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From: info**At_Symbol_Here**ilpi.com Subject: Re: [DCHAS-L] UCLA Lab Fire Date: January 6, 2009 11:11:39 AM EST (CA) I must clarify a few points and follow up on one or two. 1. The shorthand procedure Nameless Labmate used was deliberately brief, and relates the established procedure that was used in the laboratory. It was not meant to be an instruction/endorsement, and I referred readers not only to Aldrich's web page which has the link to Bulletin AL-134 (Handling Air-Sensitive Reagents) but also to my web page on pyrophoric materials that contains links to the their Bulletin AL-164 (Handling Pyrophoric Reagents). I should have taken the time to explicitly point out that there are safer techniques, but in the interest of brevity on an already long post I did not make that clear, so thank you for taking the time to point that out. 2. There is no doubt that all BuLi reagents are dangerous and water- reactive, but t-BuLi will ignite even in dry air. On an equimolar basis, t-BuLi *is* more dangerous; it is not only water-reactive, it is pyrophoric. In my personal experience, I have never seen spilled n-BuLi in the 1 to 2.5 M range spontaneously ignite in ambient air, but it obviously could if, for example, it landed near, for example, water on a condenser etc. or one was using some unusually high concentration. And to be clear, the n-BuLi I spilled on my hand was 1-2 M (as we always titrated our bottles before use). My hands are a source of moisture, and while the reagent clearly reacted with my fingers, they did not catch fire, but it they did get warm from the heat of the reaction! That said, Joseph is correct in that all of these substances need to be treated with great respect, and nobody should infer that n-BuLi is somehow "safe" or won't catch fire. 3. Sure Seal bottles are a fine device and I encourage the proper use of those bottles. I should have explicitly added to the Lessons that you have to maintain them; I alluded to that with the Parafilm comment but didn't finish up. I have seen nBuLi and Grignard Sure-Seals with gaping holes in them. If your bottle reaches that kind of state, the best thing to do is a cannula transfer into a new empty Sure Seal bottle or other suitable storage container. Parafilming and "getting by" with jury-rigged solutions contributes to accidents, a point I hope was clear from the original post. 4. A good chemist will *always* titrate their alkyllithium and related compounds before use. These are easily done on a very small scale and take just a few minutes. As Joseph notes below, akyllithiums are notoriously unstable, and the concentration in the bottle can be significantly higher (from solvent evaporation or precipitation, for example) or lower (from air/water infiltration) than the what is given on the label. Titration is even more important for Grignards which tend to come in ethers and undergo Schlenk equilibria to mixtures of RMgX, MgX2 and R2Mg. Never rely on what the bottle says for concentration, even for a "fresh" bottle. And, most importantly, use the correct titration method for your reagents. Some methods do not give good results for certain reagents, so do a careful literature search to determine the best method. Rob
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