RU2309124C2 - Method of preparing tetraamminoplatinum and tetraamminopalladium nitrates - Google Patents

Abstract

FIELD: chemistry of coordination compounds.

SUBSTANCE: tetraamminoplatinum or -palladium nitrates are prepared using, as starting materials, solutions of tetraamminoplatinum or -palladium chlorides. Initial solutions are treated with ammonium carbonate and corresponding tetrammine hydrocarbonates are precipitated. Tetrammine hydrocarbonate precipitates are dissolved in water, neutralized with nitric acid to attain pH value suitable to obtain tetraamminoplatinum or -palladium nitrate solution and the latter is then heated during a period of time required to remove carbon dioxide gas. In order to obtain purer final products, tetrammine hydrocarbonate precipitates, prior to be neutralized with nitric acid, are recrystallized by dissolving them in water on heating to 60-100°C followed by cooling solution.

EFFECT: reduced expenses and lowered level of impurities in finished products.

3 cl, 2 ex

Description

Refers to the production of chemical compounds of platinum group metals.

Tetramine nitrate of platinum (II) [(NH ₃ ) ₄ Pt] (NO ₃ ) ₂ and tetramine palladium nitrate (II) [(NH ₃ ) ₄ Pd] (NO ₃ ) _{2 are} interesting in terms of using them to create critical parts on the surface various technical devices of coatings resistant to aggressive environments at high temperatures. Such a direction of use of the above compounds is explained by their ability, upon slight heating (~ 200 ° С), to transform into the corresponding noble and at the same time refractory metals without the formation of any other gaseous products besides water vapor and nitrogen.

In the literature [Synthesis of complex compounds of platinum group metals. Handbook Ed. I.I. Chernyaev. M .: “Nauka”, 1964, p. 78] there is a known method for producing tetrammine platinum nitrate from a solution of tetrammine chloride - [(NH ₃ ) ₄ Pt] Cl ₂ . In this method, a solution of tetrammine chloride of platinum is treated with the addition of silver nitrate, calculated on the basis of the exchange reaction:

and from the resulting reaction mass, a precipitate of silver chloride is filtered off.

As experience shows, exactly in this way can be obtained from tetramine palladium chloride and tetramine palladium nitrate. This method of producing tetrammine nitrate of platinum or palladium is accepted by us as a prototype.

The disadvantages of the prototype method:

- the need to use a large amount of silver nitrate,

- the transition of part of silver and or chlorine to the target product,

- the long duration of the process of obtaining the necessary substances.

The technical result to which the invention is directed is to reduce the cost of producing tetrammine platinum nitrate or tetrammine palladium and reduce impurities in them.

The technical result is achieved in that in the method for producing platinum tetrammine nitrate from a solution of platinum tetrammine chloride or palladium tetrammine nitrate from a solution of palladium tetrammine chloride, first, tetrammine bicarbonate of platinum or palladium is precipitated with ammonium carbonate from the starting product, then the tetrammine bicarbonate precipitate is dissolved in water, the solution neutralized with nitric acid and heated for the time required to remove carbon dioxide.

Examples of implementation.

1. Obtaining tetrammine platinum nitrate.

1.1. The initial product is a solution of tetrammine platinum chloride with a metal concentration of 100 g / l. An addition of 0.31 L of a saturated solution of ammonium carbonate was added to this 1 L solution with stirring. The formation of a snow-white precipitate of tetrammine platinum bicarbonate was observed. After 30 minutes from the start of stirring, the precipitate was separated from the solution. The precipitate yield was 88.7 g. The tetramminplatinum bicarbonate precipitate was dissolved in 1.066 L of water and the resulting solution was neutralized with nitric acid until pH = 3.5–4.5. The resulting solution was heated at 40-50 ° C until gas bubbles ceased to stand out from it. The degassed solution was analyzed for platinum, chlorine and nitrogen. According to the results of the analysis, the resulting product is a solution of tetrammine platinum nitrate.

A solution of tetrammine platinum nitrate was heated at an increase in temperature to 100 ° C; during the evaporation, a snow-white precipitate was observed. The precipitate was permeated to platinum, chlorine and nitrogen. According to the results of the analysis, the obtained precipitate was identified as tetrammine platinum nitrate.

1.2. To obtain a cleaner solution and crystalline salt, an intermediate product, tetrammine platinum bicarbonate, was taken. The intermediate product weighing 88.7 g was dissolved in 0.4 l of water when it was heated to 100 ° C. The solution was cooled to room temperature (25 ° C). From the cooled solution, 50.4 g of reprecipitated crystals of platinum tetramine bicarbonate were isolated by filtration. The obtained crystals were used to obtain a solution and a crystalline salt of tetrammine platinum nitrate in the same manner as described in the previous example. At the same time, the chlorine content in the target product decreased from 1.54% to 0.02% (relative to platinum).

2. Obtaining tetrammine palladium nitrate.

2.1. The initial product is a solution of tetrammine chloride palladium with a metal concentration of 150 g / l. This solution with a volume of 1 l was heated to a temperature of 60 ° C. With stirring, an additive of 0.8 l of a saturated solution of ammonium carbonate, also preheated to 60 ° C, was introduced. The formation of a snow-white precipitate of tetrammine palladium bicarbonate was observed. After 30 minutes from the start of stirring, the precipitate was separated from the solution. The precipitate yield was 180 g. The precipitate of tetrammine palladium bicarbonate was dissolved in 0.9 l of water and the resulting solution was neutralized with nitric acid until pH = 8.5 was established. The consumption of nitric acid, with a density of 1.14 g / l, amounted to 0.15 l. The resulting solution was heated at 40-50 ° C until gas bubbles ceased to stand out from it. The degassed solution was analyzed for palladium, chlorine and nitrogen. According to the results of the analysis, the resulting product is a solution of tetrammine palladium nitrate.

A solution of tetrammine palladium was heated at an increase in temperature to 100 ° C; during the evaporation, a snow-white precipitate was observed. The precipitate was permeated to platinum, chlorine and nitrogen. According to the results of the analysis, the obtained precipitate was identified as tetrammine palladium nitrate.

1.2. To obtain a cleaner solution and crystalline salt, an intermediate product, tetrammine palladium bicarbonate, was taken. The intermediate product weighing 100 g was dissolved in 0.63 l of water when it was heated to 60 ° C. The solution was cooled to room temperature (25 ° C). 51 g of Precipitated crystals of tetrammine palladium bicarbonate were isolated from the cooled solution by filtration. The obtained crystals were used to obtain a solution and a crystalline salt of tetramine palladium nitrate in the same manner as described in the previous example. At the same time, the chlorine content in the target product decreased from 0.28 to 0.01% (relative to palladium).

Claims (3)

1. A method of producing tetrammine platinum (II) nitrate or palladium (II) from a solution of platinum (II) tetrammine chloride or palladium (II), characterized in that the platinum or palladium tetrammine chloride solution is first treated with ammonium carbonate to precipitate tetrammine hydrogen carbonate of the corresponding metal, the precipitate is separated and dissolved in water, the solution is neutralized with nitric acid and heated for a time sufficient for degassing. 2. The method according to claim 1, characterized in that when receiving a solution of tetrammine platinum nitrate, neutralization is carried out with nitric acid to a pH of 3.5-4.5, and when receiving a solution of tetrammine palladium to a pH of 8.5. 3. The method according to claim 1, characterized in that the precipitation of tetrammines of platinum or palladium tetrammines before neutralization with nitric acid is recrystallized by dissolving in water when heated to 60-100 ° C and subsequent cooling of the solution.