Triflic Acid - 19-6-2021 at 08:06
I saw the chemplayer video where they make copper hydride. I was wondering if it would work as a substitute for sodium borohydride, or if it was
possible to convert it to sodium hydride by a simple displacement reaction in something like THF or dioxane.
zed - 20-6-2021 at 00:35
Don't think so, but maybe.
Copper is very decent Hydrogenation Catalyst. Unfortunately, it is too reactive.
Platinum, Palladium, Ect... Gold Maybe. More Nobel than Copper.
Copper Chromite or Copper Barium Chromite, are good hydrogenation catalysts. But, lots of pressure is required.
Sodium Hydride and Sodium Aluminum Hydride, aren't really hard to make, but you need a pressure reactor.
draculic acid69 - 20-6-2021 at 03:29
What about copper borohydride? Just a thought.
Opylation - 20-6-2021 at 04:35
That’s interesting. If copper hydride is easily made then maybe the borohydride could be prepared and then displaced with a sodium cation?
Or maybe the copper hydride can be used to make sodium hydride by reacting it with sodium metal? If there is no issue with an amalgam(alloy?) forming
[Edited on 20-6-2021 by Opylation]
Triflic Acid - 20-6-2021 at 06:14
Actually, the thought of the hydride reacting with molten sodium seems pretty promising. I don't think the borohydride can be prepared, it bursts into
flames at high temp, and slowly decomposes at temperatures above -5C. Going on a whim, I think that the copper hydride is soluble in dioxane, and so
is sodium chloride. Sodium hydride isn't, so it might displace the copper.
zed - 20-6-2021 at 23:29
Perhaps you know too much already, to learn anything new.
Triflic Acid - 22-6-2021 at 16:04
@ zed, what does that mean?
woelen - 23-6-2021 at 13:04
Copper hydride and sodium hydride are completely different compounds. Copper hydride is some polymeric covalent species, which can exist in water,
even at low pH. It can be made from the reaction of copper(II) ions with hypophosphite in acidic solution. It is fairly stable, although on long
standing it does decompose slowly to copper metal and hydrogen. As far as I know, there is no real solvent for copper hydride. It is used as
suspension, or combined with certain ligands in order to get a coordinated species in solution, but free CuH is not produced in any solvent.
Sodium hydride, on the other hand, is an extremely strong base, which certainly cannot exist in water, not even at very high pH. Sodium hydride is an
ionic species, consisting of Na(+) ions and H(-) ions. These H(-) ions are protonated immediately and irreversibly in contact with water to produce
H2:
H(-) + H2O --> H2 + OH(-)
This reaction even occurs at pH > 14.
I do not know any solvent, in which NaH simply dissolves. There are many solvents in which it is protonated (and in the process it dissolves,
producing some other sodium salt and hydrogen gas), but I do not know any solvent, in which solvated H(-) ions are produced.
Triflic Acid - 23-6-2021 at 13:14
Ok, so no chance of converting copper hydride to sodium hydride 
draculic acid69 - 23-6-2021 at 17:38
Doesn't look like it. Just buy the steel pot,argon cylinder,ss ball valves and bubble the hydrogen thru the molten sodium. No shortcuts on this one.
zed - 23-6-2021 at 20:35
"@ zed, what does that mean? "
It means; do you want to discuss reasonable ways to make Sodium Hydride?
If you have a stirred pressure reactor, it isn't terribly difficult.
Reactions generally take place in a non-reactive hydrocarbon solvent, at moderate temperatures, and somewhat elevated hydrogen pressures.
https://patents.google.com/patent/US3222288A/en
If you can execute this, you might just as well make NaAlH4. Similar reaction conditions, just prolonged time, and in the presence of Aluminum
powder. NaAlH4 can be converted to LiAlH4.
[Edited on 24-6-2021 by zed]
[Edited on 24-6-2021 by zed]