A method for preparing propargyl alcohol by electrolyzing glycerol

Abstract

The present invention relates to the technical field of organic electrochemical synthesis, and in particular to a method for preparing propargyl alcohol by electrolyzing glycerol. The specific method comprises the following steps: adding glycerol and an aqueous chloride solution of an alkali metal or an alkaline earth metal into an electrolytic cell, electrolyzing under the action of a direct current to obtain an electrolyte containing propargyl alcohol, chlorine and hydrogen, and separating the electrolyte by a membrane to obtain propargyl alcohol. The method of the present invention produces propargyl alcohol by dehydrating glycerol in an electrolytic cell, and other substances involved in the reaction are recycled, and the entire reaction process is green and environmentally friendly. The method is simple and safe, and the propargyl alcohol is easily separated and has a high yield.

Description

Technical Field

[0001] The invention relates to the technical field of organic electrochemical synthesis, and in particular to a method for preparing propargyl alcohol by electrolyzing glycerol. Background Art

[0002] Propargyl alcohol, also known as propargyl alcohol or 2-propynyl-1-ol, is a colorless transparent liquid with a scent of bay leaves. It tends to turn yellow when left for a long time, especially when exposed to light. Its molecular formula is HC≡C-CH2OH and its molecular weight is 56.06. The melting point of propargyl alcohol is -45°C and the boiling point is 115°C. It is miscible with water, chloroform, dichloroethane, ethanol, ether, dioxane, tetrahydrofuran, pyridine, etc. It is slightly soluble in carbon tetrachloride and insoluble in aliphatic hydrocarbons. It is flammable with a flash point of 36°C and can react strongly with oxidants. It is toxic and protective measures must be taken when used. Propargyl alcohol is an important chemical raw material and is widely used in medicine, chemicals, electroplating, pesticides, steel, oil extraction and other fields. As an important intermediate in the organic synthesis industry, propargyl alcohol can be used to synthesize fosfomycin sodium, fosfomycin calcium, sulfadiazine, etc. It can also be used to produce vitamin A, acryl alcohol, acrolein and other products. In the pesticide industry, propargyl alcohol is an important intermediate for the synthesis of propargyl. At present, the demand for propargyl alcohol in the pharmaceutical and pesticide industries has exceeded 10,000 tons / year. In addition, propargyl alcohol can also be used as a solvent, herbicide, fungicide, stabilizer for chlorinated hydrocarbons, etc. In 1872, Henuy first used 2-bromopropenol to debrominate with sodium oxychloride to obtain propargyl alcohol for the first time. Sodium acetylene can also be used to react with polyoxymethylene in liquid ammonia to produce propargyl alcohol, but these methods have no industrial production value. Germany was the first country in the world to realize the industrialization of propargyl alcohol. In 1938, German scholar Reppe used acetylene copper as a catalyst to react acetylene with formaldehyde under pressure to obtain butynediol and propargyl alcohol. my country's Northeast Pharmaceutical General Administration once put into production the process route of propargyl alcohol in 1966 and achieved success. Since acetylene is unstable under high temperature and pressure, the current industrial production route is prone to explosion during operation and is relatively dangerous. Propargyl alcohol and butynediol are also produced at the same time, with low yields and difficult separation. Due to technical reasons, the production of propargyl alcohol has always been low.

[0003] Biodiesel is one of the green renewable liquid biofuels produced using animal and vegetable oils, waste oils or microbial oils as raw materials. It is the most powerful competitor to replace fossil diesel. The advantages of biodiesel mainly include green, environmentally friendly, non-toxic and biodegradable characteristics. The main component is a mixture of medium- and long-chain free fatty acid methyl esters (FAME) or ethyl esters (FAEE). The carbon chain length and other physical and chemical indicators are close to traditional diesel. It can replace petroleum diesel or be mixed with petroleum diesel in a certain proportion as automobile fuel to alleviate the rapid reduction of fossil energy. Compared with fossil diesel, biodiesel has a higher cetane number, moderate viscosity and boiling point, and a high flash point. Therefore, it has the advantages of good combustion performance, good low-temperature starting performance, excellent lubrication performance, and high safety performance. Biodiesel also contains almost no sulfur and aromatic substances, so it is a truly renewable green energy. In addition, biodiesel can also be used as a green industrial solvent and lubricant. More importantly, biodiesel can also be used as a green raw material for the production of surfactants and plasticizers. Therefore, promoting the development of the biodiesel industry has a significant effect on promoting energy substitution, reducing environmental pressure, and controlling urban air pollution, which is conducive to ensuring energy security and achieving carbon neutrality. It has been paid attention to and promoted by many countries in the world, and the global production in 2021 reached 41.6 million tons. In the production process of biodiesel, 1 ton of by-product glycerin is produced for every 10 tons of biodiesel produced. In 2021, about 4 million tons of glycerin were produced as a by-product of biodiesel production. Summary of the invention

[0004] In order to solve the technical problems of low yield and flammable and explosive production process in the existing propargyl alcohol production route and to fully utilize the by-product glycerol of biodiesel to reduce its production cost, the present invention provides a method for preparing propargyl alcohol by electrolyzing glycerol.

[0005] The technical solution of the present invention is as follows:

[0006] A method for preparing propargyl alcohol by electrolyzing glycerol, the reaction route is as follows:

[0007]

[0008] The specific method is to mix glycerol and an aqueous solution of alkali metal or alkaline earth metal chloride (MCl n -H2O) is added into an electrolytic cell, and electrolysis is performed under the action of direct current to obtain an electrolyte containing propargyl alcohol, chlorine and hydrogen, and the electrolyte is separated by a membrane to obtain propargyl alcohol.

[0009] The specific reaction principle of the present invention is as follows:

[0010] (1) adding glycerol and an aqueous solution of alkali metal or alkaline earth metal chloride into an electrolytic cell, wherein the alkali metal or alkaline earth metal chloride is ionized into metal cations and chloride anions in water, a small amount of glycerol is ionized into hydrogen cations and glycerol anions in water, and a small amount of water is ionized into hydrogen cations and hydroxide anions;

[0011]

[0012] (2) When the electrolytic cell is powered, the hydrogen ions and metal ions move toward the cathode, causing the cathode area M n+ and H + As the concentration increases, CH2OH-CHOH-CH2O - , Cl- and OH- move toward the anode area and collide with each other during migration, thus reacting to produce dichloropropanol;

[0013]

[0014] (3) Since OH- is produced during the reaction, the OH- concentration in the anode region further increases, causing OH - and CH2Cl-CHCl-CH2O - The probability of collision is greatly increased, and two molecules of hydrogen chloride are removed to form propargyl alcohol anions;

[0015]

[0016] (4) The negative ions reaching the anode are Cl - It is most likely to lose electrons to produce Cl2, while the positive ions reaching the cathode are H + It is easiest to obtain electrons and turn into H2. The solution leaving the electrolytic cell contains alkali metal or alkaline earth metal hydroxide solution and propargyl alcohol, which can be separated and purified by conventional membrane to obtain propargyl alcohol.

[0017] Furthermore, the gaseous product chlorine reacts with hydrogen to obtain hydrogen chloride, which is used to neutralize the hydroxide solution of the alkali metal or alkaline earth metal flowing out of the electrolytic cell to obtain the chloride solution of the alkali metal or alkaline earth metal for recycling.

[0018] Furthermore, the propargyl alcohol obtained by membrane separation is purified by vacuum distillation.

[0019] Furthermore, components other than pure propargyl alcohol obtained by vacuum distillation are added to an alkaline aqueous solution for standby use; gaseous products chlorine and hydrogen react to obtain hydrogen chloride, and the alkaline aqueous solution is neutralized with hydrogen chloride gas, and the obtained alkali metal or alkaline earth metal chloride solution is added to the electrolytic cell again to supplement the glycerol circulation electrolysis.

[0020] Furthermore, the chloride of the alkali metal or alkaline earth metal is at least one of lithium chloride, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, strontium chloride and barium chloride, preferably sodium chloride, potassium chloride or barium chloride.

[0021] Furthermore, the concentration of the aqueous solution of alkali metal or alkaline earth metal chloride is 5 wt% to 35 wt%, preferably 5 wt% to 15 wt%.

[0022] Furthermore, based on the mass of the aqueous solution of chloride of alkali metal or alkaline earth metal, the amount of glycerol added is 3wt% to 40wt%, preferably 5wt% to 15wt%.

[0023] Furthermore, the electrolysis temperature is 4 to 50°C, preferably 15 to 30°C.

[0024] Furthermore, the electrolytic cell voltage is 2 to 10V, preferably 2.5 to 5V.

[0025] The beneficial effects of the present invention are:

[0026] The method of the present invention produces propargyl alcohol by dehydrating glycerol in an electrolytic cell, and other substances involved in the reaction are recycled, and the entire reaction process is green and environmentally friendly. The method is simple and safe, and avoids the problem of explosion in the traditional propargyl alcohol production route during operation. The propargyl alcohol is easy to separate and has a high yield.

[0027] On the other hand, the method of the present application uses glycerol, a byproduct of biodiesel, as a raw material, thereby alleviating the pressure of large byproduct glycerol and insufficient utilization, and at the same time reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 It is the gas chromatogram of pure propargyl alcohol prepared in Example 1.

[0030] Figure 2 It is the pure propargyl alcohol prepared in Example 1 1 HNMR spectrum. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0032] Example 1

[0033] Add a 15wt% sodium chloride aqueous solution to the electrolytic cell, then add glycerol accounting for 10% of the mass of the sodium chloride aqueous solution, use a platinum electrode as the anode and a graphite electrode as the cathode, turn on the DC electrolysis switch, adjust the DC voltage to 3.5V for electrolysis, control the electrolysis temperature to 20°C, collect chlorine at the anode and hydrogen at the cathode, and stop electrolysis when the concentration of propargyl alcohol in the electrolyte reaches 3wt%. The electrolyte is separated by membrane to obtain crude propargyl alcohol and alkaline aqueous solution. The crude propargyl alcohol is purified by vacuum distillation to obtain a colorless to light yellow transparent liquid, which is pure propargyl alcohol with a purity of 99.1% and a yield of 24.8%. According to nuclear magnetic resonance detection, 1 H NMR (400MHz, Chloroform-d) δ4.28 (d, J = 2.4Hz, 2H), 2.48 (t, J = 2.4Hz, 1H), 1.69 (brs, 1H).

[0034] The other components except the pure propargyl alcohol obtained by purification are added to the alkaline aqueous solution for standby use. The collected chlorine gas is passed into hydrogen gas and ignited to produce hydrogen chloride gas, which is used to neutralize the alkaline aqueous solution. The obtained sodium chloride solution is added to the electrolytic cell again to supplement the glycerol for cyclic electrolysis.

[0035] Example 2

[0036] A potassium chloride aqueous solution with a concentration of 20wt% is added to an electrolytic cell, and then glycerol accounting for 13% of the mass of the potassium chloride aqueous solution is added, a platinum electrode is used as an anode, a graphite electrode is used as a cathode, a DC electrolysis switch is turned on, a DC voltage is adjusted to 2.8V for electrolysis, an electrolysis temperature is controlled to be 35°C, chlorine is collected at the anode, hydrogen is collected at the cathode, and electrolysis is stopped when the concentration of propargyl alcohol in the electrolyte reaches 4wt%. The electrolyte is separated by a membrane to obtain crude propargyl alcohol and an alkaline aqueous solution, and the crude propargyl alcohol is purified by vacuum distillation to obtain a colorless to light yellow transparent liquid, i.e., pure propargyl alcohol, with a purity of 98.4% and a yield of 26.3%.

[0037] The purified components except the pure propargyl alcohol are added to the alkaline aqueous solution for standby use. The collected chlorine gas is passed into hydrogen and ignited to produce hydrogen chloride gas, which is used to neutralize the alkaline aqueous solution. The obtained potassium chloride solution is added to the electrolytic cell again to supplement the glycerol cycle electrolysis.

[0038] Example 3

[0039] A 10wt% barium chloride aqueous solution is added to an electrolytic cell, and then glycerol accounting for 12% of the mass of the barium chloride aqueous solution is added, a platinum electrode is used as an anode, a graphite electrode is used as a cathode, a DC electrolysis switch is turned on, a DC voltage is adjusted to 3.0V for electrolysis, an electrolysis temperature is controlled to be 30°C, chlorine is collected at the anode, hydrogen is collected at the cathode, and electrolysis is stopped when the concentration of propargyl alcohol in the electrolyte reaches 3.5wt%. The electrolyte is separated by a membrane to obtain crude propargyl alcohol and an alkaline aqueous solution, and the crude propargyl alcohol is purified by vacuum distillation to obtain a colorless to light yellow transparent liquid, namely pure propargyl alcohol, with a purity of 97.6% and a yield of 23.5%.

[0040] The other components except the pure propargyl alcohol obtained by purification are added to the alkaline aqueous solution for standby use. The collected chlorine gas is passed into hydrogen gas and ignited to produce hydrogen chloride gas, which is used to neutralize the alkaline aqueous solution. The obtained barium chloride solution is added to the electrolytic cell again to supplement the glycerol cycle electrolysis.

[0041] Example 4

[0042] A sodium chloride aqueous solution with a concentration of 15wt% is added to an electrolytic cell, and then glycerol accounting for 6% of the mass of the sodium chloride aqueous solution is added, a platinum electrode is used as an anode, a graphite electrode is used as a cathode, a DC electrolysis switch is turned on, a DC voltage is adjusted to 3.5V for electrolysis, an electrolysis temperature is controlled to be 20°C, chlorine is collected at the anode, hydrogen is collected at the cathode, and electrolysis is stopped when the concentration of propargyl alcohol in the electrolyte reaches 2wt.%. The electrolyte is separated by a membrane to obtain crude propargyl alcohol and an alkaline aqueous solution, and the crude propargyl alcohol is purified by vacuum distillation to obtain a colorless to light yellow transparent liquid, i.e., pure propargyl alcohol, with a purity of 99.4% and a yield of 28.1%.

[0043] The other components except the pure propargyl alcohol obtained by purification are added to the alkaline aqueous solution for standby use. The collected chlorine gas is passed into hydrogen gas and ignited to produce hydrogen chloride gas, which is used to neutralize the alkaline aqueous solution. The obtained sodium chloride solution is added to the electrolytic cell again to supplement the glycerol for cyclic electrolysis.

[0044] Example 5

[0045] A sodium chloride aqueous solution with a concentration of 10wt% is added to an electrolytic cell, and then glycerol accounting for 10% of the mass of the sodium chloride aqueous solution is added, a platinum electrode is used as an anode, a graphite electrode is used as a cathode, a DC electrolysis switch is turned on, a DC voltage is adjusted to 3.2V for electrolysis, an electrolysis temperature is controlled to be 25°C, chlorine is collected at the anode, hydrogen is collected at the cathode, and when the concentration of propargyl alcohol in the electrolyte reaches 2wt%, an aqueous solution containing 10wt% sodium chloride and 10wt% glycerol is introduced into the electrolytic cell, and the electrolyte is discharged from the electrolytic cell at the same speed, and the concentration and liquid level of the propargyl alcohol in the electrolytic cell are kept substantially unchanged. The electrolyte flowing out of the electrolytic cell is subjected to membrane separation to obtain a crude propargyl alcohol product and an alkaline aqueous solution, and the crude propargyl alcohol is purified by vacuum distillation to obtain a colorless to light yellow transparent liquid, i.e., pure propargyl alcohol.

[0046] The preparation method of the aqueous solution containing 10wt% sodium chloride and 10wt% glycerol is as follows: the purified components except the pure propargyl alcohol are added to the above alkaline aqueous solution, hydrogen chloride gas (prepared by reacting chlorine and hydrogen obtained by electrolysis) is introduced into the alkaline aqueous solution for neutralization, and glycerol is added to obtain the aqueous solution.

[0047] The purity of the obtained product is 99.2%. After three cycles, the total product yield is 54.8%.

[0048] Although the present invention has been described in detail with reference to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily think of changes or substitutions within the technical scope disclosed by the present invention, and these shall be within the scope of protection of the present invention.

Claims

1. A method for preparing propargyl alcohol by electrolyzing glycerol, characterized in that: The method comprises the following steps: adding glycerol and an aqueous chloride solution of an alkali metal or alkaline earth metal into an electrolytic cell, electrolyzing under the action of a direct current to obtain an electrolyte solution containing propargyl alcohol, chlorine gas and hydrogen gas, and separating the electrolyte solution through a membrane to obtain the propargyl alcohol; The chloride of the alkali metal or alkaline earth metal is at least one of lithium chloride, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, strontium chloride and barium chloride.

2. The method according to claim 1, characterized in that The gaseous products chlorine and hydrogen react to obtain hydrogen chloride, which is used to neutralize the alkaline aqueous solution flowing out of the electrolytic cell to obtain an alkali metal or alkaline earth metal chloride solution for recycling.

3. The method according to claim 1, characterized in that The propargyl alcohol obtained by membrane separation is purified by vacuum distillation.

4. The method according to claim 3, characterized in that The components except the pure propargyl alcohol obtained by vacuum distillation are added to the alkaline aqueous solution for standby use; the gaseous products chlorine and hydrogen react to obtain hydrogen chloride, and the hydrogen chloride gas is used to neutralize the alkaline aqueous solution, and the obtained alkali metal or alkaline earth metal chloride solution is added to the electrolytic cell again to supplement the glycerol circulation electrolysis.

5. The method according to claim 1, characterized in that The concentration of the aqueous solution of alkali metal or alkaline earth metal chloride is 5wt%~35wt%.

6. The method according to claim 1, characterized in that The amount of glycerol added is 3wt% to 40wt% based on the mass of the aqueous solution of alkali metal or alkaline earth metal chloride.

7. The method according to claim 1, characterized in that The electrolysis temperature is 4~50℃.

8. The method according to claim 1, characterized in that The electrolytic cell voltage is 2~10V.

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