RU2535705C1 - Method of producing disubstituted dinitrite compounds of palladium - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention can be used in chemical industry. The method of producing disubstituted dinitrite compounds of palladium includes reacting palladium nitrate solution with NO and evaporating the obtained solution. The palladium nitrate solution is evaporated to palladium content of not less than 100 g/l and free nitric acid of not more than 300 g/l. NO is then released into said solution at 15-40°C until the end of precipitation of a nitrite-nitrosyl compound of palladium in the presence of perchloric acid in amount of 0.5-10% of the molar amount of palladium in the solution. Further, the formed nitrite-nitrosyl compound is filtered and then reacted with not less than 10 wt % solution of mono- or bidentate amine or phosphine ligand at 10-30°C.

EFFECT: invention increases stability of production and output of chemically pure disubstituted dinitrite compounds of palladium of formula [PdL₂(NO₂)₂], where L is an amine (NR₃) or phosphine (PR₃) ligand, R is H and/or an organic radical.

7 cl, 3 tbl, 2 ex

Description

The invention relates to the field of chemistry of platinum metals, in particular the synthesis of a palladium compound, namely the synthesis of disubstituted dinitrite palladium compounds, used, inter alia, as the basis of electrolytes for plating metallic palladium, as precursors of other palladium compounds or preparing a functional part of various palladium-containing materials.

A known method of producing diamindinitrite compounds of palladium by reacting diamindichloride compounds of palladium with soluble nitrite salts of alkali metals (Synthesis of complex compounds of platinum group metals / Editor II Chernyaev. Handbook. M. Science. 1964. p.190). Such a synthetic approach is considered to be general for obtaining a number of disubstituted dinitrite palladium compounds:

(where L is an amine (NR ₃ ) or phosphine (PR ₃ ) ligand, R is H and / or an organic radical).

In this case, the chloride ligand is replaced by a nitrite one due to the more complex complexation of palladium to the nitrite group, as compared with chloride. The disadvantage of this method is the staged synthesis of the target compound, since the synthesis of a dichloride compound also requires its own production scheme, which increases the duration of the whole process and reduces the yield. Moreover, the presence of chlorine in the precursor compound is often a negative factor, since its content is often regulated in the composition of the electrolyte as an impurity, which reduces the quality of the galvanic coating. Therefore, a stage of washing the target compound from chloride salts is necessary, which reduces the yield, especially when the solubility of the target compound in the washing solution.

A known method of producing diamindinitrite compounds of palladium by the interaction of its tetranitrite complex compounds with an amine (Synthesis of complex compounds of platinum group metals / Editor II Chernyaev. Handbook. M., Science., 1964, p. 191). The interaction is realized due to the equilibrium replacement of nitrite ligands with amine ones. In a more general form, the process can be represented by equilibrium interactions:

(where L is an amine (NR ₃ ) ligand, R — H and / or an organic radical).

The predominant formation of a dinitrite compound is due to the greater stability of the compound compared to tetra-, tri-, mononitrite and tetraamine.

The disadvantage of this method is the need to isolate a soluble tetranitrite palladium complex, which reduces the yield of the entire synthesis. This is necessary to remove chlorine ions, since palladium chloride compounds are usually the starting materials for it. The presence of alkali metal cations in the tetranitrite compound makes it necessary to wash the target compound from them. This, in turn, is necessary due to a decrease in the quality of the metal coating in the presence of alkaline ions in the electrolyte. The washing procedure negatively affects the yield of the product, especially when it is soluble in the washing solutions. In this case, the synthesis of phosphine compounds, according to this method, does not lead to the formation of the target compound or its formation is carried out in low yield. In a neutral environment, some phosphine ligands do not have the coordination ability to replace nitrite ligands. In slightly acidic media, the coordination ability of the nitrite group decreases (due to protonation of the nitrite group) and this can lead to their replacement. Changing the acidity of the solution during the synthesis increases the content of various ions, which leads to contamination of the target substance and requires additional washing, which can reduce the yield.

A known method of preparing a solution of nitrite complexes of palladium, resulting from the addition of salts of nitrous acid or by passing oxides of nitrogen and air into a solution of palladium nitrate (Tsyrulnikov PG, Shitova PB, Afonasenko TP // Patent of the Russian Federation No. 2282498 from August 27, 2006, Bull. No. 24). The resulting solution may be the starting material for the formation of disubstituted dinitrite palladium compounds. The disadvantage of this method is the incomplete conversion of nitrate complexes of palladium and nitric acid into a nitrite-nitrosyl solution. Therefore, the addition of a neutral electron donor ligand leads first to the neutralization of the solution and then to the interaction with palladium. Moreover, in the case of ligand instability to oxidation, residual nitric acid may be an oxidizer of the ligand, which will lead to the formation of non-target compounds, reduce the yield of target compounds and / or contaminate the target product. The presence of alkali metals in the solution of the formation of the target compound requires washing it, which causes a decrease in yield, especially when the solubility of the product in the wash solution.

A known method of producing acetate and palladium propionate, which consists in processing a solution of palladium nitrate with nitric oxide (II) with the subsequent addition of acetic or propionic acid (Mulagaleev R.F., Kirik S.D., Soloviev L.A. // RF Patent №2387633 dated April 27, 2010, Bull. No. 12). The resulting solution or suspension, prior to the introduction of the carboxylic acid, can be the initial palladium reagent for the formation of its disubstituted dinitrite compounds. This method is adopted as a prototype.

The disadvantage of this method is the residual acidity formed after processing the solution of palladium nitrate with nitric oxide (II) due to the presence of excess oxygen compounds of nitrogen (I-IV). Therefore, part of the added electron-donor ligand will be spent on the neutralization of the solution, which increases the reagent consumption. Moreover, due to the presence of an excess of nitro and nitroso compounds, which are prone to complexation with palladium and are stable, the formation of nitrite-phosphine compounds of palladium will be difficult.

The technical result to which the invention is directed is to improve the method for producing disubstituted dinitrite palladium compounds, increase the stability of their synthesis and quality, as well as achieve a high yield of the target compound.

The desired technical result is achieved by the fact that after evaporation to a palladium content in the solution of not less than 100 g / l and the content of free nitric acid of not more than 300 g / l after evaporation to the palladium nitrate content, at a temperature of the solution (15-40) ° C, NO a possible admixture of nitrogen (IV) oxides of not more than 30% of the molar amount of NO, until the evolution of the nitrite-nitrosyl compound of palladium sparingly soluble in the reaction solution is stopped, in the presence of perchloric acid in an amount of (0.5-10)% of the molar amount of palladium in the initial nitric acid solution, filtering the resulting compound, its interaction at a temperature of (10-30) ° C with at least 10% solution of a mono- or bidentant amine or phosphine ligand in water, in water-methanol or water-ethanol or water-acetone solvent (with a mass content of alcohol or acetone component of (0-80)%) or in methanol or ethanol or acetonitrile or acetone or isopropanol in the amount of (180-200)% of the molar amount of palladium in the initial solution of palladium nitrate using monodentant ligand or in the amount of (90-100)% of the same amount of palladium when using a bidentate ligand. In this case, the intermediate nitrite-nitrosyl compound of palladium after filtration dissolves in a minimal amount of solvent or, if it does not dissolve in it, it is suspended at a mass ratio of solid / liquid - 1 / (0.5-4).

The essence of the method lies in the fact that the synthesis of the disubstituted dinitrite compound of palladium (II) is carried out by reducing the solution of palladium nitrate with nitric oxide (II) to the nitrosyl nitrite compound of palladium (II), which is isolated and converted into the target compound by reaction with an amine or phosphine ligand in air atmosphere. Upon reduction with nitric oxide (II), the oxygen compounds of nitrogen (V) are reduced to oxygen compounds of nitrogen (IV-II), which are removed from the reaction zone and coordinate palladium, while nitric oxide (II) is oxidized to nitric oxide (IV). The change in the coordination environment of palladium from nitrate to nitrite-nitrosyl occurs due to more complex complexation of Pd (II) with oxygen compounds of nitrogen (II-III), compared with nitrate ligands. As a result of the interaction, a compound of the composition Pd (NO) NO _{2 is formed} , which is poorly soluble in the reaction solution. Palladium in this process, most likely, acts as a catalyst, since similar processes in the presence of other metals are not accompanied by such a deep reduction of the reaction system.

The addition of perchloric acid to the system of interaction of a solution of palladium nitrate with NO is due to an increase in the yield of nitrite-nitrosyl compound of palladium (II). Since the interaction of a solution of palladium nitrate with NO is characterized by a nitrosation process, the ability to stabilize the nitrosonium cation increases the speed of the process. Perchlorate ion can be such a nitrosation stabilizer (without changing the composition of the formed nitrite-nitrosyl palladium (II) compound).

Due to the coordination polymerization of the compound [Pd (NO) NO ₂ ], which is due to the bridged coordination of nitrite and nitrosyl groups, coordination unsaturation of palladium (II) arises. Therefore, the nitrite-nitrosyl compound of palladium (II) is quite reactive with respect to electron-donor ligands. Since the coordination bonding strength of the nitrosyl group decreases with increasing electron density on the complexing metal, in parallel with the addition of the electron donor ligand, the coordination of palladium and nitrogen of the nitrosyl group is weakened. In an atmosphere of oxygen, this leads to the oxidation of the nitrosyl group to nitrite. General interaction can be represented by the equation:

(где L - аминный (NR₃) или фосфиновый (PR₃) лиганд, R-Н и/или органический радикал)

(where L is an amine (NR ₃ ) or phosphine (PR ₃ ) ligand, R-H and / or organic radical)

For the high-quality implementation of reaction (3) and a high yield of the product, it is important to select a solvent in which the nitrite-nirozyl compound of palladium will be dissolved or suspended and the ligand, but the target substance, will be slightly soluble. As a rule, this corresponds to a wide range of solvents.

In the course of the studies, it was found that for the process of obtaining disubstituted dinitrite palladium (II) compounds from the nitrite-nitrosyl compound of palladium (II) obtained by reducing the palladium nitrate solution with nitric oxide (II), the optimal conditions are:

- the concentration of palladium in the initial solution of palladium nitrate is not less than 100 g / l;

- concentration of free nitric acid - not more than 300 g / l;

- the temperature of interaction of a solution of palladium nitrate with NO - (15-40) ° C;

- the content of nitrogen oxides (IV) in NO - not more than 30%;

- the amount of added perchloric acid - (0.5-10)% of the molar amount of palladium in a nitric acid solution;

- the amount of monodentent neutral ligand - (180-200)% of the molar amount of palladium in the initial nitric acid solution;

- the amount of bidentant neutral ligand - (90-100)% of the molar amount of palladium in the initial nitric acid solution;

- the interaction temperature of the nitrite-nitrosyl compound of palladium with the ligand is (10-30) ° C;

- the ligand content in the solution before the interaction is not less than 10%;

- the alcohol or acetone content in the water-methanol or or water-ethanol or water-acetone solution of the ligand before the interaction is (0-80)%;

- mass ratio of solid / liquid in suspension of nitrite-nitrosyl compound palladium / solvent? in which the ligand is dissolved - 1 / (0.5-4).

A decrease in the concentration of palladium in the initial nitric acid solution of less than 100 g / l leads to a dilution of the reaction solution when interacting with NO, which ultimately leads to a decrease in the yield of nitrite-nitrosyl palladium compound.

An increase in the concentration of free nitric acid of more than 300 g / l in the initial solution of palladium nitrate leads to an increase in the NO consumption during its interaction with the nitric acid solution, which makes the process more expensive and increases its duration.

An increase in the initial temperature of the interaction of the palladium nitrate solution with NO more than 40 ° C leads to an increase in the solubility of the resulting nitrite-nitrosyl palladium compound, which ultimately reduces the yield of the target product. A decrease in the initial temperature of the interaction of the palladium nitrate solution with NO less than 15 ° C increases the induction period of their interaction, which increases the duration of the process and the consumption of nitric oxide.

An increase in the content of nitrogen (IV) oxides in NO when interacting with a solution of palladium nitrate more than 30% of the molar amount of NO leads to an increase in the concentration of nitric acid in the solution for the isolation of the intermediate nitrosyl nitrite palladium compound, which reduces its yield.

An increase in the addition of perchloric acid to the initial solution of palladium nitrate more than 10% of the molar amount of palladium leads to an increase in acidity in the solution of the isolation of the intermediate nitrosyl nitrite compound of palladium, which increases its solubility and reduces the yield. A decrease in the amount of perchloric acid to less than 0.5% of the molar amount of palladium reduces the catalytic effect of the additive, which reduces the yield of the intermediate nitrosyl nitrite palladium compound.

An increase in the amount of introduced electron-donor ligand more than 200% of the molar amount of palladium in the initial nitric acid solution can increase the solubility of the target compound and leads to its excessive consumption. A decrease in the amount of introduced neutral ligand of less than 190% of the molar amount of palladium in the initial nitric acid solution leads to its lack and, as a result, causes the target product to be contaminated with an intermediate nitrite-nitrosyl compound or reduces the yield of the target product.

An increase in the temperature of the interaction of the nitrite-nitrosyl compound of palladium with the ligand more than 30 ° C can lead to the occurrence of side processes of the interaction of nitrite and electron-donor ligands catalyzed by palladium. A decrease in the reaction temperature of the nitrite-nitrosyl palladium compound with the ligand below 10 ° C can lead to partial crystallization of the ligand solution and slow implementation of the addition.

A decrease in the content of the electron-donor ligand in the solution of less than 10% leads to dilution of the suspension of the target product, which can lead to its additional solubility, which reduces the yield.

An increase in the solid / liquid mass ratio in a suspension of a palladium nitrite-nitrosyl compound and a solvent in which a ligand of more than 1 / 0.5 is dissolved leads to a lack of solvent when interacting with an electron-donor ligand, which leads to an excess viscosity of the suspension, which can cause incomplete interaction. This ultimately contaminates the target product with an intermediate nitrite-nitrosyl compound. The decrease in the mass ratio of solid / liquid in the suspension of nitrite-nitrosyl compounds of palladium and solvent less than 1/4 leads to an excess of solvent, which may cause increased dissolution of the target product and reduce its yield. And also leads to excessive consumption of solvent components.

An increase in the amount of a monodentent electron-donor ligand more than 200% of the molar amount of palladium in the initial solution of palladium nitrate and an increase in the amount of the testicular electron-donor ligand in more than 100% of the molar amount of palladium in the initial solution of palladium nitrate leads to its excess, which may be accompanied by its additional interaction with palladium to form a tri- and tetra-substituted palladium complex, which are more soluble, which ultimately reduces the yield Spruce product. A decrease in the amount of a monodentent electron-donor ligand of less than 180% of the molar amount of palladium in the initial solution of palladium nitrate and a decrease in the amount of a bidentant electron-donor ligand in less than 90% of the molar amount of palladium in the initial solution of palladium nitrate leads to its deficiency, which can lead to incomplete intermediate nitrite-nitrosyl compounds, which, ultimately, leads to their pollution of the target product.

An increase in the alcohol or acetone content in an aqueous-alcoholic or aqueous-acetone solution of an electron-donor ligand of more than 80% leads to excessive consumption of solvent components. The use of aqueous solutions of the electron-donor ligand (without the addition of alcohol or acetone) can lead to incomplete dissolution of the ligand in the solvent, which causes incompleteness of interaction and can be the cause of the presence of an impurity of an intermediate nitrite-nitrosyl compound in the target product.

Examples of the method:

Example 1

The calculated amount of concentrated perchloric acid was added to the prepared palladium nitrate solution with the required palladium and free nitric acid content and NO was passed with stirring and at the set temperature until the formation of a brown precipitate. The resulting suspension was cooled to room temperature, the precipitate was filtered off, washed with methyl acetate and dried on a filter in an air stream. The mother liquor and wash solution were poisoned for palladium regeneration. The experimental data are shown in table 1. Experiments 1-7 show the process under boundary conditions. Experiments 8-9 are close to optimal.

The precipitate of the nitrite-nitrosyl palladium compound was transferred to a reactor, dissolved in a minimal amount of solvent, and the calculated amount of ligand in the same solvent was added with stirring. The resulting target product was separated by filtration, washed with methanol, or ethanol, or acetone and dried on a filter in a stream of air, then under reduced or normal pressure in an air atmosphere at 20-25 ° C. The experimental data are shown in table 2.

Example 2

The process of obtaining the intermediate was carried out as in Example 1, but then the precipitate of the palladium nitrite-nitrosyl compound was loaded into the reactor, suspended with the required amount of solvent, and the calculated amount of the ligand solution in the same solvent was poured with stirring. The resulting target product was separated by filtration, washed with diethyl ether or methyl acetate, and dried on a filter in an air stream, then under reduced or normal pressure in an air atmosphere at 20-25 ° C. The experimental data are shown in table 3.

Explanation of the tables:

I is the concentration of palladium in the initial solution of palladium nitrate (g / l);

II - concentration of free nitric acid (g / l);

III - the amount of perchloric acid (% of the molar amount of palladium in solution);

IV - the temperature of the interaction of the solution of palladium nitrate with NO (° C);

V is the amount of impurity of nitrogen oxides (IV) in NO when interacting with a solution of palladium nitrate (% of the molar amount of NO); (the amount of nitrogen oxides (IV) was determined by changing the pH of the aqueous solution of the calculated amount of NaOH from the amount of gas passed through it);

VI - yield of Pd (NO) NO ₂ (% of the amount of palladium in a solution of palladium nitrate);

VII - used ligand and its dentistry;

VIII - a solvent in which Pd (NO) NO _{2 is} dissolved or suspended;

IX is the amount of neutral electron-donor ligand (% of the molar amount of palladium in the initial nitric acid solution);

X is the reaction temperature of the nitrite-nitrosyl compound of palladium with the ligand (° C);

XI is the ligand content in the solution before the interaction (% by weight);

XII is the alcohol or acetone content in the water-methanol or or water-ethanol or water-acetone solution of the ligand before the reaction and in the solvent in which Pd (NO) NO _{2 is} dissolved (% by weight);

XIII - the mass ratio of solid / liquid in suspension of a nitrite-nitrosyl compound palladium / solvent in which the ligand is dissolved;

XIV is the yield of the target compound (% of the amount of palladium in the initial solution of palladium nitrate);

XV - data of x-ray phase analysis of the product. Phase uniformity was evaluated by comparing the X-ray diffraction pattern of the obtained compound with the reference in the ICDD powder base. The content of the impurity phase (if any) was evaluated by analysis of the resulting mixture for palladium.

As shown in the examples, the use of the proposed method allows you to stably obtain dinitrite compounds of palladium in high yield in a chemically pure state of the composition [PdL ₂ (NO ₂ ) ₂ ], where L is an amine (NR ₃ ) or phosphine (PR ₃ ) ligand, R -H and / or organic radical and without chlorine ion impurity.

Claims (7)

1. The method of obtaining disubstituted dinitrite palladium compounds by reacting a solution of palladium nitrate with NO and evaporating the resulting solution, characterized in that in the solution of palladium nitrate after evaporation to a palladium content of at least 100 g / l and free nitric acid not more than 300 g / l at at a temperature of 15-40 ° C, NO is passed until the precipitate of the nitrite-nitrosyl palladium compound precipitates in the presence of perchloric acid in an amount of 0.5-10% of the molar amount of palladium in solution, and the images are filtered the existing nitrite-nitrosyl compound and its interaction with not less than 10% by weight of a solution of a mono- or bidentant amine or phosphine ligand at a temperature of 10-30 ° C. 2. The method according to claim 1, characterized in that the NO passed into the solution of palladium nitrate can contain an admixture of nitrogen oxides (IV) of not more than 30% of the molar amount of nitric oxide (II). 3. The method according to claim 1, characterized in that the interaction of the nitrite-nitrosyl compound of palladium with a ligand solution is carried out when it is dissolved in a minimum amount of solvent or when it is suspended with a solvent in which the ligand is dissolved, with a mass ratio of solid / liquid - 1 / (0.5-4). 4. The method according to claim 1, characterized in that ammonia, or methylamine, or ethylamine, or dimethylamine, or diethylamine, or isopropylamine, or pyridine, or 2-methylpyridine, or 3-methylpyridine, or 4- is used as the monodentant ligand methylpyridine, or pipyridine, or morpholine, or cyclohexylamine, taken in an amount of 180-200% of the molar amount of palladium in the initial solution of palladium nitrate, in the form of an aqueous or aqueous methanol, or aqueous ethanol, or aqueous acetone solution with an alcohol content or acetone 0-80% by weight of the solution. 5. The method according to claim 1, characterized in that ethylene diamine, or propylene-1,2-diamine, or propylene-1,3-diamine, or cyclohexane-1,2-diamine, or cyclohexane-1 is used as the bidentant ligand , 3-diamine, or cyclohexane-1,4-diamine, or 1,10-phenanthroline, or 2,2′-bipyridine, or 4,4′-bipyridine, or piperazine, or hexane-1,6-diamine, taken in the amount of 90-100% of the molar amount of palladium in the initial solution of palladium nitrate, in the form of an aqueous, or water-methanol, or water-ethanol, or water-acetone solution with an alcohol or acetone content of 0 -80% by weight of the solution. 6. The method according to claim 1, characterized in that acetonitrile, or benzonitrile, or aniline, or diphenylamine, or dibenzylamine, or dicyclohexylamine, or quinoline, or 1,2,3,4-tetrahydroquinoline, or phosphine is used as the monodentent ligand or trimethylphosphine or triethylphosphine or triphenylphosphine taken in an amount of 180-200% of the molar amount of palladium in the initial solution of palladium nitrate, in the form of methanol or ethanol, or acetonitrile, or acetone, or isopropanol solution. 7. The method according to claim 1, characterized in that the ortho-phenylenediamine, or para-phenylenediamine, or meta-phenylenediamine, or bis (diphenylphosphine) methylene, or bis (diphenylphosphine) ethylene taken in an amount of 90- 100% of the molar amount of palladium in the initial solution of palladium nitrate, in the form of a methanol, or ethanol, or acetonitrile, or acetone, or isopropanol solution.