Method for preparing crotyl alcohol in multiple steps by taking epichlorohydrin as raw material

Abstract

The invention belongs to the technical field of preparation of organic compounds, and particularly relates to a method for preparing crotyl alcohol in multiple steps by taking epichlorohydrin as a raw material. The method for preparing crotyl alcohol in multiple steps by taking epoxy chloropropane as a raw material comprises the following steps: adding epoxy chloropropane into tetrahydrofuran, slowly dropwise adding a tetrahydrofuran solution of methylmagnesium chloride, keeping the temperature, mixing and reacting, adjusting the pH to be neutral at room temperature after the reaction is completed, and treating to obtain 3-chloro-2-butanol; slowly adding phosphorus oxychloride into pyridine, cooling in an ice bath, adding the obtained 3-chloro-2-butanol, reacting at room temperature, pouring into an ice-water mixed solution, regulating the pH value to be neutral, and treating to obtain 1-chloro-2-butene; and adding the obtained 1-chloro-2-butene into a sodium hydroxide solution, heating to react, and treating to obtain the crotonol. The method for preparing crotyl alcohol in multiple steps by taking epichlorohydrin as the raw material provided by the invention is simple to operate, mild in condition, low in cost, high in yield and good in environmental protection property.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of organic compounds, and specifically relates to a method for preparing crotyl alcohol in multiple steps by taking epichlorohydrin as a raw material. Background Art

[0002] Crotyl alcohol (2-butenol), as an organic compound with wide application value, has shown its unique advantages in many fields such as chemical industry, medicine, cosmetics and food additives. In the chemical industry, as a key intermediate in organic synthesis, crotyl alcohol is widely used in chemical products such as synthetic fragrances, resins, plasticizers, stabilizers, etc. It can also be used as a high-quality solvent for dyes and coatings. In the pharmaceutical industry, crotyl alcohol and its derivatives are the active ingredients of anti-tumor, anti-inflammatory, antibacterial, antiviral and other drugs, showing their irreplaceable importance. In addition, crotyl alcohol also occupies a place in the formulation of high-end skin care products due to its antioxidant, anti-wrinkle and moisturizing effects. At the same time, it also plays an important role in improving the taste of food and extending the shelf life in the field of food additives.

[0003] At present, the main preparation method of crotyl alcohol is to reduce crotonaldehyde with reducing agents such as sodium borohydride, lithium aluminum tetrahydride or aluminum isopropoxide. The catalysts used in this process are mainly precious metal catalysts such as Pt, Au and Ir. These catalysts are not only expensive, but also have harsh reaction conditions and complicated processes, resulting in high production costs. What is more serious is that the traditional process will produce a large amount of metal-containing wastewater, waste gas and other three wastes during the preparation process, causing serious pollution to the environment, which does not meet the green development requirements of modern chemical industry.

[0004] In addition, some catalysts used for preparing crotyl alcohol by gas-phase hydrogenation have the disadvantages of easy deactivation and poor stability, resulting in low conversion rate and selectivity of crotyl alcohol, which further affects 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 cis / trans isomers are difficult to effectively separate, resulting in a yield of 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 of the prior art and provide a method for preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material, which has simple operation, mild conditions, low cost, high yield and good environmental protection.

[0006] The method for preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material of the present invention comprises the following steps: Step 1, maintaining the reaction temperature at 0-5°C, adding epichlorohydrin to tetrahydrofuran, slowly dropping a tetrahydrofuran solution of methylmagnesium chloride, maintaining the temperature and mixing the reaction, after completion, adjusting the pH to 6.5-7.5 at room temperature, separating the liquids to obtain an organic phase, extracting the organic phase, drying, and distilling and collecting the fractions to obtain 3-chloro-2-butanol; Step 2, slowly add phosphorus oxychloride to pyridine, cool to 0-5°C in an ice bath, add 3-chloro-2-butanol obtained in step 1, react at room temperature, pour the obtained reaction solution into a mixture of ice and water, adjust the pH to 6.5-7.5, separate the liquid to obtain an organic phase, extract the organic phase, dry it, and collect the fraction by distillation to obtain 1-chloro-2-butene; Step 3: Add 1-chloro-2-butene obtained in step 2 to the sodium hydroxide solution, heat to react at 120-140° C., cool the reaction solution, separate the liquid to obtain an organic phase, extract the organic phase, dry it, and collect the fractions by distillation to obtain crotyl alcohol.

[0007] The total molar ratio of tetrahydrofuran to epichlorohydrin in step 1 is 4.8-5:1, and precise control is performed to ensure that the methylmagnesium chloride reagent is fully dispersed and coupling by-products are reduced.

[0008] In step 1, the molar ratio of methylmagnesium chloride to epichlorohydrin is 1.2-1.3:1.

[0009] In step 2, the molar ratio of pyridine to 3-chloro-2-butanol is 3.1-3.2:1.

[0010] In step 2, the molar ratio of phosphorus oxychloride to 3-chloro-2-butanol is 3.1-3.2:1, which ensures that the hydroxyl group is completely eliminated to form a carbon-carbon double bond and avoids subsequent side reactions caused by residual hydroxyl groups.

[0011] The sodium hydroxide solution in step 3 is a sodium hydroxide solution with a mass fraction of 20% to 25%, wherein the molar ratio of sodium hydroxide to 1-chloro-2-butene in step 3 is 1.1 to 1.2:1.

[0012] In step 1, the pH is adjusted using a hydrochloric acid solution with a mass fraction of 10% to 15%, the extraction is performed using ether or dichloromethane, the organic phase is washed with a saturated NaHCO3 solution, and dried with MgSO4.

[0013] The dripping speed of the tetrahydrofuran solution of methyl magnesium chloride slowly added in step 1 is 0.7 g / min to 1.0 g / min according to the amount of methyl magnesium chloride added. The tetrahydrofuran solution of methyl magnesium chloride is prepared by first dissolving methyl magnesium chloride in tetrahydrofuran, and the dripping speed is controlled to drip at a uniform speed.

[0014] In step 2, the pH is adjusted by using a sodium hydroxide solution with a mass fraction of 20% to 25%, and the extraction is performed by using ether or dichloromethane, and the organic phase is dried by using MgSO4. The temperature of the mixture of ice and water in step 2 is generally around 0°C. Pouring the reaction solution into ice water can quickly 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 quickly cooled.

[0015] Step 3: Heat the reaction for 3-4 hours, extract with ether, and dry the organic phase with MgSO4.

[0016] Specifically, the method for preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material comprises the following steps: Step 1, keep the temperature of the reactor at 0~5°C, add anhydrous tetrahydrofuran as a solvent, add epichlorohydrin to the reactor, add a tetrahydrofuran solution of methylmagnesium chloride dropwise, and complete the addition within 1.5~2h, stir and keep the temperature between 0~5°C, and react at room temperature for 1~1.5h. After the reaction is completed, add a 10%~15% hydrochloric acid solution at room temperature until the pH is 6.5~7.5, stir and react at room temperature for 1h, separate the liquids and extract with ether / dichloromethane, wash the organic phase with a saturated NaHCO3 solution (to remove residual acid), dry with anhydrous MgSO4, and distill the obtained product to collect the fractions to obtain 3-chloro-2-butanol.

[0017] Step 2: Add pyridine as solvent to a dry reaction kettle, slowly add phosphorus oxychloride, cool to 0-5°C in an ice bath, add 3-chloro-2-butanol obtained in step 2 to the reaction mixture, stir and react at room temperature for 3 hours, 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 with 20%-25% sodium hydroxide solution, extract with ether or dichloromethane, dry the organic phase with anhydrous MgSO4, and distill to obtain 1-chloro-2-butene.

[0018] Step 3: Add 20% to 25% by mass of sodium hydroxide solution to a dry reactor, and then add 1-chloro-2-butene obtained in step 2, heat to react at 120 to 140°C for 3 to 4 hours, and after cooling, extract with ether to obtain an organic phase, and dry the organic phase with anhydrous MgSO4 to obtain crotyl alcohol.

[0019] The present invention uses methylmagnesium chloride (CH3-MgCl) as a nucleophilic reagent, and the nucleophilic reagent preferentially attacks the ring carbon atom with smaller steric hindrance to open the ring of epichlorohydrin, without the need for noble metal catalysis, and only requires cheap THF solvent and acidic quenching conditions. The elimination reaction uses a POCl3 / pyridine system for dehydroxylation. Since the carbon connected to the chlorine atom has large steric hindrance, it tends to dehydroxylate the hydrogen on the carbon with smaller steric hindrance to generate a carbon-carbon double bond during dehydroxylation. Pyridine is used as a base to neutralize the by-product HCl, avoiding the use of a metal catalyst. The substitution reaction directly replaces -Cl with a NaOH aqueous solution to generate crotyl alcohol, without the need for hydrogenation or reduction steps. The present invention uses low temperature to inhibit side reactions: the ice bath condition (0-5°C) in the elimination reaction inhibits the elimination of H adjacent to Cl, thereby improving the selectivity of 1-chloro-2-butene.

[0020] The method of the present invention for preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material has the following synthetic route: .

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) The method of preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material of the present invention reduces production costs, replaces noble metal catalysts, uses methylmagnesium chloride (CH3-MgCl) as a nucleophilic reagent, does not require noble metal catalysts (such as Pt, Au, Ir, etc.), and only requires cheap THF solvent and acidic quenching conditions. The elimination reaction uses a POCl3 / pyridine system to avoid the use of metal catalysts. The substitution reaction is directly completed by a NaOH aqueous solution, without the participation of noble metals throughout the process, the reagent cost is reduced by more than 50%, and the catalyst stability is significantly improved.

[0022] (2) The method of preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material of the present invention simplifies the reaction process, optimizes the operating conditions, and conducts the reaction at low temperature (0-5°C) and normal 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%.

[0023] (3) The method of preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material of the present invention improves selectivity and yield, realizes efficient production, and significantly improves the selectivity of 1-chloro-2-butene by precisely controlling the molar ratio of THF to epichlorohydrin and inhibiting side reactions at low temperature. 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.

[0024] (4) The method of preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material of the present invention has optimized environmental protection and operational flexibility, and there is no heavy metal pollution in the whole process. The wastewater is mainly a neutral salt solution (NaCl, NaHCO3), which is easy to handle. The solvent can be recycled with a recovery rate of ≥95%. The POCl3 byproduct phosphate can be recycled as a fertilizer raw material, and the discharge of three wastes is reduced by 70%. The process has strong operability and can be operated in batch reactions, which is suitable for small batch and multi-variety production; it can also be operated in a continuous process, which is suitable for large-scale production, improving efficiency and product stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the gas chromatogram of crotyl alcohol prepared in Example 1. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with specific embodiments.

[0027] The raw materials and auxiliary agents used in the following examples and comparative examples are all commercially available products. The tetrahydrofuran solutions of methylmagnesium chloride described below are all obtained by dissolving methylmagnesium chloride in tetrahydrofuran. The pH value of the adjustment to 6.5-7.5 is adjusted to this range without recording specific values. In the steps of each embodiment, the product of the previous step used, because its purity is all above 99%, the molar ratio of the control no longer considers its purity problem, and is all calculated according to 100% purity.

[0028] Example 1 The method for preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material comprises the following steps: Step 1, keep the temperature of the reactor at 2°C, add 31.88g of anhydrous tetrahydrofuran as solvent, add 92.52g of epichlorohydrin to the reactor, add a tetrahydrofuran solution of methyl magnesium chloride (dissolve 89.91g of methyl magnesium chloride in 314.25g of anhydrous tetrahydrofuran), add the dropwise addition within 1.5h, stir and keep the temperature at 2°C, after completion, react at room temperature for 1h, after completion, add a 15% hydrochloric acid solution at room temperature until the pH is 6.5-7.5, stir and react at room temperature for 1h, separate the liquids and extract with ether, wash the organic phase with a saturated NaHCO3 solution, dry it with anhydrous MgSO4, distill the obtained product and collect the fractions to obtain 97.93g of 3-chloro-2-butanol, with a calculated yield of 90.2%, such as Figure 1 As shown, the detected purity is 99.31%.

[0029] Step 2: Add 122.61g of pyridine as solvent to a dry reactor, slowly add 237.67g of phosphorus oxychloride, cool to 2°C in an ice bath, add 54.29g of 3-chloro-2-butanol to the obtained reaction mixture, stir and react at room temperature for 3h, 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, extract with ether, dry the organic phase with anhydrous MgSO4, and distill to obtain 39.44g of 1-chloro-2-butene, with a calculated yield of 87.1% and a detected purity of 99.23%.

[0030] Step 3: Add 88g of 20% by mass sodium hydroxide solution to a dry reactor, and then add 36.22g of 1-chloro-2-butene obtained in step 2, and heat the reaction at 120°C for 4h. After cooling, extract with ether to obtain an organic phase, and dry the organic phase with anhydrous MgSO4 to obtain 25.33g of crotyl alcohol. The calculated yield is 87.8%, and the detected purity is 99.49%.

[0031] Example 2 The method for preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material comprises the following steps: Step 1, keep the reactor temperature at 0°C, add 19.14g of anhydrous tetrahydrofuran as a solvent, add 92.52g of epichlorohydrin to the reactor, add a tetrahydrofuran solution of methylmagnesium chloride dropwise (dissolve 97.23g of methylmagnesium chloride in 341.4g of anhydrous tetrahydrofuran), add the dropwise addition within 2h, stir and keep the temperature at 0°C, react at room temperature for 1.5h, after the reaction is completed, add a 10% hydrochloric acid solution at room temperature until the pH is 6.5-7.5, stir and react at room temperature for 1h, separate the liquids and extract with ether, wash the organic phase with a saturated NaHCO3 solution, dry it with anhydrous MgSO4, and distill the obtained product to collect the fractions to obtain 99.78g of 3-chloro-2-butanol, with a calculated yield of 91.9% and a detected purity of 99.23%.

[0032] Step 2: Add 168.75 g of pyridine as solvent to a dry reactor, slowly add 327.11 g of phosphorus oxychloride, cool to 0°C in an ice bath, add 72.38 g (0.67 mol) of 3-chloro-2-butanol to the obtained reaction mixture, stir and react at room temperature for 3 hours, 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, extract with ether, dry the organic phase with anhydrous MgSO4, and distill to obtain 51.68 g of 1-chloro-2-butene, with a calculated yield of 85.6% and a detected purity of 99.11%.

[0033] Step 3: Add 96 g of 25% sodium hydroxide solution to a dry reactor, and then add 45.28 g of 1-chloro-2-butene obtained in step 2, and heat the reaction at 130°C for 3.5 hours. After cooling, extract with ether to obtain an organic phase, and dry the organic phase with anhydrous MgSO4 to obtain 31.41 g of crotyl alcohol. The calculated yield is 87.1%, and the detected purity is 99.33%.

[0034] Example 3 The method for preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material comprises the following steps: Step 1, keep the reactor temperature at 5 ° C, add 23.08g of anhydrous tetrahydrofuran as a solvent, add 92.52g of epichlorohydrin to the reactor, add a tetrahydrofuran solution of methylmagnesium chloride (dissolve 93.49g of methylmagnesium chloride in 330.25g of anhydrous tetrahydrofuran), add the dropwise addition within 2h, stir and keep the temperature at 5 ° C, react at room temperature for 1.5h, after the reaction is completed, add a 10% hydrochloric acid solution at room temperature until the pH is 6.5-7.5, stir and react at room temperature for 1h, separate the liquids and extract with dichloromethane, wash the organic phase with a saturated NaHCO3 solution, dry it with anhydrous MgSO4, and distill the obtained product to collect the fractions to obtain 82.50g of 3-chloro-2-butanol, with a calculated yield of 91.1% and a detected purity of 99.18%.

[0035] Step 2: Add 166.67g of pyridine as solvent to a dry reactor, slowly add 322g of phosphorus oxychloride, cool to 5°C in an ice bath, add 72.38g of 3-chloro-2-butanol to the obtained reaction mixture, stir and react at room temperature for 3h, 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 20% sodium hydroxide solution, extract with dichloromethane, dry the organic phase with anhydrous MgSO4, and distill to obtain 52.30g of 1-chloro-2-butene, with a calculated yield of 86.2% and a detected purity of 99.26%.

[0036] Step 3: Add 120g of 20% sodium hydroxide solution to a dry reactor, then add 45.28g of 1-chloro-2-butene, heat the reaction at 140°C for 3h, cool, extract with ether to obtain an organic phase, dry the organic phase with anhydrous MgSO4, and obtain 31.34g of crotyl alcohol. The calculated yield is 86.9% and the detected purity is 99.25%.

[0037] Comparative Example 1 This comparative example is the same as Example 1, except that the phosphorus oxychloride in step (2) is replaced by ferric chloride, and the preparation steps are as follows: Step 1, keep the reactor temperature at 2 ° C, add 31.88g of anhydrous tetrahydrofuran as a solvent, add 92.52g of epichlorohydrin to the reactor, add a tetrahydrofuran solution of methylmagnesium chloride (dissolve 89.91g of methylmagnesium chloride in 314.25g of anhydrous tetrahydrofuran), and add the addition within 1.5h. Stir and keep the temperature at 2 ° C. After completion, react at room temperature for 1h. After the reaction is completed, add a 15% hydrochloric acid solution at room temperature until the pH is 6.5-7.5, stir and react at room temperature for 1h, separate the liquids and extract with ether, wash the organic phase with a saturated NaHCO3 solution, dry it with anhydrous MgSO4, and distill the obtained product to collect the fractions to obtain 99.24g of 3-chloro-2-butanol, with a calculated yield of 91.4% and a detected purity of 99.14%.

[0038] Step 2: Add 122.61g of pyridine as solvent to a dry reactor, slowly add 251.41g of ferric chloride, cool to 2°C in an ice bath, add 54.29g of 3-chloro-2-butanol to the obtained reaction mixture, stir and react at room temperature for 3h, 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, extract with ether, dry the organic phase with anhydrous MgSO4, and distill to obtain 23.23g of 1-chloro-2-butene, with a calculated yield of 51.3% and a detected purity of 99.20%.

[0039] Step 3: Add 51.77 g of 20% sodium hydroxide solution to a dry reactor, then add 21.31 g of 1-chloro-2-butene, heat the reaction at 120°C for 4 hours, cool, extract with ether to obtain an organic phase, dry the organic phase with anhydrous MgSO4, and obtain 14.80 g of crotyl alcohol. The calculated yield is 87.2%, and the detected purity is 99.38%.

[0040] Comparative Example 2 This comparative example is the same as Example 1, except that the pyridine in step (2) is replaced by triethylamine. The preparation steps are as follows: The method for preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material comprises the following steps: Step 1, keep the reactor temperature at 2 ° C, add 31.88g of anhydrous tetrahydrofuran as a solvent, add 92.52g of epichlorohydrin to the reactor, add a tetrahydrofuran solution of methylmagnesium chloride (dissolve 89.91g of methylmagnesium chloride in 314.25g of anhydrous tetrahydrofuran), add the dropwise addition within 1.5h, stir and keep the temperature at 2 ° C, react at room temperature for 1h, after the reaction is completed, add a 15% hydrochloric acid solution at room temperature until the pH is 6.5-7.5, stir and react at room temperature for 1h, separate the liquids and extract with ether, wash the organic phase with a saturated NaHCO3 solution, dry it with anhydrous MgSO4, and distill the obtained product to collect the fractions to obtain 100.21g of 3-chloro-2-butanol, with a calculated yield of 92.3% and a detected purity of 99.11%.

[0041] Step 2: Add 297.38g of triethylamine as solvent to a dry reactor, slowly add 432.12g of phosphorus oxychloride, cool to 2°C in an ice bath, add 98.7g of 3-chloro-2-butanol to the obtained reaction mixture, stir and react at room temperature for 3h, 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, extract with ether, dry the organic phase with anhydrous MgSO4, and distill to obtain 52.94g of 1-chloro-2-butene, with a calculated yield of 64.3% and a detected purity of 99.01%.

[0042] Step 3: Add 110g of 20% sodium hydroxide solution and 45.28g of 1-chloro-2-butene to a dry reactor, heat the reaction at 120°C for 4h, cool, extract with ether to obtain an organic phase, dry the organic phase with anhydrous MgSO4 to obtain 31.52g of crotyl alcohol, with a calculated yield of 87.4% and a detected purity of 99.30%.

[0043] Comparative Example 3 This comparative example is the same as Example 1, except that tetrahydrofuran as the solvent in step (1) is replaced by dichloromethane. The preparation steps are as follows: The method for preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material comprises the following steps: Step 1, keep the reactor temperature at 2 ° C, add 37.5g of dichloromethane as a solvent, add 92.52g of epichlorohydrin to the reactor, add a dichloromethane solution of methylmagnesium chloride (dissolve 89.91g of methylmagnesium chloride in 370.16g of dichloromethane), add the dropwise addition within 1.5h, stir and keep the temperature at 2 ° C, react at room temperature for 1h, after the reaction is completed, add a 15% hydrochloric acid solution at room temperature until the pH is 6.5-7.5, stir and react at room temperature for 1h, separate the liquids and extract with ether, wash the organic phase with a saturated NaHCO3 solution, dry it with anhydrous MgSO4, and distill the obtained product to collect the fractions to obtain 54.07g of 3-chloro-2-butanol, with a calculated yield of 49.8% and a detected purity of 99.01%.

[0044] Step 2: Add 116.77g of pyridine as solvent to a dry reactor, slowly add 226.35g of phosphorus oxychloride, cool to 2°C in an ice bath, add 51.7g of 3-chloro-2-butanol to the obtained reaction mixture, stir and react at room temperature for 3h, 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, extract with ether, dry the organic phase with anhydrous MgSO4, and distill to obtain 37.30g of 1-chloro-2-butene, with a calculated yield of 86.5% and a detected purity of 99.17%.

[0045] Step 3: Add 70.97 g of 20% sodium hydroxide solution to a dry reactor, then add 29.21 g of 1-chloro-2-butene, heat the reaction at 120°C for 4 hours, cool, extract with ether to obtain an organic phase, dry the organic phase with anhydrous MgSO4, and obtain 19.92 g of crotyl alcohol. The calculated yield is 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: The following steps are involved: Step 1, maintaining the reaction temperature at 0-5°C, adding epichlorohydrin to tetrahydrofuran, adding dropwise a tetrahydrofuran solution of methylmagnesium chloride, maintaining the temperature and mixing the reaction, after completion, adjusting the pH to 6.5-7.5 at room temperature, separating the liquids to obtain an organic phase, extracting the organic phase, drying, and distilling and collecting the fractions to obtain 3-chloro-2-butanol; Step 2: adding phosphorus oxychloride to pyridine, cooling in an ice bath to 0-5°C, adding 3-chloro-2-butanol obtained in step 1, reacting at room temperature, pouring the obtained reaction solution into a mixture of ice and water, adjusting the pH to 6.5-7.5, separating the liquids to obtain an organic phase, extracting the organic phase, drying, and distilling and collecting the fractions to obtain 1-chloro-2-butene; Step 3: Add 1-chloro-2-butene obtained in step 2 to the sodium hydroxide solution, heat to react at 120-140° C., cool the reaction solution, separate the liquid to obtain an organic phase, extract the organic phase, dry it, and collect the fractions by distillation to obtain crotyl alcohol.

2. The method for preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material according to claim 1, characterized in that: The total molar ratio of tetrahydrofuran to epichlorohydrin in step 1 is 4.8-5:

1.

3. 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 molar ratio of methylmagnesium chloride to epichlorohydrin is 1.2-1.3:

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 2, the molar ratio of pyridine to 3-chloro-2-butanol is 3.1-3.2:

1.

5. The method for preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material according to claim 1, characterized in that: In step 2, the molar ratio of phosphorus oxychloride to 3-chloro-2-butanol is 3.1-3.2:

1.

6. The method for preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material according to claim 1, characterized in that: The sodium hydroxide solution in step 3 is a sodium hydroxide solution with a mass fraction of 20% to 25%, wherein the molar ratio of sodium hydroxide to 1-chloro-2-butene in step 3 is 1.1 to 1.2:

1.

7. 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% to 15%, the extraction is performed using ether or dichloromethane, the organic phase is washed with a saturated NaHCO3 solution, and dried with MgSO4.

8. The method for preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material according to claim 1, characterized in that: The dropping speed of the tetrahydrofuran solution of methylmagnesium chloride added dropwise in step 1 is calculated according to the dropping amount of methylmagnesium chloride, and the dropping speed is 0.7g / min~1.0g / min.

9. The method for preparing crotyl alcohol in multiple steps using 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% to 25%, the extraction is performed using ether or dichloromethane, and the organic phase is dried using MgSO4.

10. The method for preparing crotyl alcohol in multiple steps using epichlorohydrin as a raw material according to claim 1, characterized in that: Step 3: Heat the reaction for 3-4 hours, extract with ether, and dry the organic phase with MgSO4.

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