[Limpet Chicken]

I very occasionally need liquid NH3, because a solution of an alkali metal in anhydrous NH3 is one of the very few reducing agents I have on hand in my lab, to generate NH3 gas, I know there is a method of making NH3 through decomposition of urea, although I am not too familiar with that.

I make my NH3(g) by adding NaOH(s) to aqueous ammonia solution, my problem is, drying the gas, and then subsequent condensing to make liquid NH3.

My options for drying are:

P2O5:expensive as hell for me, and hazardous to prepare (and a waste of my white P)
Conc. H2SO4, no good, will form ammonium sulfate.
NH3NO3: hygroscopic, I have finite, limited supplies, dont know if it would work.
Anhydrous NaOH-cheap as hell, don't know if it will work.

What do you think would be the best way to dry my NH3, and an even bigger problem, the best ways of doing condensation to liquid NH3 ghetto-style?

Condensation is one of the main problems, but I might try rigging a glass U-tube from a lightbulb with a jacket with a slow constant flow of diethyl ether and ice inside of a freezer, does anyone think that would work?

Before anyone points this out as I can tell they are probably going to, I am aware of the dangers of using anhydrous NH3. (I have seen a nasty picture of a guy with his ASS burnt off too, so believe you me, I am EXTREMELY careful with NH3(l).

[movies]

Solid NaOH is a pretty good drying agent.  You might be able to rig up a glass tube with a rubber stopper at each end with NaOH pellets in the tube.  I think if you routed the NH3(g) through that it would come out pretty dry.  I don't know how well NH3 absorbs into NaOH though.  You might loose some.

For the condenser, the best thing is going to be routing it into a flask or something that is in a dry ice/acetone bath (-78 degrees C).  Ammonia boils at -33 C, so you've got to get at least that low.  It's best to keep the reaction at -78 C for the duration of the reaction.

One common problem with metal/NH3 reductions at -78 C is that the ammonia starts to get kind of thick.  If you add an equal volume of THF or ether it should stay viscous though.

Finally, be VERY CAREFUL when you warm the mixture up.  It will boil very, very fast, so warm it very slowly and open all the necks on your vessel.  DO NOT put it in an ice bath right out of the dry ice bath because that will take it to 0 C very fast and make a lot of NH3(g) right away.  The best thing is to leave it in the dry ice bath and don't add any more dry ice, then it will warm to r.t. very slowly (and safely).

[Limpet Chicken]

Thanks Movies, I will go with adding diethyl ether, as I have that in abundance.
The reactions themselves, I have all the info on them I could ever need, condensing the NH3 was the main problem really. Thanks.

Oh yes, BTW I have no access to dry ice, I don't think it it OTC in britain unfortunately, or at least, I have never seen it/heard of it for sale.

[movies]

You can usually get dry ice at fish markets.  The use it when they ship fresh fish.