Method for preparing ditrimethylolpropane

Abstract

The invention discloses a method for preparing ditrimethylolpropane, which comprises the following steps: a) trimethylolpropane and a brominating reagent are subjected to nucleophilic substitution reaction under the action of a catalyst I to obtain 2-bromo-2-ethyl-1, 3-propylene glycol; b) generating 2, 2-dimethylolbutanol sodium from trimethylolpropane under the action of a catalyst II; and c) carrying out a reaction on the 2, 2-dimethylol sodium butoxide and 2-bromo-2-ethyl-1, 3-propylene glycol under the action of a catalyst III to obtain the ditrimethylolpropane. The method has the advantages of high yield, few byproducts and high purity.

Description

Technical Field

[0001] The invention belongs to the field of organic chemical synthesis, and in particular relates to a method for preparing ditrimethylolpropane. Background Art

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

[0003] At present, the production of ditrimethylolpropane is mainly carried out by purifying the by-products in the production process of trimethylolpropane. For example, patent CN112961040 mentions a method for extracting ditrimethylolpropane from trimethylolpropane heavy components, but does not mention the yield, and requires harsh conditions such as high temperature, high vacuum, and metal organic salts as protective agents.

[0004] In addition, patent CN114181044 mentions a method for preparing high-purity ditrimethylolpropane through condensation-hydrolysis neutralization-multi-stage extraction-crystallization-filtration-decolorization-distillation and other steps, with a yield of >95% and a purity of >95%, but the color number is high (platinum-cobalt color number 24) and the process flow is complicated; patent US5840994 mentions the use of trimethylolpropane, 2-ethylacrolein, formaldehyde, and hydration to synthesize ditrimethylolpropane, but the yield is only less than 70%.

[0005] The above methods fail to achieve high yield of ditrimethylolpropane while ensuring high purity and low color number, and the process flow is complicated and energy and material consumption are high. Summary of the invention

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

[0007] In order to achieve the above invention object, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing ditrimethylolpropane comprises the following steps:

[0009] a) trimethylolpropane and a brominating agent undergo a nucleophilic substitution reaction under the action of a catalyst to obtain 2-bromo-2-ethyl-1,3-propanediol;

[0010] b) trimethylolpropane generates sodium 2,2-dihydroxymethylbutoxide under the action of catalyst 2;

[0011] c) Sodium 2,2-dihydroxymethylbutoxide reacts with 2-bromo-2-ethyl-1,3-propanediol in the presence of catalyst three to obtain ditrimethylolpropane.

[0012] The brominating agent 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 protonic acid, such as hydrochloric acid, sulfuric acid, nitric acid, preferably concentrated sulfuric acid; the catalyst two in step b) is an alkaline earth metal hydroxide or an alkaline earth metal hydride, preferably sodium hydride or sodium hydroxide; the catalyst three in step c) is an alkaline earth metal hydroxide or an alkaline earth metal hydride, preferably sodium hydride or sodium hydroxide, and more preferably, the catalyst three is the same as the catalyst two.

[0013] In step a) of the present invention, the reaction temperature is 120-180°C, preferably 120-150°C; 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 the brominating agent is 1-1.2 times, preferably 1-1.05 times, the molar amount of trimethylolpropane; and / or

[0016] In step a), the amount of catalyst 1 used is 0.1-0.5 times, preferably 0.1-0.25 times, the molar amount of trimethylolpropane.

[0017] In step b) of the present invention, the reaction temperature is 0-25°C, preferably 0-10°C; 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, preferably 1-1.5 times, the molar amount of trimethylolpropane.

[0020] In step c) of the present invention, the reaction temperature is 80-150°C, preferably 110-150°C; 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, anhydrous tetrahydrofuran; and / or

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

[0023] In step c), the catalyst three can be directly made of the catalyst two added in step b) without any additional addition; and / or

[0024] After the reaction of the present invention is completed, it also includes extraction, drying, filtration, column chromatography and other operations.

[0025] Reaction equation of the present invention is as follows:

[0026]

[0027] The beneficial effects of the present invention are:

[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 effect on product quality, and the prepared product has high purity and low color number. DETAILED DESCRIPTION

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

[0031] The conversion of trimethylolpropane was measured by area normalization of gas chromatography;

[0032] The yield of ditrimethylolpropane is the isolated yield;

[0033] The color number of ditrimethylolpropane is measured by BYK model LCS IV colorimeter using a quartz sample cell:

[0034] Gas chromatograph: Agile ent 7890; chromatographic column: DB-5; inlet temperature: 280°C; split ratio 10:1; H2:Air:N2=40:400:30 (mL / min), column flow rate 5.0 mL / min; heating program: 50°C for 2 min, increase the temperature from 50°C to 280°C at a rate of 15°C / min, and keep the temperature at 280°C for 5 min; FID detector temperature: 280°C.

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

[0036] Reagent information: Unless otherwise specified, all reagents used in the present invention were purchased from Inotech AR grade reagents.

[0037] Example 1

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

[0039] bc) NaH (1.2 mol, 28.8 g) was dissolved in anhydrous THF, trimethylolpropane (1.0 mol, 134.2 g) was added dropwise at 5°C, and the reaction was heated to 120°C after 0.5 h of addition. 2-Bromo-2-ethyl-1,3-propanediol (1.05 mol, 206.9 g) was added dropwise to the in situ generated 2,2-dihydroxymethylbutanoic acid sodium, and the reaction was continued for 12 h. After the reaction was completed, the mixture was cooled to room temperature, the organic phase was extracted with n-hexane, dried with anhydrous MgSO4, concentrated, and column chromatography (ethyl acetate: n-hexane = 2:1) was performed to obtain ditrimethylolpropane.

[0040] The H NMR spectrum data of 2-bromo-2-ethyl-1,3-propanediol is: 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 H NMR spectrum data of ditrimethylolpropane is: 1 H NMR (500 MHz, CDC 13): δ = 3.79 (s, 4H), 3.58 (s, 4H), 3.18 (s, 4H), 2.98 (s, 4H), 1.69 (q, J = 13.5 Hz, 4H), 0.83 (t, J = 13.4 Hz, 6H). The yield of ditrimethylolpropane was 92.6% (based on the initial TMP charge), the purity was 98.3%, and the color number was 10 Hazen.

[0042] Example 2

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

[0044] bc) NaH (1.5 mol, 36.0 g) was dissolved in anhydrous THF, trimethylolpropane (1.0 mol, 134.2 g) was added dropwise at 0°C, and the reaction was heated to 110°C after 0.5 h of addition. 2-bromo-2-ethyl-1,3-propanediol (1.0 mol, 197.1 g) was added dropwise to the in situ generated 2,2-dihydroxymethylbutanoic acid sodium, and the reaction was continued for 12 h. After the reaction was completed, the mixture was cooled to room temperature, the organic phase was extracted with n-hexane, dried with anhydrous MgSO4, concentrated, and column chromatography (ethyl acetate: n-hexane = 2:1) was performed to obtain ditrimethylolpropane.

[0045] The yield of ditrimethylolpropane was 94.2% (based on the initial TMP charge), 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), add Br2 (2.0 mol, 319.6 g) into a three-necked flask, add sulfuric acid (0.2 mol, 19.6 g) dropwise under stirring at 0°C, allow the reaction to return to room temperature, react at 120°C for 1 h, cool the reaction to room temperature after completion, neutralize the reaction 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) NaOH (1.0 mol, 40.0 g) was dissolved in anhydrous 1,4-dioxane, trimethylolpropane (1.0 mol, 134.2 g) was added dropwise at 10°C, and the reaction was heated to 150°C after 0.5 h of addition. 2-bromo-2-ethyl-1,3-propanediol (1.2 mol, 236.5 g) was added dropwise to the in situ generated sodium 2,2-dihydroxymethylbutoxide, and the reaction was continued for 15 h. After the reaction was completed, the mixture was cooled to room temperature, the organic phase was extracted with n-hexane, dried with anhydrous MgSO4, concentrated, and column chromatography (ethyl acetate: n-hexane = 2:1) was performed to obtain ditrimethylolpropane.

[0049] The yield of ditrimethylolpropane was 91.3% (based on the initial TMP charge), 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-ethylacrolein (1.0 mol) and triethylamine (0.5 mol) were added to the reaction kettle and reacted at 90°C for 2 h.

[0052] The yield of ditrimethylolpropane analyzed by GC was 65% (based on the initial TMP charge), and the color number was 26 Hazen.

Claims

1. A method for preparing ditrimethylolpropane, characterized in that: The following steps are involved: a) trimethylolpropane and a brominating agent undergo a nucleophilic substitution reaction under the action of a catalyst to obtain 2-bromo-2-ethyl-1,3-propanediol; b) trimethylolpropane generates sodium 2,2-dihydroxymethylbutoxide under the action of catalyst 2; c) Sodium 2,2-dihydroxymethylbutoxide reacts with 2-bromo-2-ethyl-1,3-propanediol in the presence of catalyst three to obtain ditrimethylolpropane.

2. The method according to claim 1, characterized in that The brominating agent 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; Preferably, the catalyst 1 is an inorganic protonic acid, such as hydrochloric acid, sulfuric acid, nitric acid, preferably concentrated sulfuric acid; Preferably, the catalyst 2 in step b) is an alkaline earth metal hydroxide or an alkaline earth metal hydride, preferably sodium hydride or sodium hydroxide; Preferably, the catalyst three in step c) is an alkaline earth metal hydroxide or an alkaline earth metal hydride, preferably sodium hydride or sodium hydroxide; More preferably, the catalyst three is the same as the catalyst two.

3. The method according to claim 1 or 2, characterized in that: In step a), the reaction temperature is 120-180°C, preferably 120-150°C; the reaction time is 1-5h, preferably 1-3h; and / or In step a), the reaction is carried out in a polar solvent selected from water and dichloromethane, preferably water.

4. The method according to any one of claims 1 to 3, characterized in that: In step a), the amount of the brominating agent is 1-1.2 times, preferably 1-1.05 times, the molar amount of trimethylolpropane; and / or In step a), the amount of catalyst 1 used is 0.1-0.5 times, preferably 0.1-0.25 times, the molar amount of trimethylolpropane.

5. The method according to any one of claims 1 to 4, characterized in that: In step b), the reaction temperature is 0-25°C, preferably 0-10°C; the reaction time is 0.5-2h, preferably 0.5-1h; and / or In step b), the reaction is carried out in a solvent selected from tetrahydrofuran, 1,4-dioxane, toluene, preferably tetrahydrofuran; and / or In step b), the amount of catalyst 2 added is 1-2 times, preferably 1-1.5 times, the molar amount of trimethylolpropane.

6. The method according to any one of claims 1 to 5, characterized in that: In step c), the reaction temperature is 80-150°C, preferably 110-150°C; the reaction time is 10-25h, preferably 10-15h; and / or In step c), the reaction is carried out in a solvent selected from tetrahydrofuran, 1,4-dioxane, and anhydrous tetrahydrofuran; and / or 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-dihydroxymethylbutanolate.

7. The method according to any one of claims 1 to 5, characterized in that: In step c), catalyst three is directly used as catalyst two added in step b).

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