A method for preparing methyl perfluoroisobutyrate by electrochemical fluorination

Abstract

The invention discloses a method for preparing methyl perfluoroisobutyrate by an electrochemical fluorination method. Using methacrylic acid and its derivatives as starting materials, the electrochemical fluorination reaction is carried out with hydrogen fluoride in an electrochemical reactor. , the obtained gas phase product is passed into methanol solution to fully react for esterification, and the reaction liquid is distilled to collect the product. The method of the invention uses methacrylic anhydride and its derivatives as raw materials, solves the isomerization problem of isobutyric anhydride in the electrochemical fluorination process, and has the characteristics of good reaction selectivity, no isomer by-products and high yield.

Description

technical field

[0001] The invention relates to a preparation method of methyl perfluoroisobutyrate, in particular to an electrochemical fluorination method. Background technique

[0002] Methyl perfluoroisobutyrate is a key intermediate in the synthesis of perfluoroisobutyronitrile. Perfluoroisobutyronitrile is a new type of environmentally friendly insulating gas material, which can be used as a dielectric composition for electrical equipment insulators. In recent years, it has attracted extensive attention from major electrical companies and research institutions around the world.

[0003]

[0004] Methyl perfluoroisobutyrate is not available commercially, and needs to be synthesized by itself. 3M’s patented US 2015 / 0083979Al process for preparing methyl perfluoroisobutyrate is as follows: use isobutyric anhydride as the starting material, and prepare perfluoroisobutyryl fluoride by electrochemical fluorination with hydrogen fluoride in an electrochemical reactor , a...

Examples

Embodiment 1

[0020] Put 800g of methacrylic anhydride into an electrochemical reactor containing 10kg of anhydrous hydrogen fluoride at 0°C, control the operating voltage of the electrochemical reactor to 4.5V-5.0V, and the current density at 5-10mA / cm 2 , the system temperature was maintained at 0-5°C. During the reaction process, the gaseous product generated was passed through the gas phase outlet of the reactor, and slowly passed into a reaction kettle containing 1L of methanol and 530g of anhydrous sodium fluoride, and fully reacted for 3 hours at room temperature. After the reaction was finished, the reaction solution was filtered, and the unreacted methanol was removed by distillation from the obtained filtrate, leaving 1055 g of colorless and transparent liquid methyl heptafluoroisobutyrate. The product was characterized by gas chromatography and no methyl heptafluoro-n-butyrate by-product was detected. The purity of methyl heptafluoroisobutyrate is 90.41%, the reaction selectivity...

Embodiment 2

[0022] Put 1kg of methacrylic acid into the electrochemical reactor containing 17kg of anhydrous hydrogen fluoride at 0°C, control the operating voltage of the electrochemical reactor to 5.0V-10V, and the current density at 25-30mA / cm 2 , the system temperature was maintained at 0-5°C. During the reaction process, the gaseous product produced was passed through the gas phase outlet of the reactor, and slowly passed into a reaction kettle containing 1L of methanol and 595g of anhydrous sodium fluoride, and fully reacted for 3 hours at room temperature. After the reaction, the reaction liquid was filtered, and the unreacted methanol was removed by distillation from the obtained filtrate, leaving 1105g of colorless and transparent liquid methyl heptafluoroisobutyrate, and the product was characterized by gas chromatography without detecting the by-product of methyl heptafluorobutyrate , purity 91.22%, reaction selectivity 38.05%, product yield 38.05%. 1 H NMR (500 MHz, CDCl 3 )...

Embodiment 3

[0024] Put 500g of methacryloyl chloride into an electrochemical reactor containing 5kg of anhydrous hydrogen fluoride at 0°C, control the operating voltage of the electrochemical reactor to 6.0V-10V, and the current density at 15-30mA / cm 2 , the system temperature was maintained at -10-1°C. During the reaction process, the gaseous product generated was passed through the gas phase outlet of the reactor, and slowly passed into a reaction kettle containing 1L of methanol and 250g of anhydrous sodium fluoride, and fully reacted for 2 hours at room temperature. After the reaction, the reaction liquid was filtered, and the obtained filtrate was distilled to remove unreacted methanol, leaving 458g of colorless and transparent liquid methyl heptafluoroisobutyrate, and the product was characterized by gas chromatography without detecting methyl heptafluoro-n-butyrate as a by-product , purity 93.03%, reaction selectivity 39.06%, product yield 39.06%. 1 H NMR (500 MHz, CDCl 3 )δ4.01(...

technical field

[0001] The invention relates to a preparation method of methyl perfluoroisobutyrate, in particular to an electrochemical fluorination method. Background technique

[0002] Methyl perfluoroisobutyrate is a key intermediate in the synthesis of perfluoroisobutyronitrile. Perfluoroisobutyronitrile is a new type of environmentally friendly insulating gas material, which can be used as a dielectric composition for electrical equipment insulators. In recent years, it has attracted extensive attention from major electrical companies and research institutions around the world.

[0003]

[0004] Methyl perfluoroisobutyrate is not available commercially, and needs to be synthesized by itself. 3M’s patented US 2015 / 0083979Al process for preparing methyl perfluoroisobutyrate is as follows: use isobutyric anhydride as the starting material, and prepare perfluoroisobutyryl fluoride by electrochemical fluorination with hydrogen fluoride in an electrochemical reactor , a...

Examples

Embodiment 1

[0020] Put 800g of methacrylic anhydride into an electrochemical reactor containing 10kg of anhydrous hydrogen fluoride at 0°C, control the operating voltage of the electrochemical reactor to 4.5V-5.0V, and the current density at 5-10mA / cm 2 , the system temperature was maintained at 0-5°C. During the reaction process, the gaseous product generated was passed through the gas phase outlet of the reactor, and slowly passed into a reaction kettle containing 1L of methanol and 530g of anhydrous sodium fluoride, and fully reacted for 3 hours at room temperature. After the reaction was finished, the reaction solution was filtered, and the unreacted methanol was removed by distillation from the obtained filtrate, leaving 1055 g of colorless and transparent liquid methyl heptafluoroisobutyrate. The product was characterized by gas chromatography and no methyl heptafluoro-n-butyrate by-product was detected. The purity of methyl heptafluoroisobutyrate is 90.41%, the reaction selectivity...

Embodiment 2

[0022] Put 1kg of methacrylic acid into the electrochemical reactor containing 17kg of anhydrous hydrogen fluoride at 0°C, control the operating voltage of the electrochemical reactor to 5.0V-10V, and the current density at 25-30mA / cm 2 , the system temperature was maintained at 0-5°C. During the reaction process, the gaseous product produced was passed through the gas phase outlet of the reactor, and slowly passed into a reaction kettle containing 1L of methanol and 595g of anhydrous sodium fluoride, and fully reacted for 3 hours at room temperature. After the reaction, the reaction liquid was filtered, and the unreacted methanol was removed by distillation from the obtained filtrate, leaving 1105g of colorless and transparent liquid methyl heptafluoroisobutyrate, and the product was characterized by gas chromatography without detecting the by-product of methyl heptafluorobutyrate , purity 91.22%, reaction selectivity 38.05%, product yield 38.05%. 1 H NMR (500 MHz, CDCl 3 )...

Embodiment 3

[0024] Put 500g of methacryloyl chloride into an electrochemical reactor containing 5kg of anhydrous hydrogen fluoride at 0°C, control the operating voltage of the electrochemical reactor to 6.0V-10V, and the current density at 15-30mA / cm 2 , the system temperature was maintained at -10-1°C. During the reaction process, the gaseous product generated was passed through the gas phase outlet of the reactor, and slowly passed into a reaction kettle containing 1L of methanol and 250g of anhydrous sodium fluoride, and fully reacted for 2 hours at room temperature. After the reaction, the reaction liquid was filtered, and the obtained filtrate was distilled to remove unreacted methanol, leaving 458g of colorless and transparent liquid methyl heptafluoroisobutyrate, and the product was characterized by gas chromatography without detecting methyl heptafluoro-n-butyrate as a by-product , purity 93.03%, reaction selectivity 39.06%, product yield 39.06%. 1 H NMR (500 MHz, CDCl 3 )δ4.01(...

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