I am about to carry on a click reaction. I heard of that NaN3 is a dangerous compound which is easily explodable, and HN3 is as poisonous as HCN! What details should I pay attention to? Can you give me some advice? Thanks!
NaN3 is fairly safe to use as long as the proper precautions are observed. There are minimal risks if you are using small amounts (less than 1 g) and following trusted procedures using appropriate solvents/reagents/catalysts. Things you want to avoid doing are heating NaN3 while dry - that will cause violent decomposition; scratching glass material around NaN3 when dry, or acidifying NaN3 solution (produces HN3) if not well ventilated in a proper fumehood and wearing mask or appropriate device.
Oh by the way I have used NaN3 often enough in click reactions with nitriles to make tetrazolates without ever having any problems.
The azide ion has a similar toxicity as that of cyanide ion (LD50 = 27 mg/kg for rats). Be sure to use appropriate gloves when weighing azido salts.
Sodium azide reacts violently with several common laboratory organics such as: CS2, bromine, Bronstead acids, and heavy metals.
NEVER use chlorinated solvents as reaction media! Utilizing dichloromethane or chloroform will result in the formation of explosively-unstable di- and tri- azidomethane, respectively Heavy metals (e.g., Cu, Pb, Ba) form shock and pressure sensitive compounds with azide anions. This may affect us in that an ‘azide residue’ may form of metal parts.
All organic azides decompose with introduction of external energy. Any azide synthesized should be stored below room temperature (-18°C) and in the dark.
Never use distillation or sublimation as purification techniques! Purification should be limited to extraction and precipitation. Better to react them in situ if you can.
Organic azide waste should be placed in a separate, explicitly-labeled container designated solely for azide
waste. Extra caution must be taken to make certain that azide waste not come in contact with acid. Acids will protonate the azide ion and from the highly-toxic hydrogen azide (toxicity similar to that of hydrogen cyanide).
Besides the previous suggestions, you need to ensure a secure disposal. If you put your azide containing reaction mixture in a waste container containing transition metals (say Ni) it is likely to explode. Transition metals are catalysts for N3- decomposition.
I usually destroy azide ions directly after the reaction by adding ethanolic iodine solution with sodium thiosulfate present as a catalyst (don't ask me how the reaction works, but it does). Your fine to dispose of the reaction products into non-halogenated organic waste as soon as the colour of your reaction mixture remains brown (due to excess iodine).
Avoid ground glass joints if possible, use a blast shield for safety, I think everything else has been covered.
- Badges
- Science topic