A preparation method of dibutyl (1-hydroxy-1-methylethyl) phosphonate

Abstract

The invention belongs to the technical field of reactive flame retardants, and in particular to a kind of preparation method of dibutyl (1 hydroxy 1 methylethyl) phosphonate. The present invention adds acetone dropwise to dibutyl phosphite mixed solution and carries out addition reaction, and obtains reaction solution;The dibutyl phosphite mixed solution includes dibutyl phosphite, triethylamine and magnesium chloride;The reaction solution is sequentially subjected to vacuum distillation and molecular thin film distillation to obtain distillate;The distillate and activated carbon are mixed and decoloured, and the dibutyl (1 hydroxy 1 methylethyl) phosphonate is obtained after solid-liquid separation. The dibutyl (1 hydroxy 1 methylethyl) phosphonate product purity obtained by the preparation method provided by the present invention is high, and without foul odor, while improving product quality, omitting water washing process, greatly reducing production cost, saving energy consumption, meeting the development trend of green chemistry.

Description

Technical Field

[0001] The invention belongs to the technical field of reactive flame retardants, and particularly relates to a preparation method of dibutyl (1-hydroxy-1-methylethyl) phosphonate. Background Art

[0002] Currently, most phosphate ester flame retardants are additive flame retardants, but the polymers produced by these additives are susceptible to flame retardant penetration during processing. Reactive flame retardants are added to the reaction system during polymer polymerization. Reactive flame retardants participate in the reaction as reactive monomers, forming polymers through chemical bonding. These flame-retardant polymers synthesized through chemical bonding have superior mechanical properties and are less susceptible to flame retardant penetration during processing. Most reactive flame retardants are phosphine compounds containing hydroxyl groups. These phosphine compounds contain highly reactive hydroxyl groups, making them highly reactive with isocyanates.

[0003] Phosphonates containing hydroxyl groups primarily include hydroxyethyl phosphonate, dibutyl (1-hydroxy-1-methylethyl) phosphonate, and hydroxymethyl phosphonate. Among these, dibutyl (1-hydroxy-1-methylethyl) phosphonate is more widely used. It can react with pivaloyl chloride to synthesize a novel flame retardant. This novel flame retardant exhibits low volatility and low residue, and has been partially used in flame retardant automotive sponges.

[0004] At present, the synthesis method of dibutyl (1-hydroxy-1-methylethyl) phosphonate is mainly to react n-butanol with phosphorus trichloride to produce dibutyl phosphite, and then react dibutyl phosphite with acetone. The reaction equation is as follows:

[0005]

[0006] As shown in the reaction equation above, the main raw material for synthesizing dibutyl (1-hydroxy-1-methylethyl) phosphonate is dibutyl phosphite. The main impurity in di-n-butyl phosphite is n-butyl alcohol. The n-butyl alcohol residue on the market is about 3-5%. The presence of n-butyl alcohol directly causes the purity of dibutyl (1-hydroxy-1-methylethyl) phosphonate to be lower, affecting the quality of the product. Simultaneously, when reacting according to the reaction equation above, it is necessary to react under the catalysis of triethylamine and magnesium chloride. After the reaction, it is necessary to remove the acidic and alkaline impurity residual components through the operation of pickling and alkali washing. However, the waste water produced in the pickling and alkali washing stages easily causes high production costs and serious environmental pollution. Summary of the Invention

[0007] The present invention aims to provide a method for preparing dibutyl (1-hydroxy-1-methylethyl) phosphonate. The dibutyl (1-hydroxy-1-methylethyl) phosphonate product obtained by the preparation method provided by the present invention has high purity and eliminates the water washing process, thereby greatly reducing production costs and saving energy consumption, and conforming to the development trend of green chemistry.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] The present invention provides a method for preparing dibutyl (1-hydroxy-1-methylethyl) phosphonate, comprising the following steps:

[0010] adding acetone dropwise to a dibutyl phosphite mixed solution for addition reaction to obtain a reaction solution; the dibutyl phosphite mixed solution comprises dibutyl phosphite, triethylamine and magnesium chloride;

[0011] The reaction solution is sequentially subjected to reduced pressure distillation and molecular thin film distillation to obtain a distillation product;

[0012] The distillation product is mixed with activated carbon for decolorization, and the dibutyl (1-hydroxy-1-methylethyl) phosphonate is obtained after solid-liquid separation.

[0013] Preferably, the temperature of the reduced pressure distillation is 30-75° C., and the vacuum degree is 2-5 kPa.

[0014] Preferably, the temperature of the molecular thin film distillation is 50-65° C., and the vacuum degree is 50-100 Pa.

[0015] Preferably, the molar ratio of dibutyl phosphite to acetone is 1:1-2.

[0016] Preferably, the amount of magnesium chloride used is 0.5-2% of the mass of dibutyl phosphite;

[0017] The amount of triethylamine used is 1-5% of the mass of dibutyl phosphite.

[0018] Preferably, the dropping temperature is 25 to 65° C., and the dropping time is 2 to 6 hours.

[0019] Preferably, the temperature of the addition reaction is 25 to 65° C., and the time for continuing the heat-insulating reaction after the dropwise addition is 2 to 4 hours.

[0020] Preferably, the amount of activated carbon used is 0.1 to 1% of the mass of dibutyl phosphite.

[0021] Preferably, the decolorization temperature is 60-65° C., and the decolorization time is 1-2 hours.

[0022] Preferably, the content of n-butanol in the dibutyl (1-hydroxy-1-methylethyl) phosphonate is ≤1%.

[0023] The present invention provides a preparation method of dibutyl (1-hydroxy-1-methylethyl) phosphonate, comprising the following steps: adding acetone dropwise to a dibutyl phosphite mixed solution for an addition reaction to obtain a reaction solution; the dibutyl phosphite mixed solution includes dibutyl phosphite, triethylamine and magnesium chloride; the reaction solution is sequentially subjected to vacuum distillation and molecular thin film distillation to obtain a distillation product; the distillation product is mixed with activated carbon for decolorization, and the dibutyl (1-hydroxy-1-methylethyl) phosphonate is obtained after solid-liquid separation. The preparation method provided by the present invention, on the one hand, uses vacuum distillation to recover unreacted acetone and triethylamine, eliminating the steps of acid washing and alkali washing to treat the triethylamine catalyst, greatly reducing production labor costs, saving energy consumption, and conforming to the development trend of green chemistry; on the other hand, the present invention uses molecular thin film distillation to effectively remove n-butanol impurities in the reaction product, while avoiding the phenomenon of dibutyl (1-hydroxy-1-methylethyl) phosphonate decomposition caused by high-temperature distillation for impurity removal, and the disadvantage of the product producing a foul smell. In summary, the dibutyl (1-hydroxy-1-methylethyl) phosphonate product obtained by the preparation method provided by the present invention has high purity and no foul odor, which improves product quality while eliminating the water washing process, greatly reducing production costs, saving energy consumption, and conforming to the development trend of green chemistry. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the nuclear magnetic phosphorus detection spectrum of dibutyl (1-hydroxy-1-methylethyl) phosphonate prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0025] The present invention provides a method for preparing dibutyl (1-hydroxy-1-methylethyl) phosphonate, comprising the following steps:

[0026] adding acetone dropwise to a dibutyl phosphite mixed solution for addition reaction to obtain a reaction solution; the dibutyl phosphite mixed solution comprises dibutyl phosphite, triethylamine and magnesium chloride;

[0027] The reaction solution is sequentially subjected to reduced pressure distillation and molecular thin film distillation to obtain a distillation product;

[0028] The distillation product is mixed with activated carbon for decolorization, and the dibutyl (1-hydroxy-1-methylethyl) phosphonate is obtained after solid-liquid separation.

[0029] In the present invention, unless otherwise specified, all preparation raw materials / components are commercially available products well known to those skilled in the art.

[0030] The invention adds acetone dropwise into a dibutyl phosphite mixed solution to carry out an addition reaction to obtain a reaction solution; the dibutyl phosphite mixed solution comprises dibutyl phosphite, triethylamine and magnesium chloride.

[0031] In the present invention, the molar ratio of dibutyl phosphite to acetone is preferably 1:1-2, more preferably 1:1.2-1.6.

[0032] In the present invention, the amount of magnesium chloride used is preferably 0.5-2% of the mass of dibutyl phosphite, more preferably 0.8-1.6%.

[0033] In the present invention, the amount of triethylamine used is preferably 1 to 5% of the mass of dibutyl phosphite, more preferably 1.5 to 4.5%.

[0034] In the present invention, the method for preparing the dibutyl phosphite mixed solution preferably comprises the following steps: stirring and mixing dibutyl phosphite, triethylamine and magnesium chloride to obtain the dibutyl phosphite mixed solution. In the present invention, the preparation of the dibutyl phosphite mixed solution is preferably carried out in a reactor.

[0035] In the present invention, before the dropwise addition, the dibutyl phosphite mixed solution is preferably heated to a dropwise addition temperature. In the present invention, the dibutyl phosphite mixed solution is preferably heated in a protective gas atmosphere; the protective gas is preferably nitrogen.

[0036] In the present invention, the temperature of the dropwise addition is preferably 25 to 65° C., more preferably 30 to 60° C.; the time of the dropwise addition is preferably 2 to 6 hours, more preferably 3 to 5 hours. In the present invention, the dropwise addition is preferably carried out under stirring and in a protective gas atmosphere, preferably nitrogen.

[0037] In the present invention, the temperature of the addition reaction is preferably 25 to 65° C., more preferably 30 to 60° C.; the time for continuing the heat preservation reaction after the dropwise addition is preferably 2 to 4 hours, more preferably 2.5 to 3.5 hours. In the present invention, the heat preservation reaction after the dropwise addition is preferably carried out under stirring, and the heat preservation reaction is preferably carried out in a protective gas atmosphere, and the protective gas is preferably nitrogen.

[0038] After obtaining the reaction liquid, the present invention sequentially performs vacuum distillation and molecular thin film distillation on the reaction liquid to obtain a distillation product.

[0039] In the present invention, the temperature of the reduced pressure distillation is preferably 30 to 75° C., more preferably 50 to 70° C.; the vacuum degree is preferably 2 to 5 kPa, more preferably 2.5 to 4.5 kPa.

[0040] The present invention preferably recovers acetone and triethylamine by distillation under reduced pressure.

[0041] In the present invention, the product of the vacuum distillation (heavy component product in the bottom) is subjected to the molecular thin film distillation. In the present invention, the molecular thin film distillation is preferably carried out in a molecular thin film distillation tower. In the present invention, the product of the vacuum distillation is preferably introduced into the molecular thin film distillation tower at a rate of 120 kg / h for molecular distillation.

[0042] In the present invention, the temperature of the molecular thin film distillation is preferably 50-65° C., more preferably 60-65° C.; the vacuum degree is preferably 50-100 Pa, more preferably 60-80 Pa.

[0043] The present invention preferably removes residual n-butanol from the reaction product by molecular thin film distillation. Furthermore, in the present invention, the molecular thin film distillation temperature is 50-65°C, which effectively prevents the decomposition of dibutyl (1-hydroxy-1-methylethyl) phosphonate under high temperature conditions, thereby increasing the product yield and preventing the foul odor generated by decomposition from affecting product quality.

[0044] In the present invention, the recombinant fraction obtained by the molecular thin film distillation is the distillation product.

[0045] After obtaining the distillation product, the present invention mixes the distillation product with activated carbon for decolorization, and obtains the dibutyl (1-hydroxy-1-methylethyl) phosphonate after solid-liquid separation.

[0046] In the present invention, the amount of activated carbon used is preferably 0.1-1% of the mass of dibutyl phosphite, more preferably 0.2-0.9%.

[0047] In the present invention, the decolorization is preferably carried out in an activated carbon adsorption reactor. The decolorization temperature is preferably 60-65°C, more preferably 65°C; and the decolorization time is preferably 1-2 hours, more preferably 2 hours.

[0048] In the present invention, the embodiment of the solid-liquid separation is preferably hot press filtration, wherein the temperature of the hot press filtration is 60-65°C, more preferably 65°C.

[0049] In the present invention, the dibutyl (1-hydroxy-1-methylethyl) phosphonate product obtained by the solid-liquid separation is a white transparent liquid.

[0050] The present invention adopts a reduced pressure distillation method to replace water washing steps such as acid washing and alkali washing, thereby eliminating the water washing process, greatly reducing the high labor cost of production, saving energy consumption, and complying with the development trend of future green chemistry; at the same time, the present invention adopts thin film molecular distillation to effectively remove n-butanol residues in the product, avoids high-temperature decomposition of dibutyl (1-hydroxy-1-methylethyl) phosphonate, improves product yield, avoids the malodor of the product, and greatly improves product quality.

[0051] In the present invention, the mass percentage of n-butanol in the dibutyl (1-hydroxy-1-methylethyl) phosphonate is ≤1%, and the purity of the dibutyl (1-hydroxy-1-methylethyl) phosphonate is ≥99%.

[0052] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0053] Example 1

[0054] 700 kg of dibutyl phosphite, 14 kg of triethylamine, and 7 kg of magnesium chloride are put into a 3000L reactor, stirred, and nitrogen protection is turned on. The temperature is slowly raised to 25-30°C, and 400 kg of acetone is started to be added dropwise. The process control temperature of the addition is 40-45°C, and the dropping time is 4 hours. After the dropwise addition is completed, the mixture is kept warm for 2 hours and then distilled under reduced pressure. The vacuum degree is 3 kPa and the distillation temperature is 70°C. After distillation, the temperature is reduced to 60-65°C. The mixture is then injected into a molecular film distillation tower at a speed of 120 kg / h for molecular distillation. The molecular distillation temperature is 60-65°C and the vacuum degree is 100 Pa. The heavy component obtained by molecular film distillation is injected into an activated carbon adsorption reactor for decolorization. The amount of activated carbon is 1% of the mass of the dibutyl phosphite. The decolorization temperature is 65°C and the decolorization time is 2 hours. After decolorization, hot pressure filtration is performed to obtain 874.64 kg of dibutyl (1-hydroxy-1-methylethyl) phosphonate product with a yield of 96%.

[0055] Example 2

[0056] 700 kg of dibutyl phosphite, 14 kg of triethylamine, and 7 kg of magnesium chloride were added to a 3000L reactor, stirred, and nitrogen protection was turned on. The temperature was slowly raised to 25-30°C, and 350 kg of acetone was added dropwise. The temperature of the addition process was controlled at 40-45°C and the addition time was 4 hours. After the addition was completed, the mixture was kept warm for 2 hours and then distilled under reduced pressure at a vacuum degree of 3KPa and a distillation temperature of 70°C. After the distillation was completed, the temperature was lowered to 60-65°C and the mixture was injected into a molecular film distillation tower at a speed of 120 kg / h for molecular distillation. The molecular distillation temperature was 60-65°C and the vacuum degree was 100Pa. The heavy components obtained by molecular film distillation were injected into an activated carbon adsorption reactor for decolorization. The amount of activated carbon was 0.1% of the mass of dibutyl phosphite, the decolorization temperature was 65°C, and the decolorization time was 2 hours. After decolorization, hot press filtration was performed to obtain 863.55 kg of dibutyl (1-hydroxy-1-methylethyl) phosphonate product with a yield of 95%.

[0057] Example 3

[0058] The process is basically the same as Example 1, except that the temperature is raised to 35°C and the reaction is carried out dropwise. The vacuum degree of the reduced pressure distillation is 2 KPa and the distillation temperature is 75°C. The product is 868 kg and the yield is 95.5%.

[0059] Example 4

[0060] The method is basically the same as Example 1, except that: 10 kg of triethylamine is used, 854 kg of product is obtained, and the yield is 93.9%.

[0061] Example 5

[0062] The method is basically the same as Example 1, except that: 5 kg of magnesium chloride is used, 855 kg of product is obtained, and the yield is 94%.

[0063] Comparative Example 1

[0064] Reference Chinese patent CN101044148A: 194 g of dibutyl phosphite, 5.1 g of triethylamine and 1.7 g of magnesium chloride were added to a 2-liter four-necked flask, stirred and mixed at 40 degrees, 63.8 g of acetone was added dropwise, and the reaction was allowed to proceed for 1 hour. After the reaction was completed, the mixture was heated to 60 degrees and washed with 2% dilute hydrochloric acid to remove triethylamine and magnesium chloride. The reaction solution was then washed with saturated sodium carbonate aqueous solution, washed with water to remove moisture, and the unreacted raw materials were removed by nitrogen topping at 80°C to obtain 242.2 g of sample with a yield of 96%.

[0065] Test Example 1

[0066] 1. Inspection methods:

[0067] 1) Color number determination method: GB-3143

[0068] 2) Acid value determination method: GB-264-1983;

[0069] 3) Detection method of n-butanol: external standard method

[0070] Gas phase analysis method: injection temperature: 170°C, detector: 180°C, column temperature: 70°C, heating at 15°C / min to 280°C, gas chromatography column: SE-30, 25×0.2×0.25.

[0071] 4) Purity detection method:

[0072] Nuclear magnetic phosphorus spectrum determination, the determination results are as follows Figure 1 shown.

[0073] 2. Experimental results:

[0074] 1) The test results of the embodiment and the comparative example are shown in Table 1

[0075] Table 1 Test results

[0076] project Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Color number (Platinum-Cobalt) 20 25 25 25 25 60 Acid value (mgKOH / g) 0.07 0.04 0.03 0.05 0.06 0.08 n-Butanol 0.52 0.48 0.56 0.6 0.58 2.5 Dibutyl phosphite 0 0 0 0 0 0.5 odor Odorless Odorless Odorless Odorless Odorless foul smell Yield % 96 95 95.5 93.9 94. 96 purity% 99.27 99.02 99.0 99.06 99.1 98

[0077] The results in Table 1 demonstrate that the present invention utilizes a post-reaction vacuum distillation post-treatment method, eliminating the need for acid or alkali washing to treat the catalyst, achieving excellent results. Furthermore, the molecular thin film distillation method effectively addresses residual n-butanol, controlling the residual n-butanol to less than 1%. This invention eliminates the need for water washing, significantly reducing labor costs and energy consumption, aligning with the future development trend of green chemistry.

[0078] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A method for preparing dibutyl (1-hydroxy-1-methylethyl) phosphonate, characterized in that: The following steps are involved: adding acetone dropwise to a dibutyl phosphite mixed solution for addition reaction to obtain a reaction solution; the dibutyl phosphite mixed solution comprises dibutyl phosphite, triethylamine and magnesium chloride; The reaction solution is sequentially subjected to reduced pressure distillation and molecular thin film distillation to obtain a distillation product, wherein the temperature of the reduced pressure distillation is 30-75° C. and the vacuum degree is 2-5 kPa, and the temperature of the molecular thin film distillation is 50-65° C. and the vacuum degree is 50-100 Pa; The distillation product is mixed with activated carbon for decolorization, and the dibutyl (1-hydroxy-1-methylethyl) phosphonate is obtained after solid-liquid separation. The amount of the activated carbon used is 0.1-1% of the mass of the dibutyl phosphite. The decolorization temperature is 60-65° C. and the decolorization time is 1-2 hours. The content of n-butanol in the dibutyl (1-hydroxy-1-methylethyl) phosphonate is ≤1%.

2. The preparation method according to claim 1, characterized in that The molar ratio of the dibutyl phosphite to acetone is 1:1-2.

3. The preparation method according to claim 1, characterized in that The amount of magnesium chloride used is 0.5-2% of the mass of dibutyl phosphite; The amount of triethylamine used is 1-5% of the mass of dibutyl phosphite.

4. The preparation method according to claim 1 or 3, characterized in that The temperature of the dropwise addition is 25 to 65° C., and the time of the dropwise addition is 2 to 6 hours.

5. The preparation method according to claim 1, characterized in that The temperature of the addition reaction is 25 to 65° C., and the reaction time after the dropwise addition is continued to be 2 to 4 hours.

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