Boiling Point of THC


You should see his vids!

I feel like F4200 owes @Beaker a high speed camera :exploding_head:


If you don’t mind me asking, where’d you find reliable terpene boiling temps to plug into the Clausius Clapyron equation to develop your terpene stripping protocols? The only comprehensive list I’ve found so far is that listed in the McPartland & Russo paper, which doesn’t seem to be super reliable since the data they present for THC and CBD are seemingly inaccurate when compared to other studies such as the previously cited paper by Lovestead and Bruno (2017).

Since there are terpenes that are both more and less volatile than CBD, I’d like to create or acquire a comprehensive list of terpene boiling temps so that, if the terpene profile can be obtained for the starting material, I can modulate the distillation temperature to acquire a more pure product by excluding various terpenes. In practice then if the material had more volatile terpenes than I could dispose of them by doing a first pass at lower temperatures, and if the material had less volatile terpenes (than CBD) I could just keep the temperature lower to avoid the less volatile terpenes.
I want this information because, as has been pointed out here, every batch of starting material will constitute a new mixture of compounds and will consequently have slightly differing boiling points for each compound since mixtures have different boiling points than pure compounds, and thus the temperature at which CBD is distilled is more of a range than a static number. My line of thinking is that if I know where the terpenes boiling points lie in relation to CBD and I know which terpenes are predominant in the plant, I can adjust the temperature during distillation to try to acquire a clearer and ideally purer product in real time.

If anyone has a comprehensive list or any comments on the line of thought I divulged above and it’s practicality, or if anyone has tips for obtaining high purity CBD distillate in general I’m all ears and greatly appreciate any assistance!


It was a long time ago but I used Google which led me to places such as the NIST webbook and other similar sites.


Perhaps the most practical approach for you would be to acquire purified quantities of all the terpenes you would normally expect to encounter. Then as a suggestion, I would distill each one in turn and record the results. Then I would mix them together in a few different ratios and try again to reveal any azeotropic behavior.

The advantage of observing the information yourself is that you do not need an iPad, internet, or a Google (Grandma would have washed my mouth out with soap if I had told her I Googled a friend…) to find out anything. The advantage of course here is that the boiling point you will record will be unique to your own set up. By this I mean that I could tell you personally exactly when the terps boil and at precisely which pressures AND precisely how to read the pressure and NOT the temp to determine presence of terpenes in the boiling puddle but the information would be unique to my own rig and to the placement therefor of the measuring devices (thermometer or thermocouple, and Pirani based vacuum sensor) that I use.

Using a technical paper written at some prior time to attempt to predict behavior pales in comparison to this simple test and then you have accurate real world numbers based on your own rig. Many of these technical source I have seen have info that seems great in theory but then again everyone has a theory about just about everything. (For example, I have a theory that Pluto is a planet… my proof? I have multiple textbooks still from childhood written by well respected Phd types that say so…)

I can also tell you that terps can easily be removed prior to boiling anything and have posted recently how to do this after repeating the experiment multiple times and grinding through a series of counter current seperation labs. Trust me those labs are TEDIOUS to do manually lolz but the information is golden.

So the information you seek in terms of these references you cited is actually probably the most unreliable information you could find if you compare it to personal observation. The beauty of post prohibition lack of information is we get to be pioneers for the kids born in 100 years. We are the ones who need to do these experiments now and publish accurate information in our own time so those who follow can build upon it for the good of everyone. We can pay forward our debt we owe to those who came before and built before at great effort and expense what we enjoy now for free.

Semper Fi


Ah, this is a wonderful suggestion! Thank you, I like your style!



some of your videos don’t seem to be working. :confused:


I have a 2lt short path and need some help with THC temps on the head, my vacuum is pulling at 850 microns?


Where are you measuring vacuum at ? If it’s at the head 850mic, you should be popping below 200°C mantle and 160-175°C head


Between the cold trap and the vacuum pump. If I leave the fraction to finish off at around 175-180°C then that should be the end of the THC fraction.


If it’s first pass, I’d take it all the way up to 185°C in the head and when you start to see the temps drop, slowly increase mantle temps by 1-2 degrees until you reach approx 225°C on the mantle. This will ensure you pull out most of the cannabinoids from your crude. Now for second pass, you can tighten up the tollerences as you see fit


Thank you, much appreciated.


What brand of pump are You using ?
What size of pump
Wich model ?
Because 850 is a high valeu for distillation
Might be something wrong


I have a 5cfm Refcenter 2 stage vacuum pump, I also change the oil for each run.
850 microns has been the best vacuum pressure I have been able to achieve thus far.


My second pass fractions:
Second fraction: mantel 200℃, head temp starting at 160℃ ending at 175℃ at 350 to 400 microns vacuum pressure.
Third Fraction: mantel 210℃, head temp starting at 176℃ ending at 190℃ at 350 to 400 microns vacuum pressure.


Sounds like you either have a lot of terps/gas load or a leaky system. If you’re using a mechanical pump, what is it’s CFM? Have you changed the oil recently? A bit of troubleshooting is in order.


I have 5cfm pump and I do change the oil before each run, leaky system is a concern with glass I purchased locally from South Africa and recently changed my fraction head and local grease to Dow grease, this has improved vacuum pressure to 400 to 350 microns but would love to get down to 5 microns, hopefully soon I can afford top class equipment.


I would recommend upgrading to at leasta 14CFM rotary vane pump, a 10CFM dry scroll pump, or something higher such as a 21 CFM Edwards E2M28 or Edwards 30.


Thank you, that will be my first priority.


That high a cfm pumps for a 2 liter SPD setup ?