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womble
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I was looking at the procedure listed in teh patents listed by Nicodem in the toluene to benzaldehyde through the overoxidisation of toluene to
benzoic acid then the formylation of the carboxylic acid over a solid catalyst. I began to wonder. Could a solid catalyst be made utilising MnO2 or
Cr2O3 using the same (or a similar) procedure?
If so, could the toluene/piperic acid be refluxed with an aqueous phase containing sodium bisulfite, with the reflux condenser taking the reformed
liquid through a chamber containing the oxidant? This would take the liquid into contact with the solid oxidant, for a limited period, after which it
would go back into the vessel containing the aqueous phase. The formed ?-aldehyde would form the addition product while any oxidant entering into the
lower pot would be neutralised by the bisulfite and prevented from further oxidising anything. The fact that the oxidisation would be completely
controllable and the oxidised product would be prevented, by virtue of it being a non-volatile addition product & precipitate, from further
oxidisation should ensure that the overoxidisation could be avoided.
I realise that this has not been suggested previously, and I do not presume to suggest that this is correct, however, I cannot see any reason why it
wouldn't work? Can somebody with actual knowledge please advise on the feasibility of this proposed route?
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womble
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is the structure of piperic acid as it appears to be, namely a MD-phenylacetic acid? (I AM guessing, I have been unable to find a structure diagram
for it). If so, why would you want to take it back to MD-Benzaldehyde? If however it is more similar to a phenacetaldehyde, that is different.
However, the patents for MD-mandelic acid to piperonal state that it can be done with either heat or with sulphuric acid or by the use of 1:2/3
(MD-Mandelic Acid:Nitric Acid) with a 1.5-2 x excess of hydrochloric acid.
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stoichiometric_steve
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| Quote: | Originally posted by womble
If so, could the toluene/piperic acid be refluxed with an aqueous phase containing sodium bisulfite, with the reflux condenser taking the reformed
liquid through a chamber containing the oxidant? This would take the liquid into contact with the solid oxidant, for a limited period, after which it
would go back into the vessel containing the aqueous phase. The formed ?-aldehyde would form the addition product while any oxidant entering into the
lower pot would be neutralised by the bisulfite and prevented from further oxidising anything. The fact that the oxidisation would be completely
controllable and the oxidised product would be prevented, by virtue of it being a non-volatile addition product & precipitate, from further
oxidisation should ensure that the overoxidisation could be avoided.
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piperic acid would possibly react with sodium bisulfite to form a salt, making it non-volatile. if you are refluxing toluene with piperic acid,
everything that will boil off and condense is - toluene.
i think you would just get a complete mess.
in Houben-Weyl's homework part, it says that Br2 + piperic acid -> tetrabromopiperic acid which yields piperonal on addition to dilute NaOH.
you could do that by purchasing a bromide salt, oxidising it with H2O2, and running the reaction in a 2phasic system. preferrably some ester like
EtOAc.
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womble
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Piperic (piperinic) acid is oxidised to piperonal etc. ok, fine.
The following patent deals with the oxidisation of a methylene-dioxy-phenyl-carboxylic (or di-carboxylic) acid (3,4 methylene-dioxy-mandelic acid)
to piperonal. It uses Nitric Acid to achieve this:
http://www.patentstorm.us/patents/6686482-claims.html
I am aware that it is a completely different molecule, however, why won’t it work for piperic acid?
Specifically, why can nitric acid oxidise a phenyl-glyoxylic acid and not a phenyl-carboxylic (or di-carboxylic) acid?
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stoichiometric_steve
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| Quote: | Originally posted by womble
I am aware that it is a completely different molecule, however, why won’t it work for piperic acid? |
you said it - because it is a completely different molecule.
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not_important
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| Quote: | Originally posted by stoichiometric_steve
| Quote: | Originally posted by womble
I am aware that it is a completely different molecule, however, why won’t it work for piperic acid? |
you said it - because it is a completely different molecule. |
To be more specific, it is an alpha-hydroxy-carboxylic acid. Oxidise it to the alpha-keto acid, which decarboxylates to give the aldehyde. Classic org
chem stuff.
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jefferson987
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Seperation of Piperine from resin
I've extracted piperine from 100g of balck pepper using methanol. The extraction worked, but along with piperine can the gooy and sticky resin from
the pepper. When I tried to recrystalize in acetone it didn't work very well because the resin. How can I separate the piperine from the resin?
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Nicodem
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Quote: Originally posted by jefferson987  | | I've extracted piperine from 100g of balck pepper using methanol. The extraction worked, but along with piperine can the gooy and sticky resin from
the pepper. When I tried to recrystalize in acetone it didn't work very well because the resin. How can I separate the piperine from the resin?
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The "extraction worked", but you got no piperine? If you were unable to extract piperine, then the extraction of piperine did not
work. Utmost the extraction of a mixture possibly containing piperine worked.
Anyway, I find it surprising that so many beginners try to reinvent the wheel. Someone please explain what is the reason for not following a verified
and published protocol? And why then asking how to separate piperine from the resin when there was no serious attempt to do so already in the first
place. Am I missing something obvious?
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Hexagon
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jefferson987, did you tried an hexane:acetone (2:3) mixture for the recrystalization? I just extracted 50 gs of B.P. with 200 ml of EtOH and stirring
without heating for 2 hours, filtered, washed the erlenmeyer with 50 mls more of EtOH and filtered them too. After this I obtained a little more than
225 mls of the extract, from this the alcohol was evaporated and to the resulting resinous goo I added 15mls of hot acetone and heated while swirling
until it all was dissolved, then I added 10 mls of petroleum ether (lighter fluid) heated a little more, put a lid on the beaker and left it on the
fridge.
Nicodem, dunno where is this revival on pepper coming from, I tried a pair of verified and published protocols, and every time what I got was resinous
goo or nada, may be I'm a fool, but I tried my own protocol (you can see I didn't got smoke coming out of my head while thinking too much) and at
least I obtained the crude solid, not bad! 
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jefferson987
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Wow Nicodem harsh... I was following the directions listed here: http://www.erowid.org/archive/rhodium/chemistry/3base/pipero...
Apparently there are many different solvents that can be used for the job but the resin makes things tricky. I WAS able to extract piperine from BP
because I can see the yellow crystals among the resin.
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Nicodem
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Was I was harsh? Maybe not enough, given that you reply by supporting my arguments. You should also learn to differentiate your beliefs from real
world - you know not if the yellow crystals were piperine! Until you have them isolated and characterized, they are just what they are, some "yellow
crystals among the resin".
Have you bothered comparing the isolation protocol you linked to some published one or at least those used in educational lab practice? If it works
for thousand of students each year, then how come it is not good enough for you? Why would you prefer some two line description of an unconfirmed
extraction over a detailed and confirmed one? What I'm trying to tell you is to think by using your own mind rather that not think at all. Is the
following supposed to be rational in your opinion?
| Quote: | | Piperine is extracted from B. Pepper with an organic solvent. Duh. Anhydrous alcohols are fine, ether is much cleaner. Solvent is evap'd to leave
yellow crystals. |
Where is the defating step? I see no petroleum ether mentioned there? So how is the resinous plant material and other fats removed? Where is the
recrystallization step? At least Hexagon joined the defating and recrystallization step together and it seemed to work (though he does not mention
what the mp of the product was). In that example above there is none of this!
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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Rich_Insane
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Pepper is a plant. It is lipid rich like any living organism. It will also contain proteins and such. Your sticky resin is likely a mixture of lipids,
complex sugars, and random proteins. The least you could do is add the MeOH to the pepper, wash the goo with some hexane or NP solvent, wash with cold
water (piperine has low solubility in cold water, so just wash it off very quickly), and add some hot acetone. Recrystallize the result to yield
fairly impure piperine.
There's a paper here that gives an extraction: A rapid method for isolation of piperine from the fruits of Piper nigrum Linn (Niranjan Kanaki,
Mansi Dave, Harish Padh and Mandapati Rajani)
I couldn't obtain access to the full article, but basically it seems that they extract the black pepper powder with glacial acetic acid, then
recrystallize with chloroform to yield piperine.
Here's a procedure from a chemistry course: Isolation of Piperine from Black Ground Pepper
First, CHCl2 was added to the mix. If I am not mistaken CHCl2 can be bought fairly cheaply. I think that it's been banned as a paint thinner though
(I'm in USA). This mixture was set to reflux. The remaining waste pepper was washed with more CHCl2 and the mixture was filtered.
Then, to isolate the piperine, the CHCl2 was put in a rotovap (I'm sure that some other way could be used to separate the CHCl2), a brown oil was
isolated. To this, in a very cold bath, add some cold ether. One could either extract ether from OTC sources, make it, or substitute with naphtha. It
has to be very cold. The piperine will crystallize out.
Filter this, obtain the yellow crystals, and recrystallize with a 3:2 mixture of acetone and hexane. Filter out the crystals and obtain a melting
point.
This procedure is very simple and could easily be simplified to OTC sources. Before asking a question, please do proper research.
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Melgar
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So piperine is soluble in alcohol, acetone, and dichloromethane, and insoluble in water? What about nonpolar solvents like xylene or hexane?
Rich - do you mean CH2Cl2? It's the main ingredient in lots of paint strippers in the US. The easiest way to find it is by looking for the ones that
don't have flammability warnings on them, since CH2Cl2 is one of only a small number of nonflammable solvents. It will need to be distilled though,
since paint strippers almost alyways have lots of thickeners and surfactants. It's usually listed as "methylene chloride" on the back of the
container.
Chloroform can be used instead of CH2Cl2 in most cases, which can be made by carefully mixing acetone and bleach and siphoning out the resulting
bottom layer.
[Edited on 5/19/10 by Melgar]
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Rich_Insane
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Yes, CHCl2 as in dichloromethane... Interesting. It is a useful solvent. Unfortunately I do not have a distillation apparatus. I either need to find a
cheap one or build a makeshift one. The acetone and bleach method has horrible yield. I did the reaction twice with stoichiometric amounts of bleach
and acetone in a 8-16 C ice bath, and only got around 40 or 50% yield. I'd just buy that dichloromethane. Look in the smaller hardware stores. They
tend to have purer dichloromethane than big chains.
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eesakiwi
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Extract the pepper with alcohol & filter.
Boil off most of the alcohol untill it gets a little thicker.
Add water slowly & it will change colour a bit & the tar will drop out first.
As soon as you start to see the 'glints' in the liquid (coloured sparkles, different colours in each sparkle, millions of them)
Pour it all off the tar thats bottomed out of the liquid, into another similar tall jar & keep adding water untill it starts to turn
green/creamish (typical oil/water/detergent mix colour).
About now the piperine will drop out (its the glints anyway) to the bottom.
Recrystalise from 3xAcetone/2xPet ether mix or just acetone & add Pet ether to drive the crystals out of the Acetone.
Big thing is to have a low amount of alcohol as you loose the ability to drive the stuff out of it with water if theres too much alcohol in there in
the first place.
ie the liquids will still hold onto the piperine if theres too much alcohol.
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Gualterio_Malatesta
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Why would you need piperine?
Are you aware that no one succeded yet working the oxidation step later in the process?
So you can't really obtain any piperonal. Too bad.
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Hexagon
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| Quote: Originally posted by Gualterio_Malatesta | Why would you need piperine?
Are you aware that no one succeded yet working the oxidation step later in the process?
So you can't really obtain any piperonal. Too bad. |
While piperine is an interesting compound on it self, people have reported obtaining low yields of piperonal (20% or so) from piperic acid, and that
same compound straight from piperine via manganese compounds (III & IV)
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Gualterio_Malatesta
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That sounds quite interesting if it's actually true. Can you give me any links (PM)?
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Polverone
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| Quote: Originally posted by Gualterio_Malatesta | Why would you need piperine?
Are you aware that no one succeded yet working the oxidation step later in the process?
So you can't really obtain any piperonal. Too bad. |
"No one" succeeded? KMnO4 oxidation of piperic acid is repeatedly described in late 19th century books on chemistry, pharmacy, and perfumery as a
preparation of heliotropin (piperonal) before less expensive safrole-based methods were discovered.
I will admit that the standards of documentation in that time period are lacking, so you cannot go straight from the old books to a practical and
optimized preparation as you would with e.g. a procedure from Organic Syntheses. But it is ridiculous to dismiss old results just because nobody in
the small circle of hobby chemists posting on the internet in English has claimed to reproduce the work. We might as well say that no one has produced
sodium via carbothermic processes, despite a wealth of 19th century writings to the contrary, since I have never seen it electronically documented by
modern hobbyists.
PGP Key and corresponding e-mail address
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Gualterio_Malatesta
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Well, yes, what I meant was that no clandestine chemist going this route ever yielded piperonal. I wasn't talking about 19th cent.
It's a small circle of hobby (kitchen) chemists sure, but those chemists did much more complicated reactions, and it strikes me as odd that this
fairly simple one doesn't yield what it should.
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Nicodem
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| Quote: Originally posted by Gualterio_Malatesta | | It's a small circle of hobby (kitchen) chemists sure, but those chemists did much more complicated reactions, and it strikes me as odd that this
fairly simple one doesn't yield what it should. |
You are not thinking rationally. For obvious reasons only very few "kitchen chemists" are interested in piperine due to MD(M)A. If they consider
extraction of pepper and piperine as a good starting point for such targets, it is only because they don't have enough knowledge to think of anything
else and skills to do anything else. And if they don't have enough knowledge and skills then it is absurd to expect them being able to oxidise
piperine to piperonal by any of the published methods. Just check the questions in this and other piperine extraction threads! Most of those posters
don't know anything about how these extractions work and most never even bothered checking the literature or any of the schoolbook practicum
instructions to see how it is properly done. Those who have the skills for performing the oxidation of piperine to piperonal would certainly not
bother if their motivation is due to MD(M)A. Actually, the only chance for a "kitchen chemists" to do this oxidation is for someone with the required
skills to do this out of pure enthusiasm rather than being motivated by any potential (mis)use of piperonal.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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Gualterio_Malatesta
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Well, I wasn't talking bout local (i.e. sciencemadness.org) chemists, I was talking the-hive/hyperlab. Trust me those guys failed oxidation, not due
to the lack of skills. There's smth fishy with that oxidation write-up.
And by the way, this is the most easy and promising route for many ppl due to the fact that sassafras oil is pretty much unobtainable in many parts of
the world, and other routes use non-OTC and dangerous chemicals.
Hence this method is more promising and is favourable to kitchen chemists not because they lack knowledge.
This method was tried by several skillfull chemists and failed! I must admit my info is couple of years old, maybe there were some improvements to
this oxidation step which actually yielded the desired product - Hexagon's post above (he didn't reply me though).
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Hexagon
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Yep I've been out without regular access to internet connection this days, there you have your u2u, don't expect cookbook instructions 
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Gualterio_Malatesta
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Thanks!
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cheeseandbaloney
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I would think the reason the oxidation of piperic acid usually fails because the strong oxidizers could be tearing up the methylenedioxy bridge.
Anything strong enough to rip apart a C=C bond seems like it would do somptin fierce to a R-O-CH2-O-R bond. It would be a surprise to me if the yields
on a reaction like this were consistently high...
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