Polyol full-allyl end capping method

Abstract

The invention discloses a polyhydric alcohol full-allyl end capping method, and belongs to the technical field of organic chemical industry. According to the method disclosed by the invention, the end-capping efficiency is innovatively improved by a method of multiple sodium modification-end-capping cycles, the problems that the traditional method is influenced by chemical equilibrium and the end-capping rate is not high or complete end-capping is difficult are avoided, and by adopting the method disclosed by the invention, a polyhydric alcohol all-allyl end-capped product with the purity of over 97 percent by weight can be obtained at the total yield of over 70 percent; and the product with higher purity can be obtained by further refining through a known technology in the field. The by-products generated in each step can be recycled and can be put into the process or prepared into useful products, so that the atom economy is good, and the three-waste pollution is less. The process design of each step is scientific, the operation is simple, special equipment and harsh process conditions are not needed, and industrialization is facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic chemical industry, in particular to a method for full allyl end-capping of polyols. BACKGROUND

[0002] The allyl ether of polyols has active groups such as ether groups and olefinic bonds, which endow it with isomerization, oxygen combination and polymerization properties, and is often used to prepare acrylic polymer thickening agents and is widely used as a crosslinking agent in the synthesis of unsaturated polyesters, polyurethane resins, epoxy resins, UV curing resins and other polymers. For example, the allyl ether of polyols can be oxidized into glycidyl compounds (CN102361861B, CN102666518B, CN109689634A) using hydrogen peroxide, which is widely used in the fields of coatings, composites, electronic and electrical packaging materials, adhesives and the like. Compared with the traditional epichlorohydrin method, the glycidyl compounds prepared by this method have very low halogen content, which can effectively avoid the disadvantage of low insulation properties when used in the field of electronics.

[0003] The mainstream method for preparing such allyl ethers at present is to prepare them by Williamson reaction using a compound containing alcohol hydroxyl groups, an alkali metalating agent and an allyl halide as the raw materials. The alkali metalating agent is sodium alcoholate, metallic sodium, sodium hydride, sodium hydroxide or potassium hydroxide, etc.

[0004] Patents CN112645804A, CN111848366A and literature (Journal of the American Chemical Society, 1953, Vol. 75, pp. 1248-1249) report a method for synthesizing the allyl ether of pentaerythritol, but they can only obtain mono-substituted, di-substituted and tri-substituted products, and cannot obtain fully allyl end-capped products. Patent CN104448284B discloses a method for synthesizing a double-allyl end-capped polyether under solvent-free conditions, which is only suitable for polyethers with a large molecular weight because the polyether chain is needed to dilute the reaction system, and is not suitable for the end-capping of small molecular polyols which generate a large amount of salt during the reaction process, causing the system to become dry. Patent CN101885839B discloses a method for preparing an end-capped allyl polyether, in which the synthesis of a double-allyl polyether is from a mono-allyl polyether as the starting material. This method can only end-cap one more allyl group in practice.

[0005] In summary, the traditional method of allyl end-capping is affected by chemical equilibrium, and there is a problem of low end-capping rate or difficulty in complete end-capping. SUMMARY

[0006] In order to solve the above problems, the application provides a method for full allyl end-capping of polyols to solve the problem that the prior art can only partially end-cap polyols.

[0007] The application is realized by the following technical scheme: The application provides a method for full allyl end-capping of polyols, comprising the following steps: S1. Mixing polyols and ether solvents, then adding sodium, stirring at a temperature above the melting point of sodium, and performing a sodiumization reaction; S2. After cooling, removing residual sodium floating on the surface of the reaction liquid to obtain a mixed solution containing sodium alcoholate; S3. Adding allyl bromide and stirring to perform an end-capping reaction to obtain a mixed solution containing sodium bromide; S4. After cooling, centrifugal separation is performed to remove sodium bromide in the mixed solution; S5. Reducing pressure to remove unreacted allyl bromide in the mixed solution to obtain a mixed solution containing a crude product and a partially end-capped product; S6. Returning the mixed solution containing the crude product and the partially end-capped product to step S1 to participate in the reaction; S7. When the molar percentage of the full end-capped product in the mixed solution obtained in step S5 exceeds 80% except for the solvent, performing reduced-pressure distillation to recover the ether solvent to obtain a full allyl end-capped product of polyols.

[0008] Preferably, the polyols in step S1 are alcohol compounds containing at least two hydroxyl groups and having a molecular weight of 90-200.

[0009] Preferably, the polyhydric alcohol compound includes, but is not limited to, one or more of 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 2,3-pentanediol, 2,4-pentanediol, neopentyl glycol, 3-methyl-1,3-butanediol, 1,2-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 1,2-heptanediol, 1,7-heptanediol, 2,5-dimethyl-2,5-hexanediol, 1,2-octanediol, 1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 1,2-nonanediol, 1,9-nonanediol, 1,2-decanediol, 1,10-decanediol, 1,11-undecanediol, 1,3-adamantanediol, 1,2-cyclopentanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,3-benzenedimethanol, 1,4-benzenedimethanol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, glycerol, 1,1,1-trishydroxymethylpropane, 1,2,3-butanetriol, 1,2,4-butanetriol, 1,3,5-pentanetriol, 1,2,6-hexanetriol, 1,2,7-heptanetriol, 1,2,9-nonanetriol, 1,2,10-decanetriol, 1,3,5-adamantanetriol, 2-methylbutane-1,2,4-triol, 3-methylpentane-1,3,5-triol, 1,2,3-cyclohexanetriol, 1,3,5-cyclohexanetriol, pentaerythritol.

[0010] Preferably, the ether solvent in step S1 is an ether compound with a boiling point higher than the melting point of sodium metal and a density greater than that of sodium metal, and includes, but is not limited to, one or more of 1,4-dioxane, anisole, p-methylanisole, and trioxane.

[0011] Preferably, the weight of the ether solvent added in step S1 is 0.5 to 20 times the weight of the polyhydric alcohol, the molar amount of sodium metal added is 0.1 to 0.5 times the molar amount of the polyhydric alcohol, the sodium reaction temperature is 100 to 130°C, and the reaction time is 2 to 6 hours.

[0012] Preferably, the floating sodium removed in step S2 is recovered and directly reused in step S1 without purification treatment.

[0013] Preferably, the molar amount of allyl bromide added in step S3 is 0.9 to 1.1 times the molar amount of sodium metal added in step S1, the end-capping reaction temperature in step S3 is 30 to 70°C, and the reaction time is 2 to 6 hours.

[0014] Preferably, the mixture in step S6 returns to step S1 without supplementing polyol and ether solvent, and sodium metal is added again.

[0015] Preferably, the unreacted allyl bromide removed in step S5 under reduced pressure is recovered by condensation trapping technology known in the art and then reused in step S3.

[0016] Preferably, the ether solvent recovered by distillation in step S7 is used in step S1 of the preparation of a new batch of product, and the residue obtained after distillation of the ether solvent and the polyol fully allyl-terminated product contains incompletely terminated intermediate products. The distillation residue of this step is used in step S1 of the preparation of a new batch of product instead of part of the polyol.

[0017] Preferably, the sodium bromide separated by centrifugation in step S4 is subjected to purification procedures known in the art such as recrystallization, washing, and drying to obtain a purified sodium bromide product.

[0018] Compared with the prior art, the present application has the following beneficial effects: (1) The present application innovatively improves the termination efficiency through multiple sodiumization-termination cycles, avoids the problem of low termination rate or difficulty in complete termination caused by the influence of chemical equilibrium in the traditional method, and can obtain a polyol fully allyl-terminated product with a purity of 97 wt.% or more at a total yield of 70% or more. The product can be further refined by techniques known in the art to obtain a product with higher purity.

[0019] (2) The by-products generated in each step of the present application can be recycled and reused in the process of the present application or made into useful products, have good atom economy, and cause less pollution of the three wastes.

[0020] (3) The process design of each step of the present application is scientific and simple to operate, does not require special equipment and harsh process conditions, and is easy to industrialize. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a process flow diagram of the present application; Figure 2 is a nuclear magnetic resonance spectrum of the terminated product obtained in Examples 1-3 of the present application; Figure 3 is a nuclear magnetic resonance spectrum of the terminated product obtained in Examples 4-6 of the present application; Figure 4 is a nuclear magnetic resonance spectrum of the terminated product obtained in Examples 7-9 of the present application. DETAILED DESCRIPTION

[0022] The present application will be further described below in conjunction with the drawings: A method for fully allyl-terminating a polyol, comprising the following steps: S1. Mix polyol and ether solvent, then add sodium metal, stir at a temperature above the melting point of sodium, and carry out sodium treatment; S2. After cooling, remove the residual sodium floating on the surface of the reaction solution to obtain a mixed solution containing sodium alcoholate; S3. Add allyl bromide and stir to carry out end-capping reaction to obtain a mixed solution containing sodium bromide; S4. After cooling, centrifugal separation is carried out to remove sodium bromide in the above mixed solution; S5. Remove unreacted allyl bromide in the above mixed solution under reduced pressure to obtain a mixed solution containing crude product and partially end-capped product; S6. Return the above mixed solution containing crude product and partially end-capped product to step S1 to participate in the reaction; S7. When the molar percentage of fully end-capped product in the mixed solution obtained in step S5, except for the solvent, is more than 80%, carry out reduced pressure distillation to recover the ether solvent to obtain polyol fully allyl end-capped product.

[0023] The process flow chart of the method of the present application is shown in the accompanying Figure 1 The flow chart of steps S1-S7 can be seen in the chart.

[0024] The reaction principle of the present application is shown in the following formula:

[0025] Since it is difficult to find a suitable general formula for polyol, the above formula is selected to represent the principle, and the purpose is to enable those skilled in the art to improve the understanding of the reaction.

[0026] The following examples more specifically describe the process of preparing polyol fully allyl end-capped product according to the method of the present application, and the examples are given in an illustrative manner, and the purpose is to enable those skilled in the art to understand the content of the present application and to implement it, but these examples in no way limit the scope of the present application.

[0027] The polyol, ether solvent, sodium metal, allyl bromide and other chemicals used in the comparative examples and examples of the present application are all general reagent grade or industrial grade products, which are purchased from commercial channels.

[0028] The content of each component in the end-capped product in the comparative examples and examples of the present application is determined by HPLC, and the test conditions are as follows: Instrument name: Lachrom HPLC (Merck Hitachi); Column: BP-C18 Plus (4.6´150mm, 5mm, Shanghai Pinning Analytical Technology Co., Ltd.); Detector: Alltech 500 evaporative light scattering detector (Alltech Associates, Inc.), operating at 91°C, with an atomizer gas flow of 2.34 L / min; Mobile phase: methanol, total flow rate 1 mL / min. The content of each component was determined using the peak area normalization method, which approximates the molar percentage or mass percentage.

[0029] The centrifuge used for centrifugal separation was Thermo Scientific SL1 Plus, at a speed of 5000 rpm for 10 min.

[0030] The removal of allyl bromide under reduced pressure and the recovery of ether solvents by reduced pressure distillation and the product were all routine laboratory operations, and the temperature and pressure were not recorded.

[0031] The instrument used for product nuclear magnetic resonance analysis was a Zhongke Oxford WNMR-I-400MHz nuclear magnetic resonance instrument, and the data processing software was SpinWorks 4.2.12.

[0032] Example 1: A method for fully allyl-terminated polyol, wherein the polyol is 1,4-cyclohexanedimethanol, comprising the following steps: (1) Dissolve 1,4-cyclohexanedimethanol (288.4 g, 2.0 mol) and solvent 1,4-dioxane (300 g), then add sodium metal (13.8 g, 0.6 mol), stir at 100°C, and carry out sodiumization reaction for 4 h; (2) Cool to room temperature, remove the remaining sodium floating on the surface of the reaction solution; (3) Add allyl bromide (72.6 g, 0.6 mol), stir at 50°C, and carry out termination reaction for 5 h; (4) Cool to room temperature, centrifugal separation, and remove sodium bromide in the above mixture; (5) Remove unreacted allyl bromide in the above mixture under reduced pressure; (6) Return the above mixture to step (1) to participate in the reaction, and the sodium metal added in each subsequent cycle is 13.8 g (0.6 mol) and the allyl bromide is 72.6 g (0.6 mol); (7) After sodiumization-termination for a total of 7 times (i.e. 6 times of return cycle), the content of fully terminated product in the mixture obtained in step (5) is about 83% measured by HPLC, then perform reduced pressure distillation, first recover the solvent, and then collect the first distilled fraction as the diallyl-terminated product of 1,4-cyclohexanedimethanol 336.5 g (yield 75.0%), with a purity of 97.5%.

[0033] The product structure is confirmed as 1,4-cyclohexanedimethanol bisallyl ether by nuclear magnetic resonance analysis, and the nuclear magnetic resonance spectrum is shown in Figure 1. Figure 2 The nuclear magnetic resonance data analysis is as follows: 1 H NMR (400 MHz, CDCl3, 25 °C): δ = 0.91~1.87 (m, 10H), 3.24 (d, J =6.4 Hz, 3.1H), 3.33 (d, J = 6.8 Hz, 0.9H), 3.95 (d, J = 4.4 Hz, 4H), 5.16 (d,J = 10.4 Hz, 2H), 5.27 (d, J = 17.2 Hz, 2H), 5.87~5.94 (m, 2H). It contains a pair of cis-trans isomers with a ratio of 3.1:0.9 according to the nuclear magnetic data.

[0034] Example 2: A method for fully allyl-terminated polyol, wherein the polyol is 1,4-cyclohexanedimethanol, comprising the following steps: (1) Dissolve 1,4-cyclohexanedimethanol (360.5 g, 2.5 mol) and solvent anisole (600 g) together, then add sodium metal (23.0 g, 1.0 mol), and stir at 110 °C for 5 h for sodiumization reaction; (2) Cool to room temperature, and remove the residual sodium floating on the surface of the reaction solution; (3) Add allyl bromide (133.1 g, 1.1 mol), and stir at 60 °C for 4 h for termination reaction; (4) Cool to room temperature, and centrifugally separate to remove sodium bromide in the above mixture; (5) Remove the unreacted allyl bromide in the above mixture under reduced pressure; (6) Return the above mixture to step (1) to participate in the reaction, and add 18.4 g (0.8 mol) of sodium metal and 96.8 g (0.8 mol) of allyl bromide in each subsequent cycle; (7) After sodiumization-termination for a total of 7 times, the content of the fully terminated product in the mixture obtained in step (5) is about 85% as measured by HPLC, then perform reduced pressure distillation to recover the solvent first, and then collect the first distilled fraction as 1,4-cyclohexanedimethanol bisallyl-terminated product 429.1 g (yield 76.5%), with a purity of 97.7%.

[0035] The product structure is confirmed as 1,4-cyclohexanedimethanol bisallyl ether by nuclear magnetic resonance analysis, and the nuclear magnetic resonance spectrum is shown in Figure 1. Figure 2 The product structure is confirmed as 1,4-cyclohexanedimethanol bisallyl ether by nuclear magnetic resonance analysis, and the nuclear magnetic resonance spectrum is shown in Figure 1.

[0036] Example 3: A method for full allyl-terminated polyol, wherein the polyol is 1,4- cyclohexanedimethanol, comprising the following steps: (1) Dissolve 1,4-cyclohexanedimethanol (288.4 g, 2.0 mol) and solvent 1,4- dioxane (400 g) and anisole (400 g), then add sodium metal (18.4 g, 0.8 mol), stir at 105 °C, and carry out sodium reaction for 6 h; (2) Cool to room temperature, and remove the residual sodium floating on the surface of the reaction solution; (3) Add allyl bromide (96.8 g, 0.8 mol), stir at 50 °C, and carry out termination reaction for 6 h; (4) Cool to room temperature, centrifugal separation, and remove sodium bromide in the above mixture; (5) Remove unreacted allyl bromide in the above mixture under reduced pressure; (6) Return the above mixture to step (1), and participate in the reaction by circulation. The sodium metal added in each subsequent cycle is 18.4 g (0.8 mol), and the allyl bromide is 90.7 g (0.75 mol); (7) After sodium-termination is carried out for a total of 6 times, the content of full termination product in the mixture obtained in step (5) is about 82% as measured by HPLC, then perform reduced pressure distillation, first recover the solvent, and then collect the first distilled fraction as 1,4-cyclohexanedimethanol bis-allyl-terminated product 328.4 g (yield 73.2%), and the purity is 97.6%.

[0037] The product structure is confirmed to be 1,4-cyclohexanedimethanol bis-allyl ether by nuclear magnetic resonance analysis, and the nuclear magnetic resonance spectrum is shown in FIG. 1. Figure 2

[0038] Example 4: A method for full allyl-terminated polyol, wherein the polyol is 1,1,1- trimethylolpropane, comprising the following steps: (1) Dissolve 1,1,1-trimethylolpropane (268.4 g, 2.0 mol) and solvent 1,4-dioxane (1000 g), then add sodium metal (23.0 g, 1.0 mol), stir at 100 °C, and carry out sodium reaction for 4 h; (2) Cool to room temperature, and remove the residual sodium floating on the surface of the reaction solution; (3) Add allyl bromide (114.9 g, 0.95 mol), stir at 55 °C, and carry out termination reaction for 5 h; (4) Cool to room temperature, centrifugal separation, and remove sodium bromide in the above mixture; (5) Remove unreacted allyl bromide in the above mixture under reduced pressure; ​(6) The above mixture is returned to step (1) and recycled for reaction, and the sodium added in each subsequent cycle is 20.7 g (0.9 mol) and the allyl bromide is 108.9 g (0.9 mol); (7) After the sodiumization-capping is performed for a total of 8 times, the content of the fully capped product in the mixture obtained in step (5) is about 85% as measured by HPLC, and then the mixture is subjected to vacuum distillation, and the first fraction collected is 1,1,1-trishydroxymethylpropane triallyl capping product 389.4 g (76.5% yield) with a purity of 97.5%.

[0039] The product structure is confirmed to be 1,1,1-trishydroxymethylpropane triallyl ether by nuclear magnetic resonance analysis, and the nuclear magnetic resonance spectrum is shown in FIG. 1. Figure 3 The nuclear magnetic resonance data analysis is as follows: 1 H NMR (400 MHz, CDCl3, 25 °C): δ = 0.84 (t, J = 7.6 Hz, 3H), 1.25 (q,J = 7.6 Hz, 2H), 3.75 (s, 6H), 3.95 (d, J = 4.4 Hz, 6H), 5.16 (d, J = 10.0Hz, 3H), 5.27 (d, J = 17.2 Hz, 3H), 5.86~5.94 (m, 3H).

[0040] Example 5: A method for fully allyl capping of a polyol, wherein the polyol is 1,1,1-trishydroxymethylpropane, comprising the following steps: (1) Dissolve 1,1,1-trishydroxymethylpropane (335.5 g, 2.5 mol) and solvent anisole (1500 g) to form a solution, and then add sodium (23.0 g, 1.0 mol) and stir at 120 °C for 3 h to perform sodiumization reaction; (2) Cool to room temperature, and remove the residual sodium floating on the surface of the reaction solution; (3) Add allyl bromide (121.0 g, 1.0 mol) and stir at 60 °C for 4 h to perform capping reaction; (4) Cool to room temperature, centrifugal separation, and remove sodium bromide in the above mixture; (5) Remove unreacted allyl bromide in the above mixture under reduced pressure; (6) The above mixture is returned to step (1) and recycled for reaction, and the sodium added in each subsequent cycle is 23.0 g (1.0 mol) and the allyl bromide is 121.0 g (1.0 mol); (7) After sodiumization-capping for 9 times in total, the content of the full-capped product in the mixed solution obtained in step (5) was about 84% as measured by HPLC, then vacuum distillation was performed, the solvent was recovered first, and then the first distilled fraction was collected as the triallyl-capped product of 1,1,1-trimethylolpropane 480.7 g (yield 75.6%) with a purity of 97.3%.

[0041] The product structure was confirmed as 1,1,1-trimethylolpropane triallyl ether by nuclear magnetic resonance analysis, and the nuclear magnetic resonance spectrum is shown in Figure 1. Figure 3

[0042] Example 6 A method for full allyl-capping of a polyol, wherein the polyol is 1,1,1-trimethylolpropane, comprising the following steps: (1) 1,1,1-trimethylolpropane (268.4 g, 2.0 mol) and solvent anisole (1000 g) and p-methyl anisole (1000 g) were mixed, then sodium metal (18.4 g, 0.8 mol) was added, and stirring was performed at 100°C for 4 h for sodiumization reaction; (2) cooling to room temperature, removing the remaining sodium floating on the surface of the reaction solution; (3) adding allyl bromide (102.8 g, 0.85 mol), and stirring at 45°C for 6 h for capping reaction; (4) cooling to room temperature, centrifugal separation, and removing sodium bromide in the above mixed solution; (5) removing unreacted allyl bromide in the above mixed solution under reduced pressure; (6) returning the above mixed solution to step (1) for recycling and participating in the reaction, and the sodium metal added in each subsequent cycle was 20.7 g (0.9 mol), and the allyl bromide added in each subsequent cycle was 108.9 g (0.9 mol); (7) After sodiumization-capping for 7 times in total, the content of the full-capped product in the mixed solution obtained in step (5) was about 82% as measured by HPLC, then vacuum distillation was performed, the solvent was recovered first, and then the first distilled fraction was collected as the triallyl-capped product of 1,1,1-trimethylolpropane 370.6 g (yield 72.8%) with a purity of 97.6%.

[0043] The product structure was confirmed as 1,1,1-trimethylolpropane triallyl ether by nuclear magnetic resonance analysis, and the nuclear magnetic resonance spectrum is shown in Figure 1. Figure 3

[0044] Example 7: A method for full allyl-capping of a polyol, wherein the polyol is pentaerythritol, comprising the following steps: ​​(1) Dissolve pentaerythritol (272.3 g, 2.0 mol) in solvent 1,4-dioxane (3000 g), then add sodium metal (23.0 g, 1.0 mol), and stir at 100 °C for 5 h to perform sodium reaction; (2) Cool to room temperature, and remove the residual sodium floating on the surface of the reaction solution; (3) Add allyl bromide (127.0 g, 1.05 mol), and stir at 60 °C for 4 h to perform capping reaction; (4) Cool to room temperature, and centrifugally separate to remove sodium bromide in the above mixture; (5) Remove unreacted allyl bromide in the above mixture under reduced pressure; (6) Return the above mixture to step (1) to participate in the reaction, and add 23.0 g (1.0 mol) of sodium metal and 121.0 g (1.0 mol) of allyl bromide in each subsequent cycle; (7) After sodium reaction-capping is performed for 9 times in total, the content of fully-capped product in the mixture obtained in step (5) is about 83% as measured by HPLC, then solvent is recovered by distillation under reduced pressure, and the first fraction distilled is pentaerythritol tetraallyl ether (442.8 g, yield 74.7%) with a purity of 97.3%.

[0045] The product structure is confirmed as pentaerythritol tetraallyl ether by nuclear magnetic resonance analysis, and the nuclear magnetic resonance spectrum is shown in FIG. 1, and the nuclear magnetic resonance data analysis is as follows: Figure 4 1 H NMR (400 MHz, CDCl3, 25 °C): δ = 3.24 (s, 8H), 3.95 (d, J = 4.4 Hz,8H), 5.16 (d, J = 10.0 Hz, 4H), 5.27 (d, J = 17.6 Hz, 4H), 5.87~5.94 (m, 4H).

[0046] Example 8: A method for fully capping a polyol, wherein the polyol is pentaerythritol, comprising the following steps: (1) Dissolve pentaerythritol (299.5 g, 2.2 mol) in solvent 1,4-dioxane (3000 g) and p-methyl anisole (1000 g), then add sodium metal (18.4 g, 0.8 mol), and stir at 105 °C for 5 h to perform sodium reaction; (2) Cool to room temperature, and remove the residual sodium floating on the surface of the reaction solution; (3) Add allyl bromide (102.8 g, 0.85 mol), and stir at 65 °C for 4 h to perform capping reaction;​ (4) Cool to room temperature, centrifuge to remove sodium bromide from the above mixture; (5) Remove unreacted allyl bromide from the above mixture under reduced pressure; (6) Return the above mixture to step (1) and participate in the reaction in a cycle. In each subsequent cycle, the amount of sodium metal added is 20.7 g (0.9 mol) and the amount of allyl bromide added is 114.9 g (0.95 mol). (7) After a total of 10 sodium-capping processes, the content of fully capped product in the mixture obtained in step (5) was determined by HPLC to be approximately 82%. Then, vacuum distillation was performed to recover the solvent first, and then the first distillate was collected as 481.8 g of tetraallyl-capped pentaerythritol (yield 73.9%) with a purity of 97.4%.

[0047] Nuclear magnetic resonance (NMR) analysis confirmed the product structure to be pentaerythritol tetraallyl ether; the NMR spectrum is attached. Figure 4 As shown.

[0048] Example 9: A method for allally capping a polyol, wherein the polyol is pentaerythritol, comprising the following steps: (1) Mix pentaerythritol (340.4 g, 2.5 mol) with solvents anisole (3000 g) and p-methyl anisole (2000 g), then add metallic sodium (23.0 g, 1.0 mol), stir at 120 °C, and carry out sodiumization reaction for 6 h; (2) Cool to room temperature and remove the remaining sodium floating on the surface of the reaction solution; (3) Add allyl bromide (127.0 g, 1.05 mol), stir at 60 °C, and carry out the end-capping reaction for 6 h; (4) Cool to room temperature, centrifuge to remove sodium bromide from the above mixture; (5) Remove unreacted allyl bromide from the above mixture under reduced pressure; (6) Return the above mixture to step (1) and participate in the reaction in a cycle. In each subsequent cycle, the amount of sodium metal added is 23.0 g (1.0 mol) and the amount of allyl bromide added is 121.0 g (1.0 mol). (7) After a total of 11 sodium-capping processes, the content of fully capped product in the mixture obtained in step (5) was determined by HPLC to be approximately 83%. Then, vacuum distillation was performed to recover the solvent first, and then the first distillate was collected as 552.3g of tetraallyl-capped pentaerythritol (yield 74.5%) with a purity of 97.2%.

[0049] Nuclear magnetic resonance (NMR) analysis confirmed the product structure to be pentaerythritol tetraallyl ether; the NMR spectrum is attached. Figure 4 As shown.

[0050] Comparative Example 1: 1,4-Cyclohexanedimethanol diallyl ether was prepared according to Example 1 of patent CN101885839B: A reaction kettle equipped with a reflux condenser (with a water separator), a stirrer, and a thermometer was charged with 1,4-cyclohexanedimethanol (144.2 g, 1.0 mol), solid KOH (112.2 g, 2.0 mol), and toluene (500 mL). The system was purged with nitrogen three times under stirring, heated to 110-115 °C to make the system reflux, and the water generated in the reaction was separated through the condenser and water separator. When the amount of water separated no longer increased, the reaction temperature was reduced to 60 °C, and allyl chloride (199.0 g, 2.6 mol) was slowly added through a dropping funnel. After the addition was completed, the temperature was increased to 120 °C, and the reaction was stirred for 4 h. After cooling, the solid was filtered off, and toluene was recovered by distillation under reduced pressure, and low-boiling substances were removed. A crude mixture was obtained, and the content of 1,4-cyclohexanedimethanol diallyl ether in the crude mixture was about 24%. The crude mixture was subjected to distillation under reduced pressure, and the first fraction collected was 1,4-cyclohexanedimethanol diallyl ether (34.1 g, yield 15.2%), with a purity of 96.9%.

[0051] Comparative Example 2: 1,1,1-Trimethylolpropane triallyl ether was prepared according to Example 1 of patent CN112645804A: A reaction kettle equipped with a reflux condenser (with a water separator), a dropping funnel, a stirrer, and a thermometer was charged with 1,1,1-trimethylolpropane (268.4 g, 2.0 mol), NaOH solution (48 wt.%, 333.3 g, NaOH 4.0 mol), and allyl alcohol (20 g). The system was heated to 100 °C under stirring, and allyl chloride (290.8 g, 3.8 mol) was added through the dropping funnel. The reaction temperature was maintained at 80-100 °C by controlling the addition rate, and the total addition time was about 4 h. After the addition was completed, the system was refluxed for 0.5 h, and then cooled to 40 °C. A second batch of NaOH solution (48 wt.%, 208.3 g, NaOH 2.5 mol) was added to the reaction system, and the system was heated to 100 °C under stirring. A second batch of allyl chloride (206.6 g, 2.7 mol) was added through the dropping funnel. The reaction temperature was maintained at 90-100 °C by controlling the addition rate, and the total addition time was about 3 h. After the addition was completed, the system was refluxed for 0.5 h, and then cooled. During the entire synthesis process, only the refluxed organic phase was returned to the reaction system through the water separator, and the separated water was gradually removed.

[0052] To the above reaction solution, 1200 mL of water was added to separate the oil phase from the water phase. The oil phase was removed under reduced pressure at 100°C to obtain a crude mixture. The content of 1,1,1-trishydroxymethylpropane triallyl ether in the crude mixture was about 37% as measured by HPLC. The crude mixture was subjected to reduced pressure distillation. The first fraction distilled out was 1,1,1-trishydroxymethylpropane triallyl end-capped product 146.5 g (yield 28.8%) with a purity of 97.0%.

[0053] Comparative Example 3 Pentaerythritol tetraallyl ether was prepared according to Example 1 of patent CN111848366A: a reaction kettle was charged with pentaerythritol (272.3 g, 2.0 mol), NaOH solution (30 wt.%, 1333.3 g, NaOH 10.0 mol) and TBAB / Al2O3 catalyst (40 g), and the temperature of the reaction system was raised to 70-80°C. Allyl chloride (765.3 g, 10.0 mol) was added dropwise from a tank, and the reaction temperature was maintained at 75-80°C by controlling the dropwise addition rate. The reaction was kept for 4 hours, and then the system was cooled. The catalyst was filtered off, and the low-boiling impurities in the product were removed by atmospheric distillation to obtain a crude mixture. The content of pentaerythritol tetraallyl ether in the crude mixture was about 19% as measured by HPLC. The crude mixture was subjected to reduced pressure distillation. The first fraction distilled out was pentaerythritol tetraallyl end-capped product 67.6 g (yield 11.4%) with a purity of 96.8%.

[0054] Table 1: Comparison of product purity of Examples 1-9 and Comparative Examples 1-3.

[0055] Number Polyol Content of fully capped product in crude product / % Purity of fully capped product after purification / % Yield of fully capped product after purification / % Comparative Example 1 1,4-cyclohexanedimethanol 24 96.9 15.2 Example 1 1,4-cyclohexanedimethanol 83 97.5 75.0 Example 2 1,4-cyclohexanedimethanol 85 97.7 76.5 Example 3 1,4-cyclohexanedimethanol 82 97.6 73.2 Comparative Example 2 1,1,1-trimethylolpropane 37 97.0 28.8 Example 4 1,1,1-trimethylolpropane 85 97.5 76.5 Example 5 1,1,1-trimethylolpropane 84 97.3 75.6 Example 6 1,1,1-trimethylolpropane 82 97.6 72.8 Comparative Example 3 pentaerythritol 19 96.8 11.4 Example 7 pentaerythritol 83 97.3 74.7 Example 8 pentaerythritol 82 97.4 73.9 Example 9 pentaerythritol 83 97.2 74.5 From the table data, the following conclusions can be drawn: using the method of the embodiments of the present application, a crude product with a high total end-capping rate can be obtained, and the polyol fully allyl end-capped product with a purity of more than 97 wt.% can be purified at a total yield of more than 70%, while the comparative examples can only obtain the final product at a low yield which is not practical.

[0056] In conclusion, the above is only a preferred embodiment of the present application, and is not intended to limit the scope of the present application. Any equivalent changes and modifications made in shape, structure, features and spirit described in the claims of the present application should be included in the scope of the claims of the present application.

Claims

1. A method for end-capping polyols with all-allyl groups, characterized in that: Includes the following steps: S1. Mix the polyol and ether solvent, then add metallic sodium, and stir at a temperature above the melting point of sodium to carry out the sodiumization reaction; S2. After cooling, remove the remaining sodium floating on the surface of the reaction solution to obtain a mixture containing sodium alkoxide; S3. Add allyl bromide and stir to carry out the end-capping reaction, and obtain a mixture containing sodium bromide; S4. After cooling, centrifuge to remove sodium bromide from the above mixture; S5. Remove unreacted allyl bromide from the above mixture under reduced pressure to obtain a mixture containing crude product and part of end-capped product; S6. Return the above mixture containing crude product and part of the end-capped product to step S1 for recycling in the reaction; S7. When the molar percentage of fully capped product (excluding solvent) in the mixture obtained in step S5 exceeds 80%, perform vacuum distillation to recover the ether solvent and obtain the polyol allally capped product.

2. The method for end-capping a polyol with allyl groups according to claim 1, characterized in that: In step S1, the polyol is an alcohol compound containing at least two hydroxyl groups and having a molecular weight of 90-200.

3. The method for end-capping a polyol with allyl groups according to claim 2, characterized in that: The polyol compounds include, but are not limited to, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 2,3-pentanediol, 2,4-pentanediol, neopentanediol, 3-methyl-1,3-butanediol, 1,2-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, etc. - Hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 1,2-heptanediol, 1,7-heptanediol, 2,5-dimethyl-2,5-hexanediol, 1,2-octanediol, 1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 1,2-nonanediol, 1,9-nonanediol, 1,2-decanediol, 1,10-decanediol Diols, 1,11-undecanediol, 1,3-adamantanediol, 1,2-cyclopentanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,3-benzenedimethanol, 1,4-benzenedimethanol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, glycerol, 1,1,1-trimethylolpropane, 1,2,3-butanetriol One or more of the following: 1,2,4-butanetriol, 1,3,5-pentanetriol, 1,2,6-hexanetriol, 1,2,7-heptanetriol, 1,2,9-nonanetriol, 1,2,10-decanetriol, 1,3,5-adamantanetriol, 2-methylbutane-1,2,4-triol, 3-methylpentane-1,3,5-triol, 1,2,3-cyclohexanetriol, 1,3,5-cyclohexanetriol, and pentaerythritol.

4. The method for end-capping a polyol with allyl groups according to claim 1, characterized in that: In step S1, the ether solvent is an ether compound with a boiling point higher than the melting point of metallic sodium and a density greater than that of metallic sodium. The ether solvent includes, but is not limited to, one or more of 1,4-dioxane, anisole, p-methyl anisole, and trioxymethylene.

5. The method for end-capping a polyol with allyl groups according to claim 1, characterized in that: In step S1, the weight of the ether solvent added is 0.5 to 20 times the weight of the polyol, the molar amount of added metallic sodium is 0.1 to 0.5 times the molar amount of the polyol, the sodiumization reaction temperature is 100 to 130°C, and the reaction time is 2 to 6 hours.

6. The method for end-capping a polyol with allyl groups according to claim 1, characterized in that: The sodium removed in step S2 can be directly reused in step S1 without further purification.

7. The method for end-capping a polyol with allyl groups according to claim 1, characterized in that: The molar amount of allyl bromide added in step S3 is 0.9 to 1.1 times the molar amount of metallic sodium added in step S1. The end-capping reaction temperature in step S3 is 30 to 70°C, and the reaction time is 2 to 6 hours.

8. The method for end-capping a polyol with allyl groups according to claim 1, characterized in that: When the mixture is returned to step S1 in step S6, there is no need to add polyols and ether solvents, but sodium metal needs to be added again.

9. The method for end-capping a polyol with allyl groups according to claim 1, characterized in that: The unreacted allyl bromide removed by vacuum in step S5 is recovered and reused in step S3.

10. The method for end-capping a polyol with allyl groups according to claim 1, characterized in that: In step S7, the ether solvent recovered by distillation is used in step S1 for the preparation of a new batch of products. The residue obtained after distilling off the ether solvent and the polyol allyl-terminated product contains incompletely terminated intermediate products. The distillation residue of this step is used in step S1 for the preparation of a new batch of products to replace part of the polyol.

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