Can it be substituted for sodium borohydride in the synths discussed here at the Hive???

z

Yes, if it is substituted in a stoichiometrical amount. The molar weight of KBH4 is higher than for NaBH4.

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http://rhodium.lycaeum.org

Great,  cuz it's about 1/3 the price! 

Will there be any noticeable difference in the workup of any reduction carried out with KBH4 in place of the NaBH4, or is it a completely transparent substitution?

z

Solubility of KBH4 might differ somwhat from NaBH4, but for our purposes the differences are negilible (if there are any at all). Reactivity, workup etc. can be considered exactly the same for Na and K variety.

Grazie!

Yeah, the solubility might be a bit of a problem. Only 0.7% in methanol vs. 16% for sodium borohydride.

Oooops, it is that low? Didn't know that!
On the other hand, that doesn't necessarily mean it's a disadvantage. The NaBH4 reductive amination needs slow addition of NaBH4 anyway, when you use KBH4 the concentration will be limited by the solubility. Could even be a good thing.
Post your results zooligan.

Potassium borohydride CAS-Nr.[13762-51-1]

Solub. in water (25 degrees) : 190g/L

Used for preperation of polyfluoro diketones / and for an unusual synthesis of ethers from aliphatic ketones / Reagent for the preperation of many Potassium-indolylborates and their metal complexes.

Sodium borohydride CAS-Nr.[16940-66-2]

Sulub. in water (25 degrees) : 550g/L  (slow decomposition)

Reducing agent for aldehydes, ketones, quinones etc. auxiliary in ther determination of hydride formers by ASS.


The Merck catalogue tells nothing about using KBH4 as a versatile reducing agent, but i need to give it a try since NaBH4 has the toxic symbol and therefore is impossible to obtain (at least for me).


-Le Vogue

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Tie to birds together, though they have four wings they cannot fly.

Well shit, if you're hell-bent on using K-Borohydride then why not learn how to use it and make it? How can one go about making at least one of his friend's bladder explode into an underwear-stained wet spot, decorated in blood and puss, unless the attack was only permitted on the main-stream brain? Keep it real! See ya!   

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  Yes, I said by yourself, alone! Let no one breathe, and no one see the hate you love to show me!

Since this is an old post, has anyone had results to share?

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there's a big difference between criticizing your government and criticizing your country