Looking to Use A Roto to Isolate the Individual Terpenes As Best I can From A BHO Derived HTE Any Suggestions on Moding the Roto for this? Any Help is much appreciated.
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You could add a gradient of cold traps along with more and deeper vacuum that is controllable. I’ve made a roto into a freeze dryer like this
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If you know the ultimate vac of your system you could set two condensers for your roto.
Set one of them at a temperature too high for your ethanol to condense at and you will get some degree of separation. The terpenes will undoubtedly condense before ethanol will.
Separation by fractional condensation rather than just fractional distillation. This is what the petrochemical industry does to separate petroleum distillates into their respective products of a given boiling point range, so it is effective.
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Would just have to mske sure the vapor has a decent amount of surface area for condensation before reaching the second condenser where ethanol is condensed for reuse.
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you could probably daisy chain a couple of the finger style cold traps, I don’t think you need the style that gets ran with SPDs commonly
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It will take some trial and error for sure. Having a rotovap with an integrated vacuum controller will definitely help. Some of the more advanced models have programmable distillation as well as vapor temperature logging to help you find that sweet spot.
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Now that I re read the original post, you’re not going to be able to isolate individual terpenes from one another all that effectively using this method.
I don’t think fractional distillation/condensation will get you the kind of separation you’re looking for.
At best you’ll end up with a fraction of monoterpenes, a fraction of diterpenes, and so on. Separating these fractions further wouldn’t be easy either because all the terpenes are so much like each other they will co distill along with whatever your targeting.
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I see botanically derived terpenes that are isolated such as a-pinene. How are they doing this?
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Chromatography? 
The process will be the same for more or less any natural source. Distill off then separate via chromatography of some sort. Some of the simpler terpenes can be synthesized without crazy chirality issues.
For the OP, you can run a LN cold trap after the condenser and get them like this:
Or a cold finger as the condenser with a high vacuum and very low bath temp. You’ll need to pull the finger and either scrap it or melt off the terpenes before raising the bath temp to start your ethanol recovery.
If you really need to separate them into individual terpenes then my guess is that a column with diethyl ether or maybe even dimethyl ether would be your next step. DME will have to be run cold but it will be much easier to purge afterwards.
Sounds like a shitload of trouble to go through. Most of the terpenes are available in bulk for chump change. Unless you are required to use cannabis derived terpenes, you will never be cost effective doing this.
-Eskander
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Rather through extraction from simpler matrices, and synthesis/semisynthesis.
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Use an spd not a roto
Better vacuum, better Cold trapping power
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Actually, I take that back. I remembered the monoterpenes with much lower boiling points than they actually have. King is right. You are way better off doing this in SPD.
-Eskander
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If you can, have your heating flaks be in some sort of heat fluid instead of a mantle. The reason is your mantles heating fibers are at a much higher temperature than what the probe value states and the edges of your flask are much hotter than the center of the flask. Terpenes are very delicate and you really can’t be too paranoid; nobody likes terps that smell like fish oil!
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