Volcano boil over during vacuum decarb

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Moe.Red

Moe.Red

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I just had a violent instantaneous boil out during decarb under vacuum. I don't understand.

I am decarbing 50mL of rotovap'ed ethanol based concentrate in a 250mL beaker. My vacuum oven is PID controlled and doesn't stray more than 1* C from setpoint of 125*.

I do this by the clock, but I watch for the bubbles as a general indicator. Hit the oven with a flashlight after 15 minutes, and I see stuff all over the glass, shelf and outside of beaker. WTF? Stand there and stare at it trying to figure what happened, and see tiny bubbles as normal on an ultra low simmer. Suddenly, the whole beaker erupts into a bubble volcano. Then settles back down.

I have continued on by drilling a hole in the lid of a mason jar and I am using that as the decarb vessel in case of explosion. So far it has not repeated.

WTF is going on here? It was like I was dripping water into the beaker or something. Why so energetic a release?
 
Eskander

Eskander

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Going to be taking a swag here but If you hit a critical temp for CO2 outgassing quickly then you could get a blow off. Just ball parking but .13 Moles of CO2 released into a vacuum is going to be some serious volume if it happens quickly. Old thread I realize but I'd look at the thermometers first. Did it ever happen again?

-Eskander
 
Moe.Red

Moe.Red

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Hey @Eskander , sorry I missed your reply.

Yeah, really old thread. I did something wrong, probably some sort of contamination. The batch was pretty much ruined all over the inside of the oven, so I tossed it. It has never re-occured.

I'm sure it was user error of some sort.

Can you explain your math on the .13 Moles? I've never seen the equation for CO2 release from a decarboxylation reaction. Interesting.
 
Eskander

Eskander

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Hey @Eskander , sorry I missed your reply.

Yeah, really old thread. I did something wrong, probably some sort of contamination. The batch was pretty much ruined all over the inside of the oven, so I tossed it. It has never re-occured.

I'm sure it was user error of some sort.

Can you explain your math on the .13 Moles? I've never seen the equation for CO2 release from a decarboxylation reaction. Interesting.
Fermi estimation more or less. If you can get within an order of magnitude of the right answer with an off the cuff calculation, that gets you a range of realistic expectations in a few seconds.


I estimate the mass of canabanoids from your specified volume and likely THCa content %, ballparked the density then used THCa molecular weight to determine the moles of THCa present in that mass fraction and since that number is the same as CO2 moles, there you go.

-Eskander
 
Moe.Red

Moe.Red

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Here is my math:

Screen Shot 2021 06 09 at 105218 AM
 

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