Hey all, I’ll try and keep this short,
I recently ran into an issue that has been perplexing me and I can’t seem to find any specific answers to my burning question… why did all my cannabinoids either disappear or isomerize? Both my CO2 distillate and ethanol distillate have gone the way of D-8-THC after distillation and I have scoured my notes and am unable to pinpoint the culprit. I have also pH tested our crude oil, ethanol, and filter aides in a solution of both ethanol and ethanol/water and neither are too overly acidic (nothing lower than 6.5, nothing higher than 7.5). My general process is extraction with either CO2 or ethanol (ethanol being minimum of -25degC), filter through a properly set bed of DE(bottom)/T5(middle)/AC(top) all on top of a 20-micron filter paper and 5-micron sintered disc, winterize/filter out waxes (as many times as needed), degum, filter, decarb, short path distillation (1st pass), short path distillation (2nd pass). I winterize as well between first and second pass distillation.
I’ve uploaded our test results as well. (Test Results circa 29Aug19.pdf (228.7 KB) ) The first set of results showed our cannabinoids at 80%. This was all from ethanol crude and was 3 test runs at different parameters. Once we felt like our vacuum was good enough we realized we needed to add other filtering aides and clean up processes between extraction and distillation. We did a few experiments with our crude putting it through AC scrubs (~55degC, approx 20 to 30% by weight) but ended on adding AC to the filter bed (as mentioned above, gave similar results in post processing and was less time consuming). The second and third block of tests are a much larger amount of ethanol-extracted and CO2 extracted distillate, respectively. I have also reached out to the lab that sent me the original results and had them both retested and showed the results were accurate.
I am aware that CO2 extraction can pull plant acids/create carbonic acid, some filtering aides have acidic properties, etc, but as I said I tested the pH of all combinations I could think of and didn’t find anything that was glaringly obvious.
This forum has been amazing at giving me a plethora of information to apply to my process and I wanted to reach out to all the great minds and see if anyone could help me figure out what i’m missing or where I went wrong. My apologies for the long intro, and thank you in advance for the help.
It might be helpful to describe distillation parameters, its almost certainly too hot for too long.
Well they did vary as I figured it out as we all do when learning but overall seemed to get better, especially the runs that happened after the 3 that make up the first test results (imo). The first three runs stated on that first batch of testing results were as high as 240degC (boiling flask) while collecting cannabinoids for 4 or 5 hours, maybe longer, then above that to about 260 for the tails. Once I was able to get a handle on my vacuum after realizing how high it was (probably 1800-2000+ microns) and getting better temp guages, a vac gauge, and scouring this site for better techniques, that changed to getting cannabinoids off between 2 to 3 hrs and at 170degC to 220degC temp in the boiling flask and never above 800 microns of vacuum (most of the time it was below 200 microns).
Too high of temp, try around 110-125c for same times.
This has been discussed quite a few times. It’s pretty likely that your current filtration method isnt removing all the solid particles from the solution and the remaining T5/AC is catalyzing isomerization reactions.
I admit that’s a possibility at least to a degree but the amount of isomerization stumps me. We did spend a lot of time learning to set the bed and washing it with ethanol multiple times to make sure nothing was coming through and discarding that ethanol/not mixing it back in. There would need to be quite a significant amount of T5/AC coming through to cause that much degradation from what I’ve read. A tiny amount wouldn’t cause this amount of degradation is what i’m stuck on. Some people have put 30% by weight T-41 into the BF itself during distillation and not come close to this amount of isomerization.
Thats a good point, do you decarb your extract before putting it in the boiling flask?
Yes we do. We have a hotplate we decarb on. We follow similar protocol as many other people: pull the ethanol off in a rotovap, remaining ethanol out on hotplate, then raise temp to decarb. Spin bar constantly going.
Your test results seem to indicate that you’re effectively decarbing your crude, so your isomerization issue is probably not due to the formation of carbonic acid.
How large is your spd?
Add t-5 & bentonite to help with isomerization in bf
What effect does that have? @Cheebachiefextracts
@SpiralOut_KeepGoing are you allowed to use hydrocarbons where you’re at?
WIll improve reaction time & need for thicker layer of filtration. Should be able to pull through on a 20 micron & ac with silica patty nicely. Water circulation pump assist into conical. 
Hes trying to stop isomerization not catalyze it. Inthought adding t5 to the bf will just produce more d8.
Our SPD is a 10L chinese setup. We’ve put a lot of work into it to make it seal up tight and work properly (changed hosing, etc.etc.etc.) and because of the larger amount I know our residency time is higher but we did get great results from the first few runs on it and our vacuum wasn’t even all that great.
What vacuum depth is your system able to reach when the flask is empty?
When the flask is empty i’m getting below 100. Some runs are tighter than others, but it’s a big system. I would say lately I am below 200 microns during the run 90% of the time and never over 400 during the body pull.
How many cfm are you pulling with? And do you have a cow adapter after your condenser or do you have one of those nifty collection flask isolators?
We have a cow adapter currently. Our vacuum pump pulls 14.6 CFM. Adixen 2021SD.
Do you use a Chinese mantle as well? If so, does it have two thermometers that it gathers data with or just one?
Now I’m thinking your problem is related to excessive heat being applied to your flask. You’re vac depths are fine but your pump is drastically undersized for your system in terms of displacement.
You should upsize your pump setup and shoot for 4-8 CFM per liter of capacity in your boiling flask.
How are your distillation speeds?