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Author: Subject: Piperine extraction question
LearnedAmateur
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[*] posted on 18-7-2017 at 05:56
Piperine extraction question


First off, sorry if this is in the wrong forum but it is organic chemistry after all.

I'm currently attempting a small scale isolation of piperine from black pepper, and I'm using toluene as the solvent as opposed to the more conventional ethanol/isopropyl extraction. I have not been able to find any useful information regarding this procedure, so for me it is experimental.

Previously, I had the combined solutions of three extractions. In the first image, to the left is the remainder of the decanted extract which is the appropriate colour from references I have found, and on the right, the extract which has been filtered through a Zeolite bed. The Zeolite, initially grey, has become a dark red/brown (image 2). What perplexes me is that the solution is green, even after a thorough shaking with room temp, dilute NaOH to remove fats - the toluene solution definitely has peppery hints to it indicitave of piperine. In the third image, a separatory funnel holds the processed toluene solution which has taken on an opaque character but is more yellow than the filtered extract; that's the stage I am at right now. Anyone have any ideas on what is going on?

Additional information: I am going to distil the toluene to concentrate the solution and then redissolve in ethanol for recrystallisation once my bottle arrives (that's the main reason why I used toluene initially, as it is the only non-polar solvent I have on hand).





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[*] posted on 20-7-2017 at 08:34


Piperine is insoluble in water, and if any gets in some may precipetate. I would use potash for the fat removal rather than NaOH. Did you distill right after the extraction?
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clearly_not_atara
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[*] posted on 20-7-2017 at 11:50


Aye, and if it crashed out it could form a cloudy suspension like you're seeing. It should be possible to dry the toluene over a salt (Na2CO3 is easily made by heating baking soda if nothing else) and heat it to redissolve the piperine, but it probably doesn't matter.

The yellowishness could be from lipophilic impurities not present in ethanol extracts. Recrystallization should take care of it

[Edited on 20-7-2017 by clearly_not_atara]
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[*] posted on 21-7-2017 at 04:53


@Booze: There shouldn't be any water, that's why I used the Zeolite so that it would remove any present in the pepper - I was under the impression that toluene and water were completely immiscible, unlike alcohols. Also, NaOH seems to work fine, I managed to collect a brown, gelatinous precipitate that is less dense than water but more dense than toluene. I haven't distilled it down yet so that is the initial amount of toluene I used for the extractions.

@clearly_not_atara: It hasn't crashed out, I checked the separatory funnel today and it still looks exactly the same as the image I posted. I believe it may be an emulsion of sorts, but I have doubts because it was a clean initial extraction. I would've thought that the yellow would be due to piperine, the surprising result of the extraction is in fact the green colour that appeared during filtration - it reminds me of Fe(II)/Ni(II) solutions!

I will condense the solution and proceed using ethanol when I get the chance, then make another post.


[Edited on 21-7-2017 by LearnedAmateur]
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[*] posted on 21-7-2017 at 06:36


Just performed the distillation, opaqueness immediately disappeared with the addition of mild heat (and the CaCO3 boiling chips may have had an effect?). Remaining ~5-10mL solution is a beautiful emerald green with no hint of yellow, but the smell of piperine overpowers the toluene odour.

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[*] posted on 21-7-2017 at 07:10


There you go--now onto separation and crystallization!

I am planning on doing this shortly with a new Soxhlet I purchased recently. I bought a bunch of white peppercorn powder, and am concerned about how well the solvent will be able to move through it. I was thinking about possibly mixing the powder with a finer mesh SiO2 to keep it from getting too packed together and hopefully help with transfer of the solvent once the siphon action begins.

Any thoughts?




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[*] posted on 21-7-2017 at 11:00


I figured that the extraction would still be fine, just have to follow the smell of pepper. I was just taken aback by what happened but that's amateur chemistry for you.

I've never used a Soxhlet before (I don't mind distilling solvent manually so I'd rather not fork out the money) so I honestly don't know from experience, but I have read about this extraction and it's recommended to use crushed peppercorns as opposed to the powder. Albeit, it'll be fine with just the pepper powder, just use a tad more solvent when you think you've got enough and maybe run the extraction for a little longer to purge the last of the solubles. From what I've read, white pepper has a slightly higher concentration of piperine to black pepper anyway so I wouldn't be too fussed about yields, especially considering that it's not the most expensive source and you can extract over a gram of piperine for every ounce of pepper.
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[*] posted on 4-8-2017 at 01:22
piperine


Use an extraction thimble to contain the ground spice in the Soxhlet chamber.
Use a Nitrogen bleed to reduce explosion hazard.
Highly flammable Diethyl ether or acetone give best extraction of oleoresin.Toluene is toxic.
Cheap Dipentene, +/- Limonene should work.(not tested).
Oleoresin contains 5 to 10% Piperine. Recrystalise to Mpt.129° to 130°.
Use vacuum with Nitrogen bleed to remove solvent.
Don't distill to dryness. Peroxides from solvent can detonate. Blow off residual solvent with dry Nitrogen.
Chavicine is the Piperine isomer and is the more pungent principle of black pepper. Combined principles, piperidides, of pepper oleoresin likely to be 25 to 50%. Piperittine, a homologue of Piperine is also extracted. This is almost insoluble in acids or alkalies. Mpt. 146°. ref Die Atherischen Ole, Gildermeister und Hoffmann (1929). The essential Oils , Guenther (1948).
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[*] posted on 4-8-2017 at 08:58


Don't use an inert gas "bleed" (i.e. sparge) during extraction. You can push out your solvent very easily.

Instead, lay a blanket of inert gas on top of the extractor.

If you have a standard Soxhlet, fit a stopper to the top of the condenser, with a "T" tube. one side of the tube to the gas source, the other to a slow bubbler, to maintain positive pressure.

Don't run a bleed tube to bubble into your boiling flask.
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[*] posted on 4-8-2017 at 10:37


Nitrogen bleed into the boiler also ameliorates bumping and helps to seed the boil. Assuming that the condenser and traps are efficient then solvent venting minimal.
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[*] posted on 19-9-2017 at 09:05


Quote: Originally posted by XV750SE  
Piperittine, a homologue of Piperine is also extracted. This is almost insoluble in acids or alkalies.


Interesting. I was playing around with an iPrOH piperine solution and introduced a small amount of sulphuric acid - bearing in mind that it most probably contains other alkaloids and negligible oleoresin (under the assumption it is responsible for the green extract colour). An off-white, fluffy precipitate formed immediately; I wonder if this is the piperittine?

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[*] posted on 19-9-2017 at 13:01


Quote: Originally posted by LearnedAmateur  
Quote: Originally posted by XV750SE  
Piperittine, a homologue of Piperine is also extracted. This is almost insoluble in acids or alkalies.


Interesting. I was playing around with an iPrOH piperine solution and introduced a small amount of sulphuric acid - bearing in mind that it most probably contains other alkaloids and negligible oleoresin (under the assumption it is responsible for the green extract colour). An off-white, fluffy precipitate formed immediately; I wonder if this is the piperittine?


Where do you think the piperittine is coming from? Is it a constituent of the extract?

Perhaps you hydrolyzed the piperine?




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