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**list.uvm.edu] 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 Folks- 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 here-http://www.sigmaaldrich.com/etc/medialib/docs/Aldrich/Bulletin/al_t echbull_al134.Par.0001.File.tmp/al_techbull_al134.pdf - 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 ******************************************************** This communication and any files transmitted with it may contain information that is confidential, privileged and exempt from disclosure under applicable law. It is intended solely for the use of the individual or entity to which it is addressed. If you are not the intended recipient, you are hereby notified that any use, dissemination or copying of this communication is strictly prohibited. If you have received this communication in error, please notify the sender. Thank you for your co-operation. ********************************************************
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