Preparation method of phosphorus-nitrogen synergistic flame retardant

Abstract

The invention discloses a preparation method of a phosphorus-nitrogen synergistic flame retardant. The method comprises the following steps: by taking neopentyl glycol and phosphoryl chloride as initial raw materials, reacting to obtain corresponding cyclic phosphoryl chloride, and further reacting with methanol to obtain corresponding methyl phosphate; and reacting with different diamines under the action of a strongly alkaline catalyst to obtain the phosphoramidate. The target phosphoramidate is obtained through amine-ester exchange and by selecting the specific strong basic catalyst, the problems that in the traditional acyl chloride and amine reaction process, by-products are many, and the separation cost is high can be effectively solved, and the preparation method is high in product yield and easy to separate. The phosphoramidate can be used as a phosphorus-nitrogen synergistic flame retardant.

Description

Technical Field

[0001] The invention relates to a method for preparing a phosphorus-nitrogen synergistic flame retardant. Background Art

[0002] Due to the demand for flame retardant properties of materials in various industries, flame retardants have become important additives in polymer materials such as textiles, leather and engineering plastics. Phosphorus-containing flame retardants have excellent flame retardant efficiency, and are also low-toxic and smokeless. When phosphorus-based flame retardants and nitrogen-based flame retardants are used in combination, a synergistic flame retardant effect of phosphorus and nitrogen can be achieved, but its stability and compatibility are slightly poor. The phosphorus-nitrogen synergistic single-component intumescent flame retardant can synergistically exert flame retardant effects from three dimensions: carbon source, acid source and gas source during flame retardancy. It has flame retardant effects of heat insulation, oxygen isolation, smoke suppression and prevention of droplets. It has good compatibility with the matrix and has little effect on the mechanical processing properties of the material. Therefore, it is very popular in the field of flame retardants.

[0003] Patent CN104558685B discloses a method for synthesizing a phosphorus-nitrogen intumescent flame retardant. First, at low temperature, neopentyl glycol and phosphorus oxychloride are reacted with a catalyst to generate cyclic phosphorus oxychloride; then, under the action of an acid binding agent, the reaction is carried out with a diamine compound, and after separation by distillation, a phosphorus-nitrogen intumescent flame retardant is obtained, which has a good flame retardant effect in polymer materials such as polycarbonate. The synthesis method uses phosphorus oxychloride and a polyol reaction (such as neopentyl glycol) to react to generate cyclic phosphorus oxychloride, which is then reacted with a corresponding amine to obtain aminophosphoric acid ester. The first step product of the method is phosphorus oxychloride, and the reaction releases hydrogen chloride, and hydrogen chloride is also released when phosphorus oxychloride and amine react in the second step. The hydrogen chloride generated by the two-step reaction consumes a portion of the raw material amine, increasing production costs. Even in the presence of an acid binding agent such as triethylamine, it is inevitable that part of the raw material amine is consumed by hydrogen chloride, generating by-products, and reducing the yield of the target product. In addition, the monoaminophosphoric acid ester intermediate generated by the amidation reaction of the raw material diamine in the second step will also react with the generated hydrogen chloride to generate by-products, further reducing the yield of the target product, and there are also problems such as difficult separation and poor product quality. When synthesizing phosphorus-nitrogen synergistic flame retardants, how to increase the yield of the target product and make it easy to separate is a difficult point. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an improved method for preparing a phosphorus-nitrogen synergistic flame retardant in view of the shortcomings and deficiencies of the prior art. The preparation method has a high yield of the target product, few side reactions, and the product is easy to separate with low separation cost.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A method for preparing a phosphorus-nitrogen flame retardant, the method comprising: preparing a cyclic methyl phosphate represented by formula III and diamine in the presence of a catalyst in an organic solvent to react to produce the phosphorus-nitrogen flame retardant;

[0007] The phosphorus-nitrogen flame retardant has a structure shown in Formula I or Formula II;

[0008]

[0009] In formula I, X is O or S, and R is selected from a C2-C8 alkylene group or a phenylene group;

[0010] In formula II and formula III, X is O or S;

[0011] The catalyst is selected from one or more combinations of 4-dimethylaminopyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5,7-triazabicyclo[4.4.0]decene-5-ene, potassium tert-butoxide, sodium methoxide, sodium ethoxide, potassium ethoxide, potassium hydroxide, lithium bis(trimethylsilyl)amide, sodium bis(trimethylsilyl)amide, and potassium bis(trimethylsilyl)amide.

[0012] In some embodiments, in Formula I, R is selected from C2-C6 alkylene or phenylene.

[0013] In some embodiments, in Formula I, R is selected from a C2-C6 straight chain alkylene or phenylene.

[0014] In some embodiments, in Formula I, R is selected from -CH2-, -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, -CH2CH2CH2CH2-, -CH2CH2CH2CH2CH2-, -CH2CH2CH2CH2CH2-, -CH2CH2CH2CH2CH2CH2-, or phenylene.

[0015] In some embodiments, the diamine is selected from ethylenediamine, 1,3-propylenediamine, 1,4-butylenediamine, 1,5-diaminopentane, 1,6-hexanediamine, piperazine When the diamine is piperazine, the final phosphorus-nitrogen flame retardant is of formula II structure; when the diamine is other substances, the final phosphorus-nitrogen flame retardant is of formula I structure.

[0016] In some embodiments, the organic solvent is selected from a combination of one or more of toluene, xylene, tetrahydrofuran, dioxane, ether, chloroform, and dichloroethane.

[0017] In some embodiments, the molar ratio of the cyclic methyl phosphate to the diamine is 1:0.5 to 1.0.

[0018] In some embodiments, the molar ratio of the diamine to the catalyst is 1:0.2 to 4.0.

[0019] In some embodiments, the reaction temperature is 0°C to 110°C, preferably 0°C to 90°C.

[0020] In the prior art, when synthesizing phosphorus-nitrogen flame retardants, neopentyl glycol and phosphorus oxychloride are usually used to first generate cyclic phosphorus oxychloride, which is then reacted with a diamine compound under the action of an acid binding agent, and the target phosphorus-nitrogen flame retardant is obtained after a relatively complex post-treatment. Hydrogen chloride will be released in the above two-step reaction, and the raw material amine will react with hydrogen chloride by side reaction, consuming part of the amine, resulting in a low yield of the target product of the phosphorus-nitrogen flame retardant. The inventors of the present application have found through research that instead of using cyclic phosphorus oxychloride, cyclic methyl phosphate shown in formula III is used The target phosphoramidate phosphorus-nitrogen flame retardant can be prepared by reacting with a diamine compound, and the amine ester exchange reaction is carried out under a specific strong alkaline catalyst, so that the target phosphoramidate phosphorus-nitrogen flame retardant can be prepared with high yield and easy product separation. The side reactions of the reaction are significantly suppressed, so the yield of the target product is high.

[0021] In some embodiments, the preparation method further comprises cyclophosphoxyl chloride represented by formula IV The step of reacting with methanol in the presence of an acid-binding agent to generate the cyclophosphomethyl ester shown in formula III; in formula IV, X is O or S. That is, the cyclophosphoxylic acid chloride of the present application does not react directly with the diamine compound, but first reacts with methanol to obtain the corresponding ester, and then reacts with the diamine compound.

[0022] In some embodiments, the acid binding agent is selected from a combination of one or more of triethylamine, N,N-diisopropylethylamine, pyridine, piperidine, alkali metal hydroxides, alkali metal carbonates and alkali metal bicarbonates.

[0023] In some embodiments, the alkali metal hydroxide is preferably NaOH and / or KOH, the alkali metal carbonate is preferably Na2CO3 and / or K2CO3, and the alkali metal bicarbonate is preferably NaHCO3 and / or KHCO3.

[0024] In some embodiments, the molar ratio of cyclophosphoxychloride to methanol is 1:1.5-3.2.

[0025] In some embodiments, the molar ratio of the acid binding agent to methanol is 0.3-0.8:1.

[0026] In some embodiments, in the step of generating methyl cyclic phosphate, the reaction temperature is 50°C to 110°C, preferably 80°C to 100°C.

[0027] In some embodiments, the preparation method further comprises the step of reacting neopentyl glycol with phosphorus oxychloride or phosphorus thiochloride in a solvent to generate cyclophosphoxychloride represented by formula IV.

[0028] In some embodiments, the molar ratio of the neopentyl glycol to phosphorus oxychloride or phosphorus thiochloride is 1:0.98-1.3, preferably 1:1.01-1.1.

[0029] In some embodiments, the molar ratio of methanol to neopentyl glycol is 1 to 5:1, preferably 1 to 3:1.

[0030] In some embodiments, the molar ratio of the diamine to neopentyl glycol is 0.3 to 2:1, preferably 0.5 to 1.5:1.

[0031] In some embodiments, the molar ratio of the catalyst to neopentyl glycol is 0.01 to 3:1, preferably 0.01 to 2:1.

[0032] In some embodiments, in the step of generating cyclophosphoxyl chloride, the reaction temperature is 0°C to 50°C, preferably 10°C to 30°C.

[0033] The present invention also provides a compound suitable for preparing the aforementioned phosphorus-nitrogen flame retardant, wherein the compound has a structure shown in the following formula III:

[0034]

[0035] Wherein X is O or S.

[0036] Compared with the prior art, the present invention has the following technical advantages:

[0037] The present application does not use cyclic phosphoryl chloride, but uses cyclic methyl phosphate shown in formula III The target phosphoramidate phosphorus-nitrogen flame retardant can be prepared by reacting with a diamine compound, and the amine ester exchange reaction is carried out under a specific strong alkaline catalyst, so that the target phosphoramidate phosphorus-nitrogen flame retardant can be prepared with high yield and easy product separation. The side reactions of the reaction are significantly suppressed, so the yield of the target product is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is the NMR spectrum of the target product prepared in Example 3. DETAILED DESCRIPTION

[0039] The present invention is further described below in conjunction with examples, but the examples are not intended to limit the scope of protection of the present invention.

[0040] The technical features of the embodiments described below can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the embodiments described below are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0041] The following embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, 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 attached claims.

[0042] Example 1

[0043] This embodiment provides a method for preparing a phosphorus-nitrogen synergistic flame retardant (structure of formula I, wherein X is O and R is phenylene):

[0044] In a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, 300mL of toluene and 104.15g of neopentyl glycol (1.00mol) were added, and 168.66g of phosphorus oxychloride (1.10mol) was added to the reaction system through a constant pressure dropping funnel. The reaction temperature was controlled to 20°C, and the reaction was stirred for 5h. The generated hydrogen chloride gas was discharged during the reaction. After the reaction, 111.3g of triethylamine (1.10mol) and 64.08g of methanol (2.00mol) were added, and the reaction temperature was controlled to 60°C. The reaction was continued for 4h. After the reaction was completed, the solvent was recovered by vacuum distillation. The crude product was washed 3 times with distilled water and dried under vacuum at 60°C for 6h to obtain a methyl phosphate intermediate with a yield of 95.2%.

[0045] The specific values ​​of the hydrogen nuclear magnetic resonance spectrum are as follows: 1 H NMR(CDCl3): δ0.92(s,3H),1.33(s,3H),3.95-3.99(m,2H),4.02-4.06(m,2H),4.22-4.26(m,4H),4.01(s,3H).

[0046] The methyl phosphate intermediate obtained above was added into a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, and 300mL of toluene, 54.07g of p-phenylenediamine (0.50mol) and 8.42g of potassium ethanolate (0.10mol) were added, and the mixture was reacted at 50°C for 20h. The solvent was filtered off, and the crude product was washed three times with distilled water and dried in vacuo at 60°C to obtain the target product. The yield of the entire reaction process starting from neopentyl glycol was 93.6%.

[0047] The specific values ​​of the hydrogen nuclear magnetic resonance spectrum are as follows: 1 H NMR(DMSO-d6): δ0.90(s,6H,),1.02(s,6H),3.81-3.86(m,4H),3.97-4.00(m,4H),6.23-6.25(m,2H),6.85-6.96(m,4H).

[0048] Example 2

[0049] This embodiment provides a method for preparing a phosphorus-nitrogen synergistic flame retardant (structure of formula I, wherein X is O and R is phenylene):

[0050] In a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, 300mL of dioxane and 104.15g of neopentyl glycol were added, and 168.66g of phosphorus oxychloride was added to the reaction system through a constant pressure dropping funnel. The reaction temperature was controlled to 20°C, and the reaction was stirred for 5 hours. The generated hydrogen chloride gas was discharged during the reaction. After the reaction, 82.9g of potassium carbonate (0.60mol) and 64.08g of methanol were added, and the reaction temperature was controlled to 60°C. The reaction was continued for 4 hours. After the reaction was completed, the solvent was recovered by vacuum distillation. The crude product was washed 3 times with distilled water and dried under vacuum at 60°C for 6 hours to obtain a methyl phosphate intermediate with a yield of 95.9%.

[0051] The obtained methyl phosphate intermediate was added into a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, and 300mL of dioxane, 54.07g of p-phenylenediamine and 5.4g of sodium methoxide (0.10mol) were added. The mixture was reacted at 50°C for 20h, and the solvent was removed by filtration. The crude product was washed three times with distilled water and dried in vacuo at 60°C to obtain the target product. The yield of the entire reaction process starting from neopentyl glycol was 93.7%.

[0052] The specific values ​​of the hydrogen nuclear magnetic resonance spectrum are as follows: 1 H NMR(DMSO-d6): δ0.90(s,6H,),1.02(s,6H),2.78-2.80(m,4H),6.25(m,2H),6.93-7.06(m,4H).

[0053] Example 3

[0054] This embodiment provides a method for preparing a phosphorus-nitrogen synergistic flame retardant (structure of formula I, wherein X is O and R is -CH2CH2-):

[0055] In a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, 300mL of toluene and 104.15g of neopentyl glycol were added, and 165.6g of phosphorus oxychloride (1.08mol) was added to the reaction system through a constant pressure dropping funnel. The reaction temperature was controlled to 25°C, and the reaction was stirred for 4h. The generated hydrogen chloride gas was discharged during the reaction. After the reaction, 74.2g of sodium carbonate (0.70mol) and 64.08g of methanol were added, and the reaction temperature was controlled to 70°C. The reaction was continued for 4h. After the reaction was completed, the solvent was recovered by vacuum distillation. The crude product was washed 3 times with distilled water and dried under vacuum at 60°C for 6h to obtain a methyl phosphate intermediate with a yield of 98.3%.

[0056] The obtained methyl phosphate intermediate was added into a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, and 300mL of toluene, 30.05g of ethylenediamine (0.50mol) and 30.45g of 1,8-diazabicyclo[5.4.0]undec-7-ene (0.20mol) were added, and the mixture was reacted at 70°C for 12h, and the solvent was filtered off. The crude product was washed three times with distilled water and dried under vacuum at 60°C to obtain the target product (NMR spectrum as shown in FIG. Figure 1 The yield of the whole reaction process starting from neopentyl glycol was 95.2%.

[0057] The specific values ​​of the hydrogen nuclear magnetic resonance spectrum are as follows: 1 H NMR(DMSO-d6): δ0.90(s,6H),1.02(s,6H),2.80-2.84(m,4H),3.81-3.86(m,4H),3.97-4.00(m,4H),5.18-5.23(m,2H).

[0058] Example 4

[0059] This embodiment provides a method for preparing a phosphorus-nitrogen synergistic flame retardant (structure of formula I, wherein X is O and R is -CH2CH2CH2-):

[0060] In a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, 300mL of toluene and 104.15g of neopentyl glycol were added, and 161.00g of phosphorus oxychloride (1.05mol) was added to the reaction system through the constant pressure dropping funnel, the reaction temperature was controlled to 15°C, and the reaction was stirred for 5h. The generated hydrogen chloride gas was discharged during the reaction. After the reaction was completed, 85.4g of pyridine (1.08mol) and 96.12g of methanol (3.00mol) were added, the reaction temperature was controlled to 80°C, and the reaction was carried out for 4h to obtain a methyl phosphate intermediate with a yield of 96.7%.

[0061] The obtained methyl phosphate intermediate was added into a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, and 300mL of toluene, 51.88g of 1,3-propylenediamine (0.70mol) and 41.76g of 1,5,7-triazabicyclo[4.4.0]decene-5-ene (0.30mol) were added, and the mixture was reacted at 75°C for 12h. The solvent was filtered off, and the crude product was washed three times with distilled water and dried in vacuo at 60°C to obtain the target product. The yield of the entire reaction process starting from neopentyl glycol was 95.4%.

[0062] The specific values ​​of the hydrogen nuclear magnetic resonance spectrum are as follows: 1 H NMR(DMSO-d6): δ0.90(s,6H,),1.02(s,6H),1.73-1.75(m,2H),2.61-2.64(m,4H),3.97-4.02(m,4H),4.13-4.16(m,4H),5.20-5.25(m,2H).

[0063] Example 5

[0064] This embodiment provides a method for preparing a phosphorus-nitrogen synergistic flame retardant (structure of formula I, wherein X is O and R is -CH2CH2CH2-):

[0065] In a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, 300mL of xylene and 104.15g of neopentyl glycol were added, and 159.46g of phosphorus oxychloride (1.03mol) was added to the reaction system through the constant pressure dropping funnel, and the reaction temperature was controlled to 30°C, and the reaction was stirred for 5h. The generated hydrogen chloride gas was discharged during the reaction. After the reaction was completed, 193.9g of diisopropylethylamine (1.50mol) and 64.08g of methanol were added, and the reaction temperature was controlled to 90°C. The reaction was carried out for 4h to obtain a methyl phosphate intermediate with a yield of 97.2%.

[0066] The obtained methyl phosphate intermediate was added into a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, and 300mL of xylene, 66.71g of 1,3-propylenediamine (0.90mol) and 55.68g of 1,5,7-triazabicyclo[4.4.0]decene-5-ene (0.40mol) were added, and the mixture was reacted at 75°C for 12h. The solvent was filtered off, and the crude product was washed three times with distilled water and dried in vacuo at 60°C to obtain the target product. The yield of the entire reaction process starting from neopentyl glycol was 93.7%.

[0067] The specific values ​​of the hydrogen nuclear magnetic resonance spectrum are as follows: 1H NMR(DMSO-d6): δ0.90(s,6H,),1.02(s,6H),1.73-1.75(m,2H),2.61-2.64(m,4H),3.97-4.02(m,4H),4.13-4.16(m,4H),5.20-5.25(m,2H).

[0068] Example 6

[0069] This embodiment provides a method for preparing a phosphorus-nitrogen synergistic flame retardant (structure of formula I, wherein X is O and R is -CH2CH2CH2-):

[0070] In a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, 300mL of tetrahydrofuran and 104.15g of neopentyl glycol were added, and 171.73g of phosphorus oxychloride (1.12mol) was added to the reaction system through the constant pressure dropping funnel, the reaction temperature was controlled to 25°C, and the reaction was stirred for 5h. The generated hydrogen chloride gas was discharged during the reaction. After the reaction was completed, 110.1g of potassium bicarbonate (1.10mol) and 57.67g of methanol (1.80mol) were added, the reaction temperature was controlled to 85°C, and the reaction was carried out for 4h to obtain a methyl phosphate intermediate with a yield of 98.1%.

[0071] The obtained methyl phosphate intermediate was added into a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, and 300mL of tetrahydrofuran, 52.89g of 1,3-propylenediamine (0.71mol) and 11.22g of potassium hydroxide (0.20mol) were added, and the mixture was reacted at 65°C for 12h. The solvent was filtered off, and the crude product was washed three times with distilled water and dried in vacuo at 60°C to obtain the target product. The yield of the entire reaction process starting from neopentyl glycol was 95.5%.

[0072] The specific values ​​of the hydrogen nuclear magnetic resonance spectrum are as follows: 1 H NMR(DMSO-d6): δ0.90(s,6H,),1.02(s,6H),1.73-1.75(m,2H),2.61-2.64(m,4H),3.97-4.02(m,4H),4.13-4.16(m,4H),5.20-5.25(m,2H).

[0073] Example 7

[0074] This embodiment provides a method for preparing a phosphorus-nitrogen synergistic flame retardant (structure of formula I, wherein X is O and R is -CH2CH2CH2CH2CH2CH2CH2-):

[0075] In a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, 300mL of ethylene dichloride and 104.15g of neopentyl glycol were added, and 150.4g of phosphorus oxychloride (0.98mol) was added to the reaction system through the constant pressure dropping funnel. The reaction temperature was controlled to 15°C, and the reaction was stirred for 5h. The generated hydrogen chloride gas was discharged during the reaction. After the reaction was completed, 121.4g of triethylamine and 70.49g of methanol (2.20mol) were added, and the reaction temperature was controlled to 85°C. The reaction was carried out for 4h to obtain a methyl phosphate intermediate with a yield of 98.3%.

[0076] The obtained methyl phosphate intermediate was added into a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, and 300mL of dichloroethane, 81.74g of 1,6-pentanediamine (0.70mol) and 550.11g of sodium bis(trimethylsilyl)amide (3.00mol) were added. The mixture was reacted at 25°C for 15h, and the solvent was removed by filtration. The crude product was washed three times with distilled water and dried in vacuo at 60°C to obtain the target product. The yield of the entire reaction process starting from neopentyl glycol was 95.9%.

[0077] The specific values ​​of the nuclear magnetic resonance hydrogen spectrum are as follows:.

[0078] 1 H NMR(DMSO-d6): δ0.90(s,6H,),1.02(s,6H),1.36-1.39(m,2H),1.50-1.64(m,2 H),2.78-2.80(m,4H),3.65-3.68(m,4H),3.80-3.85(m,4H),4.98-5.04(m,2H).

[0079] Example 8

[0080] This embodiment provides a method for preparing a phosphorus-nitrogen synergistic flame retardant (structure of formula I, wherein X is O and R is -CH2CH2CH2CH2CH2CH2CH2-):

[0081] In a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, 300mL of ethylene dichloride and 104.15g of neopentyl glycol were added, and 150.4g of phosphorus oxychloride was added to the reaction system through a constant pressure dropping funnel. The reaction temperature was controlled to 15°C, and the reaction was stirred for 5h. The generated hydrogen chloride gas was discharged during the reaction. After the reaction was completed, 121.4g of triethylamine (1.20mol) and 70.49g of methanol were added, and the reaction temperature was controlled to 85°C. The reaction was continued for 4h to obtain a methyl phosphate intermediate with a yield of 98.3%.

[0082] The obtained methyl phosphate intermediate was added into a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, and 300mL of dichloroethane, 92.96g of 1,6-hexanediamine (0.80mol) and 550.11g of sodium bis(trimethylsilyl)amide were added. The reaction was carried out at 25°C for 15h, and the solvent was filtered to remove the solvent. The crude product was washed three times with distilled water and dried in vacuo at 60°C to obtain the target product. The yield of the entire reaction process starting from neopentyl glycol was 95.6%.

[0083] 1 H NMR(DMSO-d6): δ0.90(s,6H,),1.02(s,6H),1.26-1.40(m,2H),1.51-1.65(m,2 H),2.78-2.80(m,4H),3.65-3.68(m,4H),3.80-3.85(m,4H),4.98-5.04(m,2H).

[0084] Example 9

[0085] This embodiment provides a method for preparing a phosphorus-nitrogen synergistic flame retardant (structure of formula I, wherein X is S and R is -CH2CH2-):

[0086] In a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, 300mL of xylene and 104.15g of neopentyl glycol were added, and 182.95g of trichlorothiophosphorus (1.08mol) was added to the reaction system through a constant pressure dropping funnel, and the reaction temperature was controlled to 40°C, and the reaction was stirred for 5h. The generated hydrogen chloride gas was discharged during the reaction. After the reaction was completed, 72.9g of potassium hydroxide and 64.08g of methanol were added, and the reaction temperature was controlled to 60°C. The reaction was continued for 4h to obtain a methyl phosphate intermediate with a yield of 97.2%.

[0087] The obtained methyl phosphate intermediate was added into a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, and 300mL of xylene, 30.05g of ethylenediamine (0.50mol) and 30.45g of 1,8-diazabicyclo[5.4.0]undec-7-ene (0.20mol) were added, and the mixture was reacted at 70°C for 12h. The solvent was filtered off, and the crude product was washed three times with distilled water and dried in vacuo at 60°C to obtain the target product. The yield of the entire reaction process starting from neopentyl glycol was 95.2%.

[0088] The specific values ​​of the hydrogen nuclear magnetic resonance spectrum of the methyl phosphate intermediate are as follows: 1H NMR(CDCl3): δ0.92(s,3H,),1.33(s,3H),3.95-3.99(m,2H),4.02-4.06(m,2H),4.22-4.26(m,4H),3.98(s,3H).

[0089] The specific values ​​of the nuclear magnetic resonance hydrogen spectrum of the final target product are as follows: 1 H NMR(DMSO-d6): δ0.90(s,6H,),1.02(s,6H),2.78-2.80(m,4H),3.64-3.68(m,4H),3.80-3.85(m,4H),4.98-5.04(m,4H).

[0090] Example 10

[0091] This embodiment provides a method for preparing a phosphorus-nitrogen synergistic flame retardant (structure of formula I, wherein X is S and R is phenylene):

[0092] In a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, 300mL of dioxane and 104.15g of neopentyl glycol were added, and 186.34g of trichlorothiophosphorus (1.1mol) was added to the reaction system through a constant pressure dropping funnel, and the reaction temperature was controlled to 20°C, and the reaction was stirred for 5h. The generated hydrogen chloride gas was discharged during the reaction. After the reaction was completed, 72.9g of potassium hydroxide and 64.08g of methanol were added, and the reaction temperature was controlled to 60°C. The reaction was continued for 4h to obtain a methyl phosphate intermediate with a yield of 97.2%.

[0093] The obtained methyl phosphate intermediate was added into a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, and 300mL of dioxane, 54.07g of p-phenylenediamine and 5.4g of sodium methoxide were added. The reaction was carried out at 50°C for 24h, and the solvent was filtered out. The crude product was washed three times with distilled water and dried in vacuo at 60°C to obtain the target product. The yield of the entire reaction process starting from neopentyl glycol was 95.4%.

[0094] The specific values ​​of the nuclear magnetic resonance hydrogen spectrum of the final target product are as follows: 1 H NMR(DMSO-d6): δ0.90(s,6H,),1.02(s,6H),3.78-3.83(m,4H),3.96-3.99(m,4H),6.20-6.23(m,2H),6.81-6.93(m,4H).

[0095] Embodiment 11

[0096] This embodiment provides a method for preparing a phosphorus-nitrogen synergistic flame retardant (structure of formula II, wherein X is O):

[0097] In a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, 300mL of xylene and 104.15g of neopentyl glycol were added, and 159.46g of phosphorus oxychloride (1.03mol) was added to the reaction system through the constant pressure dropping funnel, and the reaction temperature was controlled to 30°C, and the reaction was stirred for 5h. The generated hydrogen chloride gas was discharged during the reaction. After the reaction was completed, 193.9g of diisopropylethylamine (1.50mol) and 64.08g of methanol were added, and the reaction temperature was controlled to 90°C. The reaction was carried out for 4h to obtain a methyl phosphate intermediate with a yield of 97.2%.

[0098] The obtained methyl phosphate intermediate was added into a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a constant pressure dropping funnel, and 300mL of xylene, 77.52g of piperazine (0.90mol) and 55.68g of 1,5,7-triazabicyclo[4.4.0]decene-5-ene (0.40mol) were added, and the mixture was reacted at 75°C for 12h. The solvent was filtered off, and the crude product was washed three times with distilled water and dried in vacuo at 60°C to obtain the target product. The yield of the entire reaction process starting from neopentyl glycol was 93.2%.

[0099] The specific values ​​of the nuclear magnetic resonance hydrogen spectrum of the final target product are as follows: 1 H NMR(DMSO-d6): δ0.90(s,6H,),1.02(s,6H),2.86-2.89(m,4H),2.78-2.80(m,4H),3.65-3.68(m,4H),3.80-3.85(m,4H).

[0100] Comparative Example 1

[0101] This comparative example provides a preparation method of a phosphorus-nitrogen synergistic flame retardant (formula I structure, wherein X is O and R is -CH2CH2-): basically the same as Example 3, except that 0.20 mol of 1,8-diazabicyclo[5.4.0]undec-7-ene is replaced with 0.20 mol of triethylamine (i.e., the catalyst type of the third step amine transesterification is replaced). It is found that the yield of the entire reaction process starting from neopentyl glycol is 35.0%.

[0102] Comparative Example 2

[0103] This comparative example provides a preparation method of a phosphorus-nitrogen synergistic flame retardant (formula I structure, wherein X is O and R is -CH2CH2-): basically the same as Example 3, except that 0.20 mol of 1,8-diazabicyclo[5.4.0]undec-7-ene is replaced with 0.20 mol of N,N-diisopropylethylamine (i.e., the catalyst type of the third step amine transesterification is replaced). It is found that the yield of the entire reaction process starting from neopentyl glycol is 30.5%.

[0104] Comparative Example 3

[0105] This comparative example provides a method for preparing a phosphorus-nitrogen synergistic flame retardant (formula I structure, wherein X is O and R is -CH2CH2-): a conventional prior art method is adopted, i.e., cyclic phosphoryl chloride is directly reacted with a diamine compound to generate the target phosphorus-nitrogen flame retardant, as follows:

[0106] In a 1L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, 300mL of toluene and 104.15g of neopentyl glycol were added, and 165.6g of phosphorus oxychloride (1.08mol) was added to the reaction system through the constant pressure dropping funnel, and the reaction temperature was controlled to be 25°C, and the reaction was stirred for 4h, and the generated hydrogen chloride gas was discharged during the reaction. After the reaction was completed, 30.05g of ethylenediamine (0.50mol) and 0.20mol of sodium carbonate (as an acid binding agent) were added, and the reaction was carried out at 70°C for 12h, and the solvent was filtered to remove the solvent. The crude product was washed three times with distilled water and dried in vacuo at 60°C to obtain the target product. The yield of the entire reaction process starting from neopentyl glycol was 47.3%.

[0107] It can be seen that the present invention obtains the target phosphoramidate flame retardant by amine transesterification and selecting a specific strong alkaline catalyst, which can effectively avoid the problems of many by-products and high separation cost in the traditional reaction process of acyl chloride and amine, and the preparation method has a high product yield. When the specific type of alkaline catalyst of the present invention is not used, the yield of the target product is significantly reduced.

[0108] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a phosphorus-nitrogen flame retardant, characterized in that: The preparation method comprises the following steps: and diamine in the presence of a catalyst in an organic solvent to react to produce the phosphorus-nitrogen flame retardant; The phosphorus-nitrogen flame retardant has a structure shown in Formula I or Formula II; In formula I, X is O or S, and R is selected from a C2-C8 alkylene group or a phenylene group; In formula II and formula III, X is O or S; The catalyst is selected from one or more combinations of 4-dimethylaminopyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5,7-triazabicyclo[4.4.0]decene-5-ene, potassium tert-butoxide, sodium methoxide, sodium ethoxide, potassium ethoxide, potassium hydroxide, lithium bis(trimethylsilyl)amide, sodium bis(trimethylsilyl)amide, and potassium bis(trimethylsilyl)amide.

2. The method for preparing a phosphorus-nitrogen flame retardant according to claim 1, characterized in that: In formula I, R is selected from a C2-C6 alkylene group or a phenylene group.

3. The method for preparing a phosphorus-nitrogen flame retardant according to claim 1, characterized in that: In Formula I, R is selected from -CH2-, -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, -CH2CH2CH2CH2-, -CH2CH2CH2CH2CH2-, -CH2CH2CH2CH2CH2-, -CH2CH2CH2CH2CH2CH2- or phenylene.

4. The method for preparing a phosphorus-nitrogen flame retardant according to claim 1, characterized in that: The diamine is selected from one or more combinations of ethylenediamine, 1,3-propylenediamine, 1,4-butylenediamine, 1,5-diaminopentane, 1,6-hexanediamine, piperazine, and p-phenylenediamine; and / or the organic solvent is selected from one or more combinations of toluene, xylene, tetrahydrofuran, dioxane, ether, chloroform, and ethylene dichloride.

5. The method for preparing a phosphorus-nitrogen flame retardant according to claim 1, characterized in that: The molar ratio of the cyclomethyl phosphate to the diamine is 1:0.5-1.0; and / or the molar ratio of the diamine to the catalyst is 1:0.2-4.

0.

6. The method for preparing a phosphorus-nitrogen flame retardant according to claim 1, characterized in that: The reaction temperature is 0°C to 110°C.

7. The method for preparing a phosphorus-nitrogen flame retardant according to claim 1, characterized in that: The preparation method also includes cyclophosphoxyl chloride shown in formula IV The step of reacting with methanol in the presence of an acid binding agent to generate the cyclic methyl phosphate represented by formula III; in formula IV, X is O or S.

8. The method for preparing the phosphorus-nitrogen flame retardant according to claim 7, characterized in that: The acid binding agent is selected from a combination of one or more of triethylamine, N,N-diisopropylethylamine, pyridine, piperidine, alkali metal hydroxides, alkali metal carbonates and alkali metal bicarbonates.

9. The method for preparing a phosphorus-nitrogen flame retardant according to claim 7, characterized in that: The molar ratio of cyclophosphoxyl chloride to methanol is 1:1.5-3.2; and / or the molar ratio of the acid binding agent to methanol is 0.3-0.8:

1.

10. The method for preparing the phosphorus-nitrogen flame retardant according to claim 7, characterized in that: In the step of generating methyl cyclic phosphate, the reaction temperature is 50°C to 110°C.

11. The method for preparing a phosphorus-nitrogen flame retardant according to claim 7, characterized in that: The preparation method further comprises the step of reacting neopentyl glycol with phosphorus oxychloride or phosphorus thiochloride in a solvent to generate cyclophosphoxychloride as shown in formula IV.

12. The method for preparing a phosphorus-nitrogen flame retardant according to claim 11, characterized in that: The molar ratio of the neopentyl glycol to phosphorus oxychloride or phosphorus thiochloride is 1:0.98-1.

3.

13. The method for preparing a phosphorus-nitrogen flame retardant according to claim 11, characterized in that: The molar ratio of the methanol to the neopentyl glycol is 1 to 5:1; and / or the molar ratio of the diamine to the neopentyl glycol is 0.3 to 2:1; and / or the molar ratio of the catalyst to the neopentyl glycol is 0.01 to 3:

1.

14. The method for preparing a phosphorus-nitrogen flame retardant according to claim 11, characterized in that: In the step of generating cyclophosphyl chloride, the reaction temperature is 0°C to 50°C.

15. A compound suitable for preparing a phosphorus-nitrogen flame retardant, characterized in that: The compound has a structure shown in the following formula III: Wherein X is O or S.

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