Phosphopentene catalyst as well as preparation method and application thereof

Abstract

The invention discloses a phosphopentene catalyst as well as a preparation method and application thereof. The invention provides a compound shown as a formula I or a salt thereof, and in the formula I, R1 is C1 alkyl, C2 alkyl, C3 alkyl or C4 alkyl. The phosphopentene catalyst provided by the invention is easy to remove in the synthesis process of carbodiimide, is high in yield and high in purity, and meets the requirements of industrial production. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to a phospholene catalyst, a preparation method thereof and an application thereof. Background Art

[0002] Carbodiimide compounds are an important class of anti-hydrolysis agents and are widely used in thermoplastic plastics containing ester bonds (such as PET, PBT, PLA, PBAT, etc.), polyester-based polyurethanes, rigid and flexible polyurethane foams, as well as polyurethane coatings, adhesives, sealants and elastomers. They can also be used as cross-linking agents and solubilizers in various materials. Phospholene catalysts are a class of highly efficient catalysts widely used in the synthesis of carbodiimide compounds. For example, Zhang Jianhua et al. synthesized 3-methyl-1-phenyl-1-phospholene-3-oxide (MPPO) as a catalyst for the self-polymerization modification of MDI. Another example is that in CN104334624, cyclophosphene oxide is used as a catalyst in the synthesis of carbodiimide compounds.

[0003] The commonly used phospholene catalyst in the market is MPPO. The molecular structure of this catalyst contains a benzene ring and phosphorus elements, and has certain toxicity. In order to prevent catalyst residues, it is often necessary to remove the catalyst by distillation during use to prevent the catalyst from remaining in the material system. However, it is difficult to efficiently remove this type of catalyst under existing conditions. In order to facilitate the efficient removal of this type of catalyst during use, it is an urgent problem to prepare a new type of phospholene catalyst. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that the commonly used MPPO catalyst in the prior art is difficult to remove. The present invention thus provides a phospholene catalyst, a preparation method thereof and an application thereof. The present invention provides a phospholene catalyst, which is easy to remove during the synthesis of carbodiimide, and has a high yield and high purity, meeting the requirements of industrial production.

[0005] The present invention solves the above technical problems through the following technical solutions.

[0006] The present invention provides a compound of formula I or a salt thereof,

[0007]

[0008] wherein, R 1 is a C1 alkyl group, a C2 alkyl group, a C3 alkyl group or a C4 alkyl group.

[0009] In some embodiments of the present invention, R 1 is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or tert-butyl.

[0010] In some embodiments of the present invention, R 1 is methyl, ethyl or n-propyl.

[0011] The present invention also provides a method for preparing a compound represented by formula I, which comprises the following steps: in an organic solvent and under the action of an antioxidant, the compound represented by formula II reacts with isoprene to form a compound represented by formula III, and then undergoes a hydrolysis reaction to form a compound represented by formula I;

[0012]

[0013] wherein R 1 is as described in any one of the embodiments of the present invention.

[0014] In some embodiments of the present invention, the antioxidant is a hindered phenol antioxidant, preferably antioxidant 1010 or antioxidant 168.

[0015] In some embodiments of the present invention, the organic solvent is selected from one or more of halogenated alkyl solvents and aromatic hydrocarbon solvents, preferably one or more of 1,2-dichloroethane, toluene, xylene and chloroform, more preferably 1,2-dichloroethane or toluene.

[0016] In some embodiments of the present invention, the addition reaction is carried out under the protection of nitrogen or an inert gas, preferably nitrogen.

[0017] In some embodiments of the present invention, the molar ratio of the compound represented by formula II to isoprene is 1:(1-5), preferably 1:(1.5-3), for example 1:1.5, 1:2.2 or 1:3.

[0018] In some embodiments of the present invention, the mass ratio of the compound represented by formula II to the organic solvent is 1:(2-5), preferably 1:(2-3).

[0019] In some embodiments of the present invention, the mass ratio of the compound represented by formula II to the antioxidant is 1:(0.002-0.02), preferably 1:(0.005-0.01).

[0020] In some embodiments of the present invention, the reaction progress of the addition reaction is detected by a conventional monitoring method for such reactions in the art, such as TLC or HPLC, etc. Preferably, the complete conversion of the compound represented by formula II or the non-generation of the compound represented by formula III is used as the reaction end point. The reaction time of the addition reaction is 12 h to 96 h, preferably 24 h to 36 h, more preferably 26 h, 30 h or 36 h.

[0021] In some embodiments of the present invention, the temperature of the addition reaction is -10°C to 30°C, preferably -5°C to 20°C, more preferably 0°C, -5°C or 15°C.

[0022] In some embodiments of the present invention, the hydrolysis reaction comprises the following steps: water is added to the reaction solution, the pH is adjusted with a base, liquid separation is carried out, the solvent is removed from the organic phase, and the compound shown in Formula I is obtained by rectification.

[0023] In some embodiments of the present invention, the temperature of the water is 0 to 10°C, preferably 0 to 5°C.

[0024] In some embodiments of the present invention, the base is one or more of potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate, preferably sodium carbonate or potassium carbonate.

[0025] In some embodiments of the present invention, the base is added in the form of an aqueous solution of the base; preferably, the mass concentration of the aqueous solution of the base is 25%.

[0026] In some embodiments of the present invention, adjusting the pH is to adjust the pH to 7 to 10.

[0027] In some embodiments of the present invention, the solvent removal can be carried out by conventional methods in the art, such as rotary evaporation.

[0028] In some embodiments of the present invention, the conditions of the rectification depend on different compounds shown in Formula I; for example, the temperature of the rectification is 90°C to 115°C; the pressure of the rectification is 300 Pa to 600 Pa. <{

[0029] The present invention also provides an application of the compound shown in Formula I according to any one of the embodiments of the present invention as a catalyst in the preparation of carbodiimide compounds; preferably, the application comprises the following steps: in a nitrogen atmosphere, an isocyanate compound undergoes a condensation reaction to form a carbodiimide compound under the catalysis of the compound shown in Formula I.

[0030] In some embodiments of the present invention, the carbodiimide compound is a monomeric carbodiimide compound or a polymeric carbodiimide compound, preferably a polymeric carbodiimide compound, such as poly(4,4'-dicyclohexylmethane carbodiimide); preferably, the degree of polymerization of the polymeric carbodiimide compound is 6-20.

[0031] In some embodiments of the present invention, the temperature of the condensation reaction is 160 to 180°C, preferably 165°C.

[0032] [[ID=3۳]]On the basis of not violating the common knowledge in the art, the above preferred conditions can be arbitrarily combined to obtain various preferred examples of the present invention.

[0033] The reagents and raw materials used in the present invention are commercially available.

[0034] The positive progress effect of the present invention is:

[0035] (1) The present invention uses low-alkyl phosphorus dichloride as a raw material, and the prepared phosphotene catalyst can be removed by vacuum distillation during the carbodiimide synthesis process, thereby reducing the catalyst residue in the carbodiimide system and the toxicity of the carbodiimide, especially for the synthesis of carbodiimide compounds used in food-grade materials.

[0036] (2) The phospholene catalyst synthesized by the present invention is easy to be distilled and purified, with high yield and high purity, which meets the requirements of industrial production. DETAILED DESCRIPTION

[0037] The present invention is further illustrated by way of examples below, but the present invention is not limited to the scope of the examples. Experimental methods in the following examples where specific conditions are not specified were performed according to conventional methods and conditions, or selected according to the product specifications.

[0038] Example 1

[0039]

[0040] 116.9 g of methyl phosphonium dichloride, 102.2 g of isoprene, 233.8 g of 1,2-dichloroethane and 0.58 g of antioxidant 1010 were added to a 1000 ml three-necked flask in sequence. The three-necked flask was placed in a low-temperature constant temperature bath. The temperature of the system was lowered to 0°C while stirring. Then, high-purity nitrogen was introduced into the three-necked flask to remove the air from the system. After the air was completely exhausted, the system was placed in a closed state and continued to stir. Stir for 26 hours to complete the reaction.

[0041] After the reaction is completed, 200g of pre-prepared ice water at 0-5°C is added to the mixture. After sufficient stirring for hydrolysis, a 25% (mass concentration) sodium carbonate aqueous solution is added to the system, and the pH is adjusted to 8 during the process. The organic phase is separated and rotary evaporated to obtain a crude product of 3-methyl-1-methyl-2-phospholene oxide catalyst. The crude product is distilled at 90-95°C and 500-600Pa to obtain a purified product with a purity of 99.5% and a yield of 95.3%. 1 H-NMR characterization data are as follows:

[0042] 11H NMR (400 MHz, CD3OD) δ 4.68 - 4.78 (m, 1H), 2.16 - 2.31 (t, 2H), 1.88 - 1.99 (m, 3H), 1.73 - 1.84 (m, 2H), 1.60 - 1.75 (m, 3H).

[0043] Example 2

[0044] 130.9 g of ethyl dichlorophosphine, 204.3 g of isoprene, 392.7 g of toluene and 0.8 g of antioxidant 1010 were successively added into a 1000 ml three - necked flask. The three - necked flask was placed in a low - temperature constant - temperature bath. Under stirring, the temperature of the system was lowered to - 5°C. Then, high - purity nitrogen was introduced into the three - necked flask to remove the air in the system. After the air was exhausted, the system was kept in a closed state and continued to stir. Stirring for 30 h made the system react completely.

[0045] After the reaction ended, 200 g of ice - water at 0 - 5°C prepared in advance was added thereto. After sufficient stirring for hydrolysis, 25% (mass concentration) aqueous potassium carbonate solution was added to the system, and the pH was adjusted to 9 during the process. The organic phase was separated by liquid separation, and the crude product of 3 - methyl - 1 - ethyl - 2 - phospholene oxide catalyst was obtained after rotary evaporation. The crude product was rectified at 100 - 110°C and 400 - 500 Pa to obtain the purified product. The purity of the purified product was 99.6%, and the yield was 96.8%. The 1 1H - NMR characterization data are as follows:

[0046] 1 1H NMR (400 MHz, CD3OD) δ 4.68 - 4.78 (m, 1H), 2.16 - 2.31 (m, 2H), 1.88 - 1.99 (m, 3H), 1.73 - 1.84 (m, 2H), 1.60 - 1.75 (m, 2H), 1.06 - 1.19 (t, 3H).

[0047] Example 3

[0048] 144.9 g of n - propyl dichlorophosphine, 150 g of isoprene, 289.8 g of 1,2 - dichloroethane and 1.4 g of antioxidant 168 were successively added into a 1000 ml three - necked flask. The three - necked flask was placed in a low - temperature constant - temperature bath. Under stirring, the temperature of the system was lowered to 15°C. Then, high - purity nitrogen was introduced into the three - necked flask to remove the air in the system. After the air was exhausted, the system was kept in a closed state and continued to stir. Stirring for 36 h made the system react completely.

[0049] After the reaction is completed, 200 g of pre-prepared ice water at 0-5 °C is added thereto. After sufficient stirring and hydrolysis, an aqueous sodium carbonate solution with a mass concentration of 25% is added to the system, and the pH is adjusted to 7 during the process. The organic phase is obtained by liquid separation and the crude product of 3-methyl-1-n-propyl-2-phospholene oxide catalyst is obtained after rotary evaporation. The crude product is rectified under the conditions of 110-115 °C and 300-400 Pa to obtain a purified product with a purity of 99.2% and a yield of 97.2%. The 1 The characterization data of 1H-NMR are as follows:

[0050] 1 1H NMR (400 MHz, CD3OD) δ 4.67-4.77(m, 1H), 2.16-2.31(t, 2H), 1.88-1.96(m, 3H), 1.73-1.85(m, 2H), 1.59-1.74(m, 2H), 1.28-1.40(m, 2H), 0.95-1.10(t, 3H).

[0051] Comparative Example 1

[0052] 179 g of phenylphosphorus dichloride, 150 g of isoprene, 289.8 g of 1,2-dichloroethane and 1.4 g of antioxidant 168 were successively added to a 1000 ml three-necked flask. The three-necked flask was placed in a low-temperature constant-temperature bath, and the temperature of the system was lowered to 15 °C under stirring. Then, high-purity nitrogen was introduced into the three-necked flask to remove the air in the system. After the air was exhausted, the system was kept in a closed state and continued to stir. The system was stirred for 36 h to complete the reaction.

[0053] After the reaction is completed, 200 g of pre-prepared ice water at 0-5 °C is added thereto. After sufficient stirring and hydrolysis, an aqueous sodium carbonate solution is added to the system, and the pH is adjusted to 7 during the process. The organic phase is obtained by liquid separation and the crude product of 3-methyl-1-phenyl-2-phospholene oxide catalyst is obtained after rotary evaporation. The crude product is rectified under the conditions of 220-250 °C and 50-100 Pa to obtain a purified product with a purity of 97.5% and a yield of 95.2%.

[0054] Comparative Example 2

[0055] 130.9 g of ethylphosphorus dichloride, 204.3 g of isoprene and 392.7 g of toluene were successively added to a 1000 ml three-necked flask. The three-necked flask was placed in a low-temperature constant-temperature bath, and the temperature of the system was lowered to -5 °C under stirring. Then, high-purity nitrogen was introduced into the three-necked flask to remove the air in the system. After the air was exhausted, the system was kept in a closed state and continued to stir. The system was stirred for 30 h to complete the reaction.

[0056] After the reaction is completed, 200 g of ice water at 0-5 °C prepared in advance is added thereto. After sufficient stirring and hydrolysis, an aqueous potassium carbonate solution with a mass concentration of 25% is added to the system, and the pH is adjusted to 9 during the process. The organic phase is obtained by liquid separation, and the crude product of 3-methyl-1-ethyl-2-phospholene oxide catalyst is obtained after rotary evaporation. The crude product is rectified under the conditions of 100-110 °C and 400-500 Pa to obtain a purified product. The purity of the purified product is 98.2%, and the yield is 60%. In the absence of an antioxidant, isoprene undergoes self-polymerization, and the system yield decreases.

[0057] Comparative Example 3

[0058] 130.9 g of ethylphosphorus dichloride, 204.3 g of isoprene, 392.7 g of toluene and 0.8 g of antioxidant 1010 were successively added to a 1000 ml three-necked flask. The three-necked flask was placed in a low-temperature constant temperature bath, and the system temperature was lowered to 30 °C under stirring. Then, high-purity nitrogen was introduced into the three-necked flask to remove the air in the system. After the air was exhausted, the system was kept in a closed state and continued to stir. The system was stirred for 30 h to complete the reaction.

[0059] After the reaction is completed, 200 g of ice water at 0-5 °C prepared in advance is added thereto. After sufficient stirring and hydrolysis, an aqueous potassium carbonate solution with a mass concentration of 25% is added to the system, and the pH is adjusted to 9 during the process. The organic phase is obtained by liquid separation, and the crude product of 3-methyl-1-ethyl-2-phospholene oxide catalyst is obtained after rotary evaporation. The crude product is rectified under the conditions of 100-110 °C and 400-500 Pa to obtain a purified product. The purity of the purified product is 98.6%, and the yield is 36%. At a higher temperature, isoprene undergoes self-polymerization, and the system yield decreases.

[0060] Application Example:

[0061] Weigh 4 portions of 100 g of HMDI (4,4'-dicyclohexylmethane diisocyanate) and place them in a 250 ml three-necked flask, numbered A, B, C, and D in sequence. Add 0.2 g of the phosphacyclic catalyst prepared in Examples 1-3 and Comparative Example 1 to A, B, C, and D respectively. Stop the reaction at 165 °C under nitrogen conditions until the same degree of polymerization is reached (the product is poly-4,4'-dicyclohexylmethane carbodiimide; among them, the degree of polymerization is tracked and detected by titration method, and usually the degree of polymerization is controlled at 6-20). When the degree of polymerization is 10, the reaction times of the 4 groups of experiments are 12 h, 14 h, 15.5 h and 20 h respectively. At 165 °C and 1000 Pa pressure, the catalyst is removed by vacuum. After 1 h, the sample without the catalyst is tested for phosphorus element. The residual phosphorus element amounts in the 4 groups of samples are 0 ppm, 0 ppm, 0 ppm and 1200 ppm in sequence.

[0062] Comparing the removal effects of the catalysts prepared in the examples and comparative examples of the present invention, the catalyst removal effects of Examples 1-3 are significantly better than those of Comparative Example 1. Moreover, when the same degree of product polymerization is achieved, the reaction time catalyzed by the catalysts of Examples 1-3 is shorter and the catalytic effect is higher.

Claims

1. A compound of formula I or a salt thereof, Among them, R 1 is a C1 alkyl group, a C2 alkyl group, a C3 alkyl group or a C4 alkyl group.

2. The compound of formula I or a salt thereof according to claim 1, characterized in that, R 1 is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or tert-butyl; preferably, R 1 is methyl, ethyl or n-propyl.

3. A method for preparing a compound represented by formula I, characterized in that, which comprises the following steps: In an organic solvent, in the presence of an antioxidant, the compound of formula II undergoes an addition reaction with isoprene to form a compound of formula III, and then undergoes a hydrolysis reaction to form a compound of formula I; wherein, R 1 as described in claim 1 or 2.

4. The preparation method according to claim 3, characterized in that, The addition reaction satisfies one or more of the following conditions: (1) The antioxidant is a hindered phenol antioxidant; (2) The organic solvent is selected from one or more of halogenated alkyl solvents and aromatic hydrocarbon solvents; (3) The addition reaction is carried out under the protection of nitrogen or an inert gas; (4) The molar ratio of the compound of formula II to isoprene is 1:(1 - 5); (5) The mass ratio of the compound of formula II to the organic solvent is 1:(2 - 5); (6) The mass ratio of the compound of formula II to the antioxidant is 1:(0.002 - 0.02); (7) The temperature of the addition reaction is -10°C to 30°C.

5. The preparation method according to claim 3, characterized in that, The addition reaction satisfies one or more of the following conditions: (1) The antioxidant is antioxidant 1010 or antioxidant 168; (2) The organic solvent is selected from one or more of 1,2 - dichloroethane, toluene, xylene, and chloroform; (3) The addition reaction is carried out under the protection of nitrogen; (4) The molar ratio of the compound of formula II to isoprene is 1:(1.5 - 3); (5) The mass ratio of the compound of formula II to the organic solvent is 1:(2 - 3); (6) The mass ratio of the compound of formula II to the antioxidant is 1:(0.005 - 0.01); (7) The temperature of the addition reaction is -5°C to 20°C.

6. The preparation method according to claim 3, characterized in that, The addition reaction satisfies one or more of the following conditions: (1) The organic solvent is 1,2 - dichloroethane or toluene; (2) The molar ratio of the compound of formula II to isoprene is 1:1.5, 1:2.2, or 1:3; (3) The temperature of the addition reaction is 0°C, -5°C, or 15°C.

7. The preparation method according to claim 3, characterized in that, The hydrolysis reaction comprises the following steps: Water is added to the reaction solution, the pH is adjusted with a base, liquid separation is carried out, the solvent in the organic phase is removed, and the compound of formula I is obtained after rectification.

8. The preparation method according to claim 7, characterized in that, The hydrolysis reaction satisfies one or more of the following conditions: (1) The temperature of the water is 0 - 10°C, preferably 0 - 5°C; (2) The base is one or more of potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate, preferably sodium carbonate or potassium carbonate; (3) The base is added in the form of an aqueous solution of the base. Preferably, the mass concentration of the aqueous solution of the base is 25%; (3) Adjusting the pH is to adjust the pH to 7 - 10; (4) Removing the solvent is carried out by rotary evaporation; (5) The temperature of the rectification is 90°C - 115°C; (6) The pressure of the rectification is 300 Pa - 600 Pa.

9. Use of a compound represented by formula I as described in claim 1 or 2 as a catalyst in the preparation of carbodiimide compounds; preferably, the use comprises the following steps: in a nitrogen atmosphere, an isocyanate compound undergoes a condensation reaction under the catalysis of a compound represented by formula I to form a carbodiimide compound.

10. The application according to claim 9, characterized in that, The carbodiimide compound is a monomeric carbodiimide compound or a polymeric carbodiimide compound, preferably a polymeric carbodiimide compound, such as poly(4,4'-dicyclohexylmethane carbodiimide); preferably, the degree of polymerization of the polymeric carbodiimide compound is 6-20; and / or, the temperature of the condensation reaction is 160-180 °C, preferably 165 °C.

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