A method for synthesizing trimethylolpropane triallyl ether

Abstract

The present invention provides a method for synthesizing pentaerythritol triallyl ether. This method uses pentaerythritol and allyl chloride as starting materials, water as the reaction solvent, and reacts in two stages under strong alkaline conditions. Two kinds of phase transfer catalysts with hydrophilicity and lipophilicity are respectively used in the two-stage reaction. That is, a hydrophilic phase transfer catalyst is used in the initial stage of the reaction to ensure the catalytic efficiency and reaction efficiency, and an organic layer mainly composed of pentaerythritol monoallyl ether and pentaerythritol diallyl ether is obtained. Since the lipophilicity in the organic layer is enhanced, at this time, a lipophilic phase transfer catalyst is added, and then allyl chloride is continuously added for reaction, so as to obtain a crude product mainly composed of pentaerythritol monoallyl ether. The synthesis method of the present invention is simple in operation, uses water as the solvent, and the yield and selectivity of the obtained pentaerythritol triallyl ether product are relatively high. Moreover, the contents of other monoethers, diethers, and tetraethers can be respectively controlled below 0.05%, below 5%, and below 10%. At present, pilot-scale production has been carried out.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical intermediate synthesis, and particularly relates to a method for synthesizing pentaerythritol triallyl ether. Background Art

[0002] Pentaerythritol triallyl ether has 4 functional groups, three allyl groups and one alcohol hydroxyl group. The alcohol hydroxyl group is relatively active and is easily oxidized. The double bond in the allyl group can attach other functional molecular chain segments or groups to the molecule to be modified. It is a very important chemical intermediate and is often used as a chain extender, widely used in the synthesis of polymers such as superabsorbent resins, epoxy resins, unsaturated polyesters, and polyurethane resins.

[0003] A typical method for preparing pentaerythritol triallyl ether is the Williamson synthesis method.

[0004] For example, US Patent US3428693 discloses a method for preparing pentaerythritol allyl ether, which uses the solvent dimethyl sulfoxide, making the post-treatment relatively complex. Chinese Patent CN101200413B discloses a method for preparing pentaerythritol allyl ether. Pentaerythritol, alkali metal hydroxide, water and an inert organic solvent are mixed, and under heating and stirring, a certain amount of phase transfer catalyst is added, and allyl halide is slowly added dropwise. The ratio of pentaerythritol to alkali metal hydroxide in this reaction is 1:3.8 - 4.2, and the alkali metal is in a large excess, and there are more by-products. Chinese Patent CN1052970C uses pentaerythritol, allyl chloride and alkali metal hydroxide as raw materials, and introduces the organic solvent toluene as a water-carrying agent. The boiling point of toluene is not much different from that of the product, and it is not easy to be completely removed during vacuum distillation. Chinese Patent CN101712597A involves three steps of salt washing, alkali washing and water washing respectively after the etherification reaction. The post-treatment process is complex, and the inhibitor p-methoxyphenol is required. Chinese Patent CN100410304C discloses a method for synthesizing pentaerythritol allyl ether, in which the content of pentaerythritol triallyl ether synthesized is relatively low, and the content of pentaerythritol tetraallyl ether is relatively high, and the selectivity of the triether is not high. Chinese Patent CN111170836A discloses a method for synthesizing pentaerythritol allyl ether, in which pentaerythritol triallyl ether is used as a solvent for the reaction, and there is also a problem of relatively high content of tetraether. Therefore, it is necessary to further optimize the synthesis method of pentaerythritol triallyl ether in order to improve the reaction process, post-treatment process, yield and purity of the product. Summary of the Invention

[0005] The object of the present invention is to overcome the problems existing in the above-mentioned prior art, such as low selectivity of the triether, large feeding ratio of alkali and allyl chloride resulting in more by-products, increased post-treatment burden, and high raw material cost, and provide a method for synthesizing pentaerythritol triallyl ether.

[0006] The technical solution of the present invention is as follows:

[0007] A method for synthesizing pentaerythritol triallyl ether, comprising:

[0008] Using pentaerythritol and allyl chloride as starting materials, water as the reaction solvent, and reacting in two stages under strong alkaline conditions; in the first reaction stage, a hydrophilic phase transfer catalyst is added to catalyze the reaction of pentaerythritol and allyl chloride to obtain a mixed intermediate of pentaerythritol monoallyl ether and pentaerythritol diallyl ether; in the second stage, a lipophilic phase transfer catalyst is added to catalyze the reaction of the mixed intermediate of pentaerythritol monoallyl ether and pentaerythritol diallyl ether with allyl chloride to obtain pentaerythritol triallyl ether.

[0009] Further, in the first reaction stage, the mass ratio of pentaerythritol to the hydrophilic phase transfer catalyst is 1:(0.01 - 0.05), and the molar ratio of pentaerythritol to allyl chloride is 1:1.8 - 2.5.

[0010] Further, the hydrophilic phase transfer catalyst includes: tetraethylammonium bromide, crown ether, tetrabutylammonium bromide, tetrabutylammonium chloride, triethylammonium bromide, tributylammonium bromide.

[0011] Further, the reaction temperature in the first reaction stage is 40 - 70°C, and the heat preservation reaction time is 1 - 4 h.

[0012] Further, in the second reaction stage, the addition amount of the lipophilic phase transfer catalyst is calculated based on the mass ratio of it to pentaerythritol being (0.01 - 0.05):1, and the addition amount of allyl chloride is calculated based on the molar ratio of it to pentaerythritol being 1.0 - 1.8:1.

[0013] Further, the lipophilic phase transfer catalyst includes: cetyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride.

[0014] Further, the reaction temperature in the second reaction stage is 40 - 70°C, and the heat preservation reaction time is 1 - 4 h.

[0015] Further, the method for synthesizing pentaerythritol triallyl ether includes the following steps:

[0016] (1) Dissolve pentaerythritol in an aqueous sodium hydroxide solution, add a hydrophilic phase transfer catalyst, heat up to 40 - 70 °C, and dropwise add a certain amount of allyl chloride. During the dropping process, control the reaction temperature at 40 - 70 °C. After the dropping is completed, keep the reaction at a constant temperature for 1 - 4 h to obtain a reaction solution containing a mixed intermediate of pentaerythritol monoallyl ether and pentaerythritol diallyl ether; wherein, the mass ratio of pentaerythritol to the hydrophilic phase transfer catalyst is 1:(0.01 - 0.05), and the molar ratio of pentaerythritol to allyl chloride is 1:1.8 - 2.5;

[0017] (2) Add a certain amount of water to the reaction system in step (1), separate the layers to obtain an organic layer. Add a lipophilic phase transfer catalyst to the organic layer and mix evenly, and then add a certain amount of sodium hydroxide solution and mix evenly;

[0018] (3) Heat up the reaction system in step (2) to 40 - 70 °C, continue to dropwise add a certain amount of allyl chloride. During the dropping process, control the reaction temperature at 40 - 70 °C. After the dropping is completed, keep the reaction at a constant temperature for 1 - 4 h to obtain a reaction solution containing crude pentaerythritol triallyl ether; wherein, the addition amount of the lipophilic phase transfer catalyst is calculated based on the mass ratio of it to pentaerythritol being (0.01 - 0.05):1, and the addition amount of allyl chloride is calculated based on the molar ratio of it to pentaerythritol being 1.0 - 1.8:1;

[0019] (4) Separate the layers of the reaction solution containing crude pentaerythritol triallyl ether to obtain an organic layer. Remove the light boiling components from the organic layer by atmospheric distillation, and then obtain pure pentaerythritol triallyl ether by vacuum distillation.

[0020] Further, in step (1), the mass fraction of the aqueous sodium hydroxide solution is 45 - 50%, and the addition amount of the aqueous sodium hydroxide solution is calculated based on the molar ratio of sodium hydroxide to pentaerythritol being 2.0 - 2.5:1.

[0021] Further, in step (2), the mass fraction of the aqueous sodium hydroxide solution is 45 - 50%, and the addition amount of the aqueous sodium hydroxide solution is calculated based on the molar ratio of sodium hydroxide to pentaerythritol being 1.0 - 1.5:1.

[0022] Further, the aqueous sodium hydroxide solution is replaced with an aqueous potassium hydroxide solution.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] The present invention uses pentaerythritol and allyl chloride as starting materials, water as the reaction solvent, and reacts in two stages under strong alkaline conditions. Moreover, two types of phase transfer catalysts, namely hydrophilic and lipophilic, are used in the two-stage reaction. That is, a hydrophilic phase transfer catalyst is used in the initial stage of the reaction to ensure the catalytic efficiency and reaction efficiency, and an organic layer mainly composed of pentaerythritol monoallyl ether and pentaerythritol diallyl ether is obtained. Since the lipophilicity in the organic layer is enhanced, a lipophilic phase transfer catalyst is added at this time, and then allyl chloride is continuously added for reaction, thereby obtaining a crude product mainly composed of pentaerythritol monoallyl ether. The synthesis method of the present invention is simple in operation, uses water as the solvent, and the obtained pentaerythritol triallyl ether product has a high yield and high selectivity, reaching more than 90%. Moreover, the content of other monoethers can be controlled below 0.05%, the content of diethers can be controlled below 5%, and the content of tetraethers can be controlled below 10%. At present, pilot-scale production has been carried out. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the gas chromatogram of the pentaerythritol triallyl ether product obtained in Pilot-Scale Amplification Case 3 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] In the description of the present invention, it should be noted that for those not specifying specific conditions in the examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments not specifying the manufacturer, they are all conventional products that can be obtained by purchasing in the market.

[0027] The present invention provides a synthesis method of pentaerythritol triallyl ether, including:

[0028] Using pentaerythritol and allyl chloride as starting materials, water as the reaction solvent, and reacting in two stages under strong alkaline conditions; in the first reaction stage, a hydrophilic phase transfer catalyst is added to catalyze the reaction of pentaerythritol and allyl chloride to obtain a mixed intermediate of pentaerythritol monoallyl ether and pentaerythritol diallyl ether; in the second stage, a lipophilic phase transfer catalyst is added to catalyze the reaction of the mixed intermediate of pentaerythritol monoallyl ether and pentaerythritol diallyl ether with allyl chloride to obtain pentaerythritol triallyl ether.

[0029] The reaction principle of the present invention is as follows:

[0030] Pentaerythritol reacts with sodium hydroxide in an aqueous solution, and the formed sodium salt reacts with allyl chloride under the action of a phase transfer catalyst to obtain a mixed intermediate of pentaerythritol monoallyl ether and pentaerythritol diallyl ether. Then, water extraction is carried out. Unreacted pentaerythritol and part of the monoether (pentaerythritol monoallyl ether) enter the water layer, and the remaining mixed intermediate of monoether and diether (pentaerythritol diallyl ether) enters the organic layer and further reacts with allyl chloride to form pentaerythritol triallyl ether (triether):

[0031] The first reaction:

[0032]

[0033] The second reaction:

[0034]

[0035] The following further elaborates on the present invention in conjunction with specific embodiments to assist those skilled in the art in having a more complete, accurate, and in-depth understanding of the inventive concept and technical solution of the present invention. The protection scope of the present invention includes but is not limited to the following embodiments. Any modification made to the details and forms of the technical solution of the present invention without departing from the spirit and scope of the present application falls within the protection scope of the present invention.

[0036] In the following cases of the present invention, the method for detecting the product purity is: gas chromatography (Agilent GC-7890B, FID detector)

[0037] Examples 1-6

[0038] Examples 1-6 provide a synthesis method of pentaerythritol triallyl ether. The specific operation steps are as follows: (1) Preparation of pentaerythritol triallyl ether: Add 273 g of pentaerythritol (molecular weight 136, purity > 99.5%) and Ag NaOH solution (mass fraction B) into a 2.5 L glass reaction kettle;

[0039] (2) Add Cg catalyst X, purge with nitrogen three times, stir and heat up, and control the temperature at D °C;

[0040] (3) Add Eg allyl chloride (molecular weight 76.5) into the dropping tank. By controlling its dropping rate, keep the reaction temperature at F °C. After dropping, control the temperature at 75 °C and keep the reaction for Gh;

[0041] (4) After the reaction is completed, add deionized water and separate the layers to obtain the organic layer;

[0042] (5) Add Hg catalyst Y into the organic layer;

[0043] (6) Add Ig NaOH solution (mass fraction B)

[0044] (7) Add Jg allyl chloride into the dropping tank again. By controlling its dropping rate, keep the reaction temperature at K °C. After dropping, control the temperature at 75 °C and keep the reaction for Lh; After the reaction ends, add a certain amount of water, separate the layers, and take the upper crude product; The crude product is distilled under normal pressure at 100 °C to remove the light-boiling substances in the product, and then distilled under reduced pressure (15 mbar, 150 °C) to collect the product.

[0045] The feedstock situations of each embodiment are shown in Table 1:

[0046] Table 1 Feedstock situations of Embodiments 1-6

[0047]

[0048]

[0049] Comparative Examples 1-6

[0050] Comparative Examples 1-6 provide a method for synthesizing trimethylolpropane triallyl ether, and the specific operation steps are as follows:

[0051] (1) Preparation of trimethylolpropane triallyl ether: Add 273 g of pentaerythritol (molecular weight 136, purity > 99.5%) and (A + I) g of NaOH solution (mass fraction B) into a 2.5 L glass reaction kettle;

[0052] (2) Add (C + H) g of catalyst X, purge with nitrogen three times, stir and heat up, and control the temperature at D °C;

[0053] (3) Start to add (E + J) g of allyl chloride (molecular weight 76.5) to the dropping tank. By controlling its dropping rate, keep the reaction temperature at F °C. After dropping, control the temperature at 75 °C and keep the reaction for (G + L) h;

[0054] (4) After the reaction is completed, add deionized water and separate layers to obtain the crude product;

[0055] (5) The crude product is distilled under normal pressure at 100 °C to remove the light-boiling substances in the product, and then distilled under reduced pressure (15 mbar, 150 °C) to collect the product.

[0056] The feedstock situations of each comparative example are shown in Table 2:

[0057] Table 2 Feedstock situations of Comparative Examples 1-6

[0058]

[0059] The implementation results of all embodiments and comparative examples are shown in Table 3:

[0060] Table 3 Implementation results of all cases

[0061]

[0062]

[0063] The data in Table 3 shows that the yield of the pentaerythritol triallyl ether product obtained by using the synthesis method of the present invention is high, the selectivity can be as high as over 90%, and the content of other monoethers can be controlled below 0.05%, the content of diether can be controlled below 5%, and the content of tetraether can be controlled below 10%.

[0064] Pilot scale-up cases 1 - 3

[0065] The specific operation steps are as follows:

[0066] (1) Preparation of pentaerythritol triallyl ether: Add 6.825 kg of pentaerythritol (molecular weight 136, purity > 99.5%) and A’ kg of NaOH solution (mass fraction B’) into a 60 L reaction kettle;

[0067] (2) Add C’ g of catalyst X, purge with nitrogen three times, stir and heat up, and control the temperature at D’ °C;

[0068] (3) Add E’ kg of allyl chloride (molecular weight 76.5) into the dropping tank, control its dropping rate to keep the reaction temperature at F’ °C, after dropping, control the temperature at 75 °C and hold for G’ h;

[0069] (4) After the reaction is completed, add deionized water and separate to obtain the organic layer;

[0070] (5) Add H’ g of catalyst Y’ into the organic layer;

[0071] (6) Add I’ kg of NaOH solution (mass fraction B’)

[0072] (7) Add J’ kg of allyl chloride into the dropping tank again, control its dropping rate to keep the reaction temperature at K’ °C, after dropping, control the temperature at 75 °C and hold for L’ h; after the reaction ends, add a certain amount of water, separate, and take the upper layer crude product; the crude product is distilled under normal pressure at 100 °C to remove the light boiling components in the product, and then distilled under reduced pressure (15 mbar, 150 °C) to collect the product.

[0073] Feeding conditions of pilot scale-up examples 1 - 3 in Table 4

[0074]

[0075]

[0076] The implementation results of all pilot scale-up examples are shown in Table 5:

[0077] Implementation results of all pilot scale-up cases in Table 5

[0078] Result Pilot-scale Example 1 Pilot-scale Example 2 Pilot-scale Example 3 Monoether / % 0.02 0.02 0.02 Diether / % 4.0 2.2 2.5 Triether / % 89.5 90.1 90.8 Tetraether / % 6.4 7.6 6.6 Yield % 84.5 85.1 85.0

[0079] The gas chromatogram of the pilot-scale-up case 3 is as follows Figure 1 shown.

[0080] The data in Table 5 show that after the pilot-scale-up test of the present invention, the yield of the obtained pentaerythritol triallyl ether product is still relatively high, the selectivity remains at about 90%, and the content of other monoethers still remains stable below 0.05%, the content of diether is controlled below 5%, and the content of tetraether is controlled below 8%, having good industrial prospects.

[0081] In summary, the synthesis method of the present invention is simple to operate, uses water as a solvent, and the obtained pentaerythritol triallyl ether product has a high yield and high selectivity, reaching more than 90%. Moreover, the content of other monoethers can be controlled below 0.05%, the content of diether can be controlled below 5%, and the content of tetraether can be controlled below 10%. After being verified by pilot-scale-up, it has good industrial prospects.

[0082] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the appended claims.

Claims

1. A method for synthesizing pentaerythritol triallyl ether, characterized in that: include: Pentaerythritol and allyl chloride are used as starting materials, water is used as a reaction solvent, and a two-stage reaction is carried out under a strongly alkaline condition; in the first reaction stage, a hydrophilic phase transfer catalyst is added to catalyze the reaction of pentaerythritol and allyl chloride to obtain a mixed intermediate of pentaerythritol monoallyl ether and pentaerythritol diallyl ether, a certain amount of water is added to the mixed intermediate, and the organic layer is obtained by separation; in the second reaction stage, a lipophilic phase transfer catalyst is added to the organic layer to catalyze the reaction of the mixed intermediate of pentaerythritol monoallyl ether and pentaerythritol diallyl ether with allyl chloride to obtain pentaerythritol triallyl ether; The hydrophilic phase transfer catalyst is selected from one of tetraethylammonium bromide, crown ether, tetrabutylammonium bromide, tetrabutylammonium chloride, triethylammonium bromide and tributylammonium bromide; The reaction temperature of the first reaction stage is 40-70°C, and the insulation reaction time is 1-4 hours; The lipophilic phase transfer catalyst is selected from one of cetyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, dodecyltrimethylammonium chloride and tetradecyltrimethylammonium chloride; The reaction temperature of the second reaction stage is 40-70° C., and the insulation reaction time is 1-4 h.

2. The method for synthesizing pentaerythritol triallyl ether according to claim 1, wherein: In the first reaction stage, the mass ratio of pentaerythritol to the hydrophilic phase transfer catalyst is 1:(0.01-0.05), and the molar ratio of pentaerythritol to allyl chloride is 1:1.8-2.

5.

3. The method for synthesizing pentaerythritol triallyl ether according to claim 1, wherein: In the second reaction stage, the mass ratio of the lipophilic phase transfer catalyst to pentaerythritol is (0.01-0.05):1, and the molar ratio of allyl chloride to pentaerythritol is 1.0-1.8:

1.

4. The method for synthesizing pentaerythritol triallyl ether according to claim 1, wherein: The synthesis method of pentaerythritol triallyl ether comprises the following steps: (1) dissolving pentaerythritol in a sodium hydroxide aqueous solution, adding a hydrophilic phase transfer catalyst, raising the temperature to 40-70°C, and dropping a certain amount of allyl chloride. During the dropping process, the reaction temperature is controlled at 40-70°C. After the dropping is completed, the reaction is kept warm for 1-4 hours to obtain a reaction solution containing a mixed intermediate of pentaerythritol monoallyl ether and pentaerythritol diallyl ether. The mass ratio of pentaerythritol to the hydrophilic phase transfer catalyst is 1:(0.01-0.05), and the molar ratio of pentaerythritol to allyl chloride is 1:1.8-2.

5. (2) adding a certain amount of water to the reaction system of step (1), separating the layers to obtain an organic layer, adding a lipophilic phase transfer catalyst to the organic layer and mixing uniformly, and then adding a certain amount of sodium hydroxide solution and mixing uniformly; (3) heating the reaction system of step (2) to 40-70°C, and continuously adding a certain amount of allyl chloride dropwise, controlling the reaction temperature at 40-70°C during the addition process, and keeping the temperature to react for 1-4 hours after the addition is completed, to obtain a reaction solution containing a crude product of pentaerythritol triallyl ether; wherein the amount of the lipophilic phase transfer catalyst added is calculated by a mass ratio of the lipophilic phase transfer catalyst to the pentaerythritol of (0.01-0.05):1, and the amount of the allyl chloride added is calculated by a molar ratio of the lipophilic phase transfer catalyst to the pentaerythritol of 1.0-1.8:1; (4) The reaction solution containing the crude pentaerythritol triallyl ether is separated into layers to obtain an organic layer, the organic layer is distilled at normal pressure to remove light boiling substances, and then distilled at reduced pressure to obtain pure pentaerythritol triallyl ether.

5. The method for synthesizing pentaerythritol triallyl ether according to claim 4, wherein: In the step (1), the mass fraction of the sodium hydroxide aqueous solution is 45-50%, and the amount of the sodium hydroxide aqueous solution added is calculated based on a molar ratio of sodium hydroxide to pentaerythritol of 2.0-2.5:

1.

6. The method for synthesizing pentaerythritol triallyl ether according to claim 4, wherein: In the step (2), the mass fraction of the sodium hydroxide aqueous solution is 45-50%, and the amount of the sodium hydroxide aqueous solution added is calculated based on a molar ratio of sodium hydroxide to pentaerythritol of 1.0-1.5:1.

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