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Author: Subject: Strong Reducers on HMS Beagle!!!
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[*] posted on 22-6-2014 at 17:44
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]




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[*] posted on 22-6-2014 at 17:52


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.
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[*] posted on 22-6-2014 at 18:01


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]




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[*] posted on 22-6-2014 at 19:21


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.
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[*] posted on 22-6-2014 at 20:20


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.

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[*] posted on 22-6-2014 at 22:46


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 :o

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]




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[*] posted on 23-6-2014 at 07:20


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.




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[*] posted on 23-6-2014 at 08:27


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.
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[*] posted on 23-6-2014 at 08:38


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 :P The end results from the effort applied :cool:





Attachment: ja01182a523.pdf (55kB)
This file has been downloaded 477 times





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[*] posted on 23-6-2014 at 08:42


Thanks, I will use N2 then :)



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[*] posted on 23-6-2014 at 14:56


...And I will stick to borohydrides for the time being. Thanks for the information, gentlemen. It is much valued and very appreciated :)
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[*] posted on 24-6-2014 at 16:54


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.

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[*] posted on 24-6-2014 at 17:19


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.
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