Sciencemadness Discussion Board

Preparation of NaBH4

EvlRenne - 24-12-2022 at 03:27

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 373 times

QuantumDot - 26-12-2022 at 01:18

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)
This file has been downloaded 254 times
Attachment: NaBH4 Electrosynthesis.pdf (907kB)
This file has been downloaded 240 times

[Edited on 26-12-2022 by QuantumDot]

Tsjerk - 26-12-2022 at 01:41

Do note that they use a planetary mill, not a normal ball mill.

EvlRenne - 26-12-2022 at 10:58

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.

EvlRenne - 26-12-2022 at 11:03

Quote: Originally posted by Tsjerk  
Do note that they use a planetary mill, not a normal ball mill.


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.

QuantumDot - 27-12-2022 at 00:06

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 165 times

Attachment: bogdanovic1984.pdf (366kB)
This file has been downloaded 174 times

EvlRenne - 27-12-2022 at 08:30

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.

tyro - 28-12-2022 at 21:28

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.

EvlRenne - 29-12-2022 at 06:05

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.