dioxine
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calcium benzoate dry distillation safety
Hello. Calcium benzoate + calcium propionate seems to be very interesting method to produce propiophenone but as an amateur-chemist im not sure if i
can heat it without any temperature measuring.
Can the flask with the salts explode if i overheat it?
Autoignition temperature of 3-pentanone for example is 425 C which is same as temperature required.
Sorry for my bad english.
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Fyndium
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If the flask is closed, it cannot burn. Many things are handled above their autoignition points protected from oxygen/oxidizer. Common sense must be
always used, though.
425 is a bit on the high side for glass, IMO. It can crack, etch or if heated with direct flame, hotspots can actually reach softening point. I'd use
metal vessel for that. Pyrolysis is usually committed by slowly rising temp, collecting everything until nothing more comes over and fractional
distilling them to (attempt to) recover the desirables.
Correct me if I'm wrong, but I remember reading on the benzaldehyde topic that this pyrolysis yield is a bit on the low side.
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dioxine
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Thanks for your answer. metal vessel is what im going to use.
If im not wrong, there are still some of oxygen in distilling apparatus, isnt it? Thats what im worry about.
also could u please explain " low side" meaning since im not a native speaker and cant understand what exactly this means.
[Edited on 27-3-2021 by dioxine]
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Triflic Acid
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Mood: Slowly Oxidizing into Oblivion
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Low side just means that it is a rather small value and the yield is not very good.
There wasn't a fire, we just had an uncontrolled rapid oxidation event at the power plant.
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Prepic
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I've had first experience of the dry distillation of calcium benzoate and calcium acetate. In this case, I used a aluminum kettle, ~200cm copper
tubing leading our of the pouring spout and fire sealant to seal the whole apparatus. The kettle was heated using a camping stove.
In terms of safety, I never had any issue of leaks, air ingress or an explosion. My suggestion would be however to purge the apparatus with either CO2
or N2 to remove any air if you are concerned about that. Also, it would be prudent to use an appropriately sized vessel to limit the volume of dead
air during the reaction but also ensuing some headroom for the reaction to take place and for the product vapors to exit the apparatus. In my case
with the kettle, about 2/5th of the vessels height was filled with powder.
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Fyndium
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I have never been worried about combustion inside a vessel, no matter what heat source I'm using, because when things start to evaporate inside, the
oxygen content quickly decreases to nil and no combustion can sustain. The ingredients usually contain at least traces of volatiles like water, and
that vapor will already remove much of the oxygen.
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