I started out in distillation with next to no training, I had no idea instagram had so much info and so many people conversing on the subjects. The same goes for co2 extraction which was my previous role in the industry before SPD. So I worked many many ideas over on just running a short path efficiently to go from sludge to gold in 2 passes or less. I knew three passes caused serious amounts of degradation for me based on testing so I knew it needed to be done in less runs.
Because of this I’ve mever really gotten up to speed using preprocessing methods. The only one I really spent time on was carbon scrubs in etoh or ISO. I wrote a small article of the use of an ultrasonic bath to help speed up the process of mixing and filtering through the carbon in the solution.
For any material these days if it isn’t ethanol wash or acetone wash… I don’t bother with preprocessing. I use condenser techniques and very low vac depth techniques to removes unwanted fractions.
On first pass my apparatus typically is very long and efficient with cooling capacities. The reason for this is I typically will ramp up the temp and stir bar very quickly to 150C and then slowly work my way closer to the heavier fractions. As I do this I can soak a pump very quickly with solvents and volatiles… so the longer the chain the better.
My chain of pieces usually goes:
Boiling flask
Head
3 way adapter 105 bend (also know as a Head) used to capture the main body in a rotational section attached to the end of the actual head
Liebig condenser (or similar)
3 way adapter 75 bend (receiving via the side port.)
Dewar cold trap (or HE Friedrich currently)
Second dewar cold trap,
And sometimes 3rd dewar cold trap.
The temperatures of the Liebig and any condensers beyond that is set to the lowest temp my chiller will go… which is typically -23C
The head condenser I either keep at the same temp as my boiling flask as I scale or just below it.
When I reach my heads fraction I immediately slow down the process, I preset the BF temp 5C below current, turn down my stir bar and begin bringing up my head condenser temp to 155C. Once I am at about 135C on the condenser or more I allow the heads to start leaving the column. I do this by increasing my stir bar speed. Stir bar speed can purify a fraction ascending and give and extra umph behind the fraction to allow it to exit the port. I’ll typically set my Liebig to 10C at this point.
Typically I’ll watch for the haziness in the head and condenser to change. As well as at 155C not much of the heads should be condensing in the head condenser. It should be really condensings after the condenser and dripping into the Liebig.
I allow this fraction to continue until I see an appreciable amount of clear building in the head condenser at these temps. Then I will spin down the main body receiving flask andbump up my boiling flask temp so that I push faster through the head condenser.
There are a few tricks to the head being this hot. Pushing heads past the drop off is not easy to nail down the proper proceedure because it’s different every time. Sometimes I lower the head condenser temp because I’m seeing main body recondense on the other side, other times I bump the boiling flask temp or stir bar up more to speed it up so that the heads makes it to the other side of the boiling flask… and sometimes but rarely, I go above 155C to push junk across.
If you run so fast that 155C is too hot and main body is making it into the Liebig… then turn down the temp. But for the ultimate separation. 155C should be used and aiming at proper fraction removal prior to main body is important.
Second pass is similar but much smaller and quicker.
Setup is as follows:
Boiling flask
Head
Drop down 3 way
Liebig
Vertical 3 way
Dewar cold trap
Pump.
The reason for this is that if the first hot condenser was done right… there are no volatiles and the material already has a consistency that’s like glass to the touch.
… but I’ve never found first pass satisfactory to me… so I do a second pass
I start by evacuating the entire system. I turn nothing on except the pump. I check all fittings to make sure they’re perfect with no leaks.
Then I walk away for an hour.
When I come back the vac is usually below 4 micron.
I then begin scaling temps and get the stir bar going as fast as possible as soon as possible. When I reach 140C on the Bf… I slow down my ramp up. Set my condenser to 155C and pull a very very tight heads fraction, typically it’s green for me. I allow this to collect and slowly drag out off the Summit key. Then when it’s completely I’ll go for main body. I again aim for any heads to make it past but I never turn my head condenser temp down on this run. I aim for the speed and temp that gets just the main body to fall. You can tell based on the color and clarity of what makes it to the liebig. When I know the heads are completely done, like ultra positive, I’ll drop the head condenser to 100C and push a bit harder on the BF temp. To capture main body quickly.
As I reach tails (I can tell based on captured quantity) I start to lower my bf temp to starve off the tails as long as possible. If you do this long enough and precise enough the boiling flask will turn yellow and there may only be 50ml in there. But it’s a pain. So typically I end it sooner and capture tails.
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