pip
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pd\c in water to ethanol reference request
I've spent the last week researching but I can't find any references for making pd\c in water into pd\c in ethanol. I know what ever method is used
can't be detremental to the catalyst. can someone point me towards a paper I can read that would explain how to dehydrate the water without ruining
the catalyst preferably without inert atmosphere.
the only idea i had was to put the pd\c in water in a "cup" adding ethanol then putting the "cup" in a bowl of dissecent. however this seems extremely
crude.
Is pd\c in ethanol anhydrous or just 95%?
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zed
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I gather you have some Pd/C in water.
Take a syringe with needle, or a pipette.....affix a pea-sized ball of cotton or glass wool to the end. Submerge your little filter ball, and "Pin"
it to the bottom of your container. Then, draw the water out of the Pd/C via suction, utilizing the wad of cotton as a make-shift filter.
Add ethanol, shake. Let it settle. Draw off ethanol, as you did water. Repeat. After a few rinses, it should be pretty dry.
Don't at any stage allow your catalyst to become completely dry. Depending on how it was prepared, and what it has since been used for, it may be
pyrophoric.
If you really aren't very familiar with working with such materials, I recommend you do a heap of reading first. Vogel or Organic Synthesis, might be
a good place to start. I personally would do the same thing. I've done such things before, but it has been a while.
Also, if your solution needs to be truly anhydrous, it may require a special preparation. Off to the library!
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Nicodem
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Depends whether you throw it in anhydrous ethanol or 95% ethanol.
Honestly, I must say that I find your "problem" bizarre. What do you mean by Pd-C in water? Is that a suspension of Pd-C? Then why don't you just
filter and change the solvent?
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smuv
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why don't you just tell us what you are trying to reduce and we can tell you if any of this actually matters (I can tell you in advance it probably
doesn't).
I have never seen pd/c with ethanol, I have seen anhydrous and catalyst moistened with 50% by weight water. Of course you could take the anhydrous
stuff and treat it with ethanol, but still I am sure it is pointless.
"Titanium tetrachloride…You sly temptress." --Walter Bishop
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pip
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delta 4 carene
Dissolve 1 g Delta-3 carene in 50 ml propionic acid and heat at a suitable temperature (e.g., one- half hour at room temperature may do) in presence
of 1/2g Palladium-Carbon catalyst (5%) in ethanol and filter, evaporate in vacuum (can distill 63.5/19.5).
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zed
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Pretty arcane. An isomerization. I don't know the reaction mechanism, but I would try to get all of the water out.
It is also possible you could produce such a catalyst, by the action of NaBH4 in ethanol, upon PdCl2 and C, in ethanol.
Is this isomerization a hydrogenation/dehydrogenation?
# ^ Liebeskind, L. S.; Peña-Cabrera, E.Organic Syntheses, Coll. Vol. 10, p.9 (2004); Vol. 77, p.135 (2000). (Article)
# ^ Ralph Mozingo (1955), "Palladium Catalysts", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv3... ; Coll. Vol. 3: 685
Before I did anything wild, like actually trying to make Delta 4 Carene, I'd make damn sure it is actually worth making.
[Edited on 5-11-2010 by zed]
[Edited on 5-11-2010 by zed]
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pip
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delta 4 carene is valuable to me so its worth making or do you just mean by this method. I would like to end up with 100g so i'm open to suggestions
on other methods that work with more than a gram at a time.
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watson.fawkes
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Quote: Originally posted by pip  | | Dissolve 1 g Delta-3 carene in 50 ml propionic acid and heat at a suitable temperature (e.g., one- half hour at room temperature may do) in presence
of 1/2g Palladium-Carbon catalyst (5%) in ethanol and filter, evaporate in vacuum (can distill 63.5/19.5). |
See http://www.erowid.org/archive/rhodium/chemistry/psychedelicchemistry/chapter2.html for the full context of this quotation.
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smuv
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Mechanism:
Say you have a generic carbon chain 1-2=3 (Hydrogens implicit)
1. Alkene is adsorbed to catalyst surface at 2=3
2. H- is transfered from the catalyst surface to carbon 3, causing strong association of catalyst at carbon 2 (as it now has high electron density)
3. Transfer of H- from carbon 1 to catalyst surface (transfer from 3 back to cat. surface is a significant competing pathway which recreates starting
material)
4. transfer of electron density from 2-catalyst to 1-2 (double bond formation)
5. desorption from cat surface
3,4 might be concerted (who knows). If this is unclear essentially the H- at 3 is traded with that at 1.
Why does this produce delta-4-carene? Seems like delta-4-carene is a less stable product,why does the product form? This actually doesn't matter b/c
this is all kinetically controlled, loss of a H- to form the delta-4 product should be faster because of sterics and higher probability of a hydrogen
being close enough to get absracted (there are two on the 4 carbon vs 1 on the 3 carbon). Although the second part matters less as there is not
exactly free rotation in this specific case.
A note, for less hindered alkenes due to rotation of molecule between steps 2 and 3 you can also do cis trans isomerizations. In this case between
step 2 and 3 you get the molecule rotates, and the H- is transfered back to the same carbon it was abstracted from. The double bond doesn't move but
you get E/Z isomerizatoin.
I think it would be best to run this reaction at elevated temps. You could probably get away using Raney nickel too (its known to do this kind of
thing). Since the molecule does not look very fragile I would just run it overnight at steambath temps. I also don't think the ethanol matters. I
recommend you clean all glassware with nitric acid or any other strong oxidizer before the reaction; this is a sure way to avoid most sources of
catalyst poisoning. Also make sure you starting material is pretty clean (ie distilled) before doing rxn.
[Edited on 11-6-2010 by smuv]
"Titanium tetrachloride…You sly temptress." --Walter Bishop
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zed
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Add ethanol, shake. Let it settle. Draw off ethanol, as you did water. Repeat. After a few rinses, it should be pretty dry.
Don't at any stage allow your catalyst to become completely dry. Depending on how it was prepared, and what it has since been used for, it may be
pyrophoric.
------------------------------------------------------------------------------------
Excuse my ambiguity......
Should read: Repeat. After a few rinses, it should be pretty ANHYDROUS......(Ethanol still "wets" the Pd/C, but Most of the WATER should have been
removed.)
................................................................................................
When I say "Is it worth it?" I mean , it's old chemistry, things change, and there may be better synthetic cannibinoids now.
................................................................................................
Also, Pot quality has taken a quantum leap. In much of the US, pot is close to becoming legal. And, for a few bucks, I could get a Medical Marijuana
card, and grow my own stuff. Lots of it.
Why break out the glassware, when Nature's Uber Chemists, living cells........already do such good work?
.................................................................................................
As for Ethanolic Pd/C......Will Ethanolic Pt/C do?
There is a procedure in Vogel's Practical Organic Chemistry, 5th Ed..... Page 93 or thereabouts.
In my most recent encounters on e-bay, I found that Pt was available at about spot metal price. Pd prices were unreasonably inflated. Since Pd and
Pt, were selling for about the same actual price, but Pt is actually the more valuable metal....Pt may be a better value.
Just convert it to Chloroplatinic Acid, and you're off to the races.
[Edited on 6-11-2010 by zed]
[Edited on 6-11-2010 by zed]
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pip
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Yes this is for synthetic thc but I was hoping the discussion would not head that way. I am legal to have thc where I live and I already have olivetol
so never using it would be a shame.
I won't lie, I wish I knew someone local who was capable of this but, all I can do is read, re-read, ask, and experiment.
As far as "why breakout the glassware when you can grow" well like I said I already have olivetol and who comes to this site and doesn't want to break
out the glassware.
[Edited on 7-11-2010 by pip]
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