Laboratory Methods of Inorganic Chemistry, 2nd English Ed. 1928

CHLOROPENTAMMINECOBALTIC CHLORIDE. 173

the carbonatotetrammine salt with hydrochloric acid, there is formed, for the
most part, chloroaquotetramminecobaltic chloride. This is changed, on being
heated in an ammoniacal solution, into aquopentamminecobaltic chloride, and
the latter on being acidified with hydrochloric acid is converted into chloro-
pentamminecobaltic chloride. This is one of the best and longest-known mem-
bers of the entire series, and has, on account of its color and chlorine content,
been called chloropurpureocobaltic chloride. It may also be prepared by
thermal decomposition of luteocobalt chloride.

Add concentrated hydrochloric acid (about 4.5 c.c.) to a solution

of 3 g. carbonatotetramminecobaltic nitrate in 40 c.c. of water

until all the carbon dioxide has been expelled. Then make the

solution slightly ammoniacal; thereupon add an excess of 5 c.c.

concentrated ammonia and heat the solution for three-quarters

of an hour on the water-bath. After cooling add 50 c.c. of con-

centrated hydrochloric acid and heat the mixture once more for

an hour on the water-bath. Drain the violet-red salt which

separates and wash it with alcohol. Yield, 1.5 to 2.5 grams.

131. Chloropentamminecobaltic Chloride from Cobalt Carbonate.
     By oxidizing a strongly ammoniacal solution of hexamminecobaltous
     chloride containing a large amount of ammoniumcarbonate, carbonato-
     tetramminecobaltic chloride (cf. No. 129), aquopentamminecobaltic chloride,
     [Co(NH3) 6 H 2 O]Cl3, and oxycobaltammine chloride, [Co 2 02(NH 3 )io]Cl4, are
     formed. By adding ammonium chloride in considerable quantity to the solu-
     tion and evaporating, the last-mentioned compound is converted into chloro-
     pentamminecobaltic chloride, or into aquopentamminecobaltic chloride.
     These substances, like carbonatotetramminecobaltic chloride, can be con-
     verted into chloropentamminecobaltic chloride (cf. preceding preparation).

Dissolve 20 g. of cobalt carbonate in as little hydrochloric acid

as possible and treat th'e filtered solution in the cold with 250 c.c.

of 10% ammonia and 50 g. of ammonium carbonate dissolved in

250 c.c. of water. Oxidize the mixture by passing through it a

rapid current of air for three hours (cf. No. 107). Then add 150 g.

of ammonium chloride and evaporate the solution on the water-

bath until it becomes of pasty consistency. Acidify with hydro-

chloric acid, while stirring, until no more carbon dioxide is evolved

and then make ammoniacal once more, adding 10 c.c. of con-

centrated ammonia in excess. After diluting to 400-500 c.c. heat

the mixture again on the water-bath for an hour. Add 300 c.c.

of concentrated hydrochloric acid and leave the solution on the

water-bath until, at the end of from half to three-quarters of an