Date: Tue, 6 Jan 2009 18:40:38 -0700
Reply-To: "Latimer, Lee" <lee.latimer**At_Symbol_Here**ELAN.COM>
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: "Latimer, Lee" <lee.latimer**At_Symbol_Here**ELAN.COM>
Subject: Re: UCLA Lab Fire
Comments: To: List Moderator
In-Reply-To: A
I heartily support Joseph's comments and add some.  

My decades of experience with these reagents shows them to be capable of
safe and exciting use by following the basic guidelines in such places
as the insert that comes in the package from Aldrich.  In particular, do
not invert such bottles as you will dislodge accumulated sediments in
the bottom and reduce your titer, and create an unsafe situation of a
bottle of pyrophoric reagent controlled in your less desirable hand (the
other one that you trust more will have the syringe).  It is best to
clamp the bottle, most often at the neck.  Use a long enough needle to
easily reach the solvent level, purging the air space by bending the
needle gently over to the point the gas space may be discharged into the
bottle before careful removal of the needle.  I strongly encourage use
of needle vales available in the Aldrich catalog (at least in the past).

It is important to note that not all alkyl lithium reagents are best
stored cold.  Methyl lithium will crystallize, making things worse.
Check the bottles and commercial data from manufacturers such as Foote.

For the budget conscious chemist, realize that the cost of disposal of
large bottles which have been deemed poor exceeds the saved purchase $$
for buying in bulk.  Quenching can be done safely, but is the largest
source of organometallic fires and generally should not be done despite
the logic to do so before disposal.

Be safe,

Lee Latimer

-----Original Message-----
From: DCHAS-L Discussion List [mailto:DCHAS-L**At_Symbol_Here**] On Behalf Of
List Moderator
Sent: Tuesday, January 06, 2009 7:07 AM
To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
Subject: Re: [DCHAS-L] UCLA Lab Fire

From: "Pickel, Joseph M." 
Date: January 6, 2009 9:36:20 AM EST (CA)
Subject: RE: [DCHAS-L] UCLA Lab Fire


For what its worth, having worked in the lab for almost 10 years with  
n-BuLi, sec-BuLi, and t-BuLi, and a variety of their derivatives, I am  
dismayed by some of the advice given in the previous message.  The  
incorporation of opinions and speculation takes away from the fact  
that alkyl lithiums are truly hazardous materials and whether or not  
the author agrees with the facts of the newspaper article, it seems  
that in one way or another, some poor student has sustained serious  
burns by coming into contact with an alkyl lithium compound.  That  
being said--- these materials can be handled safely (even in sure-seal  
bottles) by personnel who understand the hazards of the material and  
take the appropriate precautions.

I will not go into great detail about what precautions must be taken  
to handle alkyl lithiums and other pyrophoric materials, but I do want  
to dispel some of the generalizations proposed in the previous note

- ***The pyrophoricity of alkyl lithiums will depend on concentration,  
solvent, humidity etc... generalizations ala t-BuLi will be more  
pyrophoric than n-BuLi are not necessarily accurate or helpful and no  
one should be given the idea that a t-BuLi is significantly more  
dangerous than others! Alkyl lithiums come in a variety of solvents at  
a variety of concentrations and almost every one of these solutions  
will catch fire if exposed to a suitably humid atmosphere.  That being  
said, the author of the previous letter was probably working with a  
very old and therefore less concentrated bottle of n-butyl lithium  
when he got it on his hand which is why it didn't burn.

- Sure-seal bottles aren't perfect, but they provide a safe way to  
handle alkyl lithium solutions in a bench top environment.  Unless the  
seal is punctured by a very large gauge syringe or a nail, the seal is  
sufficient to prevent moisture from entering the bottle and causing  
big problems.

- The technique described below for withdrawing/dispensing solutions  
from a sure-seal bottle is the lazy/ quick and dirty way of doing  
things and can lead to significant hazards- I would not recommend them  
to anybody.  Better methods are described in the Aldrich technical  
bulletin cited

- I agree that purchasing large containers of chemicals for purposes  
of cost savings is a bad idea, but that statement ignores the problem  
of how to tell an ordinary chemist with a limited budget about the  
merits of small containers. However, purchasing alkyl-lithium  
compounds in small bottle is a no-brainer even for the thrifty  
chemist!  You see- even in the best storage conditions (complete  
sealed from the atmosphere under an inert gas blanket and in the  
Fridge) alkyl lithium compounds degrade over time to more stable  
components.  Therefore, the concentration of the alkyl lithium  
solution marked on the label is almost always higher than what is  
actually in the bottle. That means for a given reaction- the chemist  
must either determine the concentration of the solution prior to each  
use or use an increasingly large excess of solution for each  
experiment... either one of the workaround techniques is less cost- 
efficient that buying a small bottle on an as needed basis.

Be safe,

Joseph M. Pickel, Ph.D., CCHO

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