Catalytic synthesis method of functional special polyether with narrow molecular weight distribution

Abstract

The invention belongs to the technical field of chemical synthesis, and particularly relates to a catalytic synthesis method of functional special polyether with narrow molecular weight distribution. The method comprises the following steps: by taking C1-C12 alcohol as an initiator, carrying out polymerization reaction with epoxide under the action of an organic catalyst, so as to prepare the functional special polyether with narrow molecular weight distribution. According to the invention, by designing an organic catalyst with a molecular structure containing phosphorus-boron (P-B) double active centers, not only is efficient catalytic ring-opening polymerization of alkylene oxide realized under a low-temperature condition, but also a special polyether product with high molecular weight and narrow molecular weight distribution is prepared. Meanwhile, by using the organic catalyst, the problems that a commercial DMC system is prone to inactivation, complex in mechanism and metal residues exist in ethylene oxide polymerization can be solved, and the application range of PAG in the fields of cosmetics, medicine and food-grade oil is widened.

Description

Technical Field

[0001] This invention belongs to the field of chemical synthesis technology, specifically relating to a catalytic synthesis method for functionalized special polyethers with narrow molecular weight distribution. Background Technology

[0002] PAG polyether base oils are linear polymers produced through ring-opening polymerization from raw materials such as ethylene oxide (EO), propylene oxide (PO), butane oxide (BO), or tetrahydrofuran (THF). They mainly include water-soluble, water-insoluble, and high-molecular-weight polyether types. As polymers, their molecular weight and distribution are core indicators affecting performance. A molecular weight of over 2000 is typically required; higher molecular weight helps enhance oil film strength and reduce volatility, while a narrow molecular weight distribution leads to better viscosity-temperature properties and a lower pour point. However, existing industrial catalytic systems struggle to simultaneously achieve both high molecular weight and narrow distribution, representing a major technological bottleneck.

[0003] Currently, the synthesis of polyethers mainly relies on base-catalyzed ring-opening polymerization, such as sodium methoxide and KOH used in CN104945613A. Although these catalysts have high activity, they are prone to initiating isomerization side reactions of monomers such as propylene oxide during polymerization, leading to the formation of unsaturated end groups in the molecular chain and premature chain termination. This ultimately results in products with low molecular weight (typically Mn < 6000) and a wide molecular weight distribution. This severely restricts further improvement in the performance of polyether products. Although some indicators can be improved through subsequent refining processes, the problems of molecular weight and distribution cannot be fundamentally solved.

[0004] To obtain polyethers with higher molecular weights, researchers have developed coordination catalysts such as bimetallic cyanide complexes (DMC) and metalloporphyrins. For example, CN112876589A discloses a bifunctional porous organic polymer catalyst. Although these catalysts can effectively suppress side reactions and obtain products with higher molecular weights, their catalytic mechanisms are complex and usually require high temperatures (>100℃) and pressures, resulting in high equipment requirements and high energy consumption. In addition, CN116003773A discloses a novel catalyst system to achieve polymerization under mild conditions, but it still struggles to simultaneously achieve high activity, high molecular weight, and extremely narrow distribution at low temperatures.

[0005] Therefore, developing a novel catalytic system capable of achieving efficient and precise ring-opening polymerization of epoxides under mild conditions, thereby synthesizing polyether lubricating oil base oils with high molecular weight, narrow molecular weight distribution, and excellent overall performance, has become a key technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a catalytic synthesis method for functionalized special polyethers with narrow molecular weight distribution.

[0007] The objective of this invention is achieved through the following technical solution: A catalytic synthesis method for functionalized specialty polyethers with narrow molecular weight distribution, using C1-C244... 12 Using alcohol as a starting agent, a polymerization reaction is carried out with epoxide under the action of an organic catalyst to obtain the functionalized special polyether with a narrow molecular weight distribution; The structural formula of the organic catalyst is: .

[0008] Furthermore, the organic catalyst is prepared by the following process: (1) Anhydrous N,N-dimethylformamide was added to liquid methylamine at -80 to -75 °C, and anhydrous potassium carbonate and 6-bromo-1-hexene were added under stirring. The mixture was then heated to room temperature for reaction. After the reaction was completed, intermediate 1 was obtained by purification. The structural formula of intermediate 1 is: ; (2) Under an inert gas atmosphere, phosphorus trichloride was added to anhydrous diethyl ether, then cooled in an ice bath, and intermediate 1 was added under stirring to carry out the reaction; after the reaction was completed, intermediate 2 was obtained by purification. The structural formula of intermediate 2 is as follows: ; (3) The intermediate 2 and 9-boronbicyclo[3.3.1]nonane were added to tetrahydrofuran for reflux reaction. After the reaction was completed, the organic catalyst was obtained by purification.

[0009] Further, in step (1), the molar ratio of liquid methylamine, anhydrous potassium carbonate and 6-bromo-1-hexene is 1:(0.1-0.11):(0.1-0.11); and the reaction time is 12-14 h.

[0010] Further, in step (2), the ratio of phosphorus trichloride to intermediate 1 is 1:(4-6); the reaction time is 1-2 h.

[0011] Further, in step (3), the molar ratio of intermediate 2 and 9-boronibirocyclo[3.3.1]nonane is 1:(1-1.2); the reflux reaction time is 12-16 h.

[0012] Furthermore, the C1 to C 12The mass ratio of alcohol, organic catalyst and epoxide is 1:(0.005~0.01):(10~20).

[0013] Further, the epoxide is at least one of ethylene oxide, propylene oxide, and 1,2-epoxide butane; when the epoxide is a mixture of ethylene oxide, propylene oxide, and 1,2-epoxide butane, the mass ratio of ethylene oxide, propylene oxide, and 1,2-epoxide butane is (5-10):(12-20):(1-10).

[0014] Furthermore, the C1 to C 12 The alcohol can be any one of primary alcohols, secondary alcohols, or diols.

[0015] Furthermore, the polymerization reaction is carried out at a temperature of -20 to 0°C for a duration of 8 to 13 hours.

[0016] The present invention has the following advantages over the prior art: 1. The organocatalyst designed in this invention contains a phosphorus-boron (PB) dual active center in its molecular structure. The phosphorus center possesses strong Lewis acidity, serving as an initiation and activation site for ring-opening of epoxy monomers, while the boron center has empty orbitals that can form reversible coordination interactions with the terminal oxygen atoms of the growing chain. This bifunctional structure produces a synergistic catalytic effect, thereby achieving precise control over the molecular weight distribution of the polyether. Furthermore, due to its unique structure and high activity, the organocatalyst of this invention can achieve highly efficient catalytic ring-opening polymerization of epoxides under low-temperature conditions. This results in polyether products that simultaneously possess the advantages of high viscosity index, high flash point, and low pour point, reaching the level of high-end fully synthetic oils.

[0017] 2. The organic catalyst of this invention has a clear synthetic route, readily available raw materials, and can be produced on a large scale. It is applicable to a variety of starting alcohols and epoxides with different structures and has good process applicability.

[0018] 3. This invention uses an organic small molecule catalyst, and the synthesis process does not involve alkali metal or heavy metal ions, overcoming the problems of easy deactivation, complex mechanism and metal residue in commercial DMC system during ethylene oxide polymerization, and broadening the application scope of PAG in cosmetics, pharmaceuticals and food-grade oils. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the reaction process of the organic catalyst of the present invention. Detailed Implementation

[0020] The technical solution of the present invention will be further described below with reference to specific embodiments. However, those skilled in the art should understand that the following embodiments are only for illustrating the present invention and should not be regarded as limiting the present invention. Specific conditions not specified in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the reagents or instruments used are all conventional products obtained through commercial channels.

[0021] Preparation Example 1 Preparation Example 1 provides an organic catalyst, and the reaction flow diagram is shown below. Figure 1 As shown, the specific steps are as follows: (1) At -75℃, anhydrous DMF (45 mL) was added to liquid methylamine (40 mL, 43.2 g, 1.4 mol) using a syringe. Anhydrous potassium carbonate (147 mmol) and 6-bromo-1-hexene (147 mmol) were added under stirring. The mixture was then heated to room temperature and reacted for 13 h. After the reaction was completed, the reaction solution was poured into water (150 mL) and extracted with ether (6 × 50 mL). The ether solutions were combined and dried with anhydrous sodium sulfate. After filtration and concentration, intermediate 1 was obtained. 1 H NMR (C7H) 15 N, 400 MHz, d6-DMSO) δ5.83-5.80(m, 1H, CH=), 5.13(d, 1H, =CH2), 4.18(d, 1H, =CH2), 3.52(s, 1H, NH),3.26(s, 3H, CH3), 2.52 (t, 2H, CH2), 2.14 (q, 2H, CH2), 1.40-1.30(m, 4H, CH2); HRMS (ESI + ): [M+H] + The calculation yields 114.12, and the result is 114.11.

[0022] (2) Under a nitrogen atmosphere, phosphorus trichloride (0.1 mol) was added to anhydrous diethyl ether (1000 mL), and then cooled in an ice bath. Intermediate 1 (0.5 mol) was added dropwise while stirring. After the addition was complete, the reaction was stirred in an ice bath for 1.5 h. After the reaction was completed, the reaction mixture was filtered under pressure under a nitrogen atmosphere. The product was washed three times with anhydrous diethyl ether. Finally, the crystal was purified by distillation at 110 °C and 0.2 kPa to obtain intermediate 2. 1 H NMR (C 21 H 42N3P, 400 MHz, d6-DMSO) δ 5.83-5.80(m, 3H, CH=), 5.13(d, 3H, =CH2), 4.88(d, 3H, =CH2), 2.52 (t,6H, CH2), 2.43(s, 9H, CH3), 2.14 (q, 6H, CH2), 1.40-1.30(m, 12H, CH2); HRMS(ESI + ): [M+H] + The calculation yields 368.31, and the result is 368.30.

[0023] (3) Add intermediate 2 (5 mmol) to a dried Schlenk flask equipped with a stir bar, then add 9-boronbicyclo[3.3.1]nonane (5.5 mmol) and tetrahydrofuran (20 mL), and reflux for 14 h; cool the reaction solution to room temperature, concentrate under vacuum to obtain crude product, wash the crude product three times with n-hexane to obtain the organic catalyst; 1 H NMR (C 45 H 87 B3N3P, 400MHz, d6-DMSO) δ 2.52 (t, 6H, CH2), 2.43(s, 9H, CH3), 1.40-1.20(m, 72H, CH2, CH); HRMS (ESI + ): [M+H] + The calculated value is 734.69, and the obtained value is 734.70.

[0024] Preparation Example 2 Preparation Example 2 provides an organic catalyst, and the reaction flow diagram is shown below. Figure 1 As shown, the specific steps are as follows: A catalytic synthesis method for functionalized specialty polyethers with narrow molecular weight distribution, comprising the following specific steps: S1. Preparation of organic catalysts, the specific reaction process is shown in the schematic diagram below. Figure 1 As shown: (1) At -80℃, anhydrous DMF (40 mL) was added to liquid methylamine (40 mL, 43.2 g, 1.4 mol) using a syringe. Anhydrous potassium carbonate (140 mmol) and 6-bromo-1-hexene (140 mmol) were then added under stirring. The mixture was then brought to room temperature and reacted for 12 h. After the reaction was complete, the reaction solution was poured into water (150 mL), extracted with ether (6 × 50 mL), and the ether solutions were combined and dried over anhydrous sodium sulfate. After filtration and concentration, intermediate 1 was obtained. The intermediate 1... 1H NMR and HRMS were consistent with those in Example 1.

[0025] (2) Under a nitrogen atmosphere, phosphorus trichloride (0.1 mol) was added to anhydrous diethyl ether (1000 mL), and then cooled in an ice bath. Intermediate 1 (0.4 mol) was added dropwise while stirring. After the addition was complete, the reaction mixture was stirred in an ice bath for 1 h. After the reaction was completed, the reaction mixture was filtered under pressure under a nitrogen atmosphere. The product was washed three times with anhydrous diethyl ether, and finally the crystals were purified by distillation at 115 °C and 0.2 kPa to obtain intermediate 2. 1 H NMR and HRMS were consistent with those in Example 1.

[0026] (3) Intermediate 2 (5 mmol) was added to a dried Schlenk flask equipped with a stir bar, followed by 9-boronibira[3.3.1]nonane (5 mmol) and tetrahydrofuran (15 mL), and the mixture was refluxed for 16 h. The reaction solution was cooled to room temperature, concentrated under vacuum to obtain a crude product, and washed three times with n-hexane to obtain the organic catalyst. 1 H NMR and HRMS were consistent with those in Example 1.

[0027] Preparation Example 3 Preparation Example 3 provides an organic catalyst, and the reaction flow diagram is shown below. Figure 1 As shown, the specific steps are as follows: (1) At -80℃, anhydrous DMF (50 mL) was added to liquid methylamine (40 mL, 43.2 g, 1.4 mol) using a syringe. Anhydrous potassium carbonate (154 mmol) and 6-bromo-1-hexene (154 mmol) were then added under stirring. The mixture was then brought to room temperature and reacted for 14 h. After the reaction was complete, the reaction solution was poured into water (150 mL), extracted with ether (6 × 50 mL), and the ether solutions were combined and dried over anhydrous sodium sulfate. After filtration and concentration, intermediate 1 was obtained. The intermediate 1... 1 H NMR and HRMS were consistent with those in Example 1.

[0028] (2) Under a nitrogen atmosphere, phosphorus trichloride (0.1 mol) was added to anhydrous diethyl ether (1000 mL), and then cooled in an ice bath. Intermediate 1 (0.6 mol) was added dropwise while stirring. After the addition was complete, the reaction mixture was stirred in an ice bath for 2 h. After the reaction was completed, the reaction mixture was filtered under pressure under a nitrogen atmosphere. The product was washed three times with anhydrous diethyl ether, and finally the crystals were purified by distillation at 110 °C and 0.2 kPa to obtain intermediate 2. 1 H NMR and HRMS were consistent with those in Example 1.

[0029] (3) Intermediate 2 (5 mmol) was added to a dried Schlenk flask equipped with a stir bar, followed by 9-boronibira[3.3.1]nonane (6 mmol) and tetrahydrofuran (20 mL). The mixture was refluxed for 12 h. The reaction solution was cooled to room temperature, concentrated under vacuum to obtain a crude product, and washed three times with n-hexane to obtain the organic catalyst. The organic catalyst... 1 H NMR and HRMS were consistent with those in Example 1.

[0030] Example 1 Example 1 provides a catalytic synthesis method for functionalized specialty polyethers with narrow molecular weight distribution, the specific steps of which are as follows: 100 g of n-octanol was added to the reactor, along with 0.7 g of the organic catalyst obtained in Preparation Example 1. The temperature was then lowered to -20°C and reacted for 1 h. Propylene oxide was then slowly fed in and the temperature was maintained at -20°C. When the amount of propylene oxide introduced reached 1500 g, the feeding was stopped, and the reaction continued for 12 h. Then, the reactor was evacuated for 5 min, and the product was discharged to obtain the functionalized special polyether with a narrow molecular weight distribution.

[0031] Example 2 Example 2 provides a catalytic synthesis method for functionalized specialty polyethers with narrow molecular weight distribution, the specific steps of which are as follows: 100 g of n-dodecyl alcohol was added to a reaction vessel, along with 1 g of the organic catalyst obtained in Preparation Example 2. The reaction was then cooled to 0°C and reacted for 0.5 h. A mixture of ethylene oxide, propylene oxide, and 1,2-epoxybutane in a mass ratio of 5:12:1 was then slowly fed to maintain the temperature at 0°C. When the amount of the epoxide mixture introduced reached 2000 g, the feeding was stopped, and the reaction continued for 8 h. Then, a vacuum was applied for 5 min, and the product was discharged to obtain the functionalized special polyether with a narrow molecular weight distribution.

[0032] Example 3 Example 3 provides a catalytic synthesis method for functionalized specialty polyethers with narrow molecular weight distribution, the specific steps of which are as follows: 100 g of 1,4-butanediol was added to a reaction vessel, along with 0.5 g of the organic catalyst obtained in Preparation Example 3. The mixture was then cooled to -10°C and reacted for 1 h. A mixture of ethylene oxide, propylene oxide, and 1,2-epoxybutane in a mass ratio of 1:2:1 was then slowly fed to maintain the temperature at -10°C. Feeding was stopped when the amount of the epoxide mixture introduced reached 2000 g, and the reaction was continued for 10 h. The mixture was then evacuated for 3 min, and the narrow molecular weight distribution functionalized special polyether was obtained.

[0033] Comparative Example 1 The difference between Comparative Example 1 and Example 1 above is that the catalyst used in the preparation of 1,2-polyether is a commercially available potassium hydroxide catalyst, and the specific preparation steps are as follows: Add 100 g of n-octanol to the reactor, add 0.2 g of potassium hydroxide, seal the reactor, replace the air in the reactor with nitrogen three times, raise the temperature to 80℃, vacuum treat at -0.09 MPa pressure for 30 min, then raise the temperature to 120-140℃, slowly feed propylene oxide, keep the reaction pressure ≤0.3 MPa, stop feeding when the amount of propylene oxide introduced reaches 1500 g, age and absorb at 120-140℃ until the reaction pressure is -0.06 MPa, evacuate for 5 min, cool and discharge to obtain polyether.

[0034] Test case The products prepared in Examples 1-3 and Comparative Example 1 were tested using the following methods: (1) The number-average molecular weight (M) of each polyether product was determined by gel permeation chromatography (GPC). n ) and molecular weight distribution index Monodisperse polystyrene samples were used as reference standards. The flow rate of the tetrahydrofuran mobile phase was 2 ml / min, and the temperature was 25℃. The results are shown in Table 1.

[0035] (2) The viscosity index of each polyether product was calculated according to GB / T 1995-1998 "Calculation Method of Viscosity Index of Petroleum Products". The results are shown in Table 1.

[0036] (3) The flash point of each polyether product was tested according to GB / T 3536-2008 "Determination of flash point and fire point of petroleum products - Cleveland open cup method". The results are shown in Table 1.

[0037] (4) The pour point (PP) of each polyether product was tested according to GB / T 3535-2006 "Determination of Pour Point of Petroleum Products". The results are shown in Table 1.

[0038] Table 1 Performance results of the polyether products obtained in Examples 1-3 and Comparative Example 1 As shown in Table 1, compared with Comparative Example 1 which used potassium hydroxide as a traditional catalyst, the products prepared in Examples 1-3 of this invention have superior performance, with a number-average molecular weight of 10870-13100 g / mol and a narrower molecular weight distribution. The viscosity index can reach 213, the flash point can be increased to 260-268℃, and the pour point can be reduced to below -40℃. These results fully demonstrate that the catalytic synthesis method provided by this invention can solve the industry problem of traditional methods failing to simultaneously achieve high molecular weight, narrow distribution, and high performance.

[0039] In summary, this invention, by designing an organic catalyst with a phosphorus-boron (PB) dual active center in its molecular structure, not only achieves highly efficient catalytic ring-opening polymerization of epoxides under low-temperature conditions, but also prepares a special polyether product with both high molecular weight and narrow molecular weight distribution. Furthermore, the use of this organic catalyst overcomes the problems of easy deactivation, complex mechanisms, and metal residues in commercial DMC systems during ethylene oxide polymerization, thus broadening the application scope of PAG in cosmetics, pharmaceuticals, and food-grade oils.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. The basic principles and main features of the present invention have been described above with specific implementation schemes. Based on the present invention, some modifications or substitutions can be made, but these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of protection claimed by the present invention.

Claims

1. A catalytic synthesis method for functionalized specialty polyethers with narrow molecular weight distribution, characterized in that, With C1~C 12 Using alcohol as a starting agent, a polymerization reaction is carried out with epoxide under the action of an organic catalyst to obtain the functionalized special polyether with a narrow molecular weight distribution; The structural formula of the organic catalyst is: 。 2. The catalytic synthesis method for functionalized specialty polyethers with narrow molecular weight distribution according to claim 1, characterized in that, The organic catalyst is prepared by the following process: (1) Anhydrous N,N-dimethylformamide was added to liquid methylamine at -80 to -75 °C, and anhydrous potassium carbonate and 6-bromo-1-hexene were added under stirring. The mixture was then heated to room temperature for reaction. After the reaction was completed, intermediate 1 was obtained by purification. The structural formula of intermediate 1 is: ； (2) Under an inert gas atmosphere, phosphorus trichloride was added to anhydrous diethyl ether, then cooled in an ice bath, and intermediate 1 was added under stirring to carry out the reaction; after the reaction was completed, intermediate 2 was obtained by purification. The structural formula of intermediate 2 is as follows: ； (3) The intermediate 2 and 9-boronbicyclo[3.3.1]nonane were added to tetrahydrofuran for reflux reaction. After the reaction was completed, the organic catalyst was obtained by purification.

3. The catalytic synthesis method for functionalized specialty polyethers with narrow molecular weight distribution according to claim 2, characterized in that, The molar ratio of liquid methylamine, anhydrous potassium carbonate and 6-bromo-1-hexene in step (1) is 1:(0.1-0.11):(0.1-0.11); the reaction time is 12-14 h.

4. The catalytic synthesis method for functionalized specialty polyethers with narrow molecular weight distribution according to claim 2, characterized in that, The molar ratio of phosphorus trichloride and intermediate 1 in step (2) is 1:(4-6); the reaction time is 1-2 h.

5. The catalytic synthesis method for functionalized specialty polyethers with narrow molecular weight distribution according to claim 2, characterized in that, The molar ratio of intermediate 2 and 9-boronibira[3.3.1]nonane in step (3) is 1:(1-1.2); the reflux reaction time is 12-16 h.

6. The catalytic synthesis method for functionalized specialty polyethers with narrow molecular weight distribution according to claim 1, characterized in that, The C1~C 12 The mass ratio of alcohol, organic catalyst and epoxide is 1:(0.005~0.01):(10~20).

7. The catalytic synthesis method for functionalized specialty polyethers with narrow molecular weight distribution according to claim 1, characterized in that, The epoxide is at least one of ethylene oxide, propylene oxide, and 1,2-epoxide butane; when the epoxide is a mixture of ethylene oxide, propylene oxide, and 1,2-epoxide butane, the mass ratio of ethylene oxide, propylene oxide, and 1,2-epoxide butane is (5-10):(12-20):(1-10).

8. The catalytic synthesis method for functionalized specialty polyethers with narrow molecular weight distribution according to claim 1, characterized in that, The C1~C 12 The alcohol can be any one of primary alcohols, secondary alcohols, or diols.

9. The catalytic synthesis method for functionalized specialty polyethers with narrow molecular weight distribution according to claim 1, characterized in that, The polymerization reaction is carried out at a temperature of -20 to 0°C for a duration of 8 to 13 hours.

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