No abstract

The thermal decomposition of azomethane (A) has been studied in a static system at temperatures between 250" and 320°C and at pressures between 5 and 402 torr, with particular attention to identification of products. Major products, in decreasing order of importance, were nitrogen, methane, ethane, methylethyldiimide, dimethylhydrazone, propane, tetramethylhydrazine, ethylene, methylpropyldiimide, and methylethylhydrazone. Carbon balance at the lowest pressure and highest temperature was 92%, but decreased with increasing pressure and decreasing temperature owing to the formation of a polymer. A fairly simple mechanism accounts reasonably well for a short chain in the decomposition, propagated by the radical CH3N2CH2 (B), and for the five most abundant products, except ethane. It turns out that there is a second source of ethane, arising by C2Hs + A + CzHs + B; this explains an anomalously high apparent activation energy for the reaction CH3 + A + CH4 + B. Ethyl radicals are also shown to be responsible for the formation of propane, ethylene, methylethylhydrazone, and methylpropyldiimide. The radical B decomposes to CHI + CH2 + Nz, and the methylene radical (probably both singlet and triplet) is shown to yield CZHS at low pressure and high temperature, and mostly polymer at high pressure and low temperature.