A process for the preparation of ditrimethylolpropane

Abstract

The application discloses a method for preparing ditrimethylolpropane, which comprises the following steps: a) trimethylolpropane is subjected to a nucleophilic substitution reaction with a bromination reagent under the action of a catalyst I to obtain 2-bromo-2-ethyl-1,3-propanediol; b) trimethylolpropane is subjected to a reaction under the action of a catalyst II to generate sodium 2,2-dimethylolbutylate; and c) sodium 2,2-dimethylolbutylate is subjected to a reaction with 2-bromo-2-ethyl-1,3-propanediol under the action of a catalyst III to obtain ditrimethylolpropane. The method has high yield, few by-products and high purity.

Description

Technical Field

[0001] This invention belongs to the field of organic chemical synthesis, and specifically relates to a method for preparing bis(trimethylolpropane). Background Technology

[0002] Di-trimethylolpropane (Di-TMP) has low volatility and good stability and antioxidant properties, and can be used in high-grade alkyd resins, plasticizers and other fields.

[0003] Currently, the production of bis(trimethylolpropane) mainly involves purifying byproducts from the production process of trimethylolpropane. For example, patent CN112961040 mentions a method for extracting bis(trimethylolpropane) from the heavy components of trimethylolpropane, but does not mention the yield and requires harsh conditions such as high temperature, high vacuum, and organometallic salts as protective agents.

[0004] In addition, patent CN114181044 mentions a method for preparing high-purity bis(trimethylolpropane) through steps such as condensation-hydrolysis neutralization-multi-stage extraction-crystallization-filtration-decolorization-distillation, with a yield >95% and purity >95%, but the color number is too high (platinum-cobalt color number 24), and the process is complex; patent US5840994 mentions the synthesis of bis(trimethylolpropane) using trimethylolpropane, 2-ethylpropenal, formaldehyde, and water, but the yield is less than 70%.

[0005] None of the above methods can achieve high purity and low color number while obtaining bis(trimethylolpropane) in high yield, and the process is complicated, energy-consuming, and material-consuming. Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned shortcomings of the prior art and provide a new method for preparing bis(trimethylolpropane). This method has the characteristics of simple process, high yield, high purity of the prepared product and low color number.

[0007] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0008] A method for preparing bis(trimethylolpropane) includes the following steps:

[0009] a) Trimethylolpropane reacts with a bromide reagent under the action of catalyst 1 to undergo a nucleophilic substitution reaction to give 2-bromo-2-ethyl-1,3-propanediol;

[0010] b) Trimethylolpropane reacts with catalyst 2 to form sodium 2,2-dimethylolbutoxide;

[0011] c) Sodium 2,2-dimethylolbutoxide reacts with 2-bromo-2-ethyl-1,3-propanediol under the action of catalyst III to give bis(trimethylolpropane).

[0012] The brominating reagent in step a) is selected from one or more of hydrogen bromide, potassium bromide, bromine, sodium bromide, or magnesium bromide, preferably one or more of hydrogen bromide, potassium bromide, or bromine. The catalyst one is an inorganic protic acid, such as hydrochloric acid, sulfuric acid, or nitric acid, preferably concentrated sulfuric acid. The catalyst two in step b) is an alkaline earth metal hydroxide or alkaline earth metal hydride, preferably sodium hydride or sodium hydroxide. The catalyst three in step c) is an alkaline earth metal hydroxide or alkaline earth metal hydride, preferably sodium hydride or sodium hydroxide. More preferably, the catalyst three is the same as the catalyst two.

[0013] In step a) of this invention, the reaction temperature is 120-180℃, preferably 120-150℃; the reaction time is 1-5h, preferably 1-3h; and / or

[0014] In step a), the reaction is carried out in a polar solvent, selected from water and dichloromethane, preferably water; and / or

[0015] In step a), the amount of brominating reagent used is 1-1.2 times the molar amount of trimethylolpropane, preferably 1-1.05 times; and / or

[0016] In step a), the amount of catalyst one is 0.1-0.5 times the molar amount of trimethylolpropane, preferably 0.1-0.25 times.

[0017] In step b) of this invention, the reaction temperature is 0-25℃, preferably 0-10℃; the reaction time is 0.5-2h, preferably 0.5-1h; and / or

[0018] In step b), the reaction is carried out in a solvent selected from tetrahydrofuran, 1,4-dioxane, toluene, preferably tetrahydrofuran; and / or

[0019] In step b), the amount of catalyst 2 added is 1-2 times the molar amount of trimethylolpropane, preferably 1-1.5 times.

[0020] In step c) of the present invention, the reaction temperature is 80-150℃, preferably 110-150℃; the reaction time is 10-25h, preferably 10-15h; and / or

[0021] In step c), the reaction is carried out in a solvent selected from tetrahydrofuran, 1,4-dioxane-toluene, anhydrous tetrahydrofuran; and / or

[0022] In step c), the amount of 2-bromo-2-ethyl-1,3-propanediol used is 1-1.5 times, preferably 1-1.2 times, the molar amount of sodium 2,2-dimethylolbutoxide; and / or

[0023] In step c), catalyst three can be directly derived from catalyst two added in step b), without the need for additional addition; and / or

[0024] After the reaction described in this invention is completed, it also includes operations such as extraction, drying, filtration, and column chromatography.

[0025] The reaction equation for this invention is as follows:

[0026]

[0027] The beneficial effects of this invention are as follows:

[0028] (1) The steps are simple, the reaction process is simple, and the yield is high;

[0029] (2) The starting material is trimethylolpropane, which has little impact on product quality. The prepared product has high purity and low color number. Detailed Implementation

[0030] The following embodiments will further illustrate the method provided by the present invention, but the present invention is not limited to the listed embodiments, and should also include any other known modifications within the scope of the claims of the present invention.

[0031] The conversion rate of trimethylolpropane was determined by area normalization using gas chromatography.

[0032] The yield of bis(trimethylolpropane) was the isolated yield;

[0033] The color number of bis(trimethylolpropane) was measured using a BYK LCS IV colorimeter with a quartz sample cell.

[0034] Gas chromatograph: Agileent 7890; Column: DB-5; Injector temperature: 280℃; Split ratio: 10:1; H2:Air:N2 = 40:400:30 (mL / min); Column flow rate: 5.0 mL / min; Temperature program: 50℃ for 2 min, increase from 50℃ to 280℃ at a rate of 15℃ / min, and hold at 280℃ for 5 min; FID detector temperature: 280℃.

[0035] Nuclear magnetic resonance spectrometer: 1H NMR, instrument model: Bruker 500MHz nuclear magnetic resonance spectrometer.

[0036] Reagent Information: Unless otherwise specified, all reagents used in this invention were purchased from Inokai AR grade reagents.

[0037] Example 1

[0038] a) Dissolve trimethylolpropane (2.0 mol, 268.3 g) in 150 g of water and add it to a three-necked flask along with HBr (2.1 mol, 169.9 g). Add 98 wt% concentrated sulfuric acid (0.5 mol, 49.0 g) dropwise with stirring at 0 °C. After the reaction is brought to room temperature, the reaction is carried out at 150 °C for 2 h. After the reaction is completed, the reaction is cooled to room temperature and neutralized with NaHCO3 to pH > 7. Extract with dichloromethane three times, combine the organic phases, dry with anhydrous Na2SO4, and concentrate to obtain 2-bromo-2-ethyl-1,3-propanediol.

[0039] bc) Dissolve NaH (1.2 mol, 28.8 g) in anhydrous THF, and add trimethylolpropane (1.0 mol, 134.2 g) dropwise at 5 °C. After the addition is complete in 0.5 h, heat the reaction to 120 °C, and add 2-bromo-2-ethyl-1,3-propanediol (1.05 mol, 206.9 g) dropwise to the sodium 2,2-dimethylolbutoxide generated in situ. React for 12 h. After the reaction is complete, cool to room temperature, extract the organic phase with n-hexane, dry with anhydrous MgSO4, concentrate, and then perform column chromatography (ethyl acetate: n-hexane = 2:1) to obtain bis(trimethylolpropane).

[0040] The 1H NMR data for 2-bromo-2-ethyl-1,3-propanediol are as follows: 1 H NMR (500MHz, CDC l3): δ = 3.67 (s, 2H), 3.46–3.39 (m, 4H), 1.51–1.36 (m, 4H), 0.82 (t, J = 13.4Hz, 3H).

[0041] The 1H NMR data for bis(trimethylolpropane) are as follows: 1 ¹H NMR (500MHz, CDCl₃): δ = 3.79 (s, 4H), 3.58 (s, 4H), 3.18 (s, 4H), 2.98 (s, 4H), 1.69 (q, J = 13.5Hz, 4H), 0.83 (t, J = 13.4Hz, 6H). The yield of bis(trimethylolpropane) was 92.6% (based on initial TMP), purity 98.3%, color number 10 Hazen.

[0042] Example 2

[0043] a) Dissolve trimethylolpropane (2.0 mol, 268.3 g) in 150 g of water and add it to a three-necked flask along with KBr (2.4 mol, 470.5 g). Add sulfuric acid (0.6 mol, 58.8 g) dropwise with stirring at 0 °C. After the reaction is brought to room temperature, the reaction is carried out at 180 °C for 3 h. After the reaction is completed, the reaction is cooled to room temperature and neutralized with NaHCO3 to pH > 7. Extract with dichloromethane three times, combine the organic phases, dry with anhydrous Na2SO4, and concentrate to obtain 2-bromo-2-ethyl-1,3-propanediol.

[0044] bc) Dissolve NaH (1.5 mol, 36.0 g) in anhydrous THF, and add trimethylolpropane (1.0 mol, 134.2 g) dropwise at 0 °C. After the addition is complete in 0.5 h, heat the reaction to 110 °C, and add 2-bromo-2-ethyl-1,3-propanediol (1.0 mol, 197.1 g) dropwise to the sodium 2,2-dimethylolbutoxide generated in situ. React for 12 h. After the reaction is complete, cool to room temperature, extract the organic phase with n-hexane, dry with anhydrous MgSO4, concentrate, and then perform column chromatography (ethyl acetate: n-hexane = 2:1) to obtain bis(trimethylolpropane).

[0045] The yield of bis(trimethylolpropane) was 94.2% (based on the initial TMP), the purity was 98.7%, and the color number was 11 Hazen.

[0046] Example 3

[0047] a) Dissolve trimethylolpropane (2.0 mol, 268.3 g) in a mixed solvent of 150 g water and dichloromethane (mass ratio 1:1), and add it to a three-necked flask along with Br2 (2.0 mol, 319.6 g). Add sulfuric acid (0.2 mol, 19.6 g) dropwise with stirring at 0 °C. After the reaction is brought to room temperature, the reaction is carried out at 120 °C for 1 h. After the reaction is completed, the reaction is cooled to room temperature and neutralized with NaHCO3 to pH > 7. Extract with dichloromethane three times, combine the organic phases, dry with anhydrous Na2SO4, and concentrate to obtain 2-bromo-2-ethyl-1,3-propanediol.

[0048] bc) Dissolve NaOH (1.0 mol, 40.0 g) in anhydrous 1,4-dioxane, and add trimethylolpropane (1.0 mol, 134.2 g) dropwise at 10 °C. After the addition is complete in 0.5 h, heat the reaction to 150 °C, and add 2-bromo-2-ethyl-1,3-propanediol (1.2 mol, 236.5 g) dropwise to the in-situ generated sodium 2,2-dimethylolbutoxide. React for 15 h. After the reaction is complete, cool to room temperature, extract the organic phase with n-hexane, dry with anhydrous MgSO4, concentrate, and then perform column chromatography (ethyl acetate: n-hexane = 2:1) to obtain bis(trimethylolpropane).

[0049] The yield of bis(trimethylolpropane) was 91.3% (based on the initial TMP), the purity was 97.5%, and the color number was 13 Hazen.

[0050] Comparative Example 1

[0051] TMP (2.5 mol), formaldehyde aqueous solution (1.0 mol), 2-ethylpropenal (1.0 mol), and triethylamine (0.5 mol) were added to the reaction vessel, and the reaction was carried out at 90°C for 2 h.

[0052] The yield of bis(trimethylolpropane) by GC analysis was 65% (based on the initial TMP), color number 26 Hazen.

Claims

1. A method for preparing bis(trimethylolpropane), characterized in that, Includes the following steps: a) Trimethylolpropane reacts with a bromide reagent under the action of catalyst one in a nucleophilic substitution reaction to give 2-bromomethyl-2-ethyl-1,3-propanediol; b) Trimethylolpropane reacts with catalyst 2 to form sodium 2,2-dimethylolbutoxide; c) Sodium 2,2-dimethylolbutoxide reacts with 2-bromomethyl-2-ethyl-1,3-propanediol under the action of catalyst III to give bis(trimethylolpropane); The catalyst is an inorganic protic acid. The catalyst in step b) is sodium hydride or sodium hydroxide. The catalyst in step c) is sodium hydride and sodium hydroxide; In step c), the reaction is carried out in a solvent, which is selected from tetrahydrofuran, 1,4-dioxane, and anhydrous tetrahydrofuran.

2. The method according to claim 1, characterized in that, The brominating reagent in step a) is selected from one or more of hydrogen bromide, potassium bromide, bromine, sodium bromide, or magnesium bromide.

3. The method according to claim 2, characterized in that, The brominating agent in step a) is one or more of hydrogen bromide, potassium bromide, or bromine.

4. The method according to claim 1, characterized in that, The catalyst is hydrochloric acid, sulfuric acid, or nitric acid.

5. The method according to claim 4, characterized in that, The catalyst is concentrated sulfuric acid.

6. The method according to claim 1, characterized in that, Catalyst 3 is the same as catalyst 2.

7. The method according to claim 1, characterized in that, In step a), the reaction temperature is 120-180℃; the reaction time is 1-5 h; and / or In step a), the reaction is carried out in a polar solvent, which is selected from water and dichloromethane.

8. The method according to claim 7, characterized in that, In step a), the reaction temperature is 120-150℃; the reaction time is 1-3 hours; and / or In step a), the reaction is carried out in a polar solvent, namely water.

9. The method according to claim 1, characterized in that, In step a), the amount of brominating reagent used is 1-1.2 times the molar amount of trimethylolpropane; and / or In step a), the amount of catalyst one is 0.1-0.5 times the molar amount of trimethylolpropane.

10. The method according to claim 9, characterized in that, In step a), the amount of brominating reagent used is 1-1.05 times the molar amount of trimethylolpropane; and / or In step a), the amount of catalyst one is 0.1-0.25 times the molar amount of trimethylolpropane.

11. The method according to claim 1, characterized in that, In step b), the reaction temperature is 0-25℃; the reaction time is 0.5-2h; and / or In step b), the reaction is carried out in a solvent selected from tetrahydrofuran, 1,4-dioxane, toluene; and / or In step b), the amount of catalyst 2 added is 1-2 times the molar amount of trimethylolpropane.

12. The method according to claim 11, characterized in that, In step b), the reaction temperature is 0-10℃; the reaction time is 0.5-1h; and / or In step b), the reaction is carried out in a solvent, specifically tetrahydrofuran; and / or In step b), the amount of catalyst 2 added is 1-1.5 times the molar amount of trimethylolpropane.

13. The method according to claim 1, characterized in that, In step c), the reaction temperature is 80-150℃; the reaction time is 10-25 h; and / or In step c), the amount of 2-bromomethyl-2-ethyl-1,3-propanediol used is 1 to 1.5 times the molar amount of sodium 2,2-dihydroxymethylbutoxide.

14. The method according to claim 13, characterized in that, In step c), the reaction temperature is 110-150℃; the reaction time is 10-15h; and / or In step c), the amount of 2-bromomethyl-2-ethyl-1,3-propanediol used is 1 to 1.2 times the molar amount of sodium 2,2-dihydroxymethylbutoxide.

15. The method according to claim 1, characterized in that, In step c), catalyst three is directly the same as catalyst two added in step b).

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