Preparation of ammonium hexachloroplumbate
10 g of lead dichloride are triturated in a mortar with 20ml of concentrated hydrochloric acid for few minutes. The almost clear supernatant liquid is decanted into a 500-ml suction flask carrying a stopper with an inlet tube leading to within one-half inch of the bottom of the vessel. The trituration operation is repeated until the lead chloride is in solution (or extremely fine suspension) in 200ml of the hydrochloric acid. The flask and reaction mixture are cooled in ice and a steady stream of chlorine is introduced (2 bubbles/sec). The liquid soon turns yellow and after 2-5 hours all of the lead dichloride has dissolved. The flask and contents should stirred occasionally during the chlorination. If the final mixture is not completely clear, it should be filtered through a glass filter. A solution of 8g of ammonium chloride in 80ml of ice-cold water is now added and the precipitate is allowed to settle for three hours in the ice bath. The yellow crystalline product is collected rapidly on a hardened filter or sintered glass funnel, drained well by suction, and washed with two 25ml portions each of cold alcohol and acetone. The material is dried in vacuo yielding 20g of ammonium hexachloroplumbate.
Good yields are obtained only if the oxidation of the divalent lead to the tetravalent stage is complete. To test for plumbous lead, add ten drops of the reaction mixture to five milliliters of water and boil gently for a few minutes to hydrolyze all the tetravalent lead to lead dioxide. When the latter settles, filter the hot mixture, cool under the tap, and add several drops of saturated potassium iodide. A yellow precipitate of lead iodide constitutes a positive test.
Inorganic laboratory preparations, by G. G. Schlessinger, 78-79, 1962
25 grams of lead tetraacetate are dissolved in 20ml of concentrated hydrochloric acid cooled to 0°C. A cold solution of 8g of ammonium chloride in 80ml of water is added slowly to the yellow liquid with stirring and continued cooling in ice. The complex ammonium salt is isolated by a similar procedure, in a yield comparable to that from (I). Care should be taken to allow for complete crystallization.
Inorganic laboratory preparations, by G. G. Schlessinger, 79-80, 1962