Schweizer's reagent dissolves cellulose.Evaporation of these solutions leaves light blue residue of copper hydroxide, reflecting the lability of the copper-ammonia bonding. If conducted under a stream of ammonia, then deep blue needle-like crystals of the tetrammine form. In presence of oxygen, concentrated solutions give rise to nitrites Cu(NO2)2(NH3)n.
Tetraamminecopper(2+) dihydroxide dissolves cellulose; used in rayon production.
Copper turnings are covered with 20% ammonia containing some NH4Cl, and air is bubbled through the suspension. An azure-blue solution of [Cu(NH3)4] (OH)2 is formed. Evaporation of the solution in a stream of dry NH3 yields long, azure-blue needles of [Cu(NH3)4](OH)2.
