ScienceHideout
Hazard to Others
Posts: 391
Registered: 12-3-2011
Location: In the Source
Member Is Offline
Mood: High Spin
|
|
Strong Reducers on HMS Beagle!!!
Awesome news!
I was just cruzin' the HMS beagle website store, and they have both LAH and Sodium Borohydride IN STOCK!!
10g LAH for $22
15g NaBH4 for $25
Price is a bit high for the amount, but I bought each; perfect amounts if you do smaller O-chem reactions!
HMS Beagle is owned by trustworthy John Kuhns and is based in Missouri. Mr. Kuhns is friendly, provides great customer service, fast shipping, and
discreet orders. He is a member of Science Madness, and best of all, a home chemist just like you and me.
EDIT: Last I checked he also has pyridine and CS2 in stock, both in small amounts but great for small experiments.
[Edited on 23-6-2014 by ScienceHideout]
hey, if you are reading this, I can't U2U, but you are always welcome to send me an email!
|
|
|
Crowfjord
Hazard to Others
Posts: 390
Registered: 20-1-2013
Location: Pacific Northwest
Member Is Offline
Mood: Ever so slowly crystallizing...
|
|
Very nice. Not sure if I noticed that they have LAH. Elemental Scientific does, too (or did, I haven't looked in a while).
A question: is LAH difficult or super dangerous to use in a home/hobby type setting? When I was doing research as an undergrad, the grad student I
worked with always used LAH under argon, in a glove box, in the fume hood. I've always wondered whether this was overkill, or completely justified, or
what.
|
|
|
ScienceHideout
Hazard to Others
Posts: 391
Registered: 12-3-2011
Location: In the Source
Member Is Offline
Mood: High Spin
|
|
I am pretty sure that the main issue is with its reactivity with water. I actually have an 'inflatable glovebox' that is like this really big plastic
bag you stick your hands into. I am sure that if I use that with an ungodly amount of dessicant inside, in my fumehood, I should survive.
No chemicals, even the most dangerous, can hurt you if they are handled with care.
Reading up on it, Baylor.edu says 'whenever large quantities are used work under an inert atmosphere.' I don't know how much you were using, but I
don't think that 10g is a large amount
[Edited on 23-6-2014 by ScienceHideout]
hey, if you are reading this, I can't U2U, but you are always welcome to send me an email!
|
|
|
Dr.Bob
International Hazard
Posts: 2659
Registered: 26-1-2011
Location: USA - NC
Member Is Offline
Mood: No Mood
|
|
I have used LAH and seen it used several times. It is quite dangerous due to both reactivity with water vapor in the air, and also its reactivity
with solvents, especially if they contain any water. At least one time, a coworker using several grams started a large fire by adding the LAH to the
solvent in one portion, and had not (apparently) used an inert enough atmosphere. This gentleman had an advanced degree and years of chemistry
experience, but got careless. Even a few grams of LAH can start a very hot fire. I would work very carefully with it, you DO need some sort of
inert atmospehere, dry solvents, and dry glassware or at least a very safe place. Hint, your kitchen is not a safe place. A separate shed or at
least some sort of hood. LAH reacts somewhat with THF to release heat, even when dry, which can start a fire easily. Diethyl ether is less reactive
with LAH, but even more more easily set on fire. And quenching it is best done with the Fieser workup, but must be done slowly, best after killing
the excess LAH with EtOAc.
|
|
|
AvBaeyer
National Hazard
Posts: 644
Registered: 25-2-2014
Location: CA
Member Is Offline
Mood: No Mood
|
|
I second Dr Bob's advisory. LAH really has no place in a home lab setting. The risk of fire or other adverse events in such a setting is just too
great.
Also, I would be somewhat skeptical of buying small amounts of air and moisture sensitive/reactive agents such as LAH since you do not know how they
have been stored or under what conditions your sample has been weighed out. You might not be getting all that you pay for.
AvB
|
|
|
woelen
Super Administrator
Posts: 7977
Registered: 20-8-2005
Location: Netherlands
Member Is Offline
Mood: interested
|
|
I can add to this, that I had a "nice" surprise with LiAlH4. Someone donated some LiAlH4 to me, it was in a tin can, hermetically sealed, and inside
the can a little plastic bag. I opened the can and the bag and poured the grey powder into a Schott Duran bottle with a very well sealing GL 45 cap.
After I poured the grey powder (which is completely free flowing) into the bottle I put the empty plastic bag aside in order to screw the cap on the
bottle. While doing this, the empty plastic bag burst into flames 
Fortunately I did this outside, I had read about high reactivity, but that it is so reactive I hardly could imagine. The plastic bag was empty, but of
course, still some powder sticked to the plastic. High surface area, combined with still air inside the plastic bag, a perfect combination for
starting a fire.
[Edited on 23-6-14 by woelen]
|
|
|
ScienceHideout
Hazard to Others
Posts: 391
Registered: 12-3-2011
Location: In the Source
Member Is Offline
Mood: High Spin
|
|
Thank you very much for the warnings with LiAlH4. I was thinking that I could store it in a desiccator, but now I am inclined to get creative and
store it in some sort of paint can with desiccant that I can flush with an inert gas.
Just wondering- is CO2 an acceptable 'inert atmosphere?' I do have access to nitrogen but CO2 is cheaper and heavier.
But anyways, I certainly will be careful when handling such a material. I trust that I will be able to do so safely, but your safety remarks are very
useful and go greatly appreciated.
hey, if you are reading this, I can't U2U, but you are always welcome to send me an email!
|
|
|
Dr.Bob
International Hazard
Posts: 2659
Registered: 26-1-2011
Location: USA - NC
Member Is Offline
Mood: No Mood
|
|
LAH will store fine in a metal can or glass bottle, especially if sealed inside an out can, jar or desiccator. The main hazard is when handling it
and mixing it with solvents or reactants. It has a very strong exotherm when reacting with some chemicals. It is also very staticy, in the winter
it will fly out of the can when you open it, in the summer, the static is not an issue, but it will absorb moisture very quickly on a humid day. So it
is best handled in the fall, if you don't have climate control in your lab area.
|
|
|
leu
Hazard to Others
Posts: 368
Registered: 13-10-2005
Member Is Offline
Mood: No Mood
|
|
Nitrogen is generally employed  Carbon dioxide has caused explosions as
mentioned in:
CAUSE OF EXPLOSIONS OCCASIONALLY OBSERVED DURING EVAPORATION OF SOLUTIONS OF ALUMINUM HYDRIDE AND RELATED COMPOUNDS
Geraldine Barbaras , Glen D. Barbaras , A. E. Finholt , H. I. Schlesinger J. Am. Chem. Soc., 1948, 70 (2), pp 877–877 DOI:
10.1021/ja01182a523
which is attached  The end results from the effort applied 
Attachment: ja01182a523.pdf (55kB)
This file has been downloaded 401 times
Chemistry is our Covalent Bond
|
|
|
ScienceHideout
Hazard to Others
Posts: 391
Registered: 12-3-2011
Location: In the Source
Member Is Offline
Mood: High Spin
|
|
Thanks, I will use N2 then
hey, if you are reading this, I can't U2U, but you are always welcome to send me an email!
|
|
|
Crowfjord
Hazard to Others
Posts: 390
Registered: 20-1-2013
Location: Pacific Northwest
Member Is Offline
Mood: Ever so slowly crystallizing...
|
|
...And I will stick to borohydrides for the time being. Thanks for the information, gentlemen. It is much valued and very appreciated
|
|
|
AvBaeyer
National Hazard
Posts: 644
Registered: 25-2-2014
Location: CA
Member Is Offline
Mood: No Mood
|
|
Sticking to borohydride is not such a bad idea. Sodium borohydride, with and without additives, can do many if not most, of the reductions that LAH
does. It also does many things that LAH cannot do because of its reactivity. There are many articles on the web about uses of sodium borohydride
under a myriad of conditions and with many type of functional groups.
AvB
|
|
|
Dr.Bob
International Hazard
Posts: 2659
Registered: 26-1-2011
Location: USA - NC
Member Is Offline
Mood: No Mood
|
|
I will agree with the use of borohydrides. I use them often, and they are much easier to use, work up, and handle. I have bottles of some of them
which are years old and still work fine. My personal favorite is sodium cyanoborohydride, which can do many things well, especially reductive
aminations, but the plain borohydride and triacetoxy variant also work well for many reductions. And there are choice of solvent, additives, and
order of addition which can control the reactivity. And I have yet to see a fire start with them, although the plain borohydride can be powerful. I
also like that cyanoborohydride can be used in methanol, acetic acid, water, DCE, and so many other solvents, which is rare for a reducing agent.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
