EvlRenne
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Preparation of NaBH4
Hello everyone,
due to the recent ban of selling quite a lot of useful compounds and an increased amount of watched chemicals in my country, purchasing NaBH4 is close
to impossible if you do not carry out a license for chem-related company/production.
I was trying to find the alternative - Alibaba/ebay/etc. all of it is a Russian roulette, and already being scammed by Alibaba's
"verified/diamond/trusted seller" for a 500$, makes me not to trust no-name online retailers.
I started to research the possible way of diy, and came across the attached paper, I saw a similar paper noticed by CJ here (on the science madness),
but the paper he was referring to was from 2013, this one is more recent.
But, to be honest, when I see yields of 99.5% with a suspiciously easy procedure I become skeptical.
How do you think, should I invest time/money into an attempt to reproduce NaBH4 preparation via Al-Mg under argon?
Honestly, I think it is too good to be true.
Attachment: NaBH4 via Mg-Al.pdf (4MB)
This file has been downloaded 337 times
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QuantumDot
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Fascinating. Never really thought of using milling in synthesis. I found another paper that synthesized NaBH4 in a mill, but without an inert
atmosphere and using magnesium hydride, sodium amide, and boron oxide; so your paper might not be completely out of reach.
I also found a paper describing its electrosynthesis in aqueous media which I think deserves a look too.
Attachment: NaBH4 Milling Synthesis (5.7MB)
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Attachment: NaBH4 Electrosynthesis.pdf (907kB)
This file has been downloaded 203 times
[Edited on 26-12-2022 by QuantumDot]
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Tsjerk
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Do note that they use a planetary mill, not a normal ball mill.
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EvlRenne
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Quote: Originally posted by QuantumDot  | Fascinating. Never really thought of using milling in synthesis. I found another paper that synthesized NaBH4 in a mill, but without an inert
atmosphere and using magnesium hydride, sodium amide, and boron oxide; so your paper might not be completely out of reach.
I also found a paper describing its electrosynthesis in aqueous media which I think deserves a look too.
[Edited on 26-12-2022 by QuantumDot] |
​
Hey there, yes, I saw those papers, every paper is out of the table, if it includes any hydride in the synthesis.
It is almost impossible to synthesize at home due to superior conditions, and if purchased, it is even more expensive then NaBH4.
I saw reports on electrochemical approaches, no-one could repeat it, so, apparently it is fake.
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EvlRenne
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Yes, I saw it, I already asked a friend of mine, will he be able to make it for me (he is a lathe master), because prices for commercial's is omfg.
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QuantumDot
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| Quote: Originally posted by EvlRenne |
Hey there, yes, I saw those papers, every paper is out of the table, if it includes any hydride in the synthesis.
It is almost impossible to synthesize at home due to superior conditions, and if purchased, it is even more expensive then NaBH4.
I saw reports on electrochemical approaches, no-one could repeat it, so, apparently it is fake. |
You're right, I couldn't find any papers replicating the electrosynthetic route; disappointing. Maybe start with making your own MgH? Bogdanovic has
published a couple of papers using anthracene to make the hydride.
Attachment: 10.1002@anie.198008181.pdf (246kB)
This file has been downloaded 144 times
Attachment: bogdanovic1984.pdf (366kB)
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EvlRenne
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| Quote: Originally posted by QuantumDot | | Quote: Originally posted by EvlRenne |
Hey there, yes, I saw those papers, every paper is out of the table, if it includes any hydride in the synthesis.
It is almost impossible to synthesize at home due to superior conditions, and if purchased, it is even more expensive then NaBH4.
I saw reports on electrochemical approaches, no-one could repeat it, so, apparently it is fake. |
You're right, I couldn't find any papers replicating the electrosynthetic route; disappointing. Maybe start with making your own MgH? Bogdanovic has
published a couple of papers using anthracene to make the hydride.
|
The reason why industrially hydrides are produced under crazy conditions - it is in the end economically and procedurally easier.
In both papers pressure up to 80atm., EtBr, chromium catalysts - it is too much for the "backyard" chemistry.
I worked once with a pressure of around 15 atm, although it was a glass reactor, and when I started to hear the cracking sound, I shitted
bricks enough to build a 2-store house.
Also, one very unpleasant factor in preparations of hydrides via metals - you have to work with nano-scale metal particles, and almost all metals
become pyrophoric in this size, which complicates the procedure further.
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tyro
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I was investigating a few different routes: milling magnesium, borax, and sodium carbonate in a ball mill and various takes on electrosynthesis.
The thread is here.
Problem with milling is the extreme conditions. I put my own attempt at milling on hold, as I felt it presented a pretty substantial risk, and
probably more so because it was unreasonably loud to run during dry testing. I feel it might be possible to mitigate some of the risks by monitoring
reaction conditions (pressure inside vessel, heat, etc) and running under inert atmosphere, though I probably will try and find a way to reduce the
noise aspect first.
On electrochemical routes: most seem to be lacking promise of substantial results. Many papers I've come across reference incredibly small amounts of
borohydride being formed. Not nearly enough to warrant running the process and extracting. Furthermore, most seem also to indicate that the
borohydride concentration peaks pretty rapidly and then declines. Perhaps some sort of continuous extraction could help here, but I feel this would be
out of the reach of the amateur.
There have been some references I've come across which indicate issues with electrostatic repulsion at the cathode, preventing formation of the
borohydride. Some have attempted to mitigate this by using some form of pulsed voltage systems, wherein the voltage differential to produce the
borohydride is applied, then a reverse polarity is applied at a potential less than that to cause an electrochemical breakdown, followed followed by a
neutral or refectory period, all at some regular interval.
I've yet to have any luck with either, but my materials, methods, and analytical equipment are all pretty basic.
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EvlRenne
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| Quote: Originally posted by tyro | I was investigating a few different routes: milling magnesium, borax, and sodium carbonate in a ball mill and various takes on electrosynthesis.
The thread is here.
Problem with milling is the extreme conditions. I put my own attempt at milling on hold, as I felt it presented a pretty substantial risk, and
probably more so because it was unreasonably loud to run during dry testing. I feel it might be possible to mitigate some of the risks by monitoring
reaction conditions (pressure inside vessel, heat, etc) and running under inert atmosphere, though I probably will try and find a way to reduce the
noise aspect first.
On electrochemical routes: most seem to be lacking promise of substantial results. Many papers I've come across reference incredibly small amounts of
borohydride being formed. Not nearly enough to warrant running the process and extracting. Furthermore, most seem also to indicate that the
borohydride concentration peaks pretty rapidly and then declines. Perhaps some sort of continuous extraction could help here, but I feel this would be
out of the reach of the amateur.
There have been some references I've come across which indicate issues with electrostatic repulsion at the cathode, preventing formation of the
borohydride. Some have attempted to mitigate this by using some form of pulsed voltage systems, wherein the voltage differential to produce the
borohydride is applied, then a reverse polarity is applied at a potential less than that to cause an electrochemical breakdown, followed followed by a
neutral or refectory period, all at some regular interval.
I've yet to have any luck with either, but my materials, methods, and analytical equipment are all pretty basic. |
The electrochemical approach proved to be a "fake news", a lot of people tried to reproduce the procedures mentioned in published papers with no
success.
The main reason, I was referring to the paper I attached to the first post - doable conditions for a "home" chemistry: working under ambient pressure,
no high temperature nor hydrides are involved in the synthesis.
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