The study of the pyrolysis of alkyl nitrites in a field ionization mass spectrometer

Abstract

The pyrolysis behaviour of ethyl, n-propyl, n-butyl and iso-butyl nitrite at low pressures was investigated in the temperature range 150–510°C, using a field ionization mass spectrometer. The three pyrolysis steps (loss of NO to form an alkoxy radical, loss of CH 2O to form an alkyl radical, and loss of an olefine to form a secondary alkyl radical or hydrogen) could be readily identified. The alkoxy radicals can be identified only indirectly via secondary reactions on the surface of the field ionization emitter, while alkyl radicals undergo surface reactions to a lesser extent and thus can be identified directly. The proportion of free alkyl radicals increases with increasing chain length and branching of the alkyl nitrite, while the optimum temperature for formation of alkyl radicals decreases correspondingly. The results not only give information on the pyrolysis behaviour of alkyl nitrites but also shed light on the reactions of alkoxy and alkyl radicals on the surface of a field ionization emitter.