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ngeneerguy
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looking for suggestions
i know that this is an unusual topic for this thread but i am an organic student looking for an experiment. i am looking for suggestions for a "top of
the line" synthysis or extraction for an assigned "special project" for my organic 2 class. in the begining i was going to extract nicotine using
standard lab practices but ran into use of picric acid and my professor told me that he could get it (and would get it for me) but prefered not to
because of the risks involved so i decided to see if any of you guys could help me choose something. i am an honors chem engineering major and this
project will be presented at this years tennessee academy of science meeting in april. please, only serious suggestions using normally available lab
chemicals. the starting matierial for extraction or for synthysis is something that, if neccessary, i will supply. give me your best guys!!!!
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Sauron
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They love something of current interest.
How about Quadricyclane?
High energy aerospace fuel also potential chemical storage of solar energy. Google it. The immediate precursor and valence isomer is not hard to
prepare (it's a Diels Alder adduct) and it is converted to quadricyclane by UV irradiation.
The strain energy can be released slowly by catalysis and is recovered as heat.
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ngeneerguy
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while i have made norbornadiene through the diels alder, im not sure the quadricyclane would be stable enough to sustain its absoulute chemsitry. so
far, everything i have read on it suggests it tends to convert to other products that are more stable because of its strained stereochemistry. i would
hate to carry out a reaction, collect my product for display, and get to the presentation and have something completely different due to reactions
with moisture or other common things in the air (moisture being the most widely cited for destabilization of this product). i do thank you for your
suggestion and if you know of a method that would stablize the final product, i would be more than happy to research more on this product because it
does seem to be related to the direction of my expected carreer and a possible "atta boy" from my professor!!! as for me, i will probably read more
about it and if i find a way to stablize it i will let you know!
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Sauron
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Quadricyclane is quite stable in absence of special and rather complex catalysts.
See Org.Syn. on the subject.
If it was unstable it would be worthless. But it is stable.
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ngeneerguy
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sauron
i hate to tell ya but after disscussing quadricyclane with my professor, he also agreed with me about the instability of the product because of its
ability to, not only gain and lose heat, but change into other products. he was quite interested in the subject but was not ready for someone to take
on a project that would require hours of study to make it stable enough to present as a viable product without having many side reactions that break
down the final product. when you say worthless, you are doing it flippantly. i am not saying that it would be something that doesnt need further
study, i am saying that it wouldnt be fesible for me to follow an avenue that would leave me in a couple of months without the much needed result that
my professor desires. im not looking for a long term research project, im looking for something that would be above and beyond the call of
duty!!.....infact, he has suggested that i find a suitable liquid-liquid extraction that would be more suited to the lab equipment that we
are working with. we do have a high end apparatus for this such purpose and after spending a few hours looking at my options i am inclined to find
what would work for such a process.
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Sauron
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Fine, good luck, godspeed.
You did ask for a synthesis, or an extraction, but now you don't want a synthesis.
Someone else can suggest an extraction.
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Ozone
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Quadricyclane actually looks relatively simple to do (and, if kept by itself (and not to hot), should be fairly stable). It is, however, quite toxic
(at least to Wistar rats).
But, if that is to out-there for you, one of my most memorable synthesis was tetrabutylammonium octachlorodirhenate. It is a stable, emerald
blue/green crystalline solid which contains a Rh-Rh quadruple bond. The worst part is the use of ethanolic HCl, which as we found, can gas the room
quite nicely... Other than that, not too bad for such a neat compound. We made 10g batches (they were blowing the stuff up at Sandia at the time and
it was expensive, so they had our class make a shitload).
Cheers,
O3
[Edited on 12-3-2007 by Ozone]
Attachment: tetrabutylammoniumoctachlorodirhenate_01.pdf (141kB)
This file has been downloaded 1174 times
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
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Sauron
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His boss barfed on buying a little picric acid because it was "risky" and so now he wants a tame liq-liq extraction rather than a preparation. They
have the apparatus on hand.
I'd have made the picric acid then used it the way he intended, but, that's just me and these are kinder, gentler times.
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Maya
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Big whup!
Nicotine isolation was no big deal back then, every body in lab did it then derivatize as the picrate
\"Prefiero ser yo extranjero en otras patrias, a serlo en la mia\"
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Sauron
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I wonder whether 2,4-DNP wouldn't have worked about as well for him w/nicotime as picric?
Anyway maybe he can extract the hangover from Black Jack Daniels. He is after all, in Tenn. "Selective Removal of Fusel Oil Congeners by Liquid-Liquid
Extration from Ethanol-Water Matrix". J. Inebr.Intox.Chem. 86 (hic) 100 (2007)
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Magpie
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If you have to have this ready for presentation in April you don't have much time. On that basis you will likely have to go with something quick and
dirty (but sexy) without much risk of not working.
Extractions are easy. Just pick some plant, eg, arborvitae, and go after one of the many wonderful organics contained therein. I know
camphor and thujone are present in arborvitae (juniper). Claim that you are looking for a chemical that will cure cancer. 
Steam distillation often works well for this. But I'm sure you would like to use your extractor if possible.
The single most important condition for a successful synthesis is good mixing - Nicodem
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ngeneerguy
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sauron:
dude, no need to get testy!! the truth is that picric acid, in many states, has been outlawed by state owned universities and schools. for this reason
and the fact that it costs alot to have an environmental cleanup person to come by and get the waste products of picric acid(no matter how little
because of minimum fees), my professor shied away from the idea of obtaining it. as for your suggestion, i would love to get into it in more depth. my
prof. and another from ut are trying to get a research grant and he, at my suggestion yesterday morning, has decided to place your suggested project
into the choices of research areas they are considering. he actually worked with this product in the mid 70s when environmentalist were pushing for
things that would harness solar power. he realizes the potential but also knows that it can shift from the product to other things by losing the
energy traped in it or through other reactions. after about an hours discussion, he urged me into another direction while urging me to apply for a
position as a researcher with his group with the express intention of working on this project. im sorry if i ruffled your feathers or disapointed you
because that was not my intention. 
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Fleaker
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| Quote: | Originally posted by Ozone
Quadricyclane actually looks relatively simple to do (and, if kept by itself (and not to hot), should be fairly stable). It is, however, quite toxic
(at least to Wistar rats).
But, if that is to out-there for you, one of my most memorable synthesis was tetrabutylammonium octachlorodirhenate. It is a stable, emerald
blue/green crystalline solid which contains a Rh-Rh quadruple bond. The worst part is the use of ethanolic HCl, which as we found, can gas the room
quite nicely... Other than that, not too bad for such a neat compound. We made 10g batches (they were blowing the stuff up at Sandia at the time and
it was expensive, so they had our class make a shitload).
Cheers,
O3
[Edited on 12-3-2007 by Ozone] |
Are you sure it's octachlorodirhenate? You said Rh-Rh bonds...and that's rhodium, do you mean rhenium instead sir?
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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Sauron
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I'm a sarcastic bastard and treat everyone and everything irreverently. Don't take yourself so seriously. Also there's a bit of culture shock
involved, I was a research assistant in the 1970s at a southern state university and cannot imagine laboring under the burdens and restrictions that
you have to endure all for the sake of the stupid inane environmentalists. Ban picric acid? I'm sure that really makes the world a safer place. What a
joke!
Question: you said you made the precursor to quadricyclane via Diels-Alder. How long did that take you to do?
From there quadricyclane is merely an irradiation with UV.
Anyway let us know how this turns out. Oh, important safety tip: don't try to halogenate the product or the diene. A group in (I think) Canada tried
that and the resulting explosion killed everyone in the lab. This was written up in the 1980s. I guess they found a way to release the strain energy
very very quickly. (Usually it is slow even under catalysis.)
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jon
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Sauron, do you really live in bangkok or is that just for laughs?
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Ozone
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Thank you, Fleaker!
I was also considering the synthesis of Wilkinson's catalyst (Tris(triphenylphosphine) rhodium(I) chloride ) for a possible project for ngeneerguy.
I must have had a "brainfart" and confused them!
Wilkinson's catalyst is a neat ruby-red crystalline material that is useful for selective hydrogenation and a host of other neat reactions including
the reductive coupling of aldehydes.
This compound is also easier to make than tetrabutylammoniumoctachlorodirhenate (with a capital Re), but is quite sexy (@Magpie--great work with
the dimethylglyoxime, by the way).
I was also considering the Sharpless asymmetric hydroxylation of, say, stilbene as a doable project.
I order to atone for this heinous act, the literature survey on enantioselective asymmetric hydroxylation (with Barry Sharpless) can be found (on a
fledgling website), here:
http://www.uncommonalchemy.com/Library_files/Entantioselecti...
Thanks again, and,
Cheers,
O3
[Edited on 13-3-2007 by Ozone]
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
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Sauron
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Yes, I really live in Bangkok, and do not really understand why that is so hard to fathom.
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ngeneerguy
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Endo-norbornene-5,6-cis-dicarboxylic Anhydride was the product we were shooting for and it turned out ok. the hardest part was when i had to crack
dicyclopentadiene. it took about 45 min to do this process then the actual reaction took about 45min or an hour to do all the rest. the product i got
wasnt quite up to pure because my melting point on the final prod was about 3 degrees shy of pure but it was close. i think the fact that our
professor didnt have the cyclopentadiene ready and didnt tell anyone till they were already started causes some problems because the lab that meets
right before mine did the same experiment and they didnt have to wait on that and theirs averaged a melting point about 2 degrees higher than mine.
while not totaly pure, it was actually a high yield experiment. i managed to get almost a 95% yield, this being compared to the average yield in both
classes of around 86-87% i thought it was pretty good.
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Sauron
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How much norbornadiene did you prepare?
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chemrox
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I would move to Thailand in a heartbeat! Spend the rest of my life in quiet contemplation .. oh well...
I got a bottle of picric from a local chem department because they were getting rid of their 'environmental liabilities'. Same year a high school
gave us sodium and potassium.
It's really a shame when you think about it. Picrate melting points are definitive for a lot of materials. I looked at a nearby University's O chem
lab book and it was full of instrumental analyses and TLC... a few extractions .. almost no syntheses ..one of my courses .. syntheses was all we did
and we had to look up how others made all the intermediates and supply the refs .. real chemistry in other words ...
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Sauron
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About ten years ago my old "boss", now a retired Prof.Emeritus told me over lunch that because of the regulatory burden basically the Chemistry
Department at my old school no longer teached practical organix synthesis.
What research is done is combi-chem and parallel synth and little tubes. Instrumented analysis only. He said, training is synthesis still gets done.
We just let other places do it. He was not very happy about it but appeared to be resigned to the situation.
Dreadful. I would expect that in less than a generation the center of gravity of the chemistry world will relocate again. It last relocated from
Germany to the US a century ago.
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mick
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As a chemistry technician I feel sorry for the Prof. When he left I hope he took all his chemicals and samples with him and disposed of them upto his
level rather than leave them for some one else to sort out. Leaving picric acid to dry out does nobody any favours.
mick
[Edited on by mick]
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Sauron
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I'm sure the department had some picris acid at some point, but it would have been either in the main stock room, which serviced the instructional
labs, or in the organic stockroom, self explanatory. There were (when I was there anyway) half a dozen or so small labs and three larger group labs.
Some of these had small hordes of reagents of their own. In any case I can assure you that no one "left picric acid to dry" anywhere in the
department. I am not at all sure why you felt a need to make a staement like that since at no time was the subject of pricric acid or any other
energetic material raised by me in connection with my former boss. He happens to be a national ACS concillor and an IUPAC committeeman as well as a
very nice fellow.
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ngeneerguy
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when we prepared norbornadiene, i believe we got about 15 g or so with the final product. we didnt make big batches but it was some of the cleanest
crystals ive seen so far. as the crystals formed they did some pretty interesting things. first of all was they made intricate crystalline laticeworks
and second of all they formed in a matter of seconds during the recrystalization. to get the maximum yeild, i placed the warm beaker straight into a
ice/salt bath and dropped the temp in a matter of seconds.
as for the sythesis being taught, my professor tends to teach more of it than most colleges and universities in the area. he spent alot of his early
career working for drug companies and a couple of labs doing synthesis of new products. he sees it as the gateway for making new things and as the
most important aspect of organic chem. most of the tests he gives consist of reactions and setting up flow charts for sythesis where we lay out the
steps to get from given products to other things. we do go over mechanisms but we are only required to know basic Sn1,2, E1,2 and nucleophilic
aromatic substitution mechanisms.
we were also talking the other day about the chemicals that were left in the cabinets when he first took over the chem department. he told me about
having to dispose of a bunch of chemicals, including about 4 or 5 jars of picric acid. it cost almost 30 thousand dollars just to have the
environmental disposal people to come out and take care of it all. for this very reason, he doesnt like ordering things that 10 or 20 ml will be used
and the rest will sit on a shelf until they either break down or get contaminated.
as for him, i couldnt think of a better professor to have because the way he challenges me to step up to the plate and learn it or go back to the
house. we started with about 55 people in my organic class and by organic 2 we are down to about 25 and out of those about 14 or 15 will make it. i
think it should be like that because if you cant pass organic the hard way then i dont want to see you in your little doctors coat sometime when i
have to go see a speciallist for some obscure health problem in my future
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Sauron
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$30,000 to take away a few bottles of picric acid.
That is monstrous.
We have created an arrogant priesthood of these environmental techs and now we must pay obeisamce to them as if we the scientists are not competent to
deal with such matters ourselves?
I can think of a lot of things I would prefer not to deal with, but picric acid is not one of them.
Picric acid is not a primary. The requirement for it to be wet is an arbitrary DOT reg. Dry, it is still safe to handle. The sole hazard with picric
acid is metal salts formation. Some metal picrates ARE primaries. Absent that picric acid is as tame as, say, TNT.
Now, I am not quarreling with your dept.chairman. I am just saying that this was a waste of $30,000. If required by law then the law is an ass.
Picric acid, if it dried out, could be remoistened. Just Add Water.
Picric acid could have been chemically destroyed. I'm sure we can all think of ways to do that. How about bleaching powder -> chloropicrin ->
nitromethane -> methylamine?
Picric acid, unconfined, merely burns. Incinerate it.
Sometimes, the law if this was law, is an ass.
$30,000!
I told you: culture shock.
Picric acid is not sweaty dynamite.
[Edited on 18-3-2007 by Sauron]
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