RU2847249C1 - Method of producing reactive-purity copper (ii) chloride from technical copper sulphate - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to industrial organic chemistry, particularly to production of reactive-purity copper (II) chloride. Copper sulphate is dissolved in water to concentration of more than 20 % while heating, wherein when bringing solution to 80-105 °C calcium chloride solution is fed and mixed. When finished, the filtrate is filtered and the filtrate is evaporated to copper chloride concentration in the solution of not less than 50 %. Obtained solution is cooled to 20-30 °C and mixed with methanol or acetone in ratio of 1:2-1:5 by volume while stirring. After evaporation of obtained solution crystalline copper chloride in form of dihydrate (CuCl₂⋅2H₂O) is separated by crystallisation or precipitated by adding 1,4-dioxane with its subsequent removal while drying crystals.

EFFECT: reduced toxicity of the method of producing copper (II) chloride and availability of starting material.

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Description

The invention relates to industrial organic chemistry, in particular to the production of reactive-grade copper (II) chloride.

Copper(II) chloride preparations are widely used in organic synthesis, oil refining, the electronics industry, woodworking, agriculture, and other fields. Currently, reagent-grade copper chloride is not produced in Russia and is entirely imported.

Various methods are known for obtaining pure copper chloride preparations, for example, by chlorination of metallic copper [CN 116673479, CN 105236465] or copper-containing raw materials [RU 2458163], by dissolving copper wire in aqua regia [Karyakin Yu.V., Angelov I.I. Pure Chemicals. Guide to the Preparation of Inorganic Reagents and Preparations in Laboratory Conditions. 4th ed., trans. and add. 1974. 408 pp., p. 241], by precipitation with barium chloride from a copper sulfate solution [Chemical Encyclopedia, vol. 3, p. 5]. All these methods use reagents that are toxic and hazardous to handle.

Methods for obtaining copper chloride reagents from waste printed circuit board etching solutions [CN 112813489] by extraction with pyridinecarboxylic acid esters followed by purification by traditional crystallization methods are also known, from copper electrode waste [RU 2094375]. Basic copper chloride ("copper oxychloride") [CN 117509708] and hydrochloric acid can be used as feedstock.

The proposed method uses reagents whose toxicity is lower than the toxicity of copper(II) chloride itself and does not use acidic reagents.

The closest analogue is the production of copper chloride by treating an aqueous solution of copper sulfate with a solution of barium chloride (for example: https://acetyl.ru/o/ncu11cl12.php)

CuSO ₄ +BaCl ₂ =BaSO ₄ +CuCl ₂ .

In this case, due to the complete insolubility of barium sulfate, the sulfate anion is quantitatively precipitated and the process of further purification is reduced to the removal of excess barium ions and impurities originally contained in the copper sulfate.

However, barium chloride is highly toxic, has a high price, is not produced in Russia and requires significant consumption (over 1.4 kg per 1 kg of copper chloride, excluding losses during product purification).

The objective of the invention is a method for producing reactive grade copper (II) chloride that does not use barium chloride.

The technical result of the invention is a reduction in the toxicity of the method for producing copper (II) chloride and the availability of the feedstock.

The said technical result is achieved due to the fact that a method for producing reactive-grade copper (II) chloride is claimed, in which copper sulfate in a concentration of over 20% is dissolved in water upon heating, and when the solution is brought to 80-105°C, a calcium chloride solution is added, mixed, and then filtered, the filtrate is evaporated until the copper chloride concentration in the solution is at least 50%, the resulting solution is cooled to 20-30°C and mixed with methanol or acetone in a ratio of 1:2...1:5 by volume under vigorous stirring, cooled; from the resulting solution, after evaporation, crystalline copper chloride in the form of dihydrate (CuCl ₂ ⋅2H ₂ O) is isolated by crystallization or precipitated by adding 1,4-dioxane, followed by its removal during drying of the crystals.

Implementation of the invention

The present invention proposes to use calcium chloride, a non-toxic, readily available and inexpensive domestic product, instead of barium chloride.

The claimed method for producing reagent-grade copper (II) chloride is based on the formation of copper chloride from concentrated (more than 20%) aqueous solutions of copper sulfate and calcium chloride. To reduce the sulfate ion content in the solution, the process is carried out at a temperature of 80...105°C. To finally remove calcium sulfate from the product, its aqueous solution is treated with methanol in a methanol:solution ratio of 2:1 to 5:1. From the resulting solution, after evaporation, crystalline copper chloride in the form of dihydrate (CuCl ₂ ⋅2H ₂ O) is isolated by traditional crystallization methods or precipitated by the addition of 1,4-dioxane, followed by its removal during drying of the crystals.

Calcium sulfate is slightly soluble in water (2.036 g per liter of water at 20°C), allowing for the conversion of almost all copper sulfate to chloride. However, this level of solubility precludes the production of a reagent-grade product. Additional measures are required to reduce the amount of calcium sulfate in the intermediate product to acceptable levels. To achieve this, calcium sulfate precipitation is carried out using concentrated solutions of copper sulfate and calcium chloride at temperatures of 80–105°C, as the solubility of calcium sulfate decreases significantly above 60°C (0.67 g per liter of water at 100°C). The resulting suspension is quickly filtered using a Nutsche or Druck filter, the precipitate is washed with hot water, and the resulting filtrate is evaporated at normal or reduced pressure. After evaporation to a copper chloride concentration of approximately 50%, the solution is cooled to 20-30°C and mixed with methanol or acetone in a ratio of 1:2-1:5 by volume with vigorous stirring. After cooling, the solution is filtered, the filter cake is washed with cold methanol (acetone), and the resulting solution is evaporated at normal or reduced pressure until all the methanol (acetone) is removed, which is sent for regeneration. Evaporation of the aqueous copper chloride solution is then continued until its content reaches 50% or more. After cooling, 1,4-dioxane is added to the solution in a ratio of 1:2-1:3 with stirring. After complete cooling, the reaction mixture is filtered. The resulting crystals are dried under reduced pressure at a temperature of 50-100°C, and the dioxane solution is sent for regeneration.

The isolation of crystalline copper(II) chloride can also be carried out without the use of dioxane, using traditional crystallization methods.

The invention is illustrated by examples.

Example 1

50.2 g of technical copper sulfate were dissolved in 100 ml of water while heating in a glass beaker. At a temperature of 100°C, a calcium chloride solution with a concentration of 151 g/L was added. 151 ml of the solution was added over 15 minutes at a temperature of 85-93°C, then stirred for another 20 minutes at 89-98°C. Upon completion, the mixture was filtered on a Buchner funnel with a paper filter under vacuum, and the precipitate was washed with 300 ml of hot water in 5 portions. The filtrate was evaporated to a volume of less than 200 ml (320 ml of water was distilled off), 400 ml of acetone was added after cooling, and after cooling to room temperature, the mixture was filtered on a Buchner funnel with a paper filter under vacuum, and the precipitate was washed with 25 ml of acetone. The semi-finished product does not contain sulfate ions when tested with barium chloride. Acetone (350 ml) was distilled from the filtrate using a rotary evaporator, then transferred to a beaker and evaporated until the organics were gone. Drying yielded 31.1 g of crystalline copper(II) chloride dihydrate (91%). Recrystallization yielded 14.9 g of crystalline copper(II) chloride dihydrate, meeting the analytical grade requirements of GOST 4167. The yield was 46% based on copper. The mother liquor was sent for copper recycling.

Example 2

A 3-liter jacketed reactor was charged with 150 g of technical copper sulfate, 350 ml of distilled water, and a solution was obtained with heating and stirring. The temperature was raised to 90°C, and 420 ml of a 16.2% calcium chloride solution at 80–87°C was added over 20 minutes with vigorous stirring. The mixture was then stirred for 30 minutes at 90–95°C. The resulting suspension was filtered using a Buchner funnel with a paper filter under vacuum, and the precipitate was washed with 400 ml of hot water in four portions. The filtrate was transferred to the reactor, and approximately 800 ml of water was evaporated. After the solution cooled, 1200 ml of methanol was added. The mixture was stirred and, after cooling to room temperature, filtered using a Buchner funnel with a paper filter under vacuum. The precipitate was washed with 400 ml of methanol in four portions. The filtrate was transferred to a reactor, and approximately 1400 ml of methanol and approximately 200 ml of water were evaporated.

The resulting solution was free of sulfate ions (a sample with barium chloride was clear within an hour). The solution was then subjected to fractional crystallization, yielding 35.1 g of crystalline copper(II) chloride dihydrate, which met the analytical grade requirements of GOST 4167. The yield was 34% based on copper. The mother liquor was recycled for copper recovery.

Example 3

A 5-liter jacketed reactor was charged with 375 g of technical copper sulfate, 750 ml of distilled water, and a solution was obtained with heating and stirring. The temperature was raised to 90°C, and 1 liter of a 16.2% calcium chloride solution at 80–88°C was added over 30 minutes with vigorous stirring. The mixture was then stirred for 30 minutes at 97–105°C. The resulting suspension was filtered using a Buchner funnel with a paper filter under vacuum, and the precipitate was washed with 500 ml of hot water in four portions. The filtrate was transferred to the reactor, and approximately 1900 ml of water was evaporated. After the solution cooled, 3.5 liters of methanol were added. The mixture was stirred and, after cooling to room temperature, filtered using a Buchner funnel with a paper filter under vacuum. The precipitate was washed with 500 ml of methanol in four portions. The filtrate was transferred to a reactor, and approximately 3.5 ml of methanol and approximately 500 ml of water were evaporated.

The resulting solution was free of sulfate ions (a sample with barium chloride was clear within an hour). The solution was then subjected to fractional crystallization, yielding 84.9 g of crystalline copper(II) chloride dihydrate, which met the analytical grade requirements of GOST 4167. The yield was 33% based on copper. The mother liquor was recycled for copper recovery.

Example 4

150 g of technical copper sulfate were dissolved in 300 ml of water in a glass beaker under heating. At a temperature of 92°C, a calcium chloride solution with a concentration of 160 g/L was added. 470 ml of the solution were added over 60 minutes at a temperature of 85-93°C, then stirred for another 20 minutes at 86-91°C. Finally, the mixture was filtered on a Buchner funnel with a paper filter under vacuum, and the precipitate was washed with 300 ml of hot water in 5 portions. The filtrate was evaporated to a volume of approximately 200 ml (600 ml of water was distilled off), 750 ml of methanol was added after cooling, and after cooling to room temperature, the mixture was filtered on a Buchner funnel with a paper filter under vacuum, the precipitate was washed with 120 ml of methanol in 3 portions. 820 ml of methanol were distilled from the filtrate using a rotary evaporator, then the solution was transferred to a beaker and evaporated until the methanol was gone. The solution was free of sulfate ions (a sample with barium chloride was clear within an hour). After cooling to room temperature, 550 ml of 1,4-dioxane was added to the resulting solution (approximately 200 ml). Dark green crystals precipitated. After removing the dioxane and vacuum drying, 78.9 g of crystalline copper(II) chloride dihydrate, meeting the analytical grade requirements of GOST 4167, were obtained. The yield was 77% based on copper. The mother liquor, after dioxane regeneration, was transferred to copper recycling.

Claims (1)

A method for producing reagent-grade copper (II) chloride characterized by dissolving copper sulfate in water to a concentration of over 20% upon heating, wherein upon bringing the solution to 80-105°C a calcium chloride solution is added, the mixture is stirred, and then filtered, the filtrate is evaporated to a copper chloride concentration in the solution of at least 50%, the resulting solution is cooled to 20-30°C and mixed with methanol or acetone in a ratio of 1:2...1:5 by volume while stirring; from the resulting solution, after evaporation, crystalline copper chloride in the form of dihydrate (CuCl ₂ ⋅2H ₂ O) is isolated by crystallization or precipitated by adding 1,4-dioxane, followed by its removal during drying of the crystals.