Sciencemadness Discussion Board

Soxhlet uses for extracting compounds?

Fyndium - 17-8-2020 at 05:57

I was wondering if soxhlet could be used in some ordinary chemistry applications except extracting compounds from vegetables? For example, it would allow to dissolve compounds with very small volume of solvent and it will recrystallize directly in the flask?

Fery - 17-8-2020 at 10:58

https://www.sciencemadness.org/whisper/viewthread.php?tid=15...

macckone - 17-8-2020 at 11:36

It can be used to separate a low yielding product from all manner of crud.
or to squeeze the last bit of yield out of a horrible sludge.
Extracting from precipitates is a primary example.

chemist1243 - 15-10-2020 at 07:47

Quote: Originally posted by Fyndium  
I was wondering if soxhlet could be used in some ordinary chemistry applications except extracting compounds from vegetables? For example, it would allow to dissolve compounds with very small volume of solvent and it will recrystallize directly in the flask?


Yes, thats pretty much the basic idea of a soxhlet extraction - use as little solvent as possible to extract as much as possible. Weather something crystallizes out on cooling depends on how much solvent you used and how much solute is in solution. Just make sure you use fresh glass wear on any food related projects, not glasswear that has already had chemicals on it.

unionised - 16-10-2020 at 05:41

This is the "calassic" use of a soxhlet as a way to force a reaction.

https://www.prepchem.com/synthesis-of-diacetone-alcohol/

TriiodideFrog - 16-10-2020 at 05:50

I used a soxhlet to extract piperine from black pepper and capsaicin from chilli peppers. I like to use the soxhlet as it is quite effective and also reduces the use of solvent. I have also seen others extract many compounds using the soxhlet extractor, so I think it will work for you.

unionised - 16-10-2020 at 06:35

Quote: Originally posted by Fyndium  
... except extracting compounds from vegetables?


Quote: Originally posted by TriiodideFrog  
I used a soxhlet to extract piperine from black pepper and capsaicin from chilli peppers.



OK, technically that is extracting compounds from fruits, rather than vegetables but... I don't think it's what the OP had in mind.

Fyndium - 16-10-2020 at 07:52

Basically something alongside a situation where there is a compound that has very low (0.1-1g/100mL) solubility and it needs to be recrystallized or purified from other stuff that has either nil or high solubility. So during long run, the fresh solvent leaches out little by little of the stuff, and it collects in the boiling flask.

It would in theory allow to recrystallize stuff from very small amount in relation to solubility, and the temp curve doesn't matter in such way because the solution will be anyways oversaturated within moments. Naturally, it would require that the substance withstands the temp of boiling solvent.

Fyndium - 21-1-2021 at 13:01

I had a wild thought if acetone(or other) could be used to extract urea from ammonium nitrate with soxhlet? This same could be turned upside down in order to remove the AN or other nitrate with a solvent where the other impurities are scarcely or nil soluble. A water bath to heat the solvent would of course be used, in order to not create any hotspots.

Nurdrage video also had clips of his produced cyanide - how terrible idea would it be to puify the cyanide with methanol extraction? With effective scrubbing and negative pressure fume hood it shouldn't pose excessive risk, if it does the job. I have the year-old batch of presumed NaCN stored away, and if this could in theory work, I could give it a hit.

Boffis - 23-1-2021 at 07:10

I have just run a soxhlet extraction of old dark green benzoquinone. I discovered something I hadn't thought about before in this context. I was following a procedure given in Woodward et al's classic 1958 paper on the total synthesis of reserpine. In their procedure they purify benzoquinone by soxhlet extraction of the crude material with octane (Bp c 125-128 C) so as not to introduce water (as would be the case if it were steam distilled). I didn't have any octane so I used 99% n-heptane (Bp 97) The extraction started out really well but then benzoquinone began to build up in the condenser because even at 97 C benzoquinone is very volatile. If anyone else ever tries this I would recommend going for cyclohexane or pet. ether Bp range 60-80 or even 40-60 C. I will not completely solve the problem but should reduce it.

Fyndium - 23-1-2021 at 09:43

I would be counter-productive to attempt to purify higly volatile materials like that. They'd just reflux along with the solvent forever, participating in the cycle.

Why ether is not used more, as it's very volatile and dissolves well? Using good condenser and airlock (like I do for acetone) will prevent fumes.

Btw, I should give a try for the cyanide purification. Shouldn't lose anything, and get pure(as pure as it is with co-dissolvents) NaCN with minimal amount of methanol.

TheMrbunGee - 23-1-2021 at 10:42

Just a friendly reminder that pressure equalizing addition funnel + condenser on top = soxhlet extractor.