[kamiyu]

Hi guys

I would like to know how you store the butyllithiums bottle. I think, clearly, parafilm is not sufficient.

Indeed, I learn from others that they use teflon adehesive tape to seal the tiny hole of the bottle septum on which the syringe was put through it.

I was inspired by this idea and I am currently using aluminum foil together with ordinary adhesive tape to seal the hole. The combination of aluminum foil and ordinary tape, I think, serve the same purpose as Teflon tape.

[discodermolide]

Parafilm and the top of the bottle should be OK for storage. I always kept mine like that and they always survived. You can the concentration check by titration.
Obviously if the septum becomes "used" then replace it.

[kamiyu]

Parafilm really works 

I never trust it. I veiw parafilm in the lab as excessive..

[discodermolide]

If that's your view then don't use it. It was perfectly ok for my work.
Aluminium foil, in my opinion should not be used for storage purposes, unless the substance is light sensitive. The alkyllithums are quite aggressive and may well start to react over time with Al.

[kamiyu]

Thanks for your reply.

1) Is there any evidence that n-butyllithium reacts with aluminum??

2) More importantly, the aluminum is used to seal the hole through which syringe is pierced through. I think that the only thing that contact with the aluminum is the solvent (hexane in this case), but not the butyllithium.

3) The reason why I think parafilm is not good is that parafilm gets slowly dissolved by organic solvent.

[PhDoc]

Regardless of how much parafilm or teflon tape is used, n-BuLi undergoes thermal decomposition. The rate (in hexanes) is slow at 0C, increasing linearly to about 20C, and then exponentially at ~25C. At temperatures >50C it readily decomposes. Although contact with air and atmospheric moisture leads to loss of titer, just how much air gets into a capped reagent bottle with the Sure Seal cap in place? When the cap weakens, and this generally takes time, it's convenient to switch to an ordinary septum to cover the sure seal (like a prophylactic).

http://www.chem.harvard.edu/groups/myers/page8/pdfs/2-organolithium%20reagents%20FINAL%20page%20number.pdf

The best thing to do when using only small quantities at a time is to purchase the 100mL bottle, take good care of it, and titrate before use. Most of the time you'll use up the reagent before it gets the chance to go "bad." Really meticulous people store their 100mL BuLi bottles in a glass desiccator.

Personally, I buy it, titrate it, use it, store it, and once the titer gets too low, I just replace it.