Sodium borohydride storage

[GC_MS]

Sodium borohydride is a moisture-sensitive substance. If you would store it without taking special precautions, the powder will form a cake and loose some of its reductive strenght. To minimize caking, I store my NaBH4 in 250 g plastic containers (do NOT use glass!), which are sealed with teflon tape. The container is stored in a desiccator. I found that my sodium borohydride remains a fine powder for an extended time.

[Barium]

Yes there are absolutely a few things to remember when storing and handling moisture sensitive things like borohydrides and aluminumhydrides. Even though sodium borohydride is nowhere near as moisture sensitive as e.g. LAH, one should still be as careful as possible with it.

If you buy 500g sodium borohydride and know this will last you about one year, do yourself a huge favor and transfer perhaps 25-50g to a smaller container. The bulk of your borohydride will now be left alone until its time to refill the smaller container. This means less exposure to humid air and less decomposition. All this will, in the end, give higher yields in the reactions.

[GC_MS]

Thanks Ba, you made me clear I forgot to mention how I stock NaBH4 "for future use". You can order a large quantity for certain industrial activities in your well-ventilated backyard, and transfer the lot to smaller baggies. I purchased a food vacuum sealer:



and it does a great job! When the lot recently arrived, I transferred the fine powdered NaBH4 into smaller bags - each containing more or less 200 g NaBH4 - and sealed them with the vacuum food sealer. These baggies are stored somewhere in a cool (ca 15°C) and well-ventilated area in the lab. Whenever my 200 g baggie is empty, I take a new one from the stock. Once the bag is opened, it is stored as in my previous post (read upwards).

Usually, NaBH4 contains anti-caking agents (magnesium sulfate?) to prevent this process to a certain extent.

[demorol]

I store my NaBH4 in 250 g plastic containers (do NOT use glass!)

Why is it necesary to use plastic containers? My borohydride is packed in glass bottles by manufacturer.

[GC_MS]

http://physchem.ox.ac.uk/MSDS/SO/sodium_borohydride.html

AFAIK, NaBH4 is always packed in plastic when sold commercially. The plastic bag is often packed in a plastic or metal box.

[Vitus_Verdegast]

Then I wonder why Acros uses PE plastic bottles for eg. phenols and p-benzoquinone, but a glass bottle for NaBH₄ ?

[Zero_To_Nine]

All the NaBH4 I have worked with was sold in glass bottles. I do remember however that NaCNBH3 was stored in PE and this again was placed in a metal container. The anti-caking agent often added (upto 0.5%) is magnesium carbonate.

[GC_MS]

NaBH4, sodium borohydride, CAS 16940-66-2
Safety: R14/15, R34, R24/25

Handling and storage

Handling: Avoid contact with skin, eyes and clothing. Wear suitable protective equipment. Avoid contact with water. Do not breathe vapours or spray mist. Wash thoroughly after handling. Ensure adequate ventilation. Keep container tighly closed.

Storage

Storage conditions: Keep containers tightly closed in a dry, cool and well-ventilated place. Keep away from heat and sources of ignition. Do not store this material in containers made of the following: glass, aluminium.
Storage temperature: < 60°C
Further information: Sodium borohydride can liberate flammable hydrogen gas upon contact with acids, oxidizing agents, water and transition metal salts. Moisture can cause the product to decompose and slowly liberate hydrogen, which can accumulate in the headspace of the storage container. Drums should be ventilated by loosening the top bung prior to opening.

Why not glass? I'm not sure, but maybe it is related to the fact that glass contains several metal ions, which might react with the borohydride. Just a guess though.

[lugh]

Two of the transition metal ions that can catalyze sodium borohydride hyrolysis are nickel and cobalt, evolving 40 cubic feet of hydrogen gas for each pound of sodium borohydride    Obviously, glass containers used for storage of sodium borohydride don't have any such transition metal ions, or the sodium borohydride wouldn't last long  

[RoundBottom]

> decompose and slowly liberate hydrogen

maybe because if it does start decomposing in a sealed glass container, it would explode from pressure? 

this happened recently to SWIM.  some peracetic acid stored in a heavy glass acid container (think moonshine jug) in the fridge for 6 months slowly built up pressure until it exploded, breaking all the other glass bottles in the fridge, shredding a plastic H2O2 container, embedding glass in the walls of the fridge, and blowing the door open (not off).

a lesson: release built up pressure regularily.