flash vacuum pyrolysis with subsequent detection of the products via mass spectroscopy or matrix IR spectroscopy allows to identify NO2, formaldehyde, and several olefins as the major decomposition products. These data allow proposing a consistent mechanistic scheme for the 2‐EHN decay.