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I need to do a reaction with dry pyridine. I know I can buy it dry, but I want to be able to keep it dry for future use. (The lab that I'm currently working in is poorly set up to do this type of thing; that's what I get for doing a sabbatical in a Materials Science and Metallurgy Department.) Can I just throw in some molecular sieves and blanket it with nitrogen after use in a glove bag?
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Pyridine is a REAL PAIN to DRY (titanium amide complex dry....) but relatively straightforward to dry (Pt phosphine complex dry).
If all you need is dry, then N2 blanket/sieves should be ok. However, if you need it DRY, you are going to have to distill from CaH2 under N2 and store under N2/sieves in a "valved reaction vessel" or bomb.
Check W. L. F. Armarego and C. L. L. Chai "Purification of Laboratory Chemicals" (Butterworth-Heinemann; 5 edition, 2003, http://www.amazon.com/exec/obidos/tg/detail/-/0750675713/) for more ideas on drying
store it in a sealable glass reaction vessel that has been dried in an oven, distill it from CaH2 prior to use.
Ideally, distill it into your storage vessel. I think you can store it over drying agents too.
Purchasing anhydrouse py isn't great, because once the seal gets broken (ie after the first needle goes through the septum), it'll be hard to keep dry, and you will have to purify your "dry" pyridine later
Would you do the same for 2,6-lutidine? I guess I'll do CaH2 under N2 - our lab plans to keep the still setup.
Should be interesting.
We've distilled picolines and 2,6-lutidine from calcium hydride in our lab, it works well with a short-path distillation under N2 or slight vacuum. Its always a good idea to put glass wool in the neck of the distilalltion peice to avoid bumping of CaH2 up into your product, which can happen when you get down to low volumes of liquid in the flask you are distilling from.
-Kyle