Hello All,
I am currently doing my first benchtop CBD isolate run. I dissolved 2g CBD distillate (~83%) in 4g Pentane. I heat to dissolve then left at room temperature for 1 hour, 5c for 1 hour, seeded the solution with isolate and -20c for 2 hours. The whole solution seems to have crystallized. I am going to leave it in the freezer longer, but do I resuspend in cold pentane to be able to filter out the CBD solute?
Thanks,
That will work, but a better way would be to put it in a centrifuge.
Or just allow it to slowly evaporate. When u cold crash how are u doing it.
Setting it in a freezer or setting it on dry ice?
Put the isolate in a funnel with a filter. Than wash with cold pentane till white and fluffy.
Also it seems you added a bit too much pentane. Try doing a 1:3 pentane to distillate ratio. So you would need 2/3g pentane: 2g disty.
My bench top isolate sop is:
Dissolve the disty 1:2 in pentane. Stir like hell and dissolve it all. Let it sit lightly covered at room temp for 24 hours. The next day put it in the freezer at -20f and wait another 24 hours. The next day u should have a nice puck of isolate att the bottom of the jar
I am putting it in a freezer. Wouldn’t the clumping mean I have impurities in it? How do I filter that out?
So I wouldn’t necessarily see the CBD isolate sink to the bottom and have a liquid pentane layer? Re-suspending and washing will get rid of the trapped impurities, correct? I am going to leave it to continue freezing for a while.
Right now its like a slurry.
You could just get fresh pentane cold in the freezer and use that to rinse the liquid fraction off the stuff that has crystallized like Adam said. Some of the CBD crystal will dissolve but you will rinse off the colored portion.
Next time to get a better result cold crashing it helps to crystallize in a container that has a high aspect ratio. As an example you will get better separation between the crystal and liquid fractions in a test tube than in a beaker if you were chilling them on dry ice.
What’s really important with this scenario is the presence of a massive temperature differential between one end of the solution/container and the other end. This forces anything thats trying to crash into the bottom of the container where the dry ice is.
When you take the container off the dry ice and allow it to come back to room temp and build up pressure, whatever moved into the bottom of the container (THC or CBD) doesn’t just rehomogenize with the solution when it gets warm. The bottom zone is now going to be where large diamonds start to form when you allow the solvent to begin to evaporate.
You guys are really suggesting to bring Cbd isolate down to dry ice temps?
Please don’t do this unless you like lower purity isolate with trapped impurities. The only thing that should be that cold is your washing solvent.
Also if you can find a way to continue to stir while it’s cooling do that and you will prevent getting a large chunk that needs broken up/pulverized.
Crash cooling 
I am cooling slowly with the final product going into the freezer. I added more cold pentane and now I have proper separation. The mixture is still in the freezer but I am getting a lot of large white crystals which I’m happy to see. This was only a trial to see what I can do!
2g distillate and 4g pentane?
Yeah I don’t think you can fast crash at that scale. Powder isolate becomes like wet sand. Meaning the powder will clump exactly like you explained. That is like making boxed mashed potatoes. It is just a volume issue at that size.
Ideally with powdered isolate, you want to maintain a slurry for as long as possible so that mother liquor separates easily.
Looks normal to me. this is what it will usually look like without agitation during precipitation.
How can you expect the crystals to form small when they are all settling down to the same place of nucleation?
Agitation will cause a lot of nucleation points and it will continually break up the formations into smaller nucleation points thus making a lot more small formations and less clumps.
This was after adding additional pentane. Originally the whole solution crystallized and there was zero separation. Once I add extra pentane then everything fell out of solution. Next time I will calculate the ratio bases on the expected amount of CBD in the distillate. I believe my distillate was too high purity that there was not enough solvent in the mixture.
Does anyone have information on pentane; temp vs solubility graphs? Trying to determine what temp exactly will CBD crash out of solution.
Check this link out. It has some pretty sold instructions: How to Crystallize CBD - Make CBD Isolate (brinstrument.com)
Seen this already, great read. I’ve already made isolate I am just looking deeper into the chemistry of it and wondering at what temp does pentane become more polar that it releases the CBD.
In that article they state 5c itll start but suggest going down to -10c. At 5c is pentane falling out of solution? At -10c what else might be falling out of solution which will effect purity?
Somewhere in the 5-10 C range seems to be where the majority happens.
The crystallization seems to be exothermic. Watch the temp of your solution. It will go down, up, down. As long as your chiller isn’t completely over powering it.
I don’t think going super cold is a good idea. Below -20 C, the solution can get goopy or the contaminants oil out. This is a problem especially with waxy material. Going very cold forces you to then make it more dilute.
Appreciate it! Are you blanketing your reactor with nitrogen?
