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Pseudo-"wet"- BH4 amination BH4

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XrLeap:
Hi Bandil,

Thanks for taking time to answer my rather stupid questions :-[ .

SWIM would like to understand in this Pseudo-"wet"- BH4 amination BH4, why is it that the alkali hydroxide is not used to push the methylamine out from water to IPA? Was it because that methylamine.hcl was used in Barium's, 40% aq was used in this case?

Was it that the mol sieves(3A) has "sucked" away the H20 and the gas would just go into IPA?

Wouldn't the mol sieves also "suck" away the methylamine a bit?

Was the stirring of before filtering the mol sieves violent, just as violent as Barium's method?

Lastly, another stupid question which SWIM has posted in another thread. The NaBH4 was added as in solid form, not as solution? Can one use IPA as solvent and then add them into the main mixture?

Oops, so many questions, so little knowledge of SWIM's :-[ .

armageddon:
Molecular sieves are able of absorbing molecules smaller than a certain diameter (with 3A sieves, this is 3 Angstrom), with 3A sieves being only able to absorb water and every molecule being smaller than water.

But methylamine is way bigger than water, when seen as a molecule. So the sieves take up water while leavingbehind the methylamine(g), which is instead taken up in the IPA.

Hence they are called "sieves"...

Greetz A

XrLeap:
SWIM attempted this Pseudo-"wet"- BH4 amination BH4 with MDP2P, faced a serious problem. The NaBH4 wouldn't dissolve in the dry IPA......

SWIM tried to just dissolve NaBH4 in IPA, it was not able to dissolve even 0.5g in 50ml(under room temperature). Pls help as how this can be done, with what temperature?

armageddon:
I guess if you're using fairly dry IPA, you could expect the NaBH4 to not dissolve at once - therefore Bandil suggested to dump it in all at once and let react overnight...

(I would at least guess that the reason for the slow rxn he mentions is exactly this low solubility - right?)

greetz

thinkgeek:
sorry to resurrect subbing for research

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