Wednesday, April 19, 2017

organic chemistry - Perchlorate salts: (explosive) reactivity with methane?


I read everywhere about the explosive reactivity of perchlorate salts (e.g., $\ce{Na}$, $\ce{Ca}$, $\ce{NH4}$ [especially]) when mixed with organic materials or solvents, yet I find no information about its reactivity with methane.


Can anyone comment please?



Answer



In general, explosion of alkali metal perchlorates (at least in small quatities) is deflagration, with the perchlorate providing oxygen for combustion of another component of a mixture, rather than detonation (due to decomposition of the perchlorate). However, perchloric acid itself and other inorganic and organic perchlorates such as cis-bis-(5-nitrotetrazolato)tetraminecobalt(III) perchlorate can transition from deflagration to brissant detonation.



So, to answer your specific question, gaseous methane would burn more readily in the presence of Group I perchlorates, but the flame-front would be limited by the small contact area and low concentration of methane at the solid/gaseous interface. On the other hand, if one were to synthesize methyl perchlorate or ethyl perchlorate, one might not be able to perform subsequent syntheses.


So, to avoid maiming or perhaps a terminal experiment, eschew perchlorates.


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