Vacuum Oven exhaust residual gas analyzer

[Chonkski]

Good! I've been waiting since 3/6/'13 for some triangulated feedback on the calculated boiling points under vacuum. G.O. Joe's been on my case about it for at least six months...

But, even if the boiling points are way off, I still feel -29.5" Hg is a good depth to limit your vacuum to avoid excessive loss of goodies.

For the conversations sake, I have retained just as much discernible taste/smell/effect by experimenting with -29.9"@100° as I have when purging a shorter amount of time -29.5"@115°.

Although I am one who leans towards 29.5 whilst using something to act as a gas ballast.

It is amusing to be able to see the reaction difference, even though I do know that just because we may not be seeing a lot of action, the surface of the patty will be a microscopic disco of evaporation(I actually have some pretty rad time lapses). But if I can be honest for a second, I am just now beginning my education in organic chem etc. so I have no "official" background to help make my guesses a little more educated. Which is why I pay full attention to those of you who are willing to share some of your heart earned fruits. If ya know whadymean

 

[G.O. Joe]

I was unaware of the controversy, don't own volume 55 of the experimental pharma handbook, and don't see bp under vacuum in my 14th addition Merk Index, but appreciate you bringing the issue to light.

I've been making the same post most times the list has been posted by you or others for at least 4 years, and have posted the link to the Merck entry before. There's no controversy - it's black and white - the chart says "Boiling/melting points (MP) recorded at atmospheric pressure (760 mmHg) unless otherise noted", but there is no noting when the temperatures given clearly indicate high vacuum. You don't need to trust anyone except Google. There is no C21 molecule that will boil at 157 without vacuum or boil lower than C10 myrcene.

 

[Gray Wolf]

I've been making the same post most times the list has been posted by you or others for at least 4 years, and have posted the link to the Merck entry before. There's no controversy - it's black and white - the chart says "Boiling/melting points (MP) recorded at atmospheric pressure (760 mmHg) unless otherise noted", but there is no noting when the temperatures given clearly indicate high vacuum. You don't need to trust anyone except Google. There is no C21 molecule that will boil at 157 without vacuum or boil lower than C10 myrcene.

OK, may we start over? I'm not in love with any number and seek only the correct ones.

If I/we'ns are not sharing the correct numbers for THC under vacuum, would you please do so and show the rest of us where you found the numbers, or how we might calculate them for ourselves?

As promised, I did forward the question to Kate, our Pharm D, and added Joe, our Biotech, cause I am our groups ignert engineer and sometimes misspell numbers above my pay grade.

We will also share the information gleaned from the next generation of Inficon MS exhaust gas analyzer trials, coming after the first of the year, because we currently can't identify what all the spikes are.

Regardless of source, it would be nice to know not only boiling points, but vapor points where they begin to sublimate off. Can you help us with those numbers or share links?

PS: Might you share the heat of vaporization of THC with me, so I can do some of my own number crunching?

 

[gholladay]

I was unaware of the controversy, don't own volume 55 of the experimental pharma handbook, and don't see bp under vacuum in my 14th addition Merk Index, but appreciate you bringing the issue to light.

I passed it on to Kate, our Pharm D, and see if she has any insight or information. More later.

This is a really interesting debate! Can't wait to hear what Kate has to say about it.

Just to make sure I'm clear, G.O. Joe you are saying the chart GW posted is incorrect because it lists the boiling point of THC delta 9 at atmospheric pressure (760 mmHG) to be 157°C? You're saying it should be 200°C at atmospheric pressure correct? And that there is no way a C21 molecule (THC) would have a lower boiling point than a C10 molecule (myrcene @ 166°C) because of it's molecular size and composition?

 

[Gray Wolf]

I've backtracked the graph far enough to find the original poster, and their math source, which was this site and an approximation.

http://www.trimen.pl/witek/calculators/wrzenie.html

If we start with a BP of 200C vis a vis 157C, and make a wild ass guess of 70 for heat of vaporization, it shows we would boil a 200C BP substance at 46C/115F and 142 microns, or about -29.77" Hg instead of -29.5" Hg.

Hopefully with all the brain trust now focused on the issue, we can get some more definitive estimates, because the issue applies not only to cannabinoids, but the shorter chain terpenes as well.

Ostensibly we will have empirical values next year, when we wring out the new Inficon, especially vaporization points, vis a vis boiling points under vacuum.

 

[NEGT1]

Thank you for bringing test results to the light. This is so important for determining ultimate methods.

I have always thought about the idea that different terpenes react differently to a vacuum. The basic idea of using a vacuum oven presumes that the vacuum helps us extract the hydrocarbons to a greater benefit than the loss of terpenes from the vacuum. Seems like the truth is in the middle...maybe not...but there has to be a point in which the pressure will rip out more than we need. Temps are pressures definitely need to be studied more. This is awesome

 

[SkyHighLer]

I'm fine with all of the above, but to cover my ass here's how this all came about,

http://www.tokecity.com/forums/showthread.php?43587-Vac-Pump-Discussion-Thread&p=1294580#post1294580

The TokeCity Forum member who's data and work is referenced, Spliff'o'matic's, is interesting in that he came up with "delta-9 THC: 66.49 kj/mol" along with the "THC:
760 torrs (AP) @ 157C." Yes, I should have pressed him for his source back then, I was new to the forums, and a little shy about questioning him, especially when I was in the process of publicly correcting his incorrect conclusion. It may be too late now, he hasn't posted anything since 4/14/'14, but I will pm him today as he is the only one to come up with a heat of vaporization figure.

"250 °C (482 °F) (range: 250–400 °C)"
http://en.wikipedia.org/wiki/Tetrahydrocannabinol

Well there's another all over the place reference... and as I recall, Wiki, when I was searching around back then, either was touting the 157C figure, or something near it.

I'm extremely grateful for GW and his high cronies for looking deeper into this (and many of the other loose ends!)

G.O. Joe you deserve much more respect here, you've got mine!

 

[prune]

That chart is not true because as I've posted many times, the McPartland and Russo numbers (the starting point) are under vacuum, without regard to whether they say so or not or whether you believe it. So - their charts, which many here have much more faith in than the Bible, may in fact contain flaws - I don't see any such admission forthcoming from the faithful. Published boiling points for cannabinoids are given at at least 1 mm, and are usually under 100 microns. There are dozens of peer-reviewed chemistry articles and books and references like the Merck Index to back that up. There are experimental difficulties in measuring boiling points and pressure at pressure that low, so there's a range of temperatures given that don't match up well and precise numbers are not very authoritative, compared to boiling points without vacuum.

"cannabinoids generally boil within the same temperature range (ca. 155C 0.05 mm)"
- R. Mechoulam
Handbook of Experimental Pharmacology, volume 55

And even if the charts were true, they still would not be valid because we are evaporating mixtures, not pure compounds. At best the charts are just clues as to what may be taking place.

 

[Chonkski]

I should have pressed him for his source back then, I was new to the forums, and a little shy about questioning him, especially when I was in the process of publicly correcting his incorrect conclusion.

The exact reason that it took me this long to bring up the subject

 

[G.O. Joe]

show the rest of us where you found the numbers

As I said it's a long and variable list - not limited to Cannabis-related chemistry articles and patents on file that can be provided - no magic number exists other than a range of temperatures and pressures. Mechoulam's quote was written down because it's very fitting, better than any list, if not a little low temperature for 50 microns in comparison to the Merck Index link's little high 200C at a pressure of 20 microns. So where to start? El-Sohly it is. See examples 3, 4, 7, 22, 26.

Regardless of source, it would be nice to know not only boiling points, but vapor points where they begin to sublimate off. Can you help us with those numbers or share links?

PS: Might you share the heat of vaporization of THC with me, so I can do some of my own number crunching?

Evaluation of a vaporizing device (Volcano®) for the pulmonary administration of tetrahydrocannabinol
Arno Hazekamp; Renee Ruhaak; Lineke Zuurman; Joop van Gerven; Rob Verpoorte
There's a delivery graph for different temperature settings.

http://www.chemspider.com/Chemical-Structure.15266.html
Predicted data is generated using the ACD/Labs Percepta Platform - PhysChem Module.
Boiling Point: 390.4±42.0 °C at 760 mmHg
Vapour Pressure: 0.0±0.9 mmHg at 25°C
Enthalpy of Vaporization: 66.5±3.0 kJ/mol

Just to make sure I'm clear, G.O. Joe you are saying the chart GW posted is incorrect because it lists the boiling point of THC delta 9 at atmospheric pressure (760 mmHG) to be 157°C?

Yes, and the 157C is from Cannabis and Cannabis Extracts: Greater Than the Sum of Their Parts? The number is probably what someone got by experiment, but McPartland and Russo or their publisher did not provide the pressure measurement given by their reference, for THC and for many other things.

You're saying it should be 200°C at atmospheric pressure correct?

A nomograph would show it would be way over 200C. The cannabinoids have some volatility at 200C, but the Volcano article shows that there wouldn't be a lot at 157C.

And that there is no way a C21 molecule (THC) would have a lower boiling point than a C10 molecule (myrcene @ 166°C) because of it's molecular size and composition?

Precisely.

G.O. Joe you deserve much more respect here, you've got mine!

Aww shucksies - erm hey I'm just an aging stoner pecking away at a keyboard, alone in a darkened room. Maybe if I made something of myself like all of you out west have, but I'm not "in the business" at all. I'm quite small in comparison to the members here.

Best wishes to all for the holidays and beyond.

 

[JColtrane]

I agree with Skyhighler ... props to you G.O. Joe. Thanks for the homework, I'll report back after I do some reading

 

[gholladay]

Great reply G.O. Joe! These sources are fantastic. Got plenty of reading to do over the holidays now!

Thank you!

 

[Gray Wolf]

As I said it's a long and variable list - not limited to Cannabis-related chemistry articles and patents on file that can be provided - no magic number exists other than a range of temperatures and pressures. Mechoulam's quote was written down because it's very fitting, better than any list, if not a little low temperature for 50 microns in comparison to the Merck Index link's little high 200C at a pressure of 20 microns. So where to start? El-Sohly it is. See examples 3, 4, 7, 22, 26.



Evaluation of a vaporizing device (Volcano®) for the pulmonary administration of tetrahydrocannabinol
Arno Hazekamp; Renee Ruhaak; Lineke Zuurman; Joop van Gerven; Rob Verpoorte
There's a delivery graph for different temperature settings.

http://www.chemspider.com/Chemical-Structure.15266.html
Predicted data is generated using the ACD/Labs Percepta Platform - PhysChem Module.
Boiling Point: 390.4±42.0 °C at 760 mmHg
Vapour Pressure: 0.0±0.9 mmHg at 25°C
Enthalpy of Vaporization: 66.5±3.0 kJ/mol



Yes, and the 157C is from Cannabis and Cannabis Extracts: Greater Than the Sum of Their Parts? The number is probably what someone got by experiment, but McPartland and Russo or their publisher did not provide the pressure measurement given by their reference, for THC and for many other things.



A nomograph would show it would be way over 200C. The cannabinoids have some volatility at 200C, but the Volcano article shows that there wouldn't be a lot at 157C.



Precisely.



Aww shucksies - erm hey I'm just an aging stoner pecking away at a keyboard, alone in a darkened room. Maybe if I made something of myself like all of you out west have, but I'm not "in the business" at all. I'm quite small in comparison to the members here.

Best wishes to all for the holidays and beyond.

Thanks for stirring the pot and the good reads, which suggest several things, one of which is that 157C is not THC's boiling point at zero gauge (atmospheric pressure).

Another question it presents, is the accuracy of the on line calculator, because if I adjust the boiling point for 200C and a heat of vaporization of 66.5, it shows that at 100 microns, that boiling point would be 36C/96.8F.

The Volcano studies, while interesting and chock full of good data, wasn't done under vacuum, but does demonstrate that the THC starts to vaporize significantly below the optimum point for maximizing the production using fractional distillation.

I also note one of the studies gives 200C as a melt point, versus Merck's 200C boiling point.

Lastly, instead of boiling points, I'm thinking we should be talking about vaporization points, as we aren't talking about how to optimize our fractional distillation, but instead how to not vaporize away our coveted target constituents.

They sublimate away before the boiling point is reached, albeit at increasingly slower rate as the temperature drops below it.

As promised, I importuned Dr Kate, and partner Joe for technical support, and Kate says she will research the question, and subject it to peer review before replying.

Joe suggested that I run it by Dr Fischedick, whom did his post doctoral work in cannabis terpenes, soooo I sent him an e-mail to see if he has time to help us in our path to cannabis enlightenment.

More when I hear back, but if any of ya'll brothers and sisters already knows the vapor points of THC and the other terpenes under vacuum, you would forever be in our hearts, if you would share it with us.

 

[Chonkski]

Not sure if mentioning this helps but the parameters for fractionating THC based on successful trials are typically noted as .08-.1mmHG @ 172-180°C

http://google.com/patents/ep1133688a4?cl=en

 

[SkyHighLer]

Not sure if mentioning this helps but the parameters for fractionating THC based on successful trials are typically noted as .08-.1mmHG @ 172-180°C

http://google.com/patents/ep1133688a4?cl=en

Interesting info Chonkski, but they seemed to be getting good results at a lower temp in several of the runs...

"Fractional Distillation:

A portion (30.5 g) of the residue collected above was subjected to fractional distillation under reduced pressure (0.1-0.15mm/Hg) . The temperature was slowly raised to 125°C and the materials collected were kept separate. The temperature was then raised between 140-160°C where the major fraction was collected (14g) . GC analysis showed > 96% THC."
http://google.com/patents/ep1133688a4?cl=en

GW, G.O. Joe

 

[NEGT1]

Is it going to get to a point where it might be more beneficial to scrap all past data and start from scratch using modern instruments and technology and thoery?

 

[Chonkski]

Interesting info Chonkski, but they seemed to be getting good results at a lower temp in several of the runs...

"Fractional Distillation:

A portion (30.5 g) of the residue collected above was subjected to fractional distillation under reduced pressure (0.1-0.15mm/Hg) . The temperature was slowly raised to 125°C and the materials collected were kept separate. The temperature was then raised between 140-160°C where the major fraction was collected (14g) . GC analysis showed > 96% THC."
http://google.com/patents/ep1133688a4?cl=en

GW, G.O. Joe

Yessir! My favorite example is no. 4.

 

[SkyHighLer]

Yessir! My favorite example is no. 4.

They seem to have gone for the deepest vacuum they could get in #4, and got excellent results at the lower temps. My quick thought on this is the final degrees of what we are calling a 'hard vacuum' are important to understand, again I recommend a decent micron meter.

 

[Rickys bong]

I wonder if there's a way to use a combination of different types of vacuum gauges to determine where various things boil off?

I'll try to elaborate... Using a vacuum gauge such as a Pirani gauge with an analog readout you'll see a sort of stepwise change or "jump" in pressure under vacuum as certain things boil off and the pressure drops to the vapor pressure of the next lowest boiling point substance. I'm talking with reference to previous experience vacuum testing high vacuum chambers, I have only started getting some instruments together for vacuum oven experiments.
Pumping down a chamber the vacuum would hold at a few torr while water boiled off, then jump to another level where some other stuff boiled off, then go down in linear fashion to the sub 10 micron (10millitorr) range and lower when everything was gone...

Digital micron gauges don't provide that intuitive feel as to what is happening in a vacuum chamber. Thermal conductivity gauges are gas sensitive, so maybe a pirani gauge in combination with a high accuracy strain gauge like this:https://shop.edwardsvacuum.com/products/d35735000/view.aspx might give reasonable indications of where to keep the vacuum level at for a consistent result without losing terps and of course THC...

Put another way, there should be an optimal pressure range where you'd pull off butane, water and any dewaxing solvent but not start evaporating the good stuff.

Maybe observation in combination with an RGA would provide an optimal pressure to maintain? A high accuracy vacuum strain gauge to readout the pressure and a pirani gauge to give some indication as to what is boiling off?

I can see the possible need for a vacuum controller to maintain the vacuum level at a precise level to get purge times down without losing any appreciable terps or product...

This make sense y'all?

RB

 

[SkyHighLer]

^ RB, "Put another way, there should be an optimal pressure range where you'd pull off butane, water and any dewaxing solvent but not start evaporating the good stuff."

And that's why I once again suggested a micron meter, not for the initial testing to work out ranges, but for anyone that cares to put the new data to practical use. The dial gauges are not going to be adequate, at least not without careful comparison with a micron gauge, like my Yellow Jacket 69075... )

Keep us updated GW