A method for preparing ethyl bicyclic phosphite

Abstract

This invention discloses a method for preparing ethyl bicyclic phosphite. The method provided by this invention, through raw material system reconstruction and reaction pathway optimization, achieves closed-loop production while completely avoiding the use of phosphorus trichloride, thus reducing raw material costs and eliminating corrosive byproducts. This provides a new solution to resolving the contradictions between economic efficiency, safety, and environmental compatibility in existing technologies.

Description

Technical Field

[0001] This invention belongs to the field of organic chemical synthesis technology, and specifically relates to a method for preparing ethyl bicyclic phosphite. Background Technology

[0002] Ethyl bicyclic phosphite (PBTO), as an important organic intermediate, has wide applications in plastic stabilizers, pesticides, and flame retardants. Currently, industrial production mainly relies on two traditional processes, both of which have significant technical drawbacks.

[0003] The direct synthesis method uses phosphorus trichloride and trimethylolpropane as raw materials. Although the route is direct, it faces two constraints in practical applications: on the one hand, the high reactivity of phosphorus trichloride requires the equipment to have strict corrosion resistance, which greatly increases the equipment investment cost; on the other hand, for every 1 mol of product generated in the reaction process, 3 mol of hydrogen chloride gas is released, which leads to increased equipment corrosion and creates pressure for acidic waste gas treatment.

[0004] The transesterification method uses trimethyl phosphite and trimethylolpropane to react under the catalysis of an organic base. Although this avoids the generation of hydrogen chloride, its raw material system has obvious economic defects - the market price of trimethyl phosphite remains high, and its upstream synthesis still depends on phosphorus trichloride as a raw material. In essence, it fails to solve the safety hazards and environmental risks brought about by the core raw materials.

[0005] It is worth noting that both processes struggle to balance production costs, equipment wear and tear, and environmental protection, creating technological bottlenecks that hinder industrial upgrading. Therefore, this study innovatively develops a novel synthesis process that, through raw material system reconstruction and reaction pathway optimization, achieves closed-loop production while completely avoiding the use of phosphorus trichloride. This reduces raw material costs and eliminates corrosive byproducts, providing a new solution to resolving the contradictions between the economy, safety, and environmental compatibility of existing technologies. Summary of the Invention

[0006] The technical problem this invention aims to solve is that existing methods for preparing ethyl bicyclic phosphite struggle to balance production costs, equipment wear and tear, and environmental protection. Therefore, this invention provides a novel method for preparing ethyl bicyclic phosphite. This method, through raw material system reconstruction and reaction pathway optimization, achieves closed-loop production while completely avoiding the use of phosphorus trichloride. This reduces raw material costs and eliminates corrosive byproducts, providing a new solution to the contradictions between economic efficiency, safety, and environmental compatibility in existing technologies.

[0007] The present invention solves the above-mentioned technical problems through the following technical solutions.

[0008] This invention provides a method for preparing ethyl bicyclic phosphite, comprising the following steps: reacting a compound of formula I, 1,1,1-trimethylolpropane, and a base in an organic solvent to obtain the ethyl bicyclic phosphite. .

[0009] Wherein, the R 1 To be optionally used by one or more R 1-1 Replace C 6-10 aryl; R 1-1 C 1-6 alkyl or C 1-6 alkoxy groups.

[0010] In this invention, R 1 In the context, C 6-10 The aryl group is either phenyl or naphthyl.

[0011] In this invention, R 1-1 In the context, C 1-6 The alkyl group is methyl, ethyl, propyl, or isopropyl or tert-butyl; preferably tert-butyl.

[0012] In this invention, R 1-1 In the context, C 1-6 The alkoxy group is methoxy, ethoxy, isopropoxy, or tert-butoxy; preferably methoxy.

[0013] In this invention, the compound represented by Formula I is , or .

[0014] In this invention, the alkali is one or more of sodium alkoxide, potassium alkoxide, and organic amine.

[0015] In this invention, the alkali is sodium methoxide.

[0016] In this invention, the organic solvent is an ether solvent, preferably tetrahydrofuran.

[0017] In this invention, the compound represented by Formula I is prepared by the following method: The compound represented by Formula II is reacted with tris(dimethylamino)phosphine in a solvent to obtain the compound represented by Formula I. .

[0018] Wherein, the R 1 As defined above.

[0019] In this invention, the solvent is an ether solvent, preferably tetrahydrofuran.

[0020] In this invention, the compound represented by Formula I is phenol, p-tert-butylphenol, or p-methoxyphenol.

[0021] In this invention, the compound represented by Formula I is phenol.

[0022] In this invention, the molar ratio of the tris(dimethylamino)phosphine to the compound of formula II is 1:(1-1.1).

[0023] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0024] The reagents and raw materials used in this invention are all commercially available.

[0025] The positive and progressive effects of this invention are as follows: 1. The method for preparing ethyl bicyclic phosphite provided by this invention avoids... The use of this method avoids the need for HCl treatment, thereby reducing the requirements for process equipment hardware and improving the safety of the process.

[0026] 2. The method for preparing ethyl bicyclic phosphite provided by this invention has a simple separation and purification process, and can prepare a product with a purity of 99.9% without distillation; moreover, the yield of this process is over 90%.

[0027] In summary, the preparation method provided by this invention has advantages in terms of high yield, high purity, safety, environmental friendliness, high efficiency, and cost, providing a new solution for the industrial production of ethyl dicyclophosphite. Attached Figure Description

[0028] Figure 1 This is a gas chromatogram of compound 1 from Example 1.

[0029] Figure 2 The NMR phosphorus spectrum of compound 1 in Comparative Example 1 is shown.

[0030] Figure 3 The gas chromatogram of compound 1 in Application Example 1 is shown.

[0031] Figure 4 The NMR phosphorus spectrum of compound 1 in Application Example 1 is shown. Detailed Implementation

[0032] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0033] Example 1: Preparation of Intermediate 1: .

[0034] Phenol (100.0 g, 1.06 mol) and tris(dimethylamino)phosphine (56.9 g, 0.35 mol) were dissolved in 1 L of tetrahydrofuran and the mixture was heated under reflux for 4–8 hours. The tetrahydrofuran was recovered under reduced pressure (the recovered tetrahydrofuran can be reused in the next reaction) to obtain the crude product. The crude product was dissolved in ethyl acetate to obtain the organic phase. The organic phase was washed with saturated brine, dried with anhydrous magnesium sulfate, and the solvent was removed under reduced pressure to obtain a colorless oily intermediate 1 (105.80 g, 97.9%).

[0035] 1 H NMR (400 MHz, CDCl3): δ 7.45 – 7.31 (m, 6H), 7.25 – 7.20 (m, 3H), 7.21 – 7.13 (m, 6H). 31 P NMR (162 MHz, CDCl3): δ 127.86. MS (ESI) m / z: [M + H] + : 311.1.

[0036] Preparation of compound 1:

[0037] Intermediate 1 (105.8 g, 0.34 mol), 1,1,1-trimethylolpropane (43.6 g, 0.32 mol), and sodium methoxide (19.3 g, 0.36 mol) were added to a reaction flask, followed by the addition of 1 L of tetrahydrofuran. The mixture was heated under reflux for 4–8 hours. The tetrahydrofuran was recovered under reduced pressure (the recovered tetrahydrofuran can be reused in the next reaction) to obtain the crude product. The crude product was dissolved in ethyl acetate to obtain the organic phase. The organic phase was washed with water in a saturated sodium carbonate solution, dried over anhydrous magnesium sulfate, and the solvent was removed under reduced pressure to obtain compound 1 (50.3 g, 95.5%).

[0038] MS (ESI) m / z: [M + H] + : 163.1.

[0039] The purity of the gas chromatography (GC) sample was 99.9%, and the experimental results are shown in Table 1 and... Figure 1 As shown.

[0040] Table 1:

[0041]

[0042] Example 2: Preparation of intermediate 2:

[0043] p-tert-butylphenol (100.0 g, 0.67 mol) and tris(dimethylamino)phosphine (35.6 g, 0.22 mol) were dissolved in 1 L of tetrahydrofuran and the mixture was heated under reflux for 4–8 hours. The tetrahydrofuran was recovered under reduced pressure (the recovered tetrahydrofuran can be reused in the next reaction) to obtain a crude product. The crude product was dissolved in ethyl acetate to obtain an organic phase. The organic phase was washed with saturated brine, dried with anhydrous magnesium sulfate, and finally the solvent was removed under reduced pressure to obtain a colorless oily intermediate 2 (97.5 g, 93.3%).

[0044] 1 H NMR (400 MHz, CDCl3): δ 7.40 (d, J = 8.5 Hz, 6H), 7.17 (d, J = 8.3Hz, 6H), 1.38 (s, 27H). 31 P NMR (162 MHz, CDCl3): δ 128.57. MS (ESI) m / z: [M +H] + : 479.2.

[0045] Preparation of compound 1:

[0046] Intermediate 2 (97.5 g, 0.20 mol), 1,1,1-trimethylolpropane (26.1 g, 0.19 mol), and sodium methoxide (11.53 g, 0.21 mol) were added to a reaction flask, followed by the addition of 1 L of tetrahydrofuran. The mixture was heated under reflux for 4–8 hours. The tetrahydrofuran was recovered under reduced pressure (the recovered tetrahydrofuran can be reused in the next reaction) to obtain a crude product. The crude product was dissolved in ethyl acetate to obtain an organic phase. The organic phase was washed with water using a saturated sodium carbonate solution, dried over anhydrous magnesium sulfate, and finally the solvent was removed under reduced pressure to obtain compound 1 (28.6 g, 90.93%). MS (ESI) m / z: [M + H] + : 163.1.

[0047] Example 3: Preparation of intermediate 3:

[0048] p-Methoxyphenol (100.0 g, 0.81 mol) and tris(dimethylamino)phosphine (43.1 g, 0.26 mol) were dissolved in 1 L of tetrahydrofuran and the mixture was heated under reflux for 4–8 hours. The tetrahydrofuran was recovered under reduced pressure (the recovered tetrahydrofuran can be reused in the next reaction) to obtain a crude product. The crude product was dissolved in ethyl acetate to obtain an organic phase. The organic phase was washed with saturated brine, dried with anhydrous magnesium sulfate, and finally the solvent was removed under reduced pressure to obtain a colorless oily intermediate 3 (92.4 g, 87.4%).

[0049] 1 H NMR (400 MHz, CDCl3): δ 7.09 (d, J = 7.4 Hz, 6H), 6.88 (d, J = 7.5Hz, 6H), 3.83 (s, 9H). 31 P NMR (162 MHz, CDCl3): δ 123.88. MS (ESI) m / z: [M + H] + : 401.1.

[0050] Preparation of compound 1:

[0051] Intermediate 3 (92.4 g, 0.23 mol), 1,1,1-trimethylolpropane (29.5 g, 0.22 mol), and sodium methoxide (13.6 g, 0.24 mol) were added to a reaction flask, followed by the addition of 1 L of tetrahydrofuran. The mixture was heated under reflux for 4–8 hours. The tetrahydrofuran was recovered under reduced pressure (the recovered tetrahydrofuran can be reused in the next reaction) to obtain a crude product. The crude product was dissolved in ethyl acetate to obtain an organic phase. The organic phase was washed with water using a saturated sodium carbonate solution, dried with anhydrous magnesium sulfate, and the solvent was removed under reduced pressure to obtain a crude product. The crude product was then purified by vacuum distillation to obtain compound 1 (26.3 g, 73.8%).

[0052] MS (ESI) m / z: [M + H] + : 163.1.

[0053] Comparative Example 1:

[0054] Trimethyl phosphite (100 g, 0.80 mol), 1,1,1-trimethylolpropane (102.99 g, 0.77 mol), and sodium methoxide (45.61 g, 0.84 mol) were added to a reaction flask, followed by the addition of 1 L of tetrahydrofuran. The mixture was heated under reflux for 4–8 hours. The tetrahydrofuran was recovered under reduced pressure (the recovered tetrahydrofuran can be reused in the next reaction) to obtain a crude product. The crude product was dissolved in ethyl acetate to obtain an organic phase. The organic phase was washed with saturated sodium carbonate solution, dried with anhydrous magnesium sulfate, and finally the solvent was removed under reduced pressure to obtain compound 1 (80.6 g, 64.77%).

[0055] MS (ESI) m / z: [M + H] + : 163.1.

[0056] Its NMR phosphorus spectrum purity is 83%, and its experimental results are as follows: Figure 2 As shown, the purity of compound 1 prepared by this method is not high, and further purification by distillation is required.

[0057] Application Example 1: Kilogram-scale pilot test:

[0058] Phenol (3.0 kg, 31.88 mol) and tris(dimethylamino)phosphine (1.71 kg, 10.45 mol) were dissolved in 20 L of tetrahydrofuran and the mixture was heated under reflux for 4–8 hours. Then, 1,1,1-trimethylolpropane (1.33 kg, 9.94 mol) and sodium methoxide (590.9 g, 10.94 mol) were added to the reaction flask, and the mixture was heated under reflux for another 4–8 hours. The reaction progress was monitored by GC-MS until the reaction was complete. The tetrahydrofuran was then recovered under reduced pressure (the recovered tetrahydrofuran can be reused in the next reaction) to obtain a crude product. The crude product was dissolved in ethyl acetate to obtain an organic phase. The organic phase was washed with saturated sodium carbonate aqueous solution, dried with anhydrous magnesium sulfate, and finally the solvent was removed under reduced pressure to obtain a colorless oily compound 1 (1.56 kg, 96.7%).

[0059] MS (ESI) m / z: [M + H] + : 163.1.

[0060] Its gas chromatographic (GC) purity is 99.1%, as shown in Table 2 and... Figure 3 As shown; its NMR phosphorus spectrum purity is 97%, and it is as follows Figure 4 As shown.

[0061] Table 2:

[0062]

[0063] Surprisingly, compared to the small-scale (hundred-gram level), the yield of compound 1 prepared by the "one-pot method" was improved in the pilot-scale (kilogram level) test, although the gas chromatographic purity of the final product decreased slightly.

Claims

1. A process for the preparation of ethyl bicyclic phosphite, characterized in that, It includes the following steps: reacting the compound of Formula I, 1,1,1-trimethylolpropane and a base in an organic solvent to obtain ethyl bicyclic phosphite, wherein the organic solvent is tetrahydrofuran; Among them, R 1 To be optionally used by one or more R 1-1 Replace C 6-10 aryl; R 1-1 is C 1-6 alkyl or C 1-6 alkoxy; The compound of formula I is prepared by the following method: reacting a compound of formula II with tris(dimethylamino)phosphine in a solvent to obtain a compound of formula I; the solvent is tetrahydrofuran. .

2. The method of preparing ethyl bicyclic phosphite according to claim 1, wherein, which satisfies one or more of the following conditions: (1) R 1 In particular, the C 6-10 The aryl group is a phenyl or naphthyl group. (2) R 1-1 In the formula, the C 1-6 The alkyl is methyl, ethyl, propyl, isopropyl or tert-butyl. (3) R 1-1 In the formula, the C 1-6 The alkoxy group is methoxy, ethoxy, isopropoxy or tert-butoxy.

3. The method of making ethyl bicyclophosphite according to claim 1, wherein, which satisfies one or more of the following conditions: (1) the compound of formula I is , or ; (2) the base is sodium methoxide.

4. The method of making ethyl bicyclophosphite of claim 1, wherein, The compound of formula I is phenol, p-tert-butylphenol or p-methoxyphenol.

5. The method of making ethyl bicyclophosphite of claim 1, wherein, The compound of formula I is phenol.

6. The method of making ethyl dicyclophosphite according to claim 1, wherein, The molar ratio of the tris(dimethylamino)phosphine to the compound of formula II is 1: (1-1.1).

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