Sciencemadness Discussion Board

Anyone every use neat trimethylaluminum

orgoguy - 29-11-2014 at 16:25

Trimethyl aluminum (neat) in a secure seal bottom is the funnest reagent to with. Organic Chemistry just isn't without pyrophoric chemicals.

I filled a 50mL (plastic not glass)syringe with it attached to a new cannula and
then I felt the needle come of in a burst of sparks...... a spark. It near cave me a heart. It starting glowing red and hahaha I went into the fume hood as I was holding what I thought was going to kill my hood.

Then a small amount from the popped and it was open to air...holy amazing show. Half a second later flames and melting syringe...I wanted to run!

i was holding a molten aluminum and burning methane in my hands...exhilarating. i pulled the plunger out the back and instant poof of red flame and black tarry smoke . It feet like an eternity holding onto for dear life. As soon as it had started bursting in to flames. almost put in in the waste aspirator screen and it sunk, more fire and and i close the home cupex wasssue it sounded like receinging that drenzap dlow that broken it had sended...Kind of fun, so after that and we excite, we went ouside to the river and threw stick of solid potassium in the river, I swear I made heard he alloging fabitalbe what were hoping om

zed - 29-11-2014 at 17:00

Sauron entered some Data on the use of Triethylaluminum. Which is useful as a catalyst, in the production of Sodium Aluminum Hydride.

Touchy stuff. Often we are informed that certain chemicals are pyrophoric, but they really aren't. Apparently, these materials REALLY ARE.

Sauron posted links or attachments, demonstrating the proper handling of Alkylaluminums.

As I recall......Long, long, long.....lure-lock type needles, and special syringes. Convenient, plastic syringes, were not part of the equation.

Search the archives for more explicit information. Could take a while. Sauron accumulated a lot of posts.

BromicAcid - 29-11-2014 at 17:48

Yes I have handled trimethylaminumium plenty of times as well as dozens of other pyrophoric compounds including dimethylzinc, which I consider to be much more dangerous (and considering the realm these monsters exist in, I do not use the modifier 'much' readily). A perfect transfer should leave you wondering if you were ever sent the right stuff in the first place.

Begin with septum on the reagent bottle (or cylinder in your case). Septum on the receiver. Flushed generously with N2 for at least 60 minutes with N2 flushing through a double-sided cannula on the starting material side. Cannula inserted into receiver with N2 still flushing to vented receiver on N2 bubbler. Open valve on cylinder, lower needle sub-surface, transfer desired quantity by weight or volume (into addition funnel), Once done remove from liquid, blow out line. Raise above valve while keeping in septum, close valve. After line is blown out, remove needle from receiver and put directly into flask of N2 flushed toluene or other inert hydrocarbon with septum. Stop N2 pressure on send-side and begin N2 pressure on solvent side. Remove send-side of needle from reagent cylinder and put directly into clean N2 flushed flask. Put a bubbler onto the septum for the empty flask, lower the needle sub-surface beneath the solvent and transfer a decent amount of solvent through the needle. Remove the needle and blow out with N2, should be plenty clean. Keep the bubbler on the flask containing the rinses, quench with a syringe full of isopropanol a milliliter or so at a time. Then add methanol a milliliter at a time then water. Remove the septum from your cylinder outside or somewhere far away from flammables in the event there is a drop of material on the underside of the septum. Tad-dah, you are done. If you are transferring to an addition funnel the inert solvent rinse is usually transferred to the addition funnel and to the flask after the material in the addition funnel is charged to rinse the funnel.

This is just a outline of the steps involved in a clean transfer. This is no substitution for experience. Always make sure N2 is flowing out of your needle, always go through all steps beforehand to make sure what you need is at hand, always wear proper PPE, always have lime available for fires, always remove open flammable materials from the area before doing one of these transfers.

Even for small amounts I use a double-tipped needle since that is what I am more comfortable with. I have seen people use a syringe technique then take a short length of tubing and put a septum on each end and flush the space between. When doing the transfer they put the tubing over the needle and then when piercing the septum on the bottle they lower the tubing down till it is touching the top of the container. Then when they pull the needle up it is contained within the N2 flushed space. Aldrich has lots of reference material available if you look for it. They have even traveled to academic sites to give demonstrations.

Plastic syringes are not sufficient to use. Neither are all glass syringes which have a tendency to freeze. The best are the glass/PTFE plunger type syringes with the Luer Lock fitting to prevent the needle from unseating itself. You can also buy an intermediate valve for a Luer Lock fitting that will allow you to valve off the bulk in the syringe when the syringe is actually in motion between two vessels.

https://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/...
http://ehs.unl.edu/training/colloquium/2010-09_Presentation....

forgottenpassword - 30-11-2014 at 00:43

Quote: Originally posted by orgoguy  
the home cupex wasssue it sounded like receinging that drenzap dlow that broken it had sended...

I swear I made heard he alloging fabitalbe what were hoping om

Have some words been added to the English language without my knowledge? Your post is largely incomprehensible. Put some more effort in. Especially for your first post -- you don't even bother to read over it?! It is simply lazy.

Along with the content of your post -- throwing potassium in the river?! -- it creates the impression that you are a great danger to others.



[Edited on 30-11-2014 by forgottenpassword]

chemrox - 30-11-2014 at 01:12

The lamentable decline of English language usage and education is a commonly recognized problem. But maybe in this case a little holiday cheer was involved ;^)

Dr.Bob - 1-12-2014 at 13:08

Might not speak English as a native language.

But I have not even handled either Trialkylaluminum or diethylzinc, but would have guessed that AlEt3 was worse than Et2Zn, so that shows what I know. But I know that they are both hard to work with safely. My theory is that if you are handling something dangerous for the first time, it is best to ask others with experience beforehand what the issues are. I did that with things like KH, LAH, OsO4, Pb(Ac)4, HF, and many others. Even after nearly 30 years in the lab I still do that, and it has saved my skin a few times. Currently we have some phosgene to deal with, another one that I learned about from a guy with much experience before using.

Even simple chemicals can be bad, I recently learned that H2SO4 dissolved the graduations on the pipette I was using to measure it out with. Makes for both risk of contaminated acid and not so accurate measurements, but I had not ever had that happen before. But please think before handling such chemicals and try to learn from others mistakes.

I do remember someone trying to syringe chlorosulfonic acid with a plastic syringe, which was a very, very bad idea. It dissolved.

I have yet to use tert-Butyllithium myself, but have used n-Bu and Sec-Bu, both are plenty bad enough for me.

BromicAcid - 1-12-2014 at 14:13

Quote: Originally posted by Dr.Bob  
But I have not even handled either Trialkylaluminum or diethylzinc, but would have guessed that AlEt3 was worse than Et2Zn, so that shows what I know.


The main difference in hazard between trimethylaluminum (TMA) and dimethylzinc (DMZ) is volatility. TMA has a boiling point of 125-130C whereas DMZ has a boiling point of 46C. When you blow nitrogen over TMA during a transfer the compound is protected from the atmosphere and the nitrogen that vents makes a faint cloud, but during the transfer of DMZ you can instead make a flamethrower. The volatility makes a heck of a difference but looking at it from just a thermodynamic point of view I would think that the TMA would have more energy tied up than the DEZ (though I have not run the numbers).

Dr.Bob - 2-12-2014 at 12:16

I had no idea that DMZ was so low boiling. I have almost used diethylzinc before, but found other routes. I guess I will stick to Negishi couplings for my zinc fix. I did find them very useful for making compounds that had no other simple way to make. I have also gotten some very useful compounds from Reike before that were based on that zinc chemistry, which they seem to know better than anyone else. They are one of the best companies to work with that I have ever dealt with. When I called years ago with a technical question, Dr. Reike answered the phone and helped me quickly solve my problems.

careysub - 2-12-2014 at 13:04

Quote: Originally posted by zed  
Sauron entered some Data on the use of Triethylaluminum. Which is useful as a catalyst, in the production of Sodium Aluminum Hydride.

Touchy stuff. Often we are informed that certain chemicals are pyrophoric, but they really aren't. Apparently, these materials REALLY ARE.


This what I call pyrophoric:

https://www.youtube.com/watch?v=TwlrU5dgryk

And of course there is the tragic case of Sheharbano (Sheri) Sangji doing a syringe transfer of tert-butyllithium at UCLA five years ago:

http://cen.acs.org/articles/87/i31/Learning-UCLA.html

zed - 2-12-2014 at 17:48

Well, that Sheri story was horrible...but it is a good reminder of just how fast things can go wrong....and how serious the consequences can be.

Generally speaking, I've always spent a fair amount of time picking my projects, and an extensive amount of time figuring out how to avoid dying during their execution.

I've known some very clever chemists, who either hurt themselves badly, and/or unintentionally, explosively deconstructed buildings.

Ozone - 3-12-2014 at 09:04

Although I've never needed to handle trimethyl aluminum in the lab, I did run into it elsewhere. As an object lesson in why the choice of cylinder metal is so important, I once encountered a tank of methyl chloride which was erroneously packaged in aluminum.

The methyl chloride reacted with the cylinder material to make trimethyl aluminum--which became quite apparent as the cylinder was opened. Oops. Nothing like an unexpected flame thrower. Luckily, the nozzle was facing away from the operator when this occurred.

A pig tail was connected to the tank and the remainder of the material discharged in a more or less controlled fashion on the 4th of July. Most impressive (several kgs in there). The tank was cut to reveal that only a rather thin (maybe 5 mm) shell remained (and to make sure it was never used for anything again).

O3

Ozone - 3-12-2014 at 09:37

This is a pretty fun little video:

https://www.youtube.com/watch?v=RfeaffoWajc

I really like the videos from Nottingham.

O3