[Nescafe]

Hi everyone,

I recall seeing posts on Sodium azide many times on this forum so excuse me if some of what I am about to ask is a repeat.

This article here resurfaces a well known source of concern about this reagent and that is why I am asking some of the following questions (for interest the article is http://cenblog.org/the-safety-zone/2010/04/sodium-azide-acid-boom-2/)

I am performing multiple reactions where I convert a leaving halogen with an Azide using NaN3 in DMF. The max quantity of azide that I will be needing is 150mgs.

1) Is there a number of how much NaN3 is actually considered dangerous? I mean let us say that you make a bad mistake of exposing it to acid, will 50mg react as unpredictably and dangerously?

2) In your experience what is the best way of performing a work up?

If anyone else has anything to share on the use of this reagent and their experience dealing with it feel free to share.

Cheers,

Nescafe.

[TheUnassuming]

I don't know at what quantity it becomes dangerous, but have used it on many multi-gram scale reactions without issue.

Depending on what else is going on in the molecule, doing a basic wash works well.  Another option that has worked well for me in the past is to dilute with several reaction volumes of something like DCM and filter off the majority of the excess NaN3.

On 150mg scale I wouldn't worry much, especially if you are somewhat careful.

[Furanone]

In an aqueous solution, I typically use 0.02% sodium azide and this is enough to prevent bacterial growth in my solutions (often with many nutrients bacteria can thrive on ie. glucose, protein, etc) for months. Cannot answer your question as to what becomes dangerous though for humans. The LD50 oral for sodium azide for rats/mice is 27 mg/kg and LD50 dermal is 20 mg/kg for rats.

http://www.sciencelab.com/msds.php?msdsId=9927588

[Nescafe]

What do you recommend is the best way to perform work up and get rid of excess sodium azide, woould using sodium nitrite solution and HCl work?

[Furanone]

Sorry, I can't help there either. Typically, I would just pour waste in a bottle labeled "Aqueous Waste" and the University had services to come and collect each month.

[discodermolide]

What do you recommend is the best way to perform work up and get rid of excess sodium azide, woould using sodium nitrite solution and HCl work?

Yes this works well, you get a great laugh as well!

[Nescafe]

Thanks disco so in which order just transfer to sep funnel add saturated solution of sodium nitrite then 1M Hcl step wise or all in one go? I thought sodium azide was sensitive to acid.

Thanks again

[discodermolide]

Add the nitrite, cool and stir for 10 minutes then add the HCl dropwise.
Watch out for vigorous gas evolution and foaming.