Alkylphosphonic acid dialkyl esters and methods for their synthesis

Abstract

The application discloses a kind of dialkyl alkylphosphonate and synthesis method thereof.Synthesis method includes using ionic catalyst, with trialkyl phosphite as raw material to carry out synthesis reaction, wherein, the ionic catalyst has the structure shown in formula (I), wherein, M is selected from metal, and n is the valence of M.Using the synthesis method can significantly improve the conversion rate of raw materials, the selectivity and yield of product, the synthesis condition is mild, and can be used for large-scale industrial production of dialkyl alkylphosphonate.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of alkylphosphonic acid dialkyl ester and its synthesis method. BACKGROUND

[0002] Alkylphosphonic acid dialkyl ester is a kind of additive organic phosphorus flame retardant, with high phosphorus content, excellent flame retardant performance, low price and small amount of addition, etc., has been widely used in epoxy resin, polyurethane foam, unsaturated polyester resin and other polymer materials as flame retardant additive, in recent years also as lithium battery electrolyte flame retardant additive is widely studied.Compared with traditional halogen-based flame retardant and inorganic flame retardant, alkylphosphonic acid dialkyl ester has advantages in environmental protection, self-extinguishing, plastic, low temperature resistance, ultraviolet resistance, antistatic property, etc., especially suitable for transparent or light and beautiful color products and spraying applications, is considered to be a new generation of high-efficiency flame retardant.

[0003] At present, the main domestic process route of alkylphosphonic acid dialkyl ester is to catalyze the isomerization reaction of trialkyl phosphite by using homogeneous catalyst, and the reaction path is as follows (cat is catalyst):

[0004]

[0005] In the early stage of research, iodine (such as CN103102369A) or iodomethane (such as CN101624402A) is used as catalyst for atmospheric reaction, and the conversion rate is high, but iodine or iodomethane has certain toxicity, low boiling point and instability, and cannot be recycled, so the cost is high, which greatly limits its industrial application. Patent application CN103073581A uses benzonitrile compound as catalyst and carries out reaction under alkaline condition, but the reaction pressure is higher than 1.2 MPa, and the yield is low. Patent application CN102702256A discloses a kind of environmental protection catalyst p-toluenesulfonic acid methyl ester for catalyzing trimethyl phosphite to produce dimethyl methylphosphonate, which has the characteristics of easy separation of product, simple synthesis process and reusable catalyst, but the catalyst is used at 7-10 wt%, the reaction temperature is 180-200℃, and the reaction time is 9-13 hours, which has the problems of harsh reaction conditions (high reaction temperature and long reaction time) and low production efficiency. SUMMARY

[0006] In view of the problems of non-industrial production, harsh reaction conditions and low production efficiency in the prior art, the present application provides a new synthesis method of alkylphosphonic acid dialkyl ester, which can significantly improve the conversion rate of raw materials, the selectivity of products and the yield of products, and the synthesis conditions are mild, which can be used for large-scale industrial production of alkylphosphonic acid dialkyl ester.

[0007] The application provides a synthesis method of dialkyl alkylphosphonate.

[0008]

[0009] Wherein, M is selected from metals, and n is the valence of M.

[0010] Preferably, the ionic catalyst is selected from at least one of aluminum triflate, iron triflate and sodium triflate.

[0011] Preferably, the trialkyl phosphite is selected from trimethyl phosphite and triethyl phosphite.

[0012] Preferably, the weight ratio of the raw material to the catalyst is 100: (1-5).

[0013] Preferably, the weight ratio of the raw material to the catalyst is 100: (2-4).

[0014] Preferably, the synthesis reaction condition comprises: reaction, the reaction temperature is 30-120 DEG C, and the reaction time is 0.1-5 hours.

[0015] Preferably, the synthesis reaction condition comprises: the reaction temperature is 40-80 DEG C, and the reaction time is 0.25-1 hour.

[0016] Preferably, the synthesis reaction pressure can be normal pressure or micro-positive pressure, for example, 1 kg-3 kg pressure (gauge pressure).

[0017] Preferably, the synthesis method further comprises product separation after the synthesis reaction.

[0018] Preferably, the separation condition comprises: the pressure is 0.1 kPa-0.5 kPa, the temperature is 110-130 DEG C, and the reflux time is 2-6 hours.

[0019] Preferably, the separation condition can comprise but is not limited to: using a batch rectifying column, the theoretical tray number is 20, the obtained product is subjected to vacuum rectification at 0.25 kPa and 110-130 DEG C, the rectifying column is totally refluxed for 4 hours, then the product containing light components is taken out, then the dialkyl alkylphosphonate with a purity higher than 99% is continuously taken out. The product in the column bottom is the catalyst containing dialkyl alkylphosphonate, which can be reused.

[0020] The application has the following beneficial effects:

[0021] The synthetic method of the present application is simple and efficient, the synthetic condition is mild, the conversion rate of raw material is high, the selectivity of the product dialkyl alkylphosphonate is high, and the method can be used for large-scale industrial production of dialkyl alkylphosphonate. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The nuclear magnetic resonance hydrogen spectrum of the raw material trimethyl phosphite of Example 1 is shown in the figure, and the peak of the methoxy group (-OCH2-H) is at a chemical shift of 3.51.

[0023] Figure 2 The chromatogram of the reaction product and reactant of Example 1 is shown in the figure. The internal standard method is used for quantitative analysis, ethylbenzene is used as the internal standard, methanol is used as the solvent, the single-point method is used for detection, and the internal standard and the measured substance are 1:1. The retention time is 1.44 min for methanol, 3.16 min for ethylbenzene, 3.49 min for the by-product dimethyl phosphite, 4.16 min for the main product dimethyl methylphosphonate (DMMP in the figure), and 4.63 min for the by-product trimethyl phosphate.

[0024] The present application will be further described by examples, but the content of the present application is not limited. DETAILED DESCRIPTION

[0025] In order to make the present application easier to understand, the present application will be described in detail below in combination with examples, which are only illustrative and do not limit the application range of the present application.

[0026] In the present application,

[0027] Trimethyl phosphite is a commercially available product with CAS number 121-45-9.

[0028] Triethyl phosphite is a commercially available product with CAS number 122-52-1.

[0029] Iron triflate is a commercially available product with CAS number 63295-48-7.

[0030] Aluminum triflate is a commercially available product with CAS number 74974-61-1.

[0031] Sodium triflate is a commercially available product with CAS number 2926-30-9.

[0032]

Example 1

[0033] A three-necked flask and trimethyl phosphite were treated in an ice water bath, and then trimethyl phosphite 100 mL, catalyst sodium triflate 1 g, and the weight ratio of raw material to catalyst was 100:1 were added to the three-necked flask under the protection of nitrogen atmosphere. The three-necked flask was placed in an oil bath, and a condenser was installed. The whole reaction was carried out under stirring and nitrogen atmosphere. The temperature was raised to 80°C under stirring, and the reaction was carried out for 5 h. The experimental results are shown in Table 1. Subsequently, the product was subjected to vacuum distillation at 0.25 kPa and 110-120°C. The distillation column was totally refluxed for 4 h, and then the product containing light components was collected, and then dimethyl methylphosphonate with a purity higher than 99% was continuously collected.

[0034] [Example 2]

[0035] A three-necked flask and trimethyl phosphite were treated in an ice water bath, and then trimethyl phosphite 100 mL, catalyst sodium triflate 1 g, and the weight ratio of raw material to catalyst was 100:1 were added to the three-necked flask under the protection of nitrogen atmosphere. The three-necked flask was placed in an oil bath, and a condenser was installed. The whole reaction was carried out under stirring and nitrogen atmosphere. The temperature was raised to 80°C under stirring, and the reaction was carried out for 5 h. The experimental results are shown in Table 1. Subsequently, the product was subjected to vacuum distillation at 0.25 kPa and 110-120°C. The distillation column was totally refluxed for 4 h, and then the product containing light components was collected, and then dimethyl methylphosphonate with a purity higher than 99% was continuously collected.

[0036] [Example 3]

[0037] A three-necked flask and trimethyl phosphite were treated in an ice water bath, and then trimethyl phosphite 100 mL, catalyst sodium triflate 1 g, and the weight ratio of raw material to catalyst was 100:1 were added to the three-necked flask under the protection of nitrogen atmosphere. The three-necked flask was placed in an oil bath, and a condenser was installed. The whole reaction was carried out under stirring and nitrogen atmosphere. The temperature was raised to 80°C under stirring, and the reaction was carried out for 5 h. The experimental results are shown in Table 1. Subsequently, the product was subjected to vacuum distillation at 0.25 kPa and 110-120°C. The distillation column was totally refluxed for 4 h, and then the product containing light components was collected, and then dimethyl methylphosphonate with a purity higher than 99% was continuously collected.

[0038] [Example 4]

[0039] A three necked flask and trimethyl phosphite were treated under ice water bath, then the raw material trimethyl phosphite 100 mL and catalyst iron triflate 1 g were added into the three necked flask under nitrogen atmosphere protection, the weight ratio of raw material to catalyst was 100:1. The three necked flask was put into oil bath, equipped with condenser, stirred, the whole reaction was carried out under nitrogen atmosphere. The temperature was raised to 80°C under stirring, the reaction was carried out for 5 h, the experimental results were shown in Table 1. The product was then distilled under reduced pressure at 0.25 kPa, 110-120°C. The distillation column was totally refluxed for 4 h, then the product containing light components was collected, then dimethyl methylphosphonate with purity higher than 99% was continuously collected.

[0040] [Example 5]

[0041] A three necked flask and trimethyl phosphite were treated under ice water bath, then the raw material trimethyl phosphite 100 mL and catalyst silver triflate 1 g were added into the three necked flask under nitrogen atmosphere protection, the weight ratio of raw material to catalyst was 100:1. The three necked flask was put into oil bath, equipped with condenser, stirred, the whole reaction was carried out under nitrogen atmosphere. The temperature was raised to 80°C under stirring, the reaction was carried out for 5 h, the experimental results were shown in Table 1. The product was then distilled under reduced pressure at 0.25 kPa, 110-120°C. The distillation column was totally refluxed for 4 h, then the product containing light components was collected, then dimethyl methylphosphonate with purity higher than 99% was continuously collected.

[0042] [Example 6]

[0043] A three necked flask and trimethyl phosphite were treated under ice water bath, then the raw material trimethyl phosphite 100 mL and catalyst iron triflate 3 g were added into the three necked flask under nitrogen atmosphere protection, the weight ratio of raw material to catalyst was 100:3. The three necked flask was put into oil bath, equipped with condenser, stirred, the whole reaction was carried out under nitrogen atmosphere. The temperature was raised to 60°C under stirring, the reaction was carried out for 2 h, the experimental results were shown in Table 1. The product was then distilled under reduced pressure at 0.25 kPa, 110-120°C. The distillation column was totally refluxed for 4 h, then the product containing light components was collected, then dimethyl methylphosphonate with purity higher than 99% was continuously collected.

[0044] [Example 7]

[0045] A three necked flask and trimethyl phosphite were treated under ice water bath, then the raw material trimethyl phosphite 100 mL and catalyst aluminum triflate 3 g were added into the three necked flask under nitrogen atmosphere protection, the weight ratio of raw material to catalyst was 100:3. The three necked flask was put into oil bath, equipped with condenser, stirred, the whole reaction was carried out under nitrogen atmosphere. The temperature was raised to 60°C under stirring, the reaction was carried out for 1 h, the experimental results were shown in Table 1. The product was then distilled under reduced pressure at 0.25 kPa, 110-120°C. The distillation column was totally refluxed for 4 h, then the product containing light components was collected, then dimethyl methylphosphonate with purity higher than 99% was continuously collected.

[0046] Example 8

[0047] A three necked flask and trimethyl phosphite were treated under ice water bath, then the raw material trimethyl phosphite 100 mL and catalyst aluminum triflate 3 g were added into the three necked flask under nitrogen atmosphere protection, the weight ratio of raw material to catalyst was 100:3. The three necked flask was put into oil bath, equipped with condenser, stirred, the whole reaction was carried out under nitrogen atmosphere. The temperature was raised to 60°C under stirring, the reaction was carried out for 1 h, the experimental results were shown in Table 1. The product was then distilled under reduced pressure at 0.25 kPa, 110-120°C. The distillation column was totally refluxed for 4 h, then the product containing light components was collected, then dimethyl methylphosphonate with purity higher than 99% was continuously collected.

[0048] Example 9

[0049] A three necked flask and trimethyl phosphite were treated under ice water bath, then the raw material trimethyl phosphite 100 mL and catalyst aluminum triflate 3 g were added into the three necked flask under nitrogen atmosphere protection, the weight ratio of raw material to catalyst was 100:3. The three necked flask was put into oil bath, equipped with condenser, stirred, the whole reaction was carried out under nitrogen atmosphere. The temperature was raised to 60°C under stirring, the reaction was carried out for 1 h, the experimental results were shown in Table 1. The product was then distilled under reduced pressure at 0.25 kPa, 110-120°C. The distillation column was totally refluxed for 4 h, then the product containing light components was collected, then dimethyl methylphosphonate with purity higher than 99% was continuously collected.

[0050] Example 10

[0051] A three necked flask and trimethyl phosphite were treated in an ice water bath, then the trimethyl phosphite 100 mL, catalyst aluminum triflate 3 g, the weight ratio of raw material to catalyst was 100:3 were added to the three necked flask under the protection of nitrogen atmosphere. The three necked flask was put into an oil bath, equipped with a condenser, stirred, and the whole reaction was carried out under the protection of nitrogen atmosphere. The temperature was raised to 50°C under stirring, and the reaction was carried out for 0.25 h. The experimental results are shown in Table 1. The product was then distilled under reduced pressure at 0.25 kPa, 110-120°C. The distillation column was totally refluxed for 4 h, then the product containing light components was collected, and then dimethyl methylphosphonate with purity higher than 99% was continuously collected.

[0052] [Example 11]

[0053] A three necked flask and trimethyl phosphite were treated in an ice water bath, then the trimethyl phosphite 100 mL, catalyst aluminum triflate 3 g, the weight ratio of raw material to catalyst was 100:3 were added to the three necked flask under the protection of nitrogen atmosphere. The three necked flask was put into an oil bath, equipped with a condenser, stirred, and the whole reaction was carried out under the protection of nitrogen atmosphere. The temperature was raised to 40°C under stirring, and the reaction was carried out for 0.25 h. The experimental results are shown in Table 1. The product was then distilled under reduced pressure at 0.25 kPa, 110-120°C. The distillation column was totally refluxed for 4 h, then the product containing light components was collected, and then dimethyl methylphosphonate with purity higher than 99% was continuously collected.

[0054] [Example 12]

[0055] A three necked flask and trimethyl phosphite were treated in an ice water bath, then the trimethyl phosphite 100 mL, catalyst aluminum triflate 3 g, the weight ratio of raw material to catalyst was 100:3 were added to the three necked flask under the protection of nitrogen atmosphere. The three necked flask was put into an oil bath, equipped with a condenser, stirred, and the whole reaction was carried out under the protection of nitrogen atmosphere. The temperature was raised to 100°C under stirring, and the reaction was carried out for 0.25 h. The experimental results are shown in Table 1. The product was then distilled under reduced pressure at 0.25 kPa, 110-120°C. The distillation column was totally refluxed for 4 h, then the product containing light components was collected, and then dimethyl methylphosphonate with purity higher than 99% was continuously collected.

[0056] [Example 13]

[0057] A three necked flask and trimethyl phosphite were treated under ice water bath, then the raw material trimethyl phosphite 100 mL and catalyst aluminum triflate 3 g were added into the three necked flask under nitrogen atmosphere protection, the weight ratio of raw material to catalyst was 100:3. The three necked flask was put into oil bath, equipped with condenser, stirred, the whole reaction was carried out under nitrogen atmosphere. The temperature was raised to 120°C under stirring, the reaction was 0.25 h, the experimental results were shown in Table 1. The product was then distilled under reduced pressure at 0.25 kPa, 110-120°C. The distillation column was totally refluxed for 4 hours, then the product containing light components was collected, then dimethyl methylphosphonate with purity higher than 99% was continuously collected.

[0058] [Example 14]

[0059] A three necked flask and trimethyl phosphite were treated under ice water bath, then the raw material trimethyl phosphite 100 mL and catalyst aluminum triflate 3 g were added into the three necked flask under nitrogen atmosphere protection, the weight ratio of raw material to catalyst was 100:3. The three necked flask was put into oil bath, equipped with condenser, stirred, the whole reaction was carried out under nitrogen atmosphere. The temperature was raised to 120°C under stirring, the reaction was 0.25 h, the experimental results were shown in Table 1. The product was then distilled under reduced pressure at 0.25 kPa, 110-120°C. The distillation column was totally refluxed for 4 hours, then the product containing light components was collected, then dimethyl methylphosphonate with purity higher than 99% was continuously collected.

[0060] [Example 15]

[0061] A three necked flask and triethyl phosphite were treated under ice water bath, then the raw material triethyl phosphite 100 mL and catalysts iron triflate 2.5 g and aluminum triflate 2.5 g were added into the three necked flask under nitrogen atmosphere protection, the weight ratio of raw material to catalyst was 100:5. The three necked flask was put into oil bath, equipped with condenser, stirred, the whole reaction was carried out under nitrogen atmosphere. The temperature was raised to 80°C under stirring, the reaction was 5 h, the experimental results were shown in Table 2. The product was then distilled under reduced pressure at 0.25 kPa, 120-130°C. The distillation column was totally refluxed for 4 hours, then the product containing light components was collected, then diethyl ethylphosphonate with purity higher than 99% was continuously collected.

[0062] [Example 16]

[0063] A three necked flask and triethyl phosphite were treated in an ice water bath and then the triethyl phosphite 100 mL, catalyst sodium triflate 1 g, ratio of raw material to catalyst 100:1 was added to the three necked flask under nitrogen atmosphere. The three necked flask was placed in an oil bath, fitted with a condenser and stirred. The temperature was raised to 80°C under stirring and the reaction was allowed to proceed for 5 hours. The results are shown in Table 2. The product was then distilled under reduced pressure at 0.25 kPa, 120-130°C. The column was refluxed for 4 hours and then the product containing light components was collected. The diethyl ethylphosphonate with purity greater than 99% was then collected continuously.

[0064] Example 17

[0065] A three necked flask and triethyl phosphite were treated in an ice water bath and then the triethyl phosphite 100 mL, catalyst aluminum triflate 3 g, ratio of raw material to catalyst 100:3 was added to the three necked flask under nitrogen atmosphere. The three necked flask was placed in an oil bath, fitted with a condenser and stirred. The temperature was raised to 60°C under stirring and the reaction was allowed to proceed for 2 hours. The results are shown in Table 2. The product was then distilled under reduced pressure at 0.25 kPa, 120-130°C. The column was refluxed for 4 hours and then the product containing light components was collected. The diethyl ethylphosphonate with purity greater than 99% was then collected continuously.

[0066] Example 18

[0067] A three necked flask and triethyl phosphite were treated in an ice water bath and then the triethyl phosphite 100 mL, catalyst aluminum triflate 3 g, ratio of raw material to catalyst 100:3 was added to the three necked flask under nitrogen atmosphere. The three necked flask was placed in an oil bath, fitted with a condenser and stirred. The temperature was raised to 60°C under stirring and the reaction was allowed to proceed for 2 hours. The results are shown in Table 2. The product was then distilled under reduced pressure at 0.25 kPa, 120-130°C. The column was refluxed for 4 hours and then the product containing light components was collected. The diethyl ethylphosphonate with purity greater than 99% was then collected continuously.

[0068] Table 1 Results of dimethyl methylphosphonate synthesis

[0069]

[0070] Table 2 Results of diethyl ethylphosphonate synthesis

[0071]

[0072] Comparative Example 1

[0073] The method of Example 5 of patent CN102702256A was used: a three-necked flask and trimethyl phosphite were treated at low temperature at 0°C, then trimethyl phosphite 50 g and catalyst methyl p-toluenesulfonate 6 g were added to the three-necked flask under the protection of nitrogen atmosphere, the weight ratio of the two was 100:12. The three-necked flask was placed in an oil bath, a condenser was installed, and stirring was performed, the whole reaction was carried out under the protection of nitrogen atmosphere. The temperature was increased to 200°C under stirring, the reaction was carried out for 13 h, and the reaction yield was 83.4%.

[0074] It can be seen from the results of the examples and comparative examples that the raw material conversion rate of the synthetic method of the present application can reach 100%, the selectivity of the product can reach more than 90%, and further, it is illustrated that the synthetic method of the present application has a high reaction yield, and under the conditions which are obviously milder than those of Comparative Example 1 (the reaction temperature and reaction time are obviously lower than those of Comparative Example 1), a yield which is obviously higher than that of Comparative Example 1 can be obtained.

[0075] In addition, it can be seen from the results of the examples and comparative examples that the raw material conversion rate of the synthetic method of the present application can reach 100%, the selectivity of the product can reach more than 90%, and further, it is illustrated that the synthetic method of the present application has a high reaction yield, and under the conditions which are obviously milder than those of Comparative Example 1 (the reaction temperature and reaction time are obviously lower than those of Comparative Example 1), a yield which is obviously higher than that of Comparative Example 1 can be obtained. Figure 1 and Figure 2 It can be seen from the results of the examples and comparative examples that the raw material conversion rate of the synthetic method of the present application can reach 100%, the selectivity of the product can reach more than 90%, and further, it is illustrated that the synthetic method of the present application has a high reaction yield, and under the conditions which are obviously milder than those of Comparative Example 1 (the reaction temperature and reaction time are obviously lower than those of Comparative Example 1), a yield which is obviously higher than that of Comparative Example 1 can be obtained. Figure 1 is the raw material chromatogram, Figure 2 is the product chromatogram after reaction. By comparison, it can be illustrated that the trimethyl phosphite raw material is completely reacted to generate dimethyl methylphosphonate and a small amount of by-product.

[0076] The above only describes the preferred examples of the present application. It should be noted that for those skilled in the art, under the technical inspiration provided by the present application, other equivalent modifications and improvements can also be made as the common knowledge in the art, and should also be considered as the protection scope of the present application.

Claims

1. A method of synthesizing a dialkyl alkylphosphonate comprising: The ion type catalyst is used to carry out a synthesis reaction with trialkyl phosphite as raw material, wherein the ion type catalyst has a structure shown in formula (I). Formula (I), M is selected from metals, and n is the valence of M, The ion type catalyst is selected from at least one of aluminum triflate, iron triflate and sodium triflate.

2. The method of synthesis of claim 1, wherein, The trialkyl phosphite is selected from trimethyl phosphite and triethyl phosphite.

3. The method of synthesis according to any one of claims 1-2, wherein, The weight ratio of the raw material to the catalyst is 100:(1-5).

4. The method of synthesis of claim 3, wherein, The weight ratio of the raw material to the catalyst is 100:(2-4).

5. The method of synthesis according to any one of claims 1-2, wherein, The synthesis reaction is carried out at a temperature of 30-120 DEG C for 0.1-5 hours.

6. The method of synthesis of claim 5, wherein, The synthesis reaction is carried out at a temperature of 40-80 DEG C for 0.25-1 hours.

7. The method of synthesis of any one of claims 1-2, wherein, The synthesis method further comprises a product separation after the synthesis reaction.

8. The method of synthesis of claim 7, wherein, The separation conditions include a pressure of 0.1-0.5 kPa, a temperature of 110-130 DEG C, and refluxing for 2-6 hours.

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