REACTIONS OF HYDROCARBONS WITH MIXTURES OF ACTIVE NITROGEN AND HYDROGEN ATOMS .I. NORMAL REACTIONS - REACTIONS OF ALKENES AND ALKANES

The reactions of ethylene, propylene, isobutylene, methane, and ethane with active nitrogen have been studied in a very fast flow, low-pressure (50 m/sec linear velocity and 0.2 mm pressure) Wood-Bonhoeffer apparatus. Under these conditions 3-body reactions are negligible and only fast 2-body reactions are observed. Addition of H atoms from a second discharge to alkene reactions increases HCN production to the extent that agreement with NO titration values for N atom concentrations is obtained. Agreement has also been obtained with alkanes, viz., C2H6 and CH4 in the presence of H atoms, at temperatures greater than 250°, and at room temperatures with HCl as a catalyst. Without a catalyst, even in the presence of H atoms, no reaction occurs with CH4 at room temperature and reaction is very slow with C2H6. The initial reaction is formation of alkyl radicals by H atom reactions; in the case of alkenes, by addition; and in the case of alkanes, by abstraction. N atoms then react rapidly with alkyl radicals larger than CH3 to produce NH and HCN. N2 is produced by disproportionation of NH radicals: NH + NH → N2 + 2H. When H atoms are added under conditions such that the reactions go to completion, N2 formation is suppressed because NH radicals are consumed by H + NH → H2 + N. This reaction also regenerates N atoms, which then form additional HCN to the extent that agreement with NO titration is obtained. NH3 formation is also discussed.