10534-89-1

solid

As reagent for pyrophosphoric acid, for the estimation of phosphate.

Synthesis of hexaamminecobalt(III) chloride
2CoCl2+10NH3+2NH4Cl+H2O2 →2[Co(NH3) 6]Cl3+2H2O
Reaction. Dissolve 2.5 g (10.5 mmol) of cobalt(II) chloride hexahydrate and 1.7 g (32 mmol) of ammonium chloride (about 195% excess) in 15 mL of distilled water. Add 0.5 g of activated charcoal and 23 mL (380 mmol) of concentrated aqueous ammonia (about 624% excess). Cool the reaction mixture to 0 oC in an ice bath. Slowly add 2 mL (19.5 mmol) of 30% hydrogen peroxide (about 271% excess), with stirring – maintain the temperature below 10°C. After the hydrogen peroxide has been added, heat the reaction mixture to 60°C for about 30 minutes. Cool the reaction mixture to 0 oC to cause precipitation of the product.

It crystallises from warm water (8mL/g) on cooling. [Bjerrum & McReynolds Inorg Synth II 217 1946.]