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Hexavalent
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Tert-Butyl Lithium
I have recently come across several experiments I would like to try that specify a tertiary-alcohol based organolithium reagent, so the first option
that came to my mind was tert-butyl lithium.
I know that it is toxic and pyrophoric, and I have what I need to handle it safely. Can anyone point me to a source?
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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zoombafu
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Wow, that stuff is dangerous!
These guys apparently have it, not sure if they will sell to you though.
http://www.optimachem.com/index.htm
Again, I have no idea if they will sell to you:
http://www.strem.com/catalog/v/93-0302/36/
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Hexavalent
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Thanks for the links, I should have mentioned however that I am UK-based and I highly doubt, even if they do sell to individuals, either of these
companies will ship over the pond without an enormous packaging cost.
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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kavu
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I would highly advise you not to use alkyllithium reagents at home. Handling them requires precautions even in a professional lab. You will need an
inert gas and a good vacuum source to flush all your equipment with dry argon (or other inert gas). You will need syringes and balloons of argon (if
you don't happen to have a Schlenk line) to even transfer the reagent from the container to a reaction flask. In larger amounts a cannula is to be
used. Watching this video will give you an idea of what precautions and apparatus are required to be safe: http://www.youtube.com/watch?v=RaMXwNBAbxc
There are many interesting reactions that do not require such dangerous materials 
[Edited on 9-1-2012 by kavu]
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ThatchemistKid
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"tertiary-alcohol based organolithium reagent", you stated a specific one was mentioned just out of curisoity what specific reagent was mentioned for
whatever you are wanting to do?
[Edited on 9-1-2012 by ThatchemistKid]
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fledarmus
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A lithium alkoxide or an alkyllithium? Alcohol-based seems to point to an alkoxide, and those aren't too bad. Tertiary alkyllithiums I wouldn't use
outside of a professional lab with people around to respond to emergencies. Even in an academic setting, I'd be sure somebody was around and knew what
I was doing.
There has been a lot on all the boards recently about a grad student at UCLA and an accident with t-butyllithium.
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peach
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I know you are in your early teens.
You are not getting t-butyl lithium. There is no public supplier in the UK who'll sell you it.
| Quote: | | I have what I need to handle it safely |
I seriously doubt that.
The level of equipment and experience required to handle these kinds of things is way beyond what you'll have available. There are
very few members here, including the guys in their 60's who have been chemists all their lives, who have that kind of equipment at home.
Just because Nurdrage has it as his ?doctorate? at the start of the videos, it doesn't make it feasible at home.
You seem to have an interest in things that are difficult for people with degrees to handle (piranha, alcl3, this). I'm not being funny and calling
you stupid, but there is a reason it's difficult for them, because it's difficult for everyone, even the older guys.
You thought my pH meter was expensive. The kind of equipment needed to handle these kind of things costs thousands of pounds. That is why at home
chemists tend to find some other option if possible.
Have a read of this to see what's entailed.
Then check the prices of that equipment on the sigma site, and keep in mind that's ex vat.
Sigma will not sell to any member of the public. If you don't believe me, try calling them. They don't bite, they'll just say no. They individually
vet each account request. Cole Parmer are the same, and BASF, and Alfa, and Fischer.
Start with AlCl3. That won't explode or spontaneously combust. Try to get it entirely anhydrous. If you can manage that, it'll immediately jump you
above 90% of the audience of science madness.
This student burnt herself to death, despite having all the equipment in a post graduate university lab, the training (a degree) and the technical
bulletin.
[Edited on 9-1-2012 by peach]
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ScienceSquirrel
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Try making and handling chromium II acetate to start with. It is quite air sensitive but just discolours if you get it wrong.
From there you can move on to Grignard reagents. They decompose on contact with moisture, react with carbon dioxide and do not like oxygen. But they
do not catch fire in air and are quite stable in dry ether even in air as the ether vapour blankets the solution.
After that try n butyl lithium. It needs a dry nitrogen blanket, argon is better, it will catch fire if provoked but it is not that bad.
After that try t- butyl or methyl lithium. In my opinion they are a lot more flammable and unstable..
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Hexavalent
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Ok, thanks for the advice. I do happen to have a somewhat homemade Schlenk line and a small argon tank and a vacuum pump (converted from a tyre
inflator), but you have pointed out to me that that still isn't enough.
Peach - thanks for your input, it was really helpful. I will have a go at making the anhydrous AlCl3, and will have a go at the Chromium (II) Acetate
as mentioned by ScienceSquirrel, and then the Grignard Reaction next (any ways to do this without ether though?)
Thanks guys.
Also, Peach, what region of the UK are you in?
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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AirCowPeaCock
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Quote: Originally posted by ScienceSquirrel  | Try making and handling chromium II acetate to start with. It is quite air sensitive but just discolours if you get it wrong.
From there you can move on to Grignard reagents. They decompose on contact with moisture, react with carbon dioxide and do not like oxygen. But they
do not catch fire in air and are quite stable in dry ether even in air as the ether vapour blankets the solution.
After that try n butyl lithium. It needs a dry nitrogen blanket, argon is better, it will catch fire if provoked but it is not that bad.
After that try t- butyl or methyl lithium. In my opinion they are a lot more flammable and unstable.. |
I don't think he needs these ideas..literally--obviously he has them all on his own!
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Hexavalent
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What do you mean by that?
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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AirCowPeaCock
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I mean what I say, and say what I mean..usually.
What do you want tert-butyl lithium for?
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Hexavalent
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http://books.google.co.uk/books?id=IlL_qLqj_nUC&pg=PA337...
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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peach
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I was in York a while ago, but am currently around the North West (near Liverpool and Chester). There are a few other active members on here from the
UK, and they're dotted around the place. However, it's not really fitting for me to start pointing them out and where they live, they can do that
themselves if they want to get in touch and help out.
Remember that you can make you own diethyl ether from sulphuric and ethanol. Entropy mentioned how he'd done it when he was about the same age.
Although I would recommend you use an oil bath sat atop your hotplate as opposed to a bunsen. He was doing this decades before youtube, eBay and fuzzy
logic digital controllers were in peoples' houses, so he had to apply some brain power of his own rather than simply copying a video, and heating
solvents with bunsens was much more commonplace.*
Ether boils at 34C, which is below body core temperature and around that of skin. A radiator can be 45C and a hot bath is usually about the same.
In this post, Len gives a detailed example of his own production of it. Notice that his ambient temperature is 42C, well above the boiling point.
His tap water is 30C, which is too close to efficiently condense it, so he's using buckets of ice cold water around the receiver.
Here in the UK, it's 10C outside now. And the tap water is about the same (since the pipes are running through the cold earth outside).
A dangerous property of diethyl ether, which isn't present even with many other volatile solvents, is that it will spontaneously combust at low
temperatures. The people who make petrol purposefully add ethers to make it ignitable down to -30C (the typical maximum negative temperature a car,
snowmobile or truck will be exposed to).
Flash point
This the temperature at which something will form a combustible mixture with the air and ignite if there is a spark or open flame (e.g. bunsen)
present. For diethyl ether, it is -45C. So you could put a beaker of it in the freezer on super freeze, then open the door, hold a lighter over it and
it'd still burn.
Autoignition
This is much more dangerous, as it is the temperature at which something will form that mixture but also ignite without the presence of a spark or
open flame, it only needs oxygen to be present. For diethyl ether, this is 160C. Which may seem a lot, but the reaction to produce it runs at 140C,
and the thing doing the heating will likely be a little hotter.
There have been a number of serious fires in universities involving diethyl ether.
One example involved it being redistilled. When someone returned to collect some of the clean ether, they opened the tap to fill their flask and a few
drips of it ended up landing on the heat source below, where it autoignited. Considering that these redistillations can involve a liter of it, all
boiling away, that isn't going to be an enjoyable experience! It's akin to boiling petrol on the kitchen stove, the vapour must be kept away from the
atmosphere and anything too hot.
*The laboratory in which Albert Hofmann first made LSD in 1938 used flames at the back of the fume hoods to draw the waste up by convection. It's
possible that the first time he noticed it, it was due to it being in the air around him.
[Edited on 11-1-2012 by peach]
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ScienceSquirrel
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I have done some air sensitive chemistry and I think it is better to start with the mildly sensitive, move on to the very oxygen reactive and then try
the pyrophoric.
It is best not to discover that your technique is not very good with something that catches fire in air.
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fledarmus
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Although diethyl ether seems to have some magic properties with some grignard reactions, for others you can get away with some less flammable and less
LEO-flagged ethers like THF or 1,4-dioxane. Like diethyl ether, both need to be carefully dried before use, of course, and either stabilized against
peroxide formation, tested before use, or used up quickly.
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Dr.Bob
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That is simply a link to a book of all tert-butyl lithium chemistry.
If you want to get useful help from other chemists, you have to be willing to provide some context of what you are doing. If I ask someone what
catalyst to use for a hydrogenation, they will need some idea what my substrate is and what I am aiming to do to be able to provide any USEFUL
information. Asking about using tert-butyl lithium reactions and pointing to a whole book of them is not helpful. No one in their right mind
should help you find such a hazardous chemical, if you can't say what you are doing with it, and more importantly, why you need tert-butyl lithium for
the reaction, not a safer base.
I have worked in chemistry for years, with a variety of hazardous reagents, and even now I would not run a reaction with it unless it was a necessity,
as most reactions that need a strong base can use other ones nearly as well. That is not because I am a coward or scared, but because I respect
chemicals and their hazards, and try to minimize risk to myself and others when there is no reason for it.
Ultimately there are very few sources of it, most going back ultimately to FMC ("Fools Making Chemicals" is the popular joke, they are WV, USA and a
few other places.), which sells it to Aldrich and most other vendors. And they are not about to sell it to a home chemist, not when a professor is
being charged with criminal negligence just for allowing a researcher to work, in a university chemistry lab, with it without "proper supervision"
which resulted in her death due to a fire.
http://www.latimes.com/news/local/la-me-1228-ucla-death-2011...
Don't get me wrong, I am all for science research in all forms, but every incident of someone setting their (or their neighbors) house on fire,
creating a hazmat situation from their meth lab, or otherwise creating bad press for chemistry will result in even fewer liberties for scientists
everywhere.
Bob
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Hexavalent
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Thanks for your suggestions. Peach - I am aware that ether can be made via distilling ethanol and sulfuric acid, but again I just have a sixth sense
that tells me that the flask will break, spraying conc. H2SO4 and ether all over my oil bath/sand bath/hotplate, which I really don't need ATM!! I
know that you should never fear chemicals and just respect them, yet I don't feel comfortable with this sort of synthesis. Any ideas?
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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ScienceSquirrel
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The easiest way to reasonable diethyl ether is via starter gas.
Spray the contents of the tin into a cold flask and fractionally distill with a hot water bath.
Or you can use the contents directly, it seems to work.
http://www.sciencemadness.org/talk/viewthread.php?tid=11050#...
[Edited on 11-1-2012 by ScienceSquirrel]
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Zan Divine
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Hexavalent,
It's been known for a long time that many Grignard reagents can be prepared in toluene (and other solvents excluding ethers).
Just Google "Grignard reaction" + toluene
I find handling pyrophoric materials easy enough at home. An argon cylinder, glass syringes, transfer needles, rubber septa. Vacuum equipment? Not
necessary at all. Air can always be removed by purging. It is the height of simplicity to reduce O2 inside a flask to just 100 parts per million.
Which, incidentally, is WAY less O2 than you need to worry about. I acquired everything needed to handle pyrophoric liquid Cs for about $100.
However....I've done this for dacades. So, for the sake of accuracy, the necessary equipment isn't priced very high. The required level of skill is
pretty high, especially if you can't afford a mistake.
Start small, although some will undoubtedly gasp at this...a fire involving 10 ml is no big deal....IF a) you're not wearing it b)you work in a
firepan c) You don't have other flammables nearby and d) you have a suitable extinguisher.
In the many years I've worked in and later supervised a purely research-oriented lab, I've seen occasional small fires and no injuries. The reason?
Adequate asking and answering of "what if..?"before you begin (the pre-write-up) and adequate equipment to deal with it when "what if...?" becomes
"oh, oh..."
That's just my philosophy, but I've never been injured nor has anyone that I've ever been supervising.
[Edited on 14-1-2012 by Zan Divine]
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Dr.Bob
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| Quote: Originally posted by Zan Divine | Hexavalent,
However....I've done this for dacades. So, for the sake of accuracy, the necessary equipment isn't priced very high. The required level of skill is
pretty high, especially if you can't afford a mistake.
Start small, although some will undoubtedly gasp at this...a fire involving 10 ml is no big deal....IF a) you're not wearing it b)you work in a
firepan c) You don't have other flammables nearby and d) you have a suitable extinguisher.
In the many years I've worked in and later supervised a purely research-oriented lab, I've seen occasional small fires and no injuries. The reason?
Adequate asking and answering of "what if..?"before you begin (the pre-write-up) and adequate equipment to deal with it when "what if...?" becomes
"oh, oh..."
That's just my philosophy, but I've never been injured nor has anyone that I've ever been supervising.
[Edited on 14-1-2012 by Zan Divine] |
As much as some people might gasp at that, I have to agree that if you work with certain chemicals, like butyl lithium, potassium hydride, Na, etc,
you will almost certainly have a small fire as syringes, spatula, and other contaminated items will want to catch fire once exposed to air. I agree
that a large part of safety is making sure that other flammables are far away, there is somewhere to put burning items that is safe ( a large beaker,
glass tray, stone bench, where they can be allowed to burn out on their own.) and not panicking when something happens.
I have seen far more damage from someone trying to put out a small metal fire and blowing it across the lab with a fire extinguisher that would not
have put it out anyway. You must plan what to do WHEN a fire starts when you handle pyrophoric reagents, as it will happen eventually.
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Hexavalent
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I keep all my flammables and explosive agents in a sealed metal cabinet far away from my fumehood which is where I would handle such reagents, so the
first point is covered.
I would also like to add that after you have finished using pyrophorics you should flush the needles/syringes with hexane, discharge into IPA and then
quench with methanol, this will significantly reduce the possibility of fires later on.
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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Neil
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Good reading for rainy days is the NFPA guide lines on fire fighting as well as their publications on techniques. I have misplaced my copies but a
little googling should pull them up for you.
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entropy51
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| Quote: Originally posted by Neil | Good reading for rainy days is the NFPA guide lines on fire fighting as well as their publications on techniques. I have misplaced my copies but a
little googling should pull them up for you.
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S.C. Wack once posted the NFPA guidelines on Fire Protection in Laboratories, but it looks like the link is
now dead. Maybe he could post them again? They are worth the read.
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Hexavalent
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http://www.youtube.com/watch?v=HCVRZuupcFw
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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