A method for preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material
Through the multi-step preparation of crotonol by epoxypropane, the methyl magnesium chloride ring opening, POCl3/pyridine dehydroxylation and NaOH substitution reactions are used to solve the problems of high cost and serious pollution of precious metal catalysts, and achieve efficient and environmentally friendly crotonol production.
Patent Information
- Application Number
- CN202510337233.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-21
- Publication Date
- 2025-07-25
- Estimated Expiration
- 2045-03-21
AI Technical Summary
In the existing crotonol preparation methods, precious metal catalysts are costly, harsh reaction conditions, severe pollution, and low yield and selectivity, making it difficult to produce on a large scale.
Epoxypropane is used as raw material, and the reaction is replaced by methyl magnesium chloride ring opening, POCl3/pyridine system dehydroxylation and NaOH aqueous solution to avoid catalysis of precious metals. The reaction is carried out under low temperature and normal pressure, and is designed as a continuous flow process.
Reduce production costs by 50%, simplify process by 30%, reduce energy consumption by 40%, improve crotonol yield to 86.9-87.8%, controllable cis/trans ratio, and reduce 3 waste emissions by 70%, suitable for small batch and large-scale production.
Smart Images
Figure CN119841709B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of the preparation of organic compounds, and particularly relates to a method for multi-step preparation of crotyl alcohol using epichlorohydrin as a raw material. Background Art
[0002] Crotyl alcohol (2-butenol), as an organic compound with wide application value, shows its unique advantages in many fields such as chemical industry, medicine, cosmetics and food additives. In the chemical industry, crotyl alcohol, as a key intermediate in organic synthesis, is widely used in the synthesis of chemical products such as spices, resins, plasticizers, stabilizers, etc., and can also be used as an excellent solvent for dyes and coatings. In the pharmaceutical industry, crotyl alcohol and its derivatives are even used as active ingredients in anti-tumor, anti-inflammatory, antibacterial, antiviral and other drugs, showing their irreplaceable importance. In addition, due to its antioxidant, anti-wrinkle, moisturizing and other effects, crotyl alcohol also occupies a place in the formula of high-end skin care products, and also plays an important role in the field of food additives in improving food taste and extending shelf life.
[0003] Currently, the main method for preparing crotyl alcohol is to reduce crotonaldehyde with reducing agents such as sodium borohydride, lithium aluminum hydride or aluminum isopropoxide. The catalysts used in this process are mainly precious metal catalysts such as Pt, Au and Ir. These catalysts not only have high costs, but also have harsh reaction conditions and cumbersome processes, resulting in high production costs. More seriously, a large amount of metal-containing wastewater, waste gas and other three wastes are discharged during the preparation process of the traditional process, causing serious pollution to the environment and not meeting the green development requirements of modern chemical industry.
[0004] In addition, some catalysts for gas-phase hydrogenation to prepare crotyl alcohol have the disadvantages of easy deactivation and poor stability, resulting in low conversion rate and selectivity of crotyl alcohol, further affecting the yield of crotyl alcohol. The high-pressure hydrogenation or complex reduction steps in the traditional process not only have harsh reaction conditions (high temperature and high pressure), but also have low selectivity, and it is difficult to effectively separate cis / trans isomers, resulting in a yield often less than 80%. These problems not only increase production costs, but also limit the large-scale production and application of crotyl alcohol. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to overcome the above-mentioned defects existing in the prior art, and provide a method for multi-step preparation of crotyl alcohol using epichlorohydrin as a raw material, which has simple operation, mild conditions, low cost, high yield and good environmental protection.
[0006] The method for multi-step preparation of crotyl alcohol using epichlorohydrin as a raw material according to the present invention comprises the following steps:
[0007] Step 1: Keep the reaction temperature at 0 - 5°C. Add epichlorohydrin to tetrahydrofuran, and slowly dropwise add a tetrahydrofuran solution of methylmagnesium chloride. Keep the temperature for mixing reaction. After completion, adjust the pH to 6.5 - 7.5 at room temperature, separate the liquid to obtain the organic phase. The organic phase is extracted, dried, and distilled to collect the fractions to obtain 3-chloro-2-butanol;
[0008] Step 2: Slowly add phosphorus oxychloride to pyridine, cool it to 0 - 5°C in an ice bath, add the 3-chloro-2-butanol obtained in Step 1, and react at room temperature. Pour the resulting reaction solution into an ice-water mixture, then adjust the pH to 6.5 - 7.5, separate the liquid to obtain the organic phase. The organic phase is extracted, dried, and distilled to collect the fractions to obtain 1-chloro-2-butene;
[0009] Step 3: Add the 1-chloro-2-butene obtained in Step 2 to a sodium hydroxide solution, heat and react at 120 - 140°C. After the resulting reaction solution is cooled, separate the liquid to obtain the organic phase. The organic phase is extracted, dried, and distilled to collect the fractions to obtain crotyl alcohol.
[0010] In Step 1, the total molar ratio of tetrahydrofuran to epichlorohydrin is 4.8 - 5:1. Precise control is ensured to fully disperse the methylmagnesium chloride reagent and reduce coupling by-products.
[0011] In Step 1, the molar ratio of methylmagnesium chloride to epichlorohydrin is 1.2 - 1.3:1.
[0012] In Step 2, the molar ratio of pyridine to 3-chloro-2-butanol is 3.1 - 3.2:1.
[0013] In Step 2, the molar ratio of phosphorus oxychloride to 3-chloro-2-butanol is 3.1 - 3.2:1, ensuring that the hydroxyl group is completely eliminated to form a carbon-carbon double bond and avoiding residual hydroxyl groups leading to subsequent side reactions.
[0014] In Step 3, the sodium hydroxide solution is a sodium hydroxide solution with a mass fraction of 20% - 25%. Among them, the molar ratio of sodium hydroxide in Step 3 to 1-chloro-2-butene is 1.1 - 1.2:1.
[0015] In Step 1, the pH is adjusted using a hydrochloric acid solution with a mass fraction of 10% - 15%. The extraction is carried out using ether or dichloromethane. The organic phase is washed with a saturated NaHCO3 solution and dried using MgSO4.
[0016] In Step 1, the dropping rate of the tetrahydrofuran solution of methylmagnesium chloride during slow dropping, calculated according to the dropping amount of methylmagnesium chloride, is 0.7 g / min - 1.0 g / min. The tetrahydrofuran solution of methylmagnesium chloride is first prepared by dissolving methylmagnesium chloride in tetrahydrofuran, and the dropping rate is controlled to be a uniform dropping.
[0017] In Step 2, the pH is adjusted using a sodium hydroxide solution with a mass fraction of 20% - 25%. Extraction is carried out using ether or dichloromethane, and the organic phase is dried with MgSO4. For the ice - water mixture in Step 2, its temperature is generally around 0 °C. Pouring the reaction solution into ice - water can rapidly reduce the temperature of the reaction system, thereby terminating the reaction. 1 - chloro - 2 - butene is insoluble in water, and 1 - chloro - 2 - butene can be separated from the reaction solution. The amount of ice - water used is not further limited as long as it can ensure that the reaction solution can be rapidly cooled down.
[0018] In Step 3, the reaction is heated for 3 - 4 h. Extraction is carried out using ether, and the organic phase is dried with MgSO4.
[0019] Specifically, the method for preparing crotyl alcohol from epichlorohydrin through multiple steps includes the following steps:
[0020] Step 1: Keep the temperature of the reaction kettle at 0 - 5 °C, add anhydrous tetrahydrofuran as a solvent, add epichlorohydrin to the reaction kettle, and dropwise add a tetrahydrofuran solution of methylmagnesium chloride. Finish the dropwise addition within 1.5 - 2 h, stir and keep the temperature between 0 - 5 °C. After completion, react at room temperature for 1 - 1.5 h. After the reaction is completed, dropwise add a hydrochloric acid solution with a mass fraction of 10% - 15% until the pH is 6.5 - 7.5 at room temperature, stir and react for 1 h at room temperature, separate the liquid, extract with ether / dichloromethane, wash the organic phase with saturated NaHCO3 solution (to remove residual acid), dry with anhydrous MgSO4, and distill the obtained product to collect the distillate to obtain 3 - chloro - 2 - butanol.
[0021] Step 2: Add pyridine as a solvent to a dry reaction kettle, slowly add phosphorus oxychloride, cool to 0 - 5 °C in an ice bath, add the 3 - chloro - 2 - butanol obtained in Step 2 to the resulting reaction mixture, stir and react at room temperature for 3 h. Pour the reaction solution into an ice - water mixture with a volume 2 - 3 times that of the reaction solution, adjust the pH to 6.5 - 7.5 using a 20% - 25% sodium hydroxide solution, separate the liquid, extract using ether or dichloromethane, dry the organic phase with anhydrous MgSO4, and distill to obtain 1 - chloro - 2 - butene.
[0022] Step 3: Add a sodium hydroxide solution with a mass fraction of 20% - 25% to a dry reaction kettle, then add the 1 - chloro - 2 - butene obtained in Step 2, heat and react at 120 - 140 °C for 3 - 4 h. After cooling, extract with ether to obtain the organic phase, and dry the organic phase with anhydrous MgSO4 to obtain crotyl alcohol.
[0023] The present invention uses methylmagnesium chloride (CH3-MgCl) as a nucleophile. The nucleophile preferentially attacks the ring carbon atom with less steric hindrance to open the ring of epichlorohydrin. Without the need for precious metal catalysis, only a cheap THF solvent and acidic quenching conditions are required. For the elimination reaction, the POCl3 / pyridine system is used to remove the hydroxyl group. Since the carbon atom connected to the chlorine atom has a large steric hindrance, when removing the hydroxyl group, it tends to remove the hydrogen on the carbon with less steric hindrance to form a carbon-carbon double bond. Pyridine acts as a base to neutralize the by-product HCl, avoiding the use of metal catalysts. For the substitution reaction, -Cl is directly substituted by an aqueous NaOH solution to generate crotyl alcohol, without the need for hydrogenation or reduction steps. The present invention uses low temperature to inhibit side reactions: in the elimination reaction, the ice bath condition (0~5°C) inhibits the elimination of the H adjacent to Cl, improving the selectivity of 1-chloro-2-butene.
[0024] The method for preparing crotyl alcohol in multiple steps from epichlorohydrin according to the present invention has a synthesis route as follows:
[0025] 。
[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0027] (1) The method for preparing crotyl alcohol in multiple steps from epichlorohydrin according to the present invention reduces production costs and replaces precious metal catalysts. Using methylmagnesium chloride (CH3-MgCl) as a nucleophile, without the need for precious metal catalysts (such as Pt, Au, Ir, etc.), only a cheap THF solvent and acidic quenching conditions are required. The POCl3 / pyridine system is used in the elimination reaction to avoid the use of metal catalysts. The substitution reaction is directly completed by an aqueous NaOH solution, without precious metals participating throughout the process. The reagent cost is reduced by more than 50%, and the stability of the catalyst is significantly improved.
[0028] (2) The method for preparing crotyl alcohol in multiple steps from epichlorohydrin according to the present invention simplifies the reaction process and optimizes the operating conditions. The reaction is carried out at low temperature (0~5°C) and atmospheric pressure, avoiding high temperature and high pressure conditions and reducing side reactions (such as epoxy ring opening isomerization). The three-step reaction (ring opening, elimination, substitution) is designed as a continuous flow process, shortening the production cycle and reducing the intermediate purification steps. The process complexity is reduced, the equipment investment is reduced by about 30%, and the energy consumption is reduced by about 40%.
[0029] (3) The method for preparing crotyl alcohol in multiple steps from epichlorohydrin according to the present invention improves the selectivity and yield, realizing efficient production. By precisely controlling the molar ratio of THF to epichlorohydrin and inhibiting side reactions at low temperature, the selectivity of 1-chloro-2-butene is significantly improved. The yield of crotyl alcohol can reach 86.9 - 87.8%, the cis / trans ratio is controllable, and the purity is ≥99%. The conversion rate of epichlorohydrin is ≥98%, the raw material utilization rate is high, and it is suitable for large-scale production.
[0030] (4)The method for preparing crotyl alcohol from epichlorohydrin in multiple steps according to the present invention has optimized environmental protection and operational flexibility. There is no heavy metal pollution throughout the process. The wastewater is mainly a neutral salt solution (NaCl, NaHCO3) and is easy to treat. The solvent can be recycled with a recovery rate ≥95%. The by-product phosphate of POCl3 can be recycled as a raw material for fertilizers, and the emissions of the three wastes are reduced by 70%. The process has strong operability. It can be operated in batch reactions, suitable for small-batch and multi-variety production; it can also be operated in a continuous process, suitable for large-scale production, improving efficiency and product stability. BRIEF DESCRIPTION OF THE DRAWINGS
[0031] Figure 1 Gas chromatogram of crotyl alcohol prepared in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0032] The present invention will be further described below in conjunction with specific embodiments.
[0033] The raw materials and auxiliaries used in the following examples and comparative examples are all commercially available products. The tetrahydrofuran solution of methylmagnesium chloride described below is obtained by dissolving methylmagnesium chloride in tetrahydrofuran. Adjusting the pH to 6.5 - 7.5 means that as long as it is adjusted within this range, no specific numerical record is made. In the steps of each example, for the product of the previous step used, since its purity is above 99%, the molar ratio controlled no longer considers its purity problem and is calculated according to a purity of 100%.
[0034] Example 1
[0035] The method for preparing crotyl alcohol from epichlorohydrin in multiple steps includes the following steps:
[0036] Step 1: Keep the temperature of the reaction kettle at 2°C, add 31.88 g of anhydrous tetrahydrofuran as a solvent, add 92.52 g of epichlorohydrin to the reaction kettle, and dropwise add the tetrahydrofuran solution of methylmagnesium chloride (dissolve 89.91 g of methylmagnesium chloride in 314.25 g of anhydrous tetrahydrofuran). Finish dropping within 1.5 h, stir and keep the temperature at 2°C. After completion, react at room temperature for 1 h. After the reaction is completed, dropwise add a 15% hydrochloric acid solution at room temperature until the pH is 6.5 - 7.5, stir and react at room temperature for 1 h, separate the liquid and extract with ether. Wash the organic phase with saturated NaHCO3 solution and dry with anhydrous MgSO4. Distill the obtained product to collect the distillate, and obtain 97.93 g of 3-chloro-2-butanol. Calculate the yield to be 90.2%. As Figure 1 shown, the detected purity is 99.31%.
[0037] Step 2: Add 122.61 g of pyridine as a solvent into a dry reaction kettle, slowly add 237.67 g of phosphorus oxychloride, cool it to 2 °C in an ice bath, add 54.29 g of 3-chloro-2-butanol to the resulting reaction mixture, stir and react at room temperature for 3 h, pour the reaction solution into an ice-water mixture with a volume three times that of the reaction solution, adjust the pH to 6.5 - 7.5 with 20% sodium hydroxide solution, perform liquid separation and extract with ether, dry the organic phase with anhydrous MgSO4, and distill to obtain 39.44 g of 1-chloro-2-butene. Calculate the yield to be 87.1% and the detected purity to be 99.23%.
[0038] Step 3: Add 88 g of 20% sodium hydroxide solution by mass into a dry reaction kettle, then add 36.22 g of 1-chloro-2-butene obtained in Step 2, heat and react at 120 °C for 4 h. After cooling, perform liquid separation and extract with ether to obtain the organic phase, dry the organic phase with anhydrous MgSO4 to obtain 25.33 g of crotyl alcohol. Calculate the yield to be 87.8% and the detected purity to be 99.49%.
[0039] Example 2
[0040] The method for multi-step preparation of crotyl alcohol using epichlorohydrin as a raw material includes the following steps:
[0041] Step 1: Keep the temperature of the reaction kettle at 0 °C, add 19.14 g of anhydrous tetrahydrofuran as a solvent, add 92.52 g of epichlorohydrin into the reaction kettle, dropwise add a tetrahydrofuran solution of methylmagnesium chloride (dissolve 97.23 g of methylmagnesium chloride in 341.4 g of anhydrous tetrahydrofuran), finish dropping within 2 h, stir and keep the temperature at 0 °C. After completion, react at room temperature for 1.5 h. After the reaction is completed, dropwise add a 10% hydrochloric acid solution at room temperature until the pH is 6.5 - 7.5, stir and react at room temperature for 1 h, perform liquid separation and extract with ether, wash the organic phase with saturated NaHCO3 solution, dry with anhydrous MgSO4, distill the obtained product and collect the distillate to obtain 99.78 g of 3-chloro-2-butanol. Calculate the yield to be 91.9% and the detected purity to be 99.23%.
[0042] Step 2: Add 168.75 g of pyridine as a solvent into a dry reaction kettle, slowly add 327.11 g of phosphorus oxychloride, cool it to 0 °C in an ice bath, add 72.38 g (0.67 mol) of 3-chloro-2-butanol to the resulting reaction mixture, stir and react at room temperature for 3 h, pour the reaction solution into an ice-water mixture with a volume three times that of the reaction solution, adjust the pH to 6.5 - 7.5 with 25% sodium hydroxide solution, perform liquid separation and extract with ether, dry the organic phase with anhydrous MgSO4, and distill to obtain 51.68 g of 1-chloro-2-butene. Calculate the yield to be 85.6% and the detected purity to be 99.11 %.
[0043] Step 3: Add 96 g of a 25% sodium hydroxide solution by mass to a dry reaction kettle, then add 45.28 g of 1-chloro-2-butene obtained in Step 2. Heat and react at 130 °C for 3.5 h. After cooling, extract with diethyl ether to obtain an organic phase. Dry the organic phase with anhydrous MgSO4 to obtain 31.41 g of crotyl alcohol. Calculate the yield to be 87.1% and the detected purity to be 99.33%.
[0044] Example 3
[0045] The method for preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material includes the following steps:
[0046] Step 1: Keep the temperature of the reaction kettle at 5 °C, add 23.08 g of anhydrous tetrahydrofuran as a solvent, add 92.52 g of epichlorohydrin to the reaction kettle, and dropwise add a tetrahydrofuran solution of methylmagnesium chloride (dissolve 93.49 g of methylmagnesium chloride in 330.25 g of anhydrous tetrahydrofuran). Finish dropping within 2 h, stir and keep the temperature at 5 °C. After completion, react at room temperature for 1.5 h. After the reaction is completed, dropwise add a 10% hydrochloric acid solution by mass at room temperature until the pH is 6.5 - 7.5, stir and react at room temperature for 1 h, separate the liquid and extract with dichloromethane. Wash the organic phase with a saturated NaHCO3 solution and dry with anhydrous MgSO4. Distill the obtained product to collect the fraction to obtain 82.50 g of 3-chloro-2-butanol. Calculate the yield to be 91.1% and the detected purity to be 99.18%.
[0047] Step 2: Add 166.67 g of pyridine as a solvent to a dry reaction kettle, slowly add 322 g of phosphorus oxychloride, cool to 5 °C in an ice bath, add 72.38 g of 3-chloro-2-butanol to the obtained reaction mixture, stir and react at room temperature for 3 h. Pour the reaction solution into an ice-water mixture with a volume twice that of the reaction solution, adjust the pH to 6.5 - 7.5 with a 20% sodium hydroxide solution, separate the liquid and extract with dichloromethane. Dry the organic phase with anhydrous MgSO4 and distill to obtain 52.30 g of 1-chloro-2-butene. Calculate the yield to be 86.2% and the detected purity to be 99.26%.
[0048] Step 3: Add 120 g of a 20% sodium hydroxide solution by mass to a dry reaction kettle, then add 45.28 g of 1-chloro-2-butene. Heat and react at 140 °C for 3 h. After cooling, extract with diethyl ether to obtain an organic phase. Dry the organic phase with anhydrous MgSO4 to obtain 31.34 g of crotyl alcohol. Calculate the yield to be 86.9% and the detected purity to be 99.25%.
[0049] Comparative Example 1
[0050] This comparative example is the same as Example 1, and replace the phosphorus oxychloride in step (2) with ferric chloride. Its preparation steps are as follows:
[0051] Step 1: Keep the temperature of the reaction kettle at 2 °C, add 31.88 g of anhydrous tetrahydrofuran as a solvent, add 92.52 g of epichlorohydrin to the reaction kettle, and dropwise add a tetrahydrofuran solution of methylmagnesium chloride (dissolve 89.91 g of methylmagnesium chloride in 314.25 g of anhydrous tetrahydrofuran). Finish the dropwise addition within 1.5 h, stir and keep the temperature at 2 °C. After completion, react at room temperature for 1 h. After the reaction is completed, dropwise add a hydrochloric acid solution with a mass fraction of 15% at room temperature until the pH is 6.5 - 7.5, stir and react at room temperature for 1 h, separate the liquid and extract with ether. Wash the organic phase with saturated NaHCO3 solution and dry it with anhydrous MgSO4. Distill the obtained product to collect the fractions, and obtain 99.24 g of 3-chloro-2-butanol. Calculate the yield to be 91.4%, and the detected purity is 99.14%.
[0052] Step 2: Add 122.61 g of pyridine as a solvent to a dry reaction kettle, slowly add 251.41 g of ferric chloride, cool it to 2 °C in an ice bath, add 54.29 g of 3-chloro-2-butanol to the obtained reaction mixture, stir and react at room temperature for 3 h. Pour the reaction solution into an ice-water mixture with a volume three times that of the reaction solution, adjust the pH to 6.5 - 7.5 with 20% sodium hydroxide solution, separate the liquid and extract with ether. Dry the organic phase with anhydrous MgSO4 and distill to obtain 23.23 g of 1-chloro-2-butene. Calculate the yield to be 51.3%, and the detected purity is 99.20%.
[0053] Step 3: Add 51.77 g of a sodium hydroxide solution with a mass fraction of 20% to a dry reaction kettle, then add 21.31 g of 1-chloro-2-butene, heat and react at 120 °C for 4 h. After cooling, extract with ether to obtain the organic phase, and dry the organic phase with anhydrous MgSO4 to obtain 14.80 g of crotyl alcohol. Calculate the yield to be 87.2%, and the detected purity is 99.38%.
[0054] Comparative Example 2
[0055] This comparative example is the same as Example 1, replacing the pyridine in step (2) with triethylamine. Its preparation steps are as follows:
[0056] The method for multi-step preparation of crotyl alcohol using epichlorohydrin as a raw material includes the following steps:
[0057] Step 1: Keep the temperature of the reaction kettle at 2°C, add 31.88 g of anhydrous tetrahydrofuran as a solvent, add 92.52 g of epichlorohydrin to the reaction kettle, and dropwise add a tetrahydrofuran solution of methylmagnesium chloride (dissolve 89.91 g of methylmagnesium chloride in 314.25 g of anhydrous tetrahydrofuran). Finish dropping within 1.5 h, stir and keep the temperature at 2°C. After completion, react at room temperature for 1 h. After the reaction is completed, dropwise add a hydrochloric acid solution with a mass fraction of 15% at room temperature until the pH is 6.5 - 7.5, stir and react at room temperature for 1 h, separate the liquid and extract with ether. Wash the organic phase with saturated NaHCO3 solution and dry it with anhydrous MgSO4. Distill the obtained product to collect the fractions to obtain 100.21 g of 3-chloro-2-butanol. Calculate the yield to be 92.3% and the detected purity to be 99.11%.
[0058] Step 2: Add 297.38 g of triethylamine as a solvent to a dry reaction kettle, slowly add 432.12 g of phosphorus oxychloride, cool to 2°C in an ice bath, add 98.7 g of 3-chloro-2-butanol to the obtained reaction mixture, stir and react at room temperature for 3 h. Pour the reaction solution into an ice-water mixture with a volume 3 times that of the reaction solution, adjust the pH to 6.5 - 7.5 with 20% sodium hydroxide solution, separate the liquid and extract with ether. Dry the organic phase with anhydrous MgSO4 and distill to obtain 52.94 g of 1-chloro-2-butene. Calculate the yield to be 64.3% and the detected purity to be 99.01%.
[0059] Step 3: Add 110 g of a 20% sodium hydroxide solution by mass to a dry reaction kettle, then add 45.28 g of 1-chloro-2-butene, heat and react at 120°C for 4 h. After cooling, extract with ether to obtain the organic phase, and dry the organic phase with anhydrous MgSO4 to obtain 31.52 g of crotyl alcohol. Calculate the yield to be 87.4% and the detected purity to be 99.30%.
[0060] Comparative Example 3
[0061] This comparative example is the same as Example 1, replacing the tetrahydrofuran used as a solvent in step (1) with dichloromethane. Its preparation steps are as follows:
[0062] The method for multi-step preparation of crotyl alcohol using epichlorohydrin as a raw material includes the following steps:
[0063] Step 1: Keep the temperature of the reaction kettle at 2 °C, add 37.5 g of dichloromethane as a solvent, add 92.52 g of epichlorohydrin to the reaction kettle, and dropwise add a dichloromethane solution of methylmagnesium chloride (dissolve 89.91 g of methylmagnesium chloride in 370.16 g of dichloromethane). Finish the dropwise addition within 1.5 h, stir and keep the temperature at 2 °C. After completion, react at room temperature for 1 h. After the reaction is completed, dropwise add a hydrochloric acid solution with a mass fraction of 15% at room temperature until the pH is 6.5 - 7.5, stir and react at room temperature for 1 h, separate the liquid and extract with ether. Wash the organic phase with saturated NaHCO3 solution, dry with anhydrous MgSO4, distill the obtained product to collect the distillate, and obtain 54.07 g of 3-chloro-2-butanol. Calculate the yield to be 49.8%, and the detected purity is 99.01%.
[0064] Step 2: Add 116.77 g of pyridine as a solvent to a dry reaction kettle, slowly add 226.35 g of phosphorus oxychloride, cool to 2 °C in an ice bath, add 51.7 g of 3-chloro-2-butanol to the obtained reaction mixture, stir and react at room temperature for 3 h. Pour the reaction solution into an ice-water mixture with a volume 3 times that of the reaction solution, adjust the pH to 6.5 - 7.5 with 20% sodium hydroxide solution, separate the liquid and extract with ether. Dry the organic phase with anhydrous MgSO4, and distill to obtain 37.30 g of 1-chloro-2-butene. Calculate the yield to be 86.5%, and the detected purity is 99.17%.
[0065] Step 3: Add 70.97 g of a 20% sodium hydroxide solution by mass to a dry reaction kettle, then add 29.21 g of 1-chloro-2-butene, heat and react at 120 °C for 4 h. After cooling, extract with ether to obtain the organic phase. Dry the organic phase with anhydrous MgSO4 to obtain 19.92 g of crotyl alcohol. Calculate the yield to be 85.6%, and the detected purity is 99.14%.
Claims
1. A method for preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material, characterized in that, It includes the following steps: Step 1: Keep the reaction temperature at 0 - 5 °C. Add epichlorohydrin to tetrahydrofuran, and dropwise add a tetrahydrofuran solution of methylmagnesium chloride. Keep the temperature for mixing reaction. After completion, adjust the pH to 6.5 - 7.5 at room temperature, separate the liquid to obtain the organic phase. The organic phase is subjected to extraction, drying, and distillation to collect the fractions to obtain 3-chloro-2-butanol; the molar ratio of methylmagnesium chloride to epichlorohydrin is 1.2 - 1.3:1; Step 2: Add phosphorus oxychloride to pyridine, cool it in an ice bath to 0 - 5 °C, add the 3-chloro-2-butanol obtained in Step 1, and react at room temperature. Pour the obtained reaction solution into an ice-water mixture, and then adjust the pH to 6.5 - 7.
5. Separate the liquid to obtain the organic phase. The organic phase is subjected to extraction, drying, and distillation to collect the fractions to obtain 1-chloro-2-butene; the molar ratio of phosphorus oxychloride to 3-chloro-2-butanol is 3.1 - 3.2:1; the molar ratio of pyridine to 3-chloro-2-butanol is 3.1 - 3.2:1; Step 3: Add the 1-chloro-2-butene obtained in Step 2 to a sodium hydroxide solution, heat and react at 120 - 140 °C. After the obtained reaction solution is cooled, separate the liquid to obtain the organic phase. The organic phase is subjected to extraction, drying, and distillation to collect the fractions to obtain crotyl alcohol.
2. The method for preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material according to claim 1, wherein: In Step 1, the total molar ratio of tetrahydrofuran to epichlorohydrin is 4.8 - 5:
1.
3. The method for multi-step preparation of crotyl alcohol using epichlorohydrin as a raw material according to claim 1, characterized in that: In Step 3, the sodium hydroxide solution is a sodium hydroxide solution with a mass fraction of 20% - 25%, and the molar ratio of sodium hydroxide in Step 3 to 1-chloro-2-butene is 1.1 - 1.2:
1.
4. The method for preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material according to claim 1, characterized in that: In Step 1, the pH is adjusted using a hydrochloric acid solution with a mass fraction of 10% - 15%. Extraction is carried out using ether or dichloromethane. The organic phase is washed with a saturated NaHCO3 solution and dried using MgSO4.
5. The method for multi-step preparation of crotyl alcohol using epichlorohydrin as a raw material according to claim 1, characterized in that: In Step 1, the dropping rate of the tetrahydrofuran solution of methylmagnesium chloride, calculated according to the dropping amount of methylmagnesium chloride, is 0.7 g / min - 1.0 g / min.
6. The method for preparing crotyl alcohol in multiple steps with epichlorohydrin as a raw material according to claim 1, characterized in that: In Step 2, the pH is adjusted using a sodium hydroxide solution with a mass fraction of 20% - 25%. Extraction is carried out using ether or dichloromethane. The organic phase is dried using MgSO4.
7. The method for multi-step preparation of crotyl alcohol using epichlorohydrin as a raw material according to claim 1, characterized in that: In Step 3, the heating reaction is carried out for 3 - 4 h. Extraction is carried out using ether. The organic phase is dried using MgSO4.
Citation Information
Patent Citations
Closed cycle production method for preparing epichlorohydrin by adopting allyl alcohol method
CN114702464A