Method of palladium acetate production

FIELD: chemistry.

SUBSTANCE: invention refers to platinum metal salts synthesis, specifically palladium salts, namely palladium (II) acetate applied as catalyst or for production of initial salt for other palladium salts. Method of palladium acetate production includes as follows. Metal palladium is dissolved in concentrated nitric acid. Prepared solution is steamed prior to crystallisation of palladium nitrate salt, processed by ice acetic acid. Deposition is filtered and processed with ice acetic acid. Nitrate palladium solution is processed with ice acetic acid with sodium acetate additive in amount 1.5 - 2 kg per 1 kg of palladium in solution. Deposition is processed and dissolved in ice acetic acid in ratio 19-21 l per 1 kg of deposition with acetamide added in amount 0.1 - 0.2 kg per 1 kg of deposition. Solution is warmed at temperature 80 - 90 °C within at least 5 h and steams until salt is formed.

EFFECT: simplification of monophase palladium (II) acetate production with decreased adverse environmental effects of process products.

2 cl, 2 tbl, 4 ex

The invention relates to the field of chemistry of the platinum metals, in particular the synthesis of the palladium compounds, namely, the synthesis of palladium(II)acetate, used as a catalyst, for example, to obtain vinyl acetate.

The closest is a method for palladium acetate, including the dissolution of metallic palladium in concentrated nitric acid, evaporation of the resulting solution and the processing of glacial acetic acid, separating the resulting precipitate, the processing of a mixture of glacial acetic acid and ethyl ester of acetic acid and heating the reaction mixture (see EN 2288214 C1, publ. 27.11.2006, bull. No. 33). The method adopted for the prototype. The disadvantage of this method is prolonged heating at high temperature the reaction mixture with ethyl ether acetic acid: 2-5 h at 60-90°and not less than 6 hours at 120-140°C. To translate nitroacetate palladium [Pd₃(CH₃COO)₅NO₂] palladium acetate [Pd₃(CH₃Soo)₆] uses ethyl ester of acetic acid. Nitric acid present in the reaction mixture when dissolved nitroacetate palladium in acetic acid is recovered ethyl ester acetic acid to nitrogen oxides which must be removed from the reaction zone, as their presence contributes to the formation of the polymer phase of palladium acetate [Pd(The N ₃Soo)₂]_n. The removal of nitrogen oxides from the reaction mixture is fraught with difficulties. When they are removed in the gas-vapor mixture (ASG) pass and a pair of acetic acid, which increases the flow rate of the reagent is acetic acid. ASG deleting partially condensed (before being cooled in the fridge), gets back into the reaction mixture, which further when the temperature leads to the formation of polymeric palladium acetate. This negative side of the prototype is particularly evident during the process of industrial equipment. And in addition, to eliminate the harmful effects of the emitted nitrogen oxides on the environment necessary for their neutralization.

The technical result, which is aimed by the invention, is:

- receipt of palladium acetate in monophasic state [Pd₃(CH₃Soo)₆];

- simplification of the process of obtaining palladium acetate;

- reducing the harmful effects of the products of the process on the environment.

The specified technical result is achieved by the fact that the nitric acid solution of palladium after evaporation, prior to the crystallization of salt nitrate, palladium(II), treated with glacial acetic acid with the addition of 1.5-2.0 kg of sodium acetate per 1 kg of palladium in the solution, the precipitate is filtered, dissolved it is glacial acetic acid with a flow rate of 19-21 liters per 1 kg of sludge with the addition of ndimethylacetamide 0.1-0.2 kg per 1 kg of precipitate and heating the solution at a temperature of 80-90° With no less than 5 hours

The essence of the method is that the synthesis of intermediate sediment - nitroacetate palladium [Pd₃(CH₃Soo)₅NO₂] carried out with addition of sodium acetate 1.5-2.0 kg per 1 kg of palladium in solution, and the processing of sludge nitroacetate palladium [Pd₃(CH₃Soo)₅NO₂] for the purpose of transfer of palladium acetate [Pd₃(CH₃Soo)₆] lead in the acetic acid medium with the addition of ndimethylacetamide 0.1-0.2 kg per 1 kg of sludge at a temperature of 80-90°C. the addition of sodium acetate in the deposition of nitroacetate palladium increases the reactivity of the system, reduces the induction period of the sediment and the total time of deposition. The introduction of ndimethylacetamide CH₃CONH₂in acetic acid in the processing of sludge nitroacetate palladium destroys oxygen compounds of nitrogen to elemental nitrogen:

Pd₃(CH₃COO)₅(NO₂)+CH₃COOH=Pd₃(CH₃Soo)₆+HNO₂,

HNO₂+CH₃CONH₂=N₂+H₂O+CH₃COOH,

thus, ndimethylacetamide contributes to the complete transformation of nitroacetate palladium acetate, palladium, and obtaining monophasic connection, eliminating the formation of polymeric palladium acetate. The absence of nitrogen oxides allows you to return the condensate acetic acid in repeated cycles, thereby reducing the consumption of ice is Noah acetic acid, and, in addition, reduces the harmful effects of the products of the process on the environment.

In the course of the research it was established that for the first stage of the process - receiving sludge nitroacetate palladium - consumption of sodium acetate is 1.5-2.0 kg per 1 kg of palladium nitrate in the solution;

Consumption of sodium acetate in the process of deposition of nitroacetate palladium from nitric acid solution of palladium is less than 1.5 kg and 2.0 kg per 1 kg of palladium in solution does not affect the induction period and the release of sediment.

For the second stage of the process - sludge treatment of nitroacetate palladium glacial acetic acid with the addition of ndimethylacetamide - optimal conditions are:

- consumption of ndimethylacetamide and glacial acetic acid (0.1 to 0.2) kg and (19-21) l, respectively, at 1 kg nitroacetate palladium;

- the temperature is warm (80-90)°C;

- the processing time of at least 5 h;

Consumption of ndimethylacetamide less than 0.1 kg per 1 kg of nitroacetate palladium leads to incomplete recovery of nitrogen compounds to elemental nitrogen and the product neponiatnogo, more than 0.2 kg per 1 kg of nitroacetate palladium increases the cost of the reagent.

Consumption of glacial acetic acid less than 19 liters per 1 kg of nitroacetate leads to incomplete dissolution of nitroacetate palladium and incomplete transition nitroacetate palladium acetate, palladium is, therefore, obtaining neponiatnogo product. Increase the flow of glacial acetic acid over 21 liters per 1 kg of nitroacetate palladium is impractical because it leads to increased cost of the reagent, the increase in the duration of the process of evaporation of the reaction mixture.

Temperature warms up less than 80°leads to the reduction reaction activity ndimethylacetamide, resulting in incomplete destruction of nitrogen oxides and education in further heating of the polymeric palladium acetate. Temperatures over 90°yields a product with a mixed phase metal palladium.

The duration of the temperature of the processing solution is less than 5 hours leads to incomplete recovery of the oxygen compounds of nitrogen and obtaining neponiatnogo product.

Examples of the method:

As the initial product for the experiments (table 1) upon receipt of palladium acetate was prepared solution of palladium nitrate by dissolving palladium metal in nitric acid and evaporation. The content of palladium in the solution - 610 g/l, free nitric acid 115 g/L.

Example 1

0.1 l nitric acid solution of palladium was added sodium acetate, previously dissolved by heating in 0.6 l of glacial acetic acid. The reaction mixture was stirred for 1 h, marked the beginning of education OS is dka (induction period). After 1 h from the start of mixing the sediment of nitroacetate palladium was separated by filtration, the filter was rinsed with water, acidified with acetic acid and dried on the filter while the vacuum. The residue was weighed, and analyzed for the content of palladium and determine the phase composition. The mother liquor is sent to regeneration. These experiments are shown in table 1.

The precipitate of nitroacetate palladium for carrying out the second stage of the process - sludge treatment in glacial acetic acid with the addition of ndimethylacetamide was obtained according to the modes of experience No. 2 (table 1), as the optimal option for the first stage of the process.

Example 2

The process of sludge treatment of nitroacetate palladium acetic acid with the addition of ndimethylacetamide carried out in a rotary evaporator with heating and trapping and cooling of exhaust fumes. To button sludge nitroacetate palladium weighing 20 g was added glacial acetic acid and ndimethylacetamide. The reaction mixture was warmed up at a given temperature and the rotation of the working flask evaporator. ASG when cooled, condensed and collected in the receiving flask condensate. Warm-up time of the reaction mixture was considered since the complete dissolution of the precipitate in the working flask. After a certain exposure at a temperature included vacuum and the solution was evaporated to a pulp with subsequent separation of the OS is dka filtering or until dry salts. The precipitate was dried, weighed, and analyzed for the content of palladium and determine the phase composition. These experiments are shown in table 2 (experiments No. 1-15).

The mother liquor after separation of the precipitate can be re-used at the stage of recrystallization.

Example 3

The precipitate of nitroacetate palladium gained experience No. 2 (table 1), was treated according to the modes of experience No. 3 (table 2), as the optimal option for the second stage of the process, but after heating the solution at (80-90)°the reaction mixture was evaporated until complete evaporation of acetic acid and obtain a dry salt. This has increased the product yield (table 2, experience No. 16).

Example 4

The precipitate of nitroacetate palladium gained experience No. 2 (table 1), was treated according to the modes of experience No. 3 (table 2), as the optimal option for the second stage of the process, but instead reagent glacial acetic acid used condensate (experiment No. 17), obtained in experiments No. 1 to 16 (table 2).

As seen from the above examples, the use of the proposed method allows to obtain the palladium acetate with high yield in a monophasic condition and with no pollution with nitrogen oxides to the environment.

1. The method of producing palladium acetate, including the dissolution of metallic palladium in concentrated nitric acid, evaporation of the resulting solution prior to the crystallization of salt nitrate, palladium (II), the processing of this solution glacial acetic acid, separating the precipitate by filtration and sludge treatment glacial acetic acid, characterized in that the processing solution of nitric acid, palladium glacial acetic acid is carried out with addition of sodium acetate 1.5-2.0 kg per 1 kg of palladium in solution, and sludge treatment glacial acetic acid are dissolved sediment in glacial acetic acid with a flow rate of 19-21 liters per 1 kg of the OCA is the AC with the addition of 0,1 ndimethylacetamide-0.2 kg per 1 kg of sediment, heat the solution at a temperature of 80-90°With at least 5 h and evaporated before the formation of salts.

2. The method according to claim 1, wherein the evaporation is carried out to obtain the dry salts.