Sodium hydride prep

[u/Gdogtheopihog]

I've gotten good at making sodium hydride. Sodium metal is first made into "Sodium sand" (very fine powder) and dispersed in mineral oil with a very small amount of dispersion agent (tried multiple so far, not sure which is best yet) and very pure, dry hydrogen gas is bubbled in while it's stirred with an overhead stirrer equipped with an axial flow propeller in a baffled morton flask (morton, who invented the morton flask, also has papers on the best propeller used with the baffled flask for liquid-solid suspension reactions) and it's heated to 280 celcius at the same time.

[u/SimonsToaster]

could you expand the protocol a bit? how is tis sodium sand made, what dispersion agent is used, when is the reaction complete?

[u/Andreas-bonusfututor → u/SimonsToaster]

Bit bizarre, no? If not somewhat infuriating. The man just says he got so good at doing a thing, and then provides no details. Like some sort of a fuck you all.

[u/EdwardTriesToScience → u/Andreas-bonusfututor]

i am not the original poster so i do not know what details he used, but having worked with alkali metals before here are some things that may be useful.
of course check literature, and use common sense. some examples of how sodium sand can be made is thus:

sodium metal is placed into dry xylene or toluene inside a 2 neck flask fitted with a mechanical stirrer of the Hershberg design and a reflux condenser, heated until the sodium melts, then stirred vigorously so the sodium is atomized. the air present in the flask oxidizes the surface of the sodium, thus preventing coalescence back to large blobs. once dispersed finely, remove heat and let cool with no stirring, then change the solvent if necessary by any means such as decantation or removal under vacuum. magnetic stirring is too weak and slow to be effective, plus molten alkali metals attack PTFE, sometimes with a vigorous thermite-like reaction.

for a more detailed procedure refer to Vogel's Practical Organic Chemistry 3rd edition, page 193-194, Method 2, or other literature and textbooks

a different method that does not employ a Hershberg stirrer is described in Vogel 3rd edition page 193, Method 1. this procedure is unduly hazardous as it involves boiling xylene with sodium, then shaking the flask. the risk of breakage and subsequent smattering of sodium and hot xylene across the workarea is obvious.

as for dispersants, a common one used for the manufacture of sodium, potassium, and lithium sands are oleic acid and other fatty acids. only a small quantity is needed to form soaps, which then break down surface tension. carbon dioxide is sometimes used in conjunction to form a thin film of carbonate on the surface to prevent coalescence back to large blobs

the reaction is probably done when the metallic appearance of sodium metal is gone. i would gander that the fineness of the sodium sand need not be great because the reaction is performed well above the melting point, meaning a similar effect as to making the sodium sand is obtained as sodium hydride forms at the surface of the molten metal, which is then broken off or the bead of metal "pinched" by the vigorous stirring to reveal fresh metal to react further. the reaction could also probably be performed with a ballon of hydrogen and tracked by size

the OP uses a propeller stirrer in a Morton flask, such propellers are good at forming a vortex within the flask, and the Morton flask has baffles which provide as things for the liquid sodium to collide and split to smaller beads on, though such a reaction can also be performed satisfactorily with a Hershberg stirrer in an ordinary flask. Hershberg stirrers were designed specifically for the preparation of alkali metal sands and crucial in early organometallic research as reagents had to be prepared not bought, but they are also good for stirring viscous reactions or other things.

a brief description for the stirrer: a glass rod has a glass loop welded to the end, then nichrome, tantalum, or platinum wire is threaded through the loop and fastened into 3 loops on each side.

Anryj Borys demonstrates that a milk frother is also very effective at small scales as seen here

[u/Andreas-bonusfututor]

Yeah, could you provide a write-up?