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?


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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  • $\begingroup$ Thank you for your detailed response and valid safety concerns. However, mine is a natural (i.e., geochemical) laboratory, so the 'career-closing' risk to my syntheses should not be an issue. $\endgroup$ – Dave Jun 5 '15 at 6:55
  • $\begingroup$ The perchlorate in question is Calcium perchlorate hydrate and the solution has methane bubbling through it. The temperature is low (~ 5°C), but the solution is under sustained pressure. While deflagration may be implied, observation (at distance!) has confirmed detonation. I presume that reaction remains thermodynamically favourable (but with a high kinetic barrier?), so is my reactant list incomplete somehow or does the pressure contribute catalytically? $\endgroup$ – Dave Jun 5 '15 at 6:55
  • $\begingroup$ There is also reason to believe that someone has subjected the site to impact-testing (but without leaving any body-parts behind!) $\endgroup$ – Dave Jun 5 '15 at 7:10
  • $\begingroup$ Though methane is pretty stable, is it possible that methyl perchlorate formed? If the pressure bomb(!) is unlined metal, it could be that the container helped catalyze the reaction, or even reacted with the calcium perchlorate solution. Sorry, these are just suppositions. $\endgroup$ – DrMoishe Pippik Jun 5 '15 at 17:41
  • $\begingroup$ Thank you again Dr. P -- the possibility of methyl perchlorate synthesis is tantalising, so I shall ask a new question on this very subject $\endgroup$ – Dave Jun 6 '15 at 8:25

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