ISSN:
0538-8066
Keywords:
Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The rate constants (kuni) for the first-order disappearance of the title molecules have been determined under VLPP conditions. The kuni 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 (kα), if the mode of decomposition is known. The heats of formation of the radicals NH2, CH3NH, and (CH3)2N 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 NH3 and H2 not and by N—N bond scission. The following values are preferred from this work (θ = 2.303RT in kcal/mole). Mode of decomposition is N - N bond scission unless noted otherwise in parenthesis: \documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{ll} \underline{{{{\rm Molecule}}}}& \underline{{{{\rm log }k_\infty /\sec ^{ - 1} (298^\circ {\rm K})}}}\\ {{{{\rm MMH}}}}&{{{13.2{\rm - }54/\theta (- {\rm NH}_{\rm 3});}}}\\ {} & {13.5{\rm - }57/\theta (- {\rm H}_{\rm 2})} \\ {{\rm UDMH}} & {17.0{\rm - }63/\theta } \\ {{\rm SDMH}} & {{\rm 13}{\rm .5 - 57/}\theta {\rm (} - {\rm H}_{\rm 2} {\rm)}} \\ {{\rm TMH}} & {{\rm 17}{\rm .4 - 54/}\theta } \\\end{array}$$\end{document}.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/kin.550040407
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