A method for preparing a solution of dinitrosoplatinous sulfate

Abstract

The present invention discloses a method for preparing a solution of dinitrosoplatinous sulfate, which method comprises: 1) slowly adding an ammonium salt to an aqueous solution of potassium hexanitritoplatinate, stirring and heating for reaction to obtain a suspension containing ammonium hexanitritoplatinate precipitate, cooling, filtering, and washing with a cold ammonium salt solution to obtain a white solid of ammonium hexanitritoplatinate; 2) mixing the solid of ammonium hexanitritoplatinate with a dilute sulfuric acid solution, stirring and heating for reaction until no brownish-red gas is generated to obtain a solution of tetranitrosoplatinic sulfate; 3) after cooling the solution to room temperature, adding a reducing agent dropwise, stirring, and reacting until no more bubbles are generated to obtain a solution of dinitrosoplatinous sulfate. The present invention solves the problems of the addition of current dechlorination reagents such as silver sulfate, incomplete chlorine removal and additional introduction of silver ions. The whole technological process is simple, the overall cost is low, the economy is high, and it is suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to a method for preparing a solution of dinitrosoplatinous acid sulfate, which is used as an electroplating solution, and belongs to the technical field of chemical synthesis. Background Art

[0002] Due to its extremely stable chemical properties, difficulty in oxidation, good heat resistance and durability, high hardness of the coating, small resistance, and solderability, noble metal platinum is widely used in industries such as electronic components, electrode coatings, medical materials, protective materials, and jewelry. In addition, platinum's unique corrosion resistance, physiological non-toxicity, good ductility, and biocompatibility have made its application in the medical field increasingly important. The excellent functions of platinum coatings have made them "supercoating" materials for medical devices and in-vivo implant devices. Currently, the platinum compound commonly used in the platinum plating process is a solution of dinitrosoplatinous acid sulfate. The sulfate-type platinum plating solution is strongly acidic. When electroplating on various substrates, thick platinum can be plated in this solution, the surface of the coating is bright, no gas is evolved during the electroplating process, and the coating has no pinholes or porosity.

[0003] US3206382A discloses a method for obtaining K2Pt(NO2)2SO4 by reacting K2Pt(NO2)4 with dilute sulfuric acid. Specifically, K2Pt(NO2)2SO4 is obtained by reacting K2PtCl4 with AgNO2 and AgSO4. In this method, a solution of potassium tetranitrosoplatinate is mixed with dilute sulfuric acid and heated to 70 °C. After the solution passes through a cation exchange resin, it is then heated to boiling for concentration to obtain bright yellow dinitrosoplatinous acid sulfate.

[0004] In the article "Full Bright Platinum Plating" (Electroplating Group, First Laboratory, Precious Metals Research Institute, Ministry of Metallurgical Industry), a preparation method of dinitrosoplatinous acid sulfate is reported: (1) Chloroplatinic acid reacts with potassium nitrite to obtain potassium tetranitrosoplatinate; chloroplatinic acid reacts with oxalic acid to obtain potassium chloroplatinate. Potassium chloroplatinate and potassium tetranitrosoplatinate with a molar ratio of 1:1 are mixed and fully reacted to obtain a solution of potassium dichlorodinitroplatinate. Then, a silver sulfate solution or solid silver sulfate is added to obtain a solution of potassium dinitrosoplatinous acid sulfate. At 70 °C, it passes through a hydrogen ion exchange resin column to obtain a sulfuric acid solution of dinitrosoplatinous acid sulfate; (2) Chloroplatinic acid reacts with potassium nitrite to obtain potassium tetranitrosoplatinate crystals and a small amount of potassium chloride and potassium nitrite. This crystal is dissolved and reacted with an excess of solid silver sulfate in the hot state to obtain potassium tetranitrosoplatinate and potassium sulfate. It passes through a hydrogen-type ion exchange resin column to obtain a dilute sulfuric acid solution of dinitrosoplatinous acid.

[0005] As can be seen from the above patent disclosure documents or literature, the preparation steps of dinitrosoplatinous sulfate or its salt solution are relatively cumbersome, with a long cycle and are prone to entrainment of other metal ions such as K ions. Among them, the current method for preparing dinitrosoplatinous sulfate requires the use of reagents silver sulfate and cation exchange resin. Silver ion reagent is used to remove chloride ions, and cation exchange resin is used to remove potassium ions and silver ions. The preparation cost is high and it is difficult to obtain a relatively pure dinitrosoplatinous sulfate solution. There has always been a lack of a fast, efficient, economical and general preparation method. Summary of the Invention

[0006] The object of the present invention is to solve the problems of cumbersome preparation process, impurities such as chloride ions, potassium ions, silver ions and their contents in the synthesis of dinitrosoplatinous sulfate solution, and to provide a preparation method with simple operation, convenience, high efficiency and economy, which is suitable for industrial-scale production of dinitrosoplatinous sulfate solution.

[0007] The synthesis steps of the present invention include:

[0008] Step (1), in an aqueous solution of potassium hexanitritoplatinate, an ammonium salt is slowly added, stirred and heated for reaction to obtain a suspension containing ammonium hexanitritoplatinate precipitate. After cooling, filtration is carried out, and it is washed twice with a 15% cold ammonium salt solution to obtain a white solid of ammonium hexanitritoplatinate;

[0009] Step (2), the ammonium hexanitritoplatinate solid is mixed with dilute sulfuric acid solution, stirred and heated for reaction until no brownish-red gas is produced, and a pale yellow solution of tetranitrosoplatinous sulfate is obtained;

[0010] Step (3), after cooling the above solution to room temperature, an appropriate amount of reducing agent is added dropwise, stirred, and the reaction is carried out until no bubbles are produced, and a yellowish-green solution of dinitrosoplatinous sulfate is obtained. The reaction formula is as follows:

[0011]

[0012] Further, in step (2), the spatial structure formula of tetranitrosoplatinous sulfate is any one or a mixture of more than one of ionic type I, ionic type II and bridged molecular type III, and its structural formula is:

[0013]

[0014] Further, in step (1):

[0015] The ammonium salt is one of ammonium chloride, ammonium carbonate, ammonium bicarbonate;

[0016] It is washed twice with a 15% cold ammonium salt solution;

[0017] The molar ratio of potassium hexanitritoplatinate to ammonium salt is 1:2 to 5, and the reaction time is 1 to 3 hours.

[0018] Further, in step (2):

[0019] The mass content of sulfuric acid in the dilute sulfuric acid solution is 20 to 60%;

[0020] The molar ratio of ammonium hexanitritoplatinate to sulfuric acid is 1:1 to 3;

[0021] The heating temperature is 50 to 80 °C and the reaction time is 0.5 to 2 h.

[0022] Further, in step (3), the reducing agent includes any one of formic acid, methanol, oxalic acid, and hydrazine hydrate.

[0023] The beneficial effects of the present invention include:

[0024] (1) The preparation method of the present invention solves the problems of using expensive reagents such as silver sulfate and cation exchange resin in the classical preparation process, as well as the problem of incomplete removal of chlorine and the additional introduction of silver ions. The whole technological process is simple, the overall cost is low, the economy is high, and it is suitable for industrial production;

[0025] (2) The present invention can simply and quickly obtain pure di-nitrosoplatinic acid sulfate without entraining impurity ions such as potassium K ions and silver ions;

[0026] (3) The reagents used in the present invention meet the requirements of atom economy, environmental friendliness, etc., and effectively avoid the influence of impurity ions such as potassium ions, silver ions, and chloride ions. Detailed implementation manners

[0027] Example 1: Preparation of di-nitrosoplatinic acid sulfate solution

[0028] Weigh 10.0 g of potassium hexanitritoplatinate, add 30 g of deionized water, stir, heat at 60 °C, and after the bright yellow potassium hexanitritoplatinate is completely dissolved, add 1.5 g of ammonium chloride solid, stir and react for 2 h to obtain an ammonium hexanitritoplatinate suspension. Filter and wash twice with 15% cold ammonium chloride solution to obtain 9.0 g of white ammonium hexanitritoplatinate solid; then mix the ammonium hexanitritoplatinate solid with 22.3 g of 20% dilute sulfuric acid, stir, and heat at 70 °C to generate red-brown NO x gas, maintain the reaction for 1.5 h to obtain a light yellow tetra-nitrosoplatinic acid sulfate solution. After this solution is cooled to room temperature, slowly add 82.8 g of 1% formic acid solution, stir and react until no bubbles are generated to obtain a yellow di-nitrosoplatinic acid sulfate solution, where the content of di-nitrosoplatinic acid sulfate is 6.95 wt% and the yield is 97.5%.

[0029] Elemental analysis:

[0030] The measured values are Pt 3.54%, N 1.67%, S 1.49%, which are consistent with the theoretical values of Pt 3.65%, N 1.65%, S 1.48%.

[0031] Example 2: Preparation of dinitrosoplatinous sulfate solution

[0032] Weigh 10.0 g of potassium hexanitritoplatinate, add 30 g of deionized water, stir, heat at 60 °C. After the bright yellow potassium hexanitritoplatinate is completely dissolved, add 2.4 g of ammonium carbonate solid, stir and react for 2 h to obtain an ammonium hexanitritoplatinate suspension. Filter it and wash it twice with 15% cold ammonium carbonate solution to obtain 8.6 g of white ammonium hexanitritoplatinate solid; then mix the ammonium hexanitritoplatinate solid with 17.5 g of 25% dilute sulfuric acid, stir, and heat at 70 °C to produce red-brown NO x gas. Keep the reaction for 1.5 h to obtain a pale yellow solution of tetranitrosoplatinic acid sulfate. After this solution is cooled to room temperature, slowly add 42.3 g of 1% oxalic acid solution, stir and react until no bubbles are produced to obtain a yellow dinitrosoplatinous sulfate solution, in which the content of dinitrosoplatinous sulfate is 6.7 wt%, and the yield is 96.5%.

[0033] Elemental analysis:

[0034] The measured values are Pt 3.48%, N 1.71%, S 1.45%, which are consistent with the theoretical values of Pt 3.65%, N 1.65%, S 1.48%.

[0035] Example 3: Preparation of dinitrosoplatinous sulfate solution

[0036] Weigh 10.0 g of potassium hexanitritoplatinate, add 30 g of deionized water, stir, heat at 60 °C. After the bright yellow potassium hexanitritoplatinate is completely dissolved, add 4.5 g of ammonium bicarbonate solid, stir and react for 2.5 h to obtain an ammonium hexanitritoplatinate suspension. Filter it and wash it twice with 15% cold ammonium bicarbonate solution to obtain 8.2 g of white ammonium hexanitritoplatinate solid; then mix the ammonium hexanitritoplatinate solid with 20.6 g of 20% dilute sulfuric acid, stir, and heat at 70 °C to produce red-brown NO x gas. Keep the reaction for 1.5 h to obtain a pale yellow solution of tetranitrosoplatinic acid sulfate. After this solution is cooled to room temperature, slowly add 1.0 g of 50% methanol solution, stir and react until no bubbles are produced to obtain a yellow dinitrosoplatinous sulfate solution, in which the content of dinitrosoplatinous sulfate is 6.1 wt%, and the yield is 93.5%.

[0037] Elemental analysis:

[0038] The measured values are Pt 3.58%, N 1.61%, S 1.43%, which are consistent with the theoretical values of Pt 3.65%, N 1.65%, S 1.48%.

[0039] Example 4: Preparation of dinitrosoplatinous sulfate solution

[0040] Weigh 100.0 g of potassium hexanitritoplatinate, add 260 g of deionized water, stir, and heat at 70 °C. After the bright yellow potassium hexanitritoplatinate is completely dissolved, add 16 g of ammonium chloride solid, stir and react for 2 h to obtain a white suspension of ammonium hexanitritoplatinate. Filter it and wash it twice with 15% cold ammonium chloride solution to obtain 88.5 g of white ammonium hexanitritoplatinate solid. Then mix the ammonium hexanitritoplatinate solid with 143 g of 35% dilute sulfuric acid, stir, and heat at 70 °C to produce a large amount of red-brown NO x gas. Maintain the reaction for 2.0 h to obtain a pale yellow solution of tetranitrosoplatinic acid sulfate. After this solution is cooled to room temperature, slowly add 820 g of 1% formic acid solution, stir and react to produce a large amount of bubbles. React until no bubbles are produced to obtain a yellow dinitrosoplatinous sulfate solution, in which the content of dinitrosoplatinous sulfate is 6.64 wt% and the yield is 95.5%.

[0041] Elemental analysis:

[0042] The measured values are Pt 3.46%, N 1.61%, S 1.53%, which are consistent with the theoretical values of Pt 3.65%, N 1.65%, S 1.48%.

[0043] Example 5: Preparation of dinitrosoplatinous sulfate solution

[0044] Weigh 100.0 g of potassium hexanitritoplatinate, add 260 g of deionized water, stir, and heat at 70 °C. After the bright yellow potassium hexanitritoplatinate is completely dissolved, add 23 g of ammonium carbonate solid, stir and react for 2 h to obtain a white suspension of ammonium hexanitritoplatinate. Filter it and wash it twice with 15% cold ammonium carbonate solution to obtain 88.5 g of white ammonium hexanitritoplatinate solid. Then mix the ammonium hexanitritoplatinate solid with 112 g of 45% dilute sulfuric acid, stir, and heat at 70 °C to produce a large amount of red-brown NO x gas. Maintain the reaction for 2.0 h to obtain a pale yellow solution of tetranitrosoplatinic acid sulfate. After this solution is cooled to room temperature, slowly add 16.5 g of 50% hydrazine hydrate solution, stir and react to produce a large amount of bubbles. React until no bubbles are produced to obtain a yellow dinitrosoplatinous sulfate solution, in which the content of dinitrosoplatinous sulfate is 6.58 wt% and the yield is 93.6%.

[0045] Elemental analysis:

[0046] The measured values are Pt 3.41%, N 1.58%, S 1.56%, which are consistent with the theoretical values of Pt 3.65%, N 1.65%, S 1.48%.

Claims

1. A method for preparing a dinitrosoplatinous acid sulfate solution, characterized in that: The following steps are involved: Step (1), slowly adding ammonium salt to an aqueous solution of potassium hexanitrosoplatinate, stirring and heating to react, to obtain a suspension containing ammonium hexanitrosoplatinate precipitate, cooling, filtering, and washing with a cold ammonium salt solution to obtain a white ammonium hexanitrosoplatinate solid; Step (2) mixing the ammonium hexanitrosoplatinate solid with the dilute sulfuric acid solution, stirring, heating, and reacting until no brown-red gas is generated to obtain a sulfuric acid tetranitrosoplatinic acid solution; Step (3), after cooling the above solution to room temperature, add an appropriate amount of reducing agent dropwise, stir, and react until no bubbles are generated to obtain a sulfuric acid dinitrosoplatinous acid solution, the reaction formula of which is as follows: 。 2. The method according to claim 1, wherein: The spatial structural formula of tetranitrosoplatinic acid sulfate in step (2) is a mixture of any one or more of ionic type I, ionic type II and bridging molecule type III, and its structural formula is: 。 3. The method according to claim 1, wherein: In step (1), the ammonium salt includes any one of ammonium chloride, ammonium carbonate, and ammonium bicarbonate.

4. The method according to claim 1, wherein: In step (1), wash twice with 15% cold ammonium salt solution.

5. The method according to claim 1, wherein: In step (1), the molar ratio of potassium hexanitroplatinate to ammonium salt is 1:2-5, and the reaction time is 1-3 hours.

6. The method according to claim 1, wherein: In step (2), the mass content of sulfuric acid in the dilute sulfuric acid solution is 20-60%.

7. The method according to claim 1, wherein: In step (2), the molar ratio of the ammonium hexanitrosoplatinate to the sulfuric acid is 1:1-3.

8. The method according to claim 1, wherein: In step (2), the heating temperature is 50-80°C and the reaction time is 0.5-2 h.

9. The method according to any one of claims 1 to 8, characterized in that: In step (3), the reducing agent includes any one of formic acid, methanol, oxalic acid, and hydrazine hydrate.

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