CaO base + NH4Cl --> anhydrous NH3

[algebra]

could CaO be used to liberate *anhydrous* NH3 according to the following scheme? the H2O produced is simultaneously dried by the CaO...

(1) 2CaO + 2H20 -------> 2Ca(OH)2

(2) 2Ca(OH)2 + 2 NH4Cl --> CaCl2 + Ca(OH)2  + 2H2O + 2NH3

Overall -
2CaO + 2NH4Cl --> CaCl2 + Ca(OH)2  +  2NH3

if it was possible to contain the reaction (dangerous) the NH3(an) could subsequently just be tapped off after allowing to cool to rt ....

[Rhodium]

And what is the boiling point of anhydrous ammonia?

[algebra]

my understanding (assumption) is based on what happens when the valve of an lpg cyclinder is cracked open. the cooling involved with the release and expansion of some of the gas enables liquified lpg to also be released. only have a hazy idea but thought there was something similar going on when famers agricultural tanks are tapped off and this is the source of stories of folks running across the countryside carrying boiling pales of liquified ammonia?

the basic idea would be add the CaO and NH4Cl to some type of steel containing vessel and then close  it off. let the reaction run (reaction conditions?)- then after the thing has cooled down tap off the NH3 relying on the effect of the expansion of some of the pressurised ammonia to permit liquified ammonia to also be drawn off.

alternatively and more economically a CO2 tank could also be employed. one idea would be to judge the molar ammounts of NH4Cl and CaO to keep a small qty of H2O in the system to allow complete formation of the NH3 and then use a slight excess of lithium in the birch to get it totally dry. trying to consider ways of avoiding the elaborate setup involving a distillation rig, seperate CaCl2 drying tube and some type of cooling system for condensing the NH3.

[Rhodium]

I'm afraid that you would need to allow too much ammonia to escape (huge noxious corrosive cloud) - just to effect the cooling you are looking for - to make this a proposition of interest. Also, without any cryogenic distillation of the ammonia I believe it would be unfit for a birch reduction.

[algebra]

Cool, thanks for your thoughts Rhodium - especially wrt the value of undistilled ammonia for use in a birch reaction. was reading some old posts about using Li to release NH3 from NH4Cl as well as being the source for solvated electrons so was thinking about variations on the idea.

[WizardX]

I'm afraid that you would need to allow too much ammonia to escape (huge noxious corrosive cloud) - just to effect the cooling you are looking for - to make this a proposition of interest.

True!

Also, without any cryogenic distillation of the ammonia I believe it would be unfit for a birch reduction.

Compress the anhydrous NH3 in to a cylinder in a dryice/acetone freezing mixture in a container that the acetone will not dissolve in a deep freezer.