Very low‐pressure pyrolysis. VII. The decomposition of methylhydrazine, 1,1‐dimethylhydrazine, 1,2‐dimethylhydrazine, and tetramethylhydrazine. Concerted deamination and dehydrogenation of methylhydrazine

The rate constants ( k uni ) for the first‐order disappearance of the title molecules have been determined under VLPP conditions. The k uni are not the rate constants of ultimate interest since they reflect the fact that energy transfer competes with the chemical decomposition. Use of the Rice‐Ramsperger‐Kassel‐(Marcus) [RRK(M)] theory allows the determination of the high‐pressure rate constants ( k α ), if the mode of decomposition is known. The heats of formation of the radicals NH 2 , CH 3 NH, and (CH 3 ) 2 N are known. These values should be usable for prediction of the activation energy for NN bond homolysis in the hydrazines. Measured rate constants for UDMH and TMH bear this out, but the rate constant for MMH does not. This and other evidence lead to the conclusion that MMH decomposes via molecular concerted elimination of NH 3 and H 2 not and by NN bond scission. The following values are preferred from this work (θ = 2.303 RT in kcal/mole). Mode of decomposition is N—N bond scission unless noted otherwise in parenthesis: .