An electrochemical process for the synthesis of dihydrocarbyl ether compounds from hydrocarbyl alcohols

Abstract

The present application relates to a kind of electrochemical methods for synthesizing dihydrocarbyl ether compound by hydrocarbyl alcohol, which uses pulse power, with hydrocarbyl alcohol as main starting material, one-step synthesis of dihydrocarbyl ether compound, electrolysis under pulse current in electrolyte containing hydrocarbyl alcohol, i.e. the dehydration etherification between alcohol hydroxyl group can occur, after etherification reaction stops, the electrolysis mother liquor is separated to obtain dihydrocarbyl ether compound.The method described in the present application selects pulse power, uses graphite or platinum or other conductive materials that can resist electrolyte corrosion as electrode, power on and complete electrolysis, through conventional separation and purification, dihydrocarbyl ether compound is obtained.The method is simple in equipment, mild in condition, environmentally friendly in process, and good in etherification effect.

Description

Technical Field

[0001] This invention relates to an electrochemical method for synthesizing dialkyl ether compounds from hydrocarbon alcohols, and more particularly to a method for synthesizing dialkyl ether compounds using electrochemical technology with hydrocarbon alcohols as the main raw materials. Background Technology

[0002] The disclosed synthetic methods for ether compounds mainly involve the dehydration of hydroxyl groups between hydrocarbon alcohols to form ether bonds under the action of a catalyst. For example, solid acid is used as a catalyst to catalyze the synthesis of dialkyl ethers (CN105601478A, CN101386569A, CN101386569B, CN101993355A, CN104250256A, CN104250256B, CN103319316A, CN103319316B, CN102924241A, CN102924241B, CN10175). 7942A, CN101757942B, US09139503B2, AU2008299809A1, UA95019C2); Ether compounds can also be synthesized by reacting the hydroxyl group of a hydrocarbon alcohol with the double bond of an alkene under the action of a catalyst (CN101386568A, CN101386568B); Ether compounds can also be synthesized by group exchange method (CN101033176A, CN100569723C, CN100567240C, CN101033177A).

[0003] All of the methods described above utilize thermocatalysis, sharing the common characteristic of employing a catalyst and requiring specific temperatures or pressures for the reaction. The physical state of a particular raw material necessitates a reactor with a corresponding reactor structure, and the chemical structure of the raw material also requires catalysts of varying compositions and forms. This introduces complexity into the reaction operation and results in the incompatibility of production equipment. The inherent nature of thermocatalysis dictates that it must operate at a high cost.

[0004] In this invention, graphite, platinum, or other conductive materials that can withstand corrosion from acids, alcohols, and various solvents are used as anodes. The two electrodes are placed in an electrolyte containing hydrocarbon alcohols, acids, and solvents. Under the action of a pulsed electric field of a certain frequency, the hydrocarbon alcohols undergo dehydration between hydroxyl groups on the electrodes, i.e., hydroxyl etherification reaction, to form dialkyl ether compounds.

[0005] This invention fundamentally changes the preparation method of dialkyl ether compounds. The core of this invention is the use of electrolysis technology to directly synthesize dialkyl ether compounds from a raw material hydrocarbon alcohol in a single reaction under mild conditions and in a simple electrolyte. Compared with traditional thermocatalytic methods, it has the advantages of not involving high temperature and high pressure conditions, and the equipment used is simple and easy to implement. Summary of the Invention

[0006] The purpose of this invention is to provide an electrochemical method for synthesizing dialkyl ether compounds from hydrocarbon alcohols. This method employs a pulsed power supply, using hydrocarbon alcohols as the main starting material, to synthesize dialkyl ether compounds in one step. Electrolysis under pulsed current occurs in an electrolyte containing hydrocarbon alcohols, leading to dehydration and etherification between the hydroxyl groups of the alcohol. After the etherification reaction stops, the mother electrolyte is separated to obtain the dialkyl ether compounds. The method uses a pulsed power supply and employs graphite, platinum, or other conductive materials resistant to electrolyte corrosion as electrodes. After electrolysis, the compounds are separated and purified using conventional methods to obtain the dialkyl ether compounds. This method features simple equipment, mild conditions, an environmentally friendly process, and good etherification results.

[0007] The present invention discloses an electrochemical method for synthesizing dialkyl ether compounds from hydrocarbon alcohols. This method employs pulsed current electrolysis of a conductive alcohol-containing solution, and the specific operation is carried out according to the following steps:

[0008] a. Mix the hydroxyl alcohol and acid in a molar ratio of 100:10-100:0.5 to form an electrolyte. The hydroxyl alcohol is one or two of methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, cyclohexanol, and phenethyl alcohol. The acid is one or two of p-toluenesulfonic acid, benzenesulfonic acid, methylbenzenesulfonic acid, sulfuric acid, hydrochloric acid, sodium bisulfate, nitric acid, or perchloric acid.

[0009] b. Use a power supply that can output sinusoidal, square, triangular, or arbitrary wave pulses. Connect the two output terminals of the power supply to graphite, boron-doped diamond, platinum, or titanium-coated electrodes. Immerse the two electrodes in the electrolyte prepared in step a. Turn on the power supply and control the voltage range of the pulse current to 0.1-30 volts, the frequency of the pulse current to 1 Hz-100 kHz, the duty cycle of the pulse current to 1-99%, and the electrolyte temperature to 20-50°C. Perform electrolysis with a current density of 0.1-5 amperes per cubic decimeter. Stop electrolysis when the charge is 1.5-3.0 times the required theoretical charge. Separate and purify the target ether compound using conventional methods.

[0010] The present invention discloses an electrochemical method for synthesizing dialkyl ether compounds from hydrocarbon alcohols. This method uses pulsed current to electrolyze a conductive alcohol-containing solution. When the acid and alcohol cannot form a liquid phase solution, an inert solvent can be used to dissolve them to form a homogeneous electrolyte. Detailed Implementation

[0011] Example 1

[0012] a. Mix methanol and sulfuric acid evenly at a molar ratio of 100:0.5 to prepare an electrolyte;

[0013] b. Using a power supply capable of outputting sinusoidal pulse current, both output terminals of the power supply are connected to graphite electrodes. Both electrodes are then immersed in the electrolyte prepared in step a. Electrolysis is performed by turning on the power supply. The sinusoidal pulse power supply outputs a pulse current with a frequency of 50 Hz, a pulse current duty cycle of 50%, and a pulse voltage of 10 V. The current density in the electrolyte is 0.5 amperes per cubic decimeter, the electrolyte temperature is 25°C, and the current density is 0.1 amperes per cubic decimeter. Electrolysis is stopped after the amount of charge passed is 1.5 times the required theoretical amount of charge. The mother electrolyte is then heated to 40°C, and the evaporated gas is introduced into a -40°C cold trap for purification to obtain the target compound, dimethyl ether.

[0014] Example 2

[0015] a. Mix ethanol and p-toluenesulfonic acid evenly at a molar ratio of 100:8 to prepare an electrolyte;

[0016] b. Using a power supply capable of outputting square wave pulse current, both output terminals of the power supply are connected to boron-doped diamond electrodes. Both electrodes are then immersed in the electrolyte prepared in step a. Electrolysis is performed by turning on the power supply. The square wave pulse power supply outputs a pulse current with a frequency of 1000 Hz, a pulse current duty cycle of 25%, and a pulse voltage of 15 V. The current density in the electrolyte is 0.3 amperes per cubic decimeter, the electrolyte temperature is 30°C, and the current density is 0.5 amperes per cubic decimeter. Electrolysis is stopped after the amount of charge passed is 2.0 times the required theoretical amount of charge. The mother liquor of the electrolyte is heated and distilled. The gas at the top of the distillation column is introduced into a -20°C cold trap for purification to obtain the target compound, diethyl ether.

[0017] Example 3

[0018] a. Mix isopropanol and hydrochloric acid evenly at a molar ratio of 100:6 to prepare an electrolyte;

[0019] b. Using a power supply capable of outputting triangular wave pulse current, both output terminals of the power supply are connected to graphite electrodes. Both electrodes are then immersed in the electrolyte prepared in step a. Electrolysis is performed by turning on the power supply. The triangular wave pulse power supply outputs a pulse current with a frequency of 100 Hz, a pulse current duty cycle of 60%, and a pulse voltage of 20 V. The current density in the electrolyte is 0.6 amperes per cubic decimeter, the electrolyte temperature is 35°C, and the current density is 2 amperes per cubic decimeter. Electrolysis is stopped after the amount of charge passed is 2.0 times the required theoretical amount of charge. The mother liquor of the electrolyte is heated and distilled. The gas at the top of the distillation column is introduced into a -10°C cold trap for purification to obtain the target compound, diisopropyl ether.

[0020] Example 4

[0021] a. Mix n-butanol and nitric acid evenly at a molar ratio of 100:10 to prepare an electrolyte;

[0022] b. A power supply capable of outputting arbitrary wave pulse current is used. Both output terminals of the power supply are connected to titanium-coated electrodes with stable dimensions. Both electrodes are then immersed in the electrolyte prepared in step a. Electrolysis is performed by turning on the power supply. The arbitrary wave pulse power supply outputs a pulse current with a frequency of 200 Hz, a pulse current duty cycle of 40%, and a pulse voltage of 25 V. The current density in the electrolyte is 0.8 amperes per cubic decimeter, the electrolyte temperature is 40°C, and the current density is 3.2 amperes per cubic decimeter. Electrolysis is stopped after the amount of charge passed is 3.0 times the required theoretical amount of charge. The mother liquor of the electrolyte is heated and distilled. The liquid obtained in the reboiler of the distillation column is thoroughly washed with 20% sodium carbonate and then separated. The oil phase is taken from the separated liquid to obtain the target compound, di-n-butyl ether.

[0023] Example 5

[0024] a. Mix tert-butanol and methanol with perchloric acid in a molar ratio of 30:70:10 to prepare an electrolyte.

[0025] b. Using a power supply capable of outputting sinusoidal pulse current, both output terminals of the power supply are connected to graphite electrodes. Both electrodes are then immersed in the electrolyte prepared in step a. Electrolysis is performed by turning on the power supply. The sinusoidal pulse power supply outputs a pulse current with a frequency of 500 Hz, a pulse current duty cycle of 50%, and a pulse voltage of 15 V. The current density in the electrolyte is 1.0 amperes per cubic decimeter, the electrolyte temperature is 40°C, and the current density is 4.5 amperes per cubic decimeter. Electrolysis is stopped after the amount of charge passed is 3.0 times the required theoretical amount of charge. The mother liquor of the electrolyte is heated and distilled. The gas at the top of the distillation column is introduced into a -10°C cold trap for purification to obtain the target compound tert-butyl methyl ether.

[0026] Example 6

[0027] a. Mix cyclohexanol and toluenesulfonic acid at a molar ratio of 100:10. Gradually add acetonitrile solvent to the mixture of cyclohexanol and toluenesulfonic acid and continue stirring until the mixture is homogeneous. Stop adding acetonitrile solvent after the acetonitrile, cyclohexanol and toluenesulfonic acid form a homogeneous phase. Prepare the electrolyte.

[0028] b. Using a power supply capable of outputting arbitrary wave pulse current, both output terminals of the power supply are connected to graphite electrodes. Both electrodes are then immersed in the electrolyte prepared in step a. Electrolysis is performed by turning on the power supply. The arbitrary wave pulse power supply outputs a pulse current with a frequency of 80 Hz, a pulse current duty cycle of 45%, and a pulse voltage of 20 volts. The current density in the electrolyte is 0.4 amperes per cubic decimeter, the electrolyte temperature is 40°C, and the current density is 5.0 amperes per cubic decimeter. Electrolysis is stopped after the amount of charge passing through is 2.0 times the required theoretical amount of charge. The mother liquor of the electrolyte is heated and distilled. The liquid obtained in the reboiler of the distillation column is thoroughly washed with 20% sodium carbonate and then separated. The oil phase is collected from the separation, which yields the target compound, dicyclohexyl ether.

[0029] Example 7

[0030] a. Mix cyclohexanol and methanol with sulfuric acid in a molar ratio of 40:60:10 to prepare an electrolyte;

[0031] b. Use a power supply capable of outputting square wave pulse current. Connect both output terminals of the power supply to graphite electrodes. Immerse both electrodes in the electrolyte prepared in step a. Turn on the power supply for electrolysis. The square wave pulse power supply outputs a pulse current with a frequency of 40 Hz, a pulse current duty cycle of 35%, and a pulse voltage of 20 volts. The current density in the electrolyte is 0.5 amperes per cubic decimeter. The electrolyte temperature is 30°C, and the current density is 2.5 amperes per cubic decimeter. Stop electrolysis after the amount of charge passing through is 1.5 times the required theoretical amount of charge. Heat the mother liquor for distillation. The liquid obtained in the reboiler of the distillation column is thoroughly washed with 20% sodium carbonate and then separated. Take the oil phase from the separation to obtain the target compound cyclohexylmethyl ether.

[0032] Example 8

[0033] a. Mix phenethyl alcohol and methanol with toluenesulfonic acid in a molar ratio of 40:60:10 to form an electrolyte;

[0034] b. A power supply capable of outputting triangular wave pulse current is used. Both output terminals of the power supply are connected to titanium-coated electrodes with stable dimensions. Both electrodes are then immersed in the electrolyte prepared in step a. Electrolysis is performed by turning on the power supply. The triangular wave pulse power supply outputs a pulse current with a frequency of 300 Hz, a pulse current duty cycle of 50%, and a pulse voltage of 25 V. The current density in the electrolyte is 1.5 A / dm³, the electrolyte temperature is 35℃, and the current density is 0.8 A / dm³. Electrolysis is stopped after the amount of electricity passed is 1.5 times the required theoretical amount. Excess methanol is distilled off from the mother liquor under normal pressure. The remaining liquid is then heated for rectification. The gas at the top of the rectification column is introduced into a -10℃ cold trap, thus purifying and obtaining the target compound, phenethyl methyl ether.

[0035] Example 9

[0036] a. Mix tert-butanol and ethanol with sulfuric acid in a molar ratio of 60:40:10 to prepare an electrolyte;

[0037] b. Using a power supply capable of outputting sinusoidal pulse current, both output terminals of the power supply are connected to graphite electrodes. Both electrodes are then immersed in the electrolyte prepared in step a. Electrolysis is performed by turning on the power supply. The sinusoidal pulse power supply outputs a pulse current with a frequency of 50 Hz, a pulse current duty cycle of 50%, and a pulse voltage of 20 V. The current density in the electrolyte is 2.5 amperes per cubic decimeter, the electrolyte temperature is 30°C, and the current density is 0.9 amperes per cubic decimeter. Electrolysis is stopped after the amount of electricity passed is 2.5 times the required theoretical amount of electricity. The mother liquor of the electrolyte is heated and distilled. The gas at the top of the distillation column is introduced into a cold trap at -10°C, thus purifying and obtaining the target compound tert-butyl ethyl ether.

Claims

1. An electrochemical method for synthesizing dialkyl ether compounds from hydrocarbon alcohols, characterized in that... This method uses pulsed current electrolysis to dissolve a conductive alcohol-containing solution. The specific operation is carried out according to the following steps: a. Mix the hydroxyl alcohol and acid in a molar ratio of 100:10-100:0.5 to form an electrolyte. The hydroxyl alcohol is one or two of methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, cyclohexanol, and phenethyl alcohol. The acid is one or two of p-toluenesulfonic acid, benzenesulfonic acid, methylbenzenesulfonic acid, sulfuric acid, hydrochloric acid, sodium bisulfate, nitric acid, or perchloric acid. b. Use a power supply that can output sinusoidal, square, triangular, or arbitrary wave pulses. Connect the two output terminals of the power supply to graphite, boron-doped diamond, platinum, or titanium-coated electrodes. Immerse the two electrodes in the electrolyte prepared in step a. Turn on the power supply and control the voltage range of the pulse current to 0.1-30 volts, the frequency of the pulse current to 1 Hz-100 kHz, the duty cycle of the pulse current to 1-99%, and the electrolyte temperature to 20-50°C. Perform electrolysis with a current density of 0.1-5 amperes per cubic decimeter. Stop electrolysis when the charge is 1.5-3.0 times the required theoretical charge. Separate and purify the target ether compound using conventional methods.