Boiling hexane Soxhlet extraction

Gotta love the Soxhlet rig. It is simple, easy to run and it is exhaustive on the extraction.

I know that a bunch of you do industrial sized runs, and scaling these up is not normally done. Therefore, I assume that small batch runs are its prime forte.

I have a 55/50 size, and it is so small. Every sample is only 15-20 gms, so it does take a while to run a larger quantity.

The nicest thing is the ability to really load up the solvent with extracted oil. The Soxhlet extractor is a reflux setup, so clean fresh solvent is always hitting your sample. Once one sample is exhausted (I usually see this around the 4th or 5th dump), I can replace it with fresh material.

I use a glass thimble in my setup. It is heavy, and could easily break the chamber wall, if dropped. I have tried to minimize this possibility by packing cotton into the chamber. The thimble sits on top of the cotton.

Once you exhaust your sample, and desire to change out the thimble, you have to get it out of the extraction chamber. This has been a small stumbling block…it’s hot in there. I have been using tongs, but it is sketchy, so want to research other choices. How would you remove a hot thimble?

Oh, BTW, a word of warning. When placing a new sample, you might choose to add a small quantity of new solvent directly into the thimble. If your new sample is dry, it will absorb and hold some solvent. The solvent volume in the boiling flask will gradually decrease, if you are using only the reflux to wet your sample. Not a big problem, unless you let the solvent get too low.

Dry material can actually make life easier, by holding solvent that you would otherwise have to remove later. If you pay attention, you can gradually decrease the solvent level in the boiling flask, making post-processing faster.

Recovery of the solvent is possible, via simple distillation.

The extract that I just made is super-terpinated. I am having difficulty getting it to firm up.

Anybody put any thought to drawing a vacuum in a Soxhlet? I have thought about pulling a vacuum through the open end. Has anyone pulled a vacuum in a Soxhlet rig?


I have run numerous vacuum assisted soxhlet extractions, it’s really hard on the glass and often a small bump or vibration will cause breakage, esp on the cheaper glass that most of the decent sized soxhlets 1000-2000ml I have used are made from.

You will need to attach a vac hose to the top of the condenser and also make something called an elbulliator which is simply a capillary tube which sits below the surface level of your solvent in the boiling flask and helps keep boiling constant and prevents bumping.

There is actually a paper from he olden times about vacuum soxhlets that describes how they are made, interesting read

Now you will be pleased to hear that I am currently putting together a parts list for a massive 8x48” Soxhlet extractor made from stainless steel that will fit on top of a jacketed reactor. The design will be easily scaled up or down and be able to function under vac very simply and without worry of glass breakage.

I’m planning on running pentane in mine at atmosphere or only slightly vac assisted as it doesn’t need much help in terms of BP- should make for some very fast extractions- thimbles won’t be swapped so much as the whole material column will be changed out.


These guys are selling a large steel unit, but hot damn what a ripoff on that price- this whole thing can’t cost more than $1000 and it’s a manually drained system which sort of defeats the point

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WOW! $4500 I think that I have most of the pieces shown in their picture. I have been mulling over constructing a stainless one. Maybe the time has come. Would be nice to see a more detailed picture.

Looking at that setup, it is easy to see the hot vapor path, but the spillover is not obvious.

Really not a big deal, as I know how they work. Might set something up soon.


The spillover is manual- the braided steel line at the bottom of the material column has to be switched on and off- dumb- just use a hemispherical bottom with an NPT sideport and work out a siphon tube via stainless steel tubing/compression fittings that drains into the boiler.

The amount of work that it took to charge that much for some triclamp fittings and not figure out a proper siphon tube makes me sad.

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Found this…it looks nice, you can see what’s going on, and it looks really easy to build.


Yes but tinyyy

I wanna be able to do pounds of fresh flowers at a time

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Only $40.50

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Hose barns tho? What hose you runnin with hexane vapors?

I am running a completely glass setup. Yeah, the hoses are sketchy, probably get eaten immediately.

That came from here:

They have a lot of unique pieces. Anyone work with these folks before?

use tygon fuel tubing its made for gasoline hardware store has it its the yellow gasoline line hexane is gasoline lol

Liquid gasoline- not vapor. Assumptions can be dangerous

ive done my best disty with the soxhlet my first thought was fuck i should scale this up out of steel and do a vacuum assist

there is no issue look at the white papers for the tygon

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THTa k you for confirmation

if it can handle the solvent in question at bp temp on material you should be just fine i been dreaming about this for a while lol

Wish List: Would love to see that kit (shown above) with NPT connections. Would be REALLY nice to see it offered in sizes other than 2".


And I want to super size it with this

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cant you get ptfe level 5 flourinated plastic tubing pretty sure thats what a lab would use lol

there is tygon chemical resistant tubing as well

the yellow tygon has a higher temp 160 F it holds its physical properties I’m sure it can go higher would love to see an example extraction done and residual contamination done I have not the time or equipment or I would myself

I can get this made in any size

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Can you go thru your process here? Would love some data