Preparation method of allyl alcohol with high yield

Abstract

The invention provides a method for preparing high-yield allyl alcohol, comprising mixing acetaldehyde, an organic chloride and a phase transfer catalyst, reacting under alkaline conditions, extracting to obtain an aqueous phase; sequentially dehydrating and acidifying the aqueous phase and performing reduced pressure distillation to obtain acrylic acid; finally, mixing the acrylic acid with a reducing agent for reaction, and performing atmospheric distillation to obtain allyl alcohol. The invention selects acetaldehyde and an organic chloride capable of synthesizing carbene as raw materials, and fully and effectively converts them into a target product under the action of a phase transfer catalyst and a carbene substrate, thereby avoiding the generation of by-products. At the same time, molecular distillation technology is used to make the reaction and separation more efficient, and the obtained allyl alcohol has high purity and high yield. The preparation method is carried out under normal pressure and relatively low temperature, and no harmful waste is generated during the reaction. The method has the characteristics of simple process, low energy consumption, economy, environmental protection, and suitability for industrial large-scale production, and overcomes the technical defects in the traditional allyl alcohol preparation method, thereby providing a new method for the industrial production of allyl alcohol.

Description

Technical Field

[0001] The invention relates to the technical field of industrial chemical synthesis, and in particular to a method for preparing high-yield allyl alcohol. Background Art

[0002] Allyl alcohol is a colorless, transparent liquid (boiling point is 96-98°C). Its molecular structure contains enol (carbon-carbon double bond and hydroxyl) functional groups. Therefore, it has both the reactivity of olefin double bonds and the hydrophilicity and activity of alcohols. It can react with ethers, esters, acetals and other compounds. It is an intermediate in the production of glycerol, drugs, surfactants and other products. As an important organic compound, allyl alcohol can be widely used in the chemical and material industries.

[0003] At present, there are many industrial synthesis methods for allyl alcohol, which mainly include: 3-chloropropylene alkaline hydrolysis method, acrolein reduction method, allyl acetate hydrolysis method and propylene oxide isomerization method according to the raw material route. Due to the small scale and high cost of propylene oxide production in China, the propylene oxide isomerization method is difficult to become the mainstream method for producing allyl alcohol. Therefore, the industry mainly adopts several other methods for preparing allyl alcohol. For example, the invention patent (application number is CN 201310271353.0) discloses a method for preparing allyl alcohol using propylene acetate, by using propylene acetate and water as raw materials, using a strong base as a catalyst, heating to the reaction temperature, and vigorously stirring the reaction; in this process, the strong base acts as both a catalyst and an acid binding agent in the reaction system, so that the reaction equilibrium is promoted in the positive direction, thereby improving the conversion rate of propylene acetate; however, the raw materials of this method are expensive, the waste liquid post-treatment is difficult, and the environmental pollution is serious.

[0004] In addition, in the method for preparing vinyl alcohol by 3-chloropropylene alkaline hydrolysis, because 3-chloropropylene has a low normal pressure boiling point (45°C), it needs to be hydrolyzed under the condition of high temperature and high pressure (150°C, 0.8MPa), there are technical defects such as large process operation difficulty, harsh conditions, high requirements on equipment material strength, and it is not suitable for large-scale industrial production, and the production post-processing is troublesome, and the environmental pollution is serious. The method for preparing vinyl alcohol by catalytic hydrogenation reduction of acrolein, due to the participation of hydrogen in the reaction process, has a large potential safety hazard, is unfavorable for large-scale production, and has a low product recovery rate, high equipment requirements, and a large problem of process operation difficulty.

[0005] In view of this, it is necessary to design an improved method for preparing allyl alcohol with high yield to solve the above problems. Summary of the invention

[0006] The invention aims to provide a method for preparing allyl alcohol with high yield. Acetaldehyde and an organic chloride capable of synthesizing carbene are selected as raw materials, and are fully and effectively converted into a target product under the action of a phase transfer catalyst, and the generation of by-products is avoided. The molecular distillation technology is used to make the reaction and separation more efficient, and the yield and purity of the obtained allyl alcohol product are high.

[0007] To achieve the above object of the invention, the present invention provides a method for preparing allyl alcohol with high yield, comprising the following steps:

[0008] S1. Mix acetaldehyde, an organic chloride, and a phase transfer catalyst, and react them under alkaline conditions for a preset time; after the reaction is completed, add an equal volume of water and an organic solvent immiscible with water to extract to obtain an aqueous phase containing 2-hydroxypropionate; the organic chloride is one of chloroform, dichloromethane, trichloroacetic acid, or trichloroacetate;

[0009] S2, sequentially dehydrating, acidifying and distilling the aqueous phase obtained in step S1 under reduced pressure, and collecting fractions to obtain acrylic acid;

[0010] S3, mixing the acrylic acid obtained in step S2 with a reducing agent in an organic solvent, reacting for a preset time, and then distilling under normal pressure, collecting the fraction at 90° C. to 95° C. to obtain allyl alcohol; the yield of the allyl alcohol is above 94%.

[0011] As a further improvement of the present invention, in step S1, the phase transfer catalyst includes one of triethylbenzylammonium chloride, tetrabutylammonium bromide, dodecyltrimethylammonium chloride, and 8-crown ether-6.

[0012] As a further improvement of the present invention, in step S1, the reaction temperature under alkaline conditions is 50-70° C., and the preset time is 3-4 hours.

[0013] As a further improvement of the present invention, in step S1, the molar ratio of acetaldehyde, organic chloride and phase transfer catalyst is 1:(1.2-3):(0.05-0.1).

[0014] As a further improvement of the present invention, in step S3, the reducing agent is one of red aluminum, diisobutylaluminum hydride, lithium aluminum tetrahydride, and sodium borohydride.

[0015] As a further improvement of the present invention, the molar ratio of the acrylic acid to the reducing agent is 1:(1.1-1.3).

[0016] As a further improvement of the present invention, in step S2, the dehydration and acidification process is: adding concentrated sulfuric acid to the aqueous phase, and performing dehydration and acidification at 170°C for 5 to 10 hours; the amount of concentrated sulfuric acid added is such that the molar ratio of the concentrated sulfuric acid to the 2-hydroxypropionate in the aqueous phase is (1.1 to 1.5):1.

[0017] As a further improvement of the present invention, in step S3, the reaction temperature is 0-30°C, and the preset time is 4-6h.

[0018] As a further improvement of the present invention, in step S2, the temperature of the reduced pressure distillation is 100°C±10°C, and the vacuum degree is 300-600 Pa; in step S3, the temperature of the atmospheric pressure distillation is 120±5°C.

[0019] As a further improvement of the present invention, in step S1, the organic solvent includes one of esters, long-chain alcohols, ethers and halogenated hydrocarbons.

[0020] As a further improvement of the present invention, in step S1, the alkaline condition is to drop a sodium hydroxide solution with a concentration of 30% to 60% into the mixed solution of acetaldehyde, organic chloride and phase transfer catalyst.

[0021] As a further improvement of the present invention, in step S1, the organic solvent is one of petroleum ether, n-hexane, ethyl acetate, n-octanol, dichloromethane, chloroform, ethyl ether or methyl ethyl ketone; in step S3, the organic solvent includes one of tetrahydrofuran and acetone.

[0022] As a further improvement of the present invention, in step S1, the specific process is: first, the organic chloride is mixed with the phase transfer catalyst, and then acetaldehyde is introduced. After the temperature rises to 50-70°C, a strong alkali solution is started to be dripped therein, and the dripping speed is controlled, and the reaction is kept at 50-70°C for 3-4 hours.

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

[0024] 1. The method for preparing high-yield allyl alcohol of the present invention comprises the following steps: mixing acetaldehyde, an organic chloride and a phase transfer catalyst, reacting them under alkaline conditions, extracting and obtaining an aqueous phase containing 2-hydroxypropionate; then sequentially dehydrating and acidifying the aqueous phase and performing vacuum distillation to obtain acrylic acid; finally, mixing the acrylic acid with a reducing agent, reacting and performing atmospheric distillation to obtain allyl alcohol. The present invention selects acetaldehyde and an organic chloride capable of synthesizing carbene as raw materials, and fully and effectively converts them into a target product under the action of a phase transfer catalyst and a carbene substrate, thereby avoiding the generation of by-products. At the same time, the molecular distillation technology is used to make the reaction and separation more efficient. The obtained allyl alcohol product has high purity and high yield, which is more than 94%, and is suitable for industrial production and application.

[0025] 2. In the preparation method of the present invention, an organic chloride, such as chloroform, dichloromethane, trichloroacetic acid or trichloroacetate, reacts with a strong base under the action of a phase transfer catalyst to generate carbene, and the carbene reacts with acetaldehyde to generate 2-hydroxypropionate through rearrangement and hydrolysis. Through this reaction pathway, the reaction temperature is greatly reduced, the reaction time is shortened, the utilization rate of the raw materials and the conversion rate of 2-hydroxypropionate are improved, and the yield and purity of acrylic acid collected by dehydration acidification and reduced pressure distillation are improved, and the yield of allyl alcohol obtained by the reaction of acrylic acid and a reducing agent is improved, which has a high economic benefit.

[0026] 3. The preparation method of the present invention obtains allyl alcohol by reacting at normal pressure and relatively low temperature, and generates very little waste during the reaction process. The method has the characteristics of simple process, low energy consumption, economy, environmental protection, and suitability for industrial large-scale production. The method overcomes the technical defects of the traditional allyl alcohol preparation method, which requires harsh conditions of high temperature and high pressure, has high requirements on the material strength of the equipment, and has great difficulty in process operation, and provides a new method for the industrial production of allyl alcohol. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below in conjunction with specific embodiments.

[0028] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the scheme of the present invention are shown, while other details that are not closely related to the present invention are omitted.

[0029] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0030] A method for preparing high-yield allyl alcohol comprises the following steps:

[0031] S1. Mix acetaldehyde, an organic chloride and a phase transfer catalyst, and react for a preset time under alkaline conditions; after the reaction is completed, add an equal volume of water and an organic solvent immiscible with water for extraction to obtain an aqueous phase containing 2-hydroxypropionate; the organic chloride is one of chloroform, dichloromethane, trichloroacetic acid or trichloroacetate; in this process, an organic chloride (such as chloroform) and a strong base (such as sodium hydroxide) generate carbene under the action of a phase transfer catalyst, and the carbene reacts with acetaldehyde and undergoes rearrangement and hydrolysis to generate 2-hydroxypropionate. Through this reaction pathway, the reaction temperature is greatly reduced, the reaction time is shortened, and the utilization rate of the raw materials and the conversion rate of 2-hydroxypropionate are improved. The specific reaction mechanism is shown in formula (1):

[0032]

[0033] S2, sequentially dehydrating, acidifying and distilling the aqueous phase obtained in step S1 under reduced pressure, and collecting fractions to obtain acrylic acid;

[0034] S3, mixing the acrylic acid obtained in step S2 with a reducing agent in an organic solvent, reacting for a preset time, and then distilling under normal pressure, collecting the fraction at 90° C. to 95° C. to obtain allyl alcohol; the yield of allyl alcohol is above 94%.

[0035] Specifically, in step S1, the phase transfer catalyst includes one of triethylbenzylammonium chloride (TEBAC), tetrabutylammonium bromide (TBAB), dodecyltrimethylammonium chloride, and 8-crown ether-6. By selecting acetaldehyde and an organic chloride that can synthesize carbene as raw materials, under the action of the phase transfer catalyst and the carbene substrate, they are fully and effectively converted into the target product, avoiding the formation of by-products. For example, when the raw materials are acetaldehyde and chloroform, and the phase transfer catalyst is tetrabutylammonium bromide (TBAB), sodium 2-hydroxypropionate is obtained, and the reaction equation is shown in formula (2):

[0036]

[0037] In some specific embodiments, the trichloroacetate salt is sodium trichloroacetate to avoid the introduction of other impurities in the reaction.

[0038] In step S1, the reaction temperature is 50-70°C, and the preset time is 3-4h; the molar ratio of acetaldehyde, organic chloride and phase transfer catalyst is 1:(1.2-3):(0.05-0.1); thus, by controlling the reaction temperature, time and the ratio of raw materials to phase transfer catalyst, the smooth progress of the reaction is ensured, the target product can be better obtained, and the utilization rate of the raw materials is improved.

[0039] In step S1, the water-immiscible organic solvent includes one of esters, long-chain alcohols, ethers and halogenated hydrocarbons, specifically including but not limited to petroleum ether, n-hexane, ethyl acetate, n-octanol, dichloromethane, chloroform, ether or methyl ethyl ketone. In step S3, the organic solvent includes one of tetrahydrofuran and acetone.

[0040] It should be noted that in step S1, the alkaline condition is to drip a sodium hydroxide solution with a mass percentage concentration of 30% to 60% in a mixed solution of acetaldehyde, organic chloride and phase transfer catalyst to provide an alkaline environment for the reaction. In actual operation, the specific process is: first, the organic chloride is mixed with the phase transfer catalyst, and then acetaldehyde is introduced. After the temperature rises to 50 to 70°C, a strong alkali solution (sodium hydroxide solution) is started to be dripped therein, and the dripping speed is controlled, and the reaction is kept at 50 to 70°C for 3 to 4 hours. First, the organic chloride is mixed with the phase transfer catalyst, which is conducive to the rapid generation of carbene by the organic chloride and the strong base after the strong base is dripped, which is conducive to the phase transfer catalyst to exert the maximum catalytic effect. The strong base is dripped in a manner to avoid the reaction instability caused by the excessively high local temperature, thereby affecting the problem of reaction yield.

[0041] In step S2, the dehydration and acidification process is as follows: concentrated sulfuric acid is added to the aqueous phase (sodium 2-hydroxypropionate), and dehydration and acidification are performed at 170° C. for 5 to 10 hours; the amount of concentrated sulfuric acid added is such that the molar ratio of the concentrated sulfuric acid to the 2-hydroxypropionate in the aqueous phase is (1.1 to 1.5):1, and the reaction equation for dehydration and acidification is shown in Formula (3).

[0042] The temperature of reduced pressure distillation is 100℃±10℃, and the vacuum degree is 300~600Pa.

[0043]

[0044] Specifically, in step S3, the reducing agent is one of red aluminum (Red-Al), diisobutyl aluminum hydride (DIBAL-H), lithium aluminum tetrahydride (LiAlH4), and sodium borohydride (NaBH4). The molar ratio of acrylic acid to the reducing agent is 1: (1.1-1.3), the reaction temperature is 0-30°C, and the preset time is 4-6h; the temperature of atmospheric distillation is 120±5°C. By using molecular distillation technology, the reaction and separation of the present invention are more efficient, and the obtained allyl alcohol product has high purity and high yield, which is more than 94%, and is suitable for industrial production and application. Acrylic acid and the reducing agent react in tetrahydrofuran to obtain the reaction equation of allyl alcohol as shown in formula (4):

[0045]

[0046] The preparation method of the invention obtains allyl alcohol by reaction under normal pressure and relatively low temperature, generates very little waste during the reaction process, has the characteristics of simple process, low energy consumption, economy, environmental protection, and suitability for industrial large-scale production, overcomes the technical defects of requiring high temperature and high pressure in the traditional allyl alcohol preparation method, thus requiring high material strength of equipment and difficult process operation, and provides a new method for the industrial production of allyl alcohol.

[0047] Example 1

[0048] This embodiment provides a method for preparing allyl alcohol with high yield, comprising the following steps:

[0049] S1. TEBAC (161.1 g, 0.05 mol) and chloroform (1.8 kg, 14.9 mol) were added to a three-necked round-bottom flask equipped with a magnetic stirrer and a reflux condenser, and acetaldehyde (440.3 g, 10.0 mol) was then introduced into the feed liquid using a peristaltic pump. After the temperature reached 60°C, 1500 mL of a 50% NaOH solution was added dropwise, and the addition rate was controlled (about 5 h) to complete the dripping, and then the reaction was kept at 60°C ± 5°C for 4 h; after the reaction was completed, heating was stopped, and the feed liquid was poured into a mixed solution of 1 L of water and 1 L of ethyl acetate for extraction, and the mixture was allowed to stand for 0.5 h after sufficient stirring, and the lower layer was a 2-hydroxypropionic acid sodium (sodium lactate) solution;

[0050] S2, after the aqueous phase containing sodium lactate obtained in step S1 is concentrated to a viscous state, concentrated sulfuric acid (1.1 kg, 11.2 mol) is slowly added thereto, and then the mixture is kept warm for reaction at 170° C. for 6 hours; after the reaction is completed, a distillation apparatus is set up, and distillation is first performed at 100° C. under normal pressure until almost no droplets are produced, and then a reduced pressure distillation apparatus is set up, and the temperature is set to 100° C. ± 10° C., and the vacuum degree is 400 Pa, and 761.2 g of acrylic acid is collected, with a water content of 10.0% and a yield of 95.1%;

[0051] S3. In an ice bath, acrylic acid (500.0 g, 6.9 mol) and tetrahydrofuran 800 mL were added to a three-necked round-bottom flask equipped with a magnetic stirrer and a reflux condenser, and then a toluene solution (70 wt%) containing red aluminum (1535.2 g, 7.6 mol) was added dropwise using a constant pressure dropping funnel. The dropping time was about 5 h. The temperature was kept below 10 ° C during the dropping process. After the dropping was completed, the mixture was reacted at 10 ° C for 4 h; then a distillation apparatus was set up, tetrahydrofuran was first collected by atmospheric distillation at 80 ° C, and then the temperature was raised to 120 ° C for atmospheric distillation, about 20.0 g of the distillation head was collected, and then the 90 ° C fraction was collected. A total of 543.3 g of allyl alcohol was collected, with a water content of 29.8% and a yield of 94.3%.

[0052] Example 2

[0053] This embodiment provides a method for preparing allyl alcohol with high yield, comprising the following steps:

[0054] S1. A phase transfer catalyst TEBAC (307.2 g, 0.95 mol) and chloroform (3.3 kg, 27.2 mol) were added to a three-necked round-bottom flask equipped with a magnetic stirrer and a reflux condenser, and then acetaldehyde (600.0 g, 13.6 mol) was introduced into the feed liquid with a peristaltic pump. After the temperature rose to 60°C, 2100 mL of a 50% NaOH solution was added dropwise, and the addition rate was controlled (about 5 h) to complete the dripping, and then the reaction was kept at 60°C ± 5°C for 4 h; after the reaction was completed, heating was stopped, and the feed liquid was poured into a mixed solution of 1.5 L water and 1.5 L ethyl acetate for extraction, and the mixture was allowed to stand for 0.5 h after sufficient stirring, and the lower layer was a 2-hydroxypropionic acid sodium (sodium lactate) solution;

[0055] S2, after the aqueous phase containing sodium lactate obtained in step S1 is concentrated to a viscous state, concentrated sulfuric acid (1.5 kg, 14.9 mol) is slowly added thereto, and then the mixture is kept warm for reaction at 170° C. for 6 hours; after the reaction is completed, a distillation apparatus is set up, and distillation is first performed at 100° C. under normal pressure until almost no droplets are produced, and then a reduced pressure distillation apparatus is set up, and the temperature is set to 100° C. ± 10° C., and the vacuum degree is 400 Pa, and 1054.3 gg of acrylic acid is collected, with a water content of 10.0% and a yield of 96.7%;

[0056] S3. In an ice bath, acrylic acid (800.0 g, 11.1 mol) and tetrahydrofuran 800 mL were added to a three-necked round-bottom flask equipped with a magnetic stirrer and a reflux condenser, and then a toluene solution (70 wt%) containing red aluminum (2466.8 g, 12.2 mol) was added dropwise using a constant pressure dropping funnel. The dropping time was about 7.5 h. The temperature was kept below 10°C during the dropping process. After the dropping was completed, the mixture was reacted at 10°C for 4 h. A distillation apparatus was then set up. The tetrahydrofuran was first collected by atmospheric distillation at 80°C, and then the temperature was raised to 120°C for atmospheric distillation. About 60.0 g of the distillation head was collected, and then a 90°C fraction was collected. A total of 887.5 g of allyl alcohol was collected, with a water content of 29.6% and a yield of 96.4%.

[0057] Example 3

[0058] This embodiment provides a method for preparing allyl alcohol with high yield, comprising the following steps:

[0059] S1. Triethylbenzylammonium chloride (TEBAC) (242.9 g, 1.1 mol) and chloroform (2.8 kg, 23.1 mol) were added to a three-necked round-bottom flask equipped with a magnetic stirrer and a reflux condenser, and then acetaldehyde (783.0 g, 17.8 mol) was introduced into the feed liquid with a peristaltic pump. After the temperature rose to 60°C, 1900 mL of a 50% NaOH solution was added dropwise, and the addition speed was controlled (about 5 h) to complete the dripping, and then the reaction was kept at 60°C ± 5°C for 4 h; after the reaction was completed, heating was stopped, and the feed liquid was poured into a mixed solution of 1.3 L of water and 1.3 L of ethyl acetate for extraction, and the mixture was allowed to stand for 0.5 h after sufficient stirring, and the lower layer was a 2-hydroxypropionic acid sodium (sodium lactate) solution;

[0060] S2, after the aqueous phase containing sodium lactate obtained in step S1 is concentrated to a viscous state, concentrated sulfuric acid (2.1 kg, 21.3 mol) is slowly added thereto, and then the mixture is kept warm for reaction at 170° C. for 6 hours; after the reaction is completed, a distillation apparatus is set up, and distillation is first performed at 100° C. under normal pressure until almost no liquid droplets are produced, and then a reduced pressure distillation apparatus is set up, and the temperature is set to 100° C. ± 10° C., and the vacuum degree is 400 Pa, and 1.4 kg of acrylic acid is collected, with a water content of 10.0% and a yield of 98.4%;

[0061] S3. In an ice bath, acrylic acid (1.1 kg, 15.3 mol) and tetrahydrofuran 1100 mL were added to a three-necked round-bottom flask equipped with a magnetic stirrer and a reflux condenser, and then a toluene solution (70 wt%) containing red aluminum (1374.9 g, 6.8 mol) was added dropwise using a constant pressure dropping funnel. The dropping time was about 8 h. The temperature was kept below 10 ° C during the dropping process. After the dropwise addition was completed, the mixture was reacted at 10 ° C for 4 h; then a distillation apparatus was set up, tetrahydrofuran was first collected by atmospheric distillation at 80 ° C, and then the temperature was raised to 120 ° C for atmospheric distillation, about 87 g of distillation head was collected, and then a 90 ° C fraction was collected. A total of 1241.5 g of allyl alcohol was collected, with a water content of 30.1% and a yield of 97.9%.

[0062] It can be seen from the preparation results of Examples 1 to 3 that the method of the present invention, under the action of a phase transfer catalyst and a carbene substrate, reduces the reaction temperature, shortens the reaction time, and improves the yield of acrylic acid. At the same time, the molecular distillation technology is used to make the reaction and separation more efficient. The yield of allyl alcohol obtained is above 94%, which is suitable for industrial production.

[0063] Comparative Example 1

[0064] Comparative Example 1 provides a method for preparing allyl alcohol. Compared with Example 1, the difference is that in step S1, no phase transfer catalyst is added. The rest is substantially the same as Example 1 and will not be described again.

[0065] Comparative Example 2

[0066] Comparative Example 2 provides a method for preparing allyl alcohol. Compared with Example 1, the difference is that in step S1, no NaOH solution is added dropwise. The rest is substantially the same as Example 1 and will not be described again.

[0067] Comparative Example 3

[0068] Comparative Example 3 provides a method for preparing allyl alcohol. Compared with Example 1, the difference is that in step S1, carbon tetrachloride is used instead of chloroform. The rest is roughly the same as Example 1 and will not be repeated here.

[0069] Comparative Example 4

[0070] Comparative Example 4 provides a method for preparing allyl alcohol, specifically adopting the traditional 3-chloropropylene alkaline hydrolysis method to prepare allyl alcohol.

[0071] Comparative Example 5

[0072] Comparative Example 5 provides a method for preparing allyl alcohol, specifically adopting a traditional acrolein reduction method to prepare allyl alcohol.

[0073] Comparative Example 6

[0074] Comparative Example 6 provides a method for preparing allyl alcohol, specifically adopting the traditional allyl acetate hydrolysis method to prepare allyl alcohol.

[0075] Example 4

[0076] Example 4 provides a method for preparing allyl alcohol with high yield. Compared with Example 1, the difference is that in step S1, sodium trichloroacetate is used instead of chloroform. The rest is roughly the same as Example 1 and will not be repeated here.

[0077] Example 5

[0078] Example 5 provides a method for preparing allyl alcohol with high yield. Compared with Example 1, the difference is that in step S1, dichloromethane is used instead of chloroform. The rest is roughly the same as Example 1 and will not be repeated here.

[0079] Example 6

[0080] Example 6 provides a method for preparing allyl alcohol with high yield. Compared with Example 1, the difference is that in step S1, trichloroacetic acid is used instead of chloroform. The rest is roughly the same as Example 1 and will not be repeated here.

[0081] The yield and water content of allyl alcohol prepared in Examples 4 to 6 and Comparative Examples 1 to 6 were detected and calculated, and the results obtained are shown in Table 1.

[0082] Table 1 Product test results of Examples 4 to 6 and Comparative Examples 1 to 6

[0083] Yield (%) Water content (%) Example 4 88.6％ 29.1％ Example 5 80.3％ 29.5％ Example 6 84.4％ 28.9％ Comparative Example 1 20.4％ 29.6％ Comparative Example 2 11.2％ 27.5％ Comparative Example 3 74.4％ 28.5％ Comparative Example 4 44.6％ 27.6％ Comparative Example 5 37.2％ 35.5％ Comparative Example 6 70.9％ 27.1％

[0084] As shown in Table 1, Examples 4 to 6 use sodium trichloroacetate, dichloromethane or trichloroacetic acid instead of chloroform, and can still obtain allyl alcohol with a relatively high yield, but the yield is lower than that of Examples 1 to 3. In Comparative Examples 1 to 2, it is difficult to generate carbene without adding a phase transfer catalyst or NaOH solution, so that the yield of allyl alcohol obtained is extremely low; in Comparative Example 3, when carbon tetrachloride is used instead of chloroform, the yield of allyl alcohol obtained is relatively low; Comparative Examples 4 to 6 use a traditional allyl alcohol preparation method, and the yield of allyl alcohol obtained is low, which is far less than the allyl alcohol preparation method provided by the present invention.

[0085] In summary, the present invention provides a method for preparing allyl alcohol with high yield, wherein acetaldehyde, organic chloride and phase transfer catalyst are mixed, reacted under alkaline conditions, and an aqueous phase containing 2-hydroxypropionate is obtained after extraction; the aqueous phase is then dehydrated, acidified and distilled under reduced pressure in sequence to obtain acrylic acid; finally, acrylic acid is mixed with a reducing agent, and atmospheric distillation is performed after the reaction to obtain allyl alcohol. The present invention selects acetaldehyde and organic chloride that can synthesize carbene as raw materials, and fully and effectively converts them into target products under the action of phase transfer catalyst and carbene substrate, thereby avoiding the generation of by-products, and at the same time uses molecular distillation technology to make the reaction and separation more efficient, and the obtained allyl alcohol product has high purity and high yield, which is more than 94%, and is suitable for industrial production and application. The preparation method of the invention obtains allyl alcohol by reaction under normal pressure and relatively low temperature, generates very little waste during the reaction process, has the characteristics of simple process, low energy consumption, economy, environmental protection, and suitability for industrial large-scale production, overcomes the technical defects of requiring harsh conditions of high temperature and high pressure in the traditional method for preparing allyl alcohol, and requiring high material strength of equipment and difficult process operation, and provides a new method for the industrial production of allyl alcohol.

[0086] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing high-yield allyl alcohol, characterized in that: The following steps are involved: S1. Mix acetaldehyde, an organic chloride and a phase transfer catalyst, and react for a preset time under alkaline conditions; after the reaction is completed, add an equal volume of water and an organic solvent immiscible with water to extract to obtain an aqueous phase containing 2-hydroxypropionate; the organic chloride is one of chloroform, dichloromethane, trichloroacetic acid or sodium trichloroacetate; the phase transfer catalyst is triethylbenzylammonium chloride or tetrabutylammonium bromide; S2, sequentially dehydrating, acidifying and distilling the aqueous phase obtained in step S1 under reduced pressure, and collecting fractions to obtain acrylic acid; S3, mixing the acrylic acid obtained in step S2 with a reducing agent in an organic solvent, wherein the reducing agent is red aluminum, reacting for a preset time, and then distilling at atmospheric pressure, collecting a fraction at 90° C. to 95° C. to obtain allyl alcohol.

2. The method for preparing high-yield allyl alcohol according to claim 1, characterized in that: In step S1, the reaction temperature under alkaline conditions is 50-70°C, and the preset time is 3-4 h.

3. The method for preparing high-yield allyl alcohol according to claim 1, characterized in that: In step S1, the molar ratio of acetaldehyde, organic chloride and phase transfer catalyst is 1:(1.2-3):(0.05-0.1).

4. The method for preparing high-yield allyl alcohol according to claim 1, characterized in that: The molar ratio of the acrylic acid to the reducing agent is 1:(1.1-1.3).

5. The method for preparing high-yield allyl alcohol according to claim 1, characterized in that: In step S2, the dehydration and acidification process is: adding concentrated sulfuric acid to the aqueous phase, and performing dehydration and acidification at 170°C for 5 to 10 hours; the amount of concentrated sulfuric acid added is such that the molar ratio of the concentrated sulfuric acid to the 2-hydroxypropionate in the aqueous phase is (1.1 to 1.5):

1.

6. The method for preparing high-yield allyl alcohol according to claim 1, characterized in that: In step S3, the reaction temperature is 0-30°C and the preset time is 4-6 h.

7. The method for preparing high-yield allyl alcohol according to claim 1, characterized in that: In step S2, the temperature of the reduced pressure distillation is 100°C±10°C, and the vacuum degree is 300-600 Pa; in step S3, the temperature of the atmospheric pressure distillation is 120±5°C.

8. The method for preparing high-yield allyl alcohol according to claim 1, characterized in that: In step S1, the organic solvent includes one of esters, long-chain alcohols, ethers and halogenated hydrocarbons; in step S3, the organic solvent includes one of tetrahydrofuran and acetone.

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