Dechlorinating agent and preparation method thereof, dechlorinating agent supported membrane and preparation method and application thereof

Abstract

The invention relates to a thiocyano active substance dechlorinating agent, a preparation method and a novel supported membrane prepared from the thiocyano active substance dechlorinating agent, the membrane is applied to a TDI (toluene diisocynate) production process, organic chlorine impurities can be effectively removed, the TDI monomer yield is not reduced, and preparation of low-hydrolytic chlorine, high-purity and high-stability toluene diisocynate can be realized.

Description

Technical Field

[0001] The present invention relates to a dechlorinating agent and a preparation method thereof, a dechlorinating agent-loaded membrane and a preparation method thereof, and also relates to the application of the loaded membrane in the preparation of low-hydrolytic-chlorine toluene diisocyanate. Background Art

[0002] Toluene diisocyanate (TDI) can be prepared by the phosgenation reaction of toluene diamine. Hydrolytic chlorine is an important index of TDI products, which directly affects the activity of downstream foaming applications and the color number of prepolymers. It refers to the active chlorine atoms present in toluene diisocyanate.

[0003] In early patents, such as US Patent No. US3179680, it was disclosed that heating an organic isocyanate in the presence of a small amount of water can reduce the concentration of hydrolytic chlorine therein. However, water reacts with the isocyanate, which may reduce the yield or cause other processing problems.

[0004] US Patent No. US3219678 pointed out that after heating an isocyanate containing hydrolytic chlorine under temperature conditions much higher than those required for the decomposition of carbamyl chloride into an organic isocyanate and hydrogen chloride, passing an inert gas through the isocyanate to remove HCl can reduce hydrolytic chlorine. However, this method will cause the problem of re-formation of hydrolytic chlorine.

[0005] US Publication No. US3857871 pointed out that sending a liquid polyisocyanate at a temperature of 177-232°C for countercurrent treatment with an inert gas can reduce the hydrolytic chlorine content of polymethylene polyphenyl polyisocyanate and improve the reactivity. However, only heat and inert gas do not seem to be able to remove the hydrolytic chlorine of other isocyanates to the maximum extent, and heat treatment will further reduce the yield of isocyanate.

[0006] Patent CN112239416 A discloses the preparation of TDI by a two-step phosgenation method of hot and cold, and in the hot reaction process, the hot reaction liquid is subjected to high-temperature stripping treatment with a mixed gas formed by the phosgene tail gas rich in carbon monoxide generated in the cold reaction and nitrogen dioxide, so as to control the content of chlorine and bromine impurities at the source. The total content of hydrolytic chlorine and hydrolytic bromine in the prepared TDI product can be as low as 2 ppm.

[0007] There are also many methods to reduce the hydrolytic chlorine content in toluene diisocyanate. However, since the boiling points of chlorine and bromine impurities are very close to those of pure TDI after they are generated, it is difficult to remove them during the TDI refining process. Therefore, the existing methods basically sacrifice a large amount of energy consumption and material consumption for further refining and purification to meet the downstream TDI application requirements, with a high treatment cost and an extremely complex process flow at the same time.

[0008] In addition, researchers in this technical field have tried to remove hydrolyzable chlorine by chemical methods, mixing isocyanate compounds containing hydrolyzable chlorine with trace amounts of alkali metal carbonates at high temperature for a long time to reduce hydrolyzable chlorine. However, after this method is processed, it is difficult to separate the isocyanate compound and the carbonate, resulting in inevitable losses. There is also a method of synthesizing isocyanate in a water-insoluble solvent and washing it with an aqueous sodium bicarbonate solution to reduce hydrolyzable chlorine. However, in this method, white insoluble substances are deposited at the boundary between the water phase and the organic phase, which hinders the subsequent separation process or causes pollution to the equipment, limiting the production scale and industrial application.

[0009] Therefore, the existing methods for obtaining isocyanates with low hydrolyzable chlorine content all have corresponding drawbacks, and it is necessary to seek a new method to obtain toluene diisocyanate with low hydrolyzable chlorine content on the premise of not affecting the product quality, not affecting the product yield, and being easier to operate. Summary of the Invention

[0010] As described above, in the process of producing toluene diisocyanate, due to side reactions occurring during the photochemical reaction process, the formation of dichloroimine and bromochloro impurities leads to a high hydrolyzable chlorine content. In view of this, the present invention first provides a dechlorinating agent of thiocyano active substance and a preparation method thereof, as well as a novel supported membrane prepared therefrom. Applying this membrane to the TDI production process can effectively remove organic chlorine impurities without loss of the TDI monomer yield, and can achieve the preparation of toluene diisocyanate with low hydrolyzable chlorine, high purity, and high stability.

[0011] In order to achieve the above invention object, the technical solution adopted by the present invention is as follows:

[0012] In the first aspect, the present invention provides a dechlorinating agent, whose structure is shown in Formula 1 below:

[0013]

[0014] In Formula 1, R is selected from C1-C5 alkyl groups, C6-C9 alkaryl groups, preferably C1-C3 alkyl groups, phenyl groups.

[0015] In the second aspect, the present invention provides a preparation method of the dechlorinating agent shown in Formula 1 above, and the method comprises the following steps:

[0016] 1) Reacting N-R group-3-oxo-3-phenylpropanamide shown in Formula 2 and a fluorine reagent as raw materials to prepare intermediate A shown in Formula 3;

[0017] 2) Reacting N-chlorosuccinimide (NCS) and thiocyanate as raw materials to prepare intermediate B shown in Formula 4;

[0018] 3) Using the intermediate A prepared in step 1) and the intermediate B prepared in step 2) as raw materials, and using a chiral bisoxazoline ligand as a catalyst, a dechlorinating agent shown in formula 1 is prepared through a reaction;

[0019] Among them, the N-R group-3-oxo-3-phenylpropanamide shown in formula 2, the intermediate A shown in formula 3, and the intermediate B shown in formula 4 have the following structures:

[0020]

[0021] In formula 2 and formula 3, the definition of R is the same as the definition of R in formula 1.

[0022] In the present invention, the N-R group-3-oxo-3-phenylpropanamide in step 1) is selected from at least one of N-(C1-C5 alkyl)-3-oxo-phenylpropanamide and N-(alkaryl group with C6-C9)-3-oxo-phenylpropanamide, preferably at least one of N-methyl-3-oxo-phenylpropanamide and N-phenyl-3-oxo-phenylpropanamide.

[0023] In the present invention, the fluorinating agent in step 1) is 1-chloromethyl-4-fluoro-1,4-diazabicyclo[2.2.2]octane bis(tetrafluoroborate) (CAS 140681-55-6).

[0024] In the present invention, the molar ratio of the N-R group-3-oxo-3-phenylpropanamide to the fluorinating agent in step 1) is 1:0.5 to 1:4, such as 1:0.5, 1:1, 1:2, 1:3, 1:4, preferably 1:0.8 to 1:1.2.

[0025] In the present invention, for the reaction in step 1), the system further optionally contains a solvent, and the solvent is selected from at least one of an acetonitrile-water mixture, an N-methylformamide-water mixture, and an N-methylpyrrolidone-water mixture, preferably an acetonitrile-water mixture with a volume ratio of 1:2 to 2:1, such as 1:2, 1:1, 2:1;

[0026] Preferably, the amount of the solvent used is 150-250 ml / mol of N-R group-3-oxo-phenylpropanamide, such as 150, 175, 200, 225, 250 ml / mol of N-R group-3-oxo-phenylpropanamide.

[0027] In the present invention, for the reaction in step 1), the temperature is 20-40 °C, such as 20, 25, 30, 35, 40 °C, preferably 25-30 °C, and the time is 2-8 h, such as 2, 4, 6, 8 h, preferably 3-6 h;

[0028] After the reaction is completed, it also includes post-treatment processes such as extraction with an organic solvent such as ethyl acetate, standing for phase separation, and rotary evaporation to remove the extractant, etc. These are all conventional operation methods in the field, and the present invention has no special requirements.

[0029] In the present invention, the thiocyanate in step 2) is selected from at least one of potassium thiocyanate, sodium thiocyanate, and ammonium thiocyanate.

[0030] In the present invention, the molar ratio of N-chlorosuccinimide to thiocyanate in step 2) is 1:1 to 1:4, such as 1:1, 1:2, 1:3, 1:4, and preferably 1:2 to 1:3.

[0031] In the present invention, for the reaction in step 2), the system may also contain an optional solvent, and the solvent is selected from at least one of N-methylformamide, N-methylpyrrolidone, and acetonitrile, and preferably acetonitrile;

[0032] Preferably, the amount of the solvent used is 150 - 250 ml / mol of N-chlorosuccinimide, such as 150, 175, 200, 225, 250 ml / mol of N-chlorosuccinimide.

[0033] In the present invention, for the reaction in step 2), the temperature is 20 - 40 °C, such as 20, 25, 30, 35, 40 °C, preferably 25 - 30 °C, and the time is 15 - 60 min, such as 15, 30, 45, 60 min, preferably 30 - 45 min;

[0034] After the reaction is completed, it also includes post-treatment processes such as filtering to remove salts and rotary evaporation to remove the solvent, etc. These are all conventional operation methods in the field, and the present invention has no special requirements.

[0035] In the present invention, the molar ratio of intermediate A to intermediate B in step 3) is 2:1 to 1:4, such as 2:1, 1:1, 1:2, 1:3, 1:4, and preferably 1:1 to 1:1.5.

[0036] In the present invention, the chiral bis(dioxo) ligand in step 3) is selected from at least one of 2,3-bipyridine dioxide, 2,5-dimethylpyrazine dioxide, and phenazine dioxide;

[0037] Preferably, the amount of the chiral bis(dioxo) ligand catalyst used is 1 - 10% of the total mass of intermediate A and intermediate B, such as 1, 3, 6, 9, 10%, and preferably 3 - 7%.

[0038] In the present invention, for the reaction in step 3), the system may also contain an optional solvent, and the solvent is selected from at least one of petroleum ether, dichloromethane, chloroform, and dichloroethane, and preferably chloroform;

[0039] Preferably, the amount of the solvent is 150 - 250 ml / mol (Intermediate A + Intermediate B), such as 150, 175, 200, 225, 250 ml / mol (Intermediate A + Intermediate B).

[0040] In the present invention, for the reaction in step 3), the temperature is 25 - 50 °C, such as 20, 25, 30, 35, 40, 45, 50 °C, preferably 25 - 35 °C, and the time is 0.5 - 8 h, such as 0.5, 2, 4, 6, 8 h, preferably 1 - 3 h;

[0041] After the reaction is completed, it also includes post-treatment processes such as silica gel column separation, elution, rotary evaporation to remove the solvent, etc., which are all conventional operation methods in the field. There are no special requirements in the present invention. Preferably, silica gel column chromatography with 300 - 400 mesh is used to separate the catalyst and the product, and n-hexane:ethyl acetate = 1:1 is used for elution.

[0042] In a third aspect, the present invention provides a dechlorinating agent-loaded membrane, which is prepared by loading the dechlorinating agent shown in Formula 1 above on a base membrane. The steps include:

[0043] (1) Cleaning the base membrane with a solvent and then air-drying it naturally;

[0044] (2) Immersing the base membrane dried in step (1) in an organic acid buffer solution for reaction to construct an organic acid-mediated layer on the membrane surface;

[0045] (3) Immersing the base membrane with the mediated layer constructed in (2) into an organic solution of the dechlorinating agent shown in Formula 1 to obtain a dechlorinating agent-loaded base membrane;

[0046] (4) Immersing the dechlorinating agent-loaded base membrane in (3) in a capping agent for capping reaction to prepare the dechlorinating agent-loaded membrane.

[0047] In the present invention, the base membrane in step (1) is selected from membranes formed by polymers, preferably at least one of polyvinylidene fluoride membrane (PVDF) and polytetrafluoroethylene membrane (PTFE).

[0048] In the present invention, the solvent in step (1) is selected from at least one of alkyl alcohols, acetone, and water, preferably at least one of methanol and acetone, and more preferably acetone;

[0049] The cleaning is a conventional operation in the field, and it is only necessary to clean it thoroughly. There are no special requirements in the present invention.

[0050] In the present invention, the pH value of the organic acid buffer solution in step (2) is 3 - 10, such as 3, 5, 7, 9, 10;

[0051] Among them, the organic acid is selected from at least one of formic acid, acetic acid, salicylic acid, and maleic acid, and preferably an acetic acid - ammonium acetate buffer system;

[0052] Preferably, in the organic acid buffer solution, the concentration of the organic acid is 1-5 wt%, such as 1, 2, 3, 4, 5 wt%.

[0053] In the present invention, for the reaction in step (2), the reaction temperature is 30-60 °C, such as 30, 35, 40, 45, 50, 55, 60 °C, preferably 35-45 °C, and the reaction time is 8-24 h, such as 8, 10, 13, 16, 19, 22, 24 h, preferably 10-12 h.

[0054] In the present invention, for the organic solution of the dechlorinating agent in step (3), the organic solvent is selected from at least one of benzene, toluene, acetone, cyclohexane, ethyl acetate, and diethyl isophthalate, preferably diethyl isophthalate;

[0055] Preferably, in the organic solution of the dechlorinating agent, the concentration of the dechlorinating agent is 0.5-3 wt%, such as 0.5, 1, 1.5, 2, 2.5, 3 wt%.

[0056] In the present invention, for the soaking in step (3), the time is 4-8 h, such as 4, 5, 6, 7, 8 h, preferably 5-6 h, and the temperature is 40-80 °C, such as 40, 50, 60, 70, 80 °C, preferably 50-60 °C.

[0057] In the present invention, the capping agent in step (4) is selected from at least one of basic amine substances, preferably at least one of trimethylamine, diethylamine, triethylamine, etc., and more preferably triethylamine.

[0058] In the present invention, for the capping reaction in step (4), there is no special requirement for the temperature, and room temperature is acceptable. The time is 4-8 h, such as 4, 5, 6, 7, 8 h, preferably 5-6 h.

[0059] Fourthly, the present invention provides a dechlorinating agent-loaded membrane prepared by the above method.

[0060] Fifthly, the present invention provides the application of the dechlorinating agent-loaded membrane prepared by the above method in the preparation of TDI.

[0061] The crude TDI is prepared by using the conventional cold and hot two-step phosgenation method. Under certain temperature and pressure, the dechlorinating agent-loaded membrane prepared by the above method is used to perform membrane treatment on the TDI taken out from the gas phase after the crude TDI is defoamed, and the organic chlorine impurities can be removed. On this basis, a TDI product with a hydrolytic chlorine content lower than 1 ppm is separated;

[0062] Specifically, the dechlorinating agent-loaded membrane is applied to the gas-phase extraction material port after the crude toluene diisocyanate is defoamed. After the material passes through the loaded membrane, a toluene diisocyanate product with a hydrolytic chlorine content of <1 ppm is obtained;

[0063] Preferably, the operating temperature for the dechlorinating agent-loaded membrane is 120 to 180 °C, such as 120, 130, 140, 150, 160, 170, 180 °C, and the pressure is 1 to 10 kPa, such as 1, 3, 5, 7, 9, 10 kPa.

[0064] Compared with the prior art, the advantages of the present invention are as follows:

[0065] (1) The dechlorinating agent adopts a novel thiocyanate dechlorination group, and its activity is much higher than that of conventional dechlorinating agents (such as alcohols and organic amines). Its dechlorination efficiency is as high as 99%, and this process does not introduce foreign impurities and does not require the removal of dechlorination reagents.

[0066] (2) Dechlorination is carried out by loading the active group on the membrane. Compared with the existing rectification dechlorination and chemical additive dechlorination methods, the process is simple, saves steam energy consumption, and does not cause additional side reactions. Detailed implementation mode

[0067] The present invention will be further described below in conjunction with embodiments, but the present invention is not limited thereby.

[0068] The total chlorine and total bromine contents in the TDI product of the present invention are analyzed by X-ray fluorescence spectroscopy (manufacturer, Agilent, USA);

[0069] The hydrolyzable chlorine in the TDI product of the present invention is analyzed according to Standard GB / T 12009.2-2016;

[0070] The purity of the TDI product of the present invention is measured using an Agilent 7890, chromatographic column: HP-5 gas chromatographic column, specifications 30m * 0.32mm * 0.25u; flow rate: 1.0 ml / min; injection volume: 0.5 ul; split ratio 30:1; vaporization chamber temperature 280 °C.

[0071] The sources of the chemical reagent raw materials in the following examples are shown in the following table. Other raw materials and reagents are obtained through commercial channels without special instructions:

[0072]

[0073]

[0074]

Example 1

[0075] Synthesis of dechlorinating agent intermediate A - Example 1:

[0076] Dissolve 1 mol of N-methyl-3-oxo-phenylpropanamide and 0.8 mol of fluorinating reagent in 200 ml of a mixture of acetonitrile and water (V:V = 1:1), add it to a 500 ml reactor equipped with a thermometer and a reflux condenser, control the temperature of the reaction system at 25 °C, and stir the reaction for 4 h. After completion, the reaction product is extracted with ethyl acetate. After standing and phase separation, the organic phase is taken out, and at 50 °C and a pressure of 25 mmHg, the ethyl acetate extractant is removed by rotary evaporation to obtain intermediate A-1; the reaction formula is as follows:

[0077]

[0078] 1 H NMR (DMSO-d6, 300 MHz): 2.80 (s, 3H), 5.77 (s, 1H), 7.51 - 7.59 (d, J = 12.4 Hz, 2H), 7.68 (d, J = 12.4 Hz, 1H), 7.98 - 8.02 (d, J = 12.4 Hz, 2H), 10.02 (s, 1H).

[0079] Synthesis of dechlorination agent intermediate A - Example 2:

[0080] Dissolve 1 mol of N-methyl-3-oxo-phenylpropanamide and 1 mol of fluorinating reagent in 180 ml of a mixture of N-methylpyrrolidone and water (V:V = 1:1.5), add it to a 500 ml reactor equipped with a thermometer and a reflux condenser, control the temperature of the reaction system at 30 °C, and stir the reaction for 6 h. After completion, the reaction product is extracted with ethyl acetate. After standing and phase separation, the organic phase is taken out, and at 50 °C and a pressure of 25 mmHg, the ethyl acetate extractant is removed by rotary evaporation to obtain intermediate A-1; the reaction formula is as follows:

[0081]

[0082] 1 H NMR (DMSO-d6, 300 MHz): 2.80 (s, 3H), 5.77 (s, 1H), 7.51 - 7.59 (d, J = 12.4 Hz, 2H), 7.68 (d, J = 12.4 Hz, 1H), 7.98 - 8.02 (d, J = 12.4 Hz, 2H), 10.02 (s, 1H).

[0083] Synthesis of dechlorination agent intermediate A - Example 3:

[0084] Dissolve 1 mol of 2-benzoylacetanilide and 1.1 mol of fluorinating reagent in 250 ml of a mixture of acetonitrile and water (V:V = 2:1). Add them to a 500-ml reactor equipped with a thermometer and a reflux condenser. Control the temperature of the reaction system at 30 °C and stir the reaction for 5 h. After completion, extract the reaction product with ethyl acetate. After standing for phase separation, take out the organic phase and rotary evaporate to remove the ethyl acetate extractant at 50 °C and 25 mmHg pressure to obtain intermediate A-2. The reaction formula is as follows:

[0085]

[0086] 1 H NMR (DMSO-d6, 300 MHz): 5.93 (s, 1H), 7.07 (d, J = 12.4 Hz, 1H), 7.28 - 7.32 (d, J = 12.4 Hz, 2H), 7.51 - 7.55 (d, J = 12.4 Hz, 2H), 7.57 - 7.61 (d, J = 12.4 Hz, 2H), 7.68 (d, J = 12.4 Hz, 1H), 7.97 - 8.02 (d, J = 12.4 Hz, 2H), 10.02 (s, 1H).

[0087] Synthesis of dechlorination agent intermediate A - Example 4:

[0088] Dissolve 1 mol of 2-benzoylacetanilide and 1.2 mol of fluorinating reagent in 200 ml of a mixture of N-methylformamide and water (V:V = 1.5:1). Add them to a 500-ml reactor equipped with a thermometer and a reflux condenser. Control the temperature of the reaction system at 25 °C and stir the reaction for 6 h. After completion, extract the reaction product with ethyl acetate. After standing for phase separation, take out the organic phase and rotary evaporate to remove the ethyl acetate extractant at 50 °C and 25 mmHg pressure to obtain intermediate A-2. The reaction formula is as follows:

[0089]

[0090] 1 H NMR (DMSO-d6, 300 MHz): 5.93 (s, 1H), 7.07 (d, J = 12.4 Hz, 1H), 7.28 - 7.32 (d, J = 12.4 Hz, 2H), 7.51 - 7.55 (d, J = 12.4 Hz, 2H), 7.57 - 7.61 (d, J = 12.4 Hz, 2H), 7.68 (d, J = 12.4 Hz, 1H), 7.97 - 8.02 (d, J = 12.4 Hz, 2H), 10.02 (s, 1H).

[0091]

Example 2

[0092] Synthesis of dechlorination agent intermediate B - Example 1:

[0093] Dissolve 1 mol of NCS (N-chlorosuccinimide) and 2 mol of potassium thiocyanate in 200 ml of acetonitrile solvent. Add them to a 500 ml reactor equipped with a thermometer and a reflux condenser. Control the temperature of the reaction system at 25 °C, stir the reaction for 30 min, filter to remove the excess salt, and rotary evaporate the solvent and unreacted NCS at 50 °C and 25 mmHg pressure to obtain intermediate B; the reaction formula is as follows:

[0094]

[0095] 1 H NMR (DMSO-d6, 300 MHz): 2.64 (s, 4H).

[0096] Synthesis of the dechlorination agent intermediate B - Example 2:

[0097] Dissolve 1 mol of NCS (N-chlorosuccinimide) and 3 mol of ammonium thiocyanate in 250 ml of N-methylpyrrolidone solvent. Add them to a 500 ml reactor equipped with a thermometer and a reflux condenser. Control the temperature of the reaction system at 30 °C, stir the reaction for 40 min, filter to remove the excess salt, and rotary evaporate the solvent and unreacted NCS at 50 °C and 25 mmHg pressure to obtain intermediate B; the reaction formula is as follows:

[0098]

[0099] 1 H NMR (DMSO-d6, 300 MHz): 2.64 (s, 4H).

[0100]

Example 3

[0101] Synthesis of the dechlorination agent - Example 1:

[0102] Dissolve 0.5 mol of intermediate A-1 (R group is methyl) and 0.5 mol of intermediate B in 200 ml of chloroform solvent. Add 2,3'-bipyridine-dioxide, which is 3% of the total mass of intermediate A + intermediate B, as a catalyst. Add them to a 500 ml reactor equipped with a thermometer and a reflux condenser. Stir the reaction at 25 °C for 2 h. Separate the catalyst and the product by column chromatography on silica gel with a mesh size of 300 - 400. Use n-hexane:ethyl acetate = 1:1 for elution. Rotary evaporate the solvent at 50 °C and 25 mmHg pressure to obtain the dechlorination agent-1; the reaction formula is as follows:

[0103]

[0104] 11H NMR (DMSO-d6, 300 MHz): δ 2.80 (s, 3H), 7.51 - 7.59 (d, J = 12.4 Hz, 2H), 7.68 (d, J = 12.4 Hz, 1H), 7.98 - 8.02 (d, J = 12.4 Hz, 2H), 10.02 (s, 1H).

[0105] Synthesis of dechlorination agent - Example 2:

[0106] Dissolve 0.5 mol of intermediate A-1 (R group is methyl) and 0.75 mol of intermediate B in 300 ml of dichloromethane solvent. Add 2,3'-bipyridine-dioxide as a catalyst, which is 5% of the total mass of intermediate A + intermediate B. Add them to a 500 ml reactor equipped with a thermometer and a reflux condenser. Stir and react at 35 °C for 1.5 h. Separate the catalyst and the product from the reaction solution by silica gel column chromatography with a mesh size of 300 - 400. Use n-hexane:ethyl acetate = 1:2 for elution. Evaporate the solvent under the conditions of 50 °C and 25 mmHg pressure to obtain dechlorination agent - 1; The reaction formula is as follows:

[0107]

[0108] 1 1H NMR (DMSO-d6, 300 MHz): δ 2.80 (s, 3H), 7.51 - 7.59 (d, J = 12.4 Hz, 2H), 7.68 (d, J = 12.4 Hz, 1H), 7.98 - 8.02 (d, J = 12.4 Hz, 2H), 10.02 (s, 1H).

[0109] Synthesis of dechlorination agent - Example 3:

[0110] Dissolve 0.5 mol of intermediate A-2 (R group is phenyl) and 0.4 mol of B in 200 ml of chloroform solvent. Add 2,3'-bipyridine-dioxide as a catalyst, which is 4% of the total mass of intermediate A + intermediate B. Add them to a 500 ml reactor equipped with a thermometer and a reflux condenser. Stir and react at 35 °C for 2 h. Separate the catalyst and the product from the reaction solution by silica gel column chromatography with a mesh size of 300 - 400. Use n-hexane:ethyl acetate = 1:2 for elution. Evaporate the solvent under the conditions of 50 °C and 25 mmHg pressure to obtain dechlorination agent - 2; The reaction formula is as follows:

[0111]

[0112] 11H NMR (DMSO-d6, 300 MHz): δ 7.07 (d, J = 12.4 Hz, 1H), 7.28 - 7.32 (d, J = 12.4 Hz, 2H), 7.51 - 7.55 (d, J = 12.4 Hz, 2H), 7.57 - 7.61 (d, J = 12.4 Hz, 2H), 7.68 (d, J = 12.4 Hz, 1H), 7.97 - 8.02 (d, J = 12.4 Hz, 2H), 10.02 (s, 1H).

[0113] Synthesis of dechlorination agent - Example 4:

[0114] Dissolve 0.5 mol of intermediate A-2 (R group is phenyl) and 0.35 mol of B in 180 ml of dichloromethane solvent. Add 2,3'-bipyridine-dioxide, which is 5% of the total mass of intermediate A + intermediate B, as a catalyst. Add it to a 500 ml reactor equipped with a thermometer and a reflux condenser. Stir and react at 35 °C for 2.5 h. Separate the catalyst and the product by silica gel column chromatography with a mesh size of 300 - 400. Use n-hexane:ethyl acetate = 1:3 for elution. Rotate and evaporate the solvent at 50 °C and 25 mmHg pressure to obtain dechlorination agent - 2; The reaction formula is as follows:

[0115]

[0116] 1 1H NMR (DMSO-d6, 300 MHz): δ 7.07 (d, J = 12.4 Hz, 1H), 7.28 - 7.32 (d, J = 12.4 Hz, 2H), 7.51 - 7.55 (d, J = 12.4 Hz, 2H), 7.57 - 7.61 (d, J = 12.4 Hz, 2H), 7.68 (d, J = 12.4 Hz, 1H), 7.97 - 8.02 (d, J = 12.4 Hz, 2H), 10.02 (s, 1H).

[0117]

Example 4

[0118] Preparation of dechlorination agent - loaded membrane - Example 1:

[0119] Clean the polyvinylidene fluoride membrane (PVDF) with acetone solvent and air dry it naturally.

[0120] Immerse the cleaned membrane material in a 2 wt% organic acid buffer solution (10 mg / mL acetic acid + 50 mM ammonium acetate aqueous solution, pH = 5.4), and soak and react at 40 °C for 12 h to construct a polyorganic acid mediated layer on the surface of the base membrane.

[0121] At 50 °C, immerse the base membrane with the polyorganic acid mediated layer in diethyl isophthalate containing 1 wt% dechlorination agent - 1 for 5 h to load the dechlorination agent.

[0122] Finally, the base membrane of the dechlorination agent was soaked in triethylamine at room temperature for 5 h for end-capping reaction to obtain the dechlorination agent-loaded membrane-1.

[0123] Preparation of dechlorination agent-loaded membrane - Example 2:

[0124] The polyvinylidene fluoride membrane (PVDF) was cleaned with methanol solvent and dried naturally.

[0125] The cleaned membrane material was soaked in a 3 wt% organic acid buffer solution (10 mg / mL formic acid + 50 mM sodium formate aqueous solution, pH 4.4) and soaked and reacted at 35 °C for 8 h to construct a polyorganic acid-mediated layer on the surface of the base membrane.

[0126] Under the condition of 60 °C, the base membrane with the polyorganic acid-mediated layer was soaked in ethyl acetate containing 2 wt% dechlorination agent-1 for 5 h to load the dechlorination agent.

[0127] Finally, the base membrane loaded with the dechlorination agent was soaked in diethylamine at room temperature for 6 h for end-capping reaction to obtain the dechlorination agent-loaded membrane-1.

[0128] Preparation of dechlorination agent-loaded membrane - Example 3:

[0129] The polyvinylidene fluoride membrane (PVDF) was cleaned with acetone solvent and dried naturally.

[0130] The cleaned membrane material was soaked in a 2 wt% organic acid buffer solution (10 mg / mL acetic acid + 50 mM ammonium acetate aqueous solution, pH 5.4) and soaked and reacted at 40 °C for 9 h to construct a polyorganic acid-mediated layer on the surface of the base membrane.

[0131] Under the condition of 55 °C, the base membrane with the polyorganic acid-mediated layer was soaked in diethyl phthalate containing 1 wt% dechlorination agent-2 for 6 h to load the dechlorination agent.

[0132] Finally, the base membrane loaded with the dechlorination agent was soaked in triethylamine at room temperature for 5 h for end-capping reaction to obtain the dechlorination agent-loaded membrane-2.

[0133] Preparation of dechlorination agent-loaded membrane - Example 4:

[0134] The polyvinylidene fluoride membrane (PVDF) was cleaned with methanol solvent and dried naturally.

[0135] The cleaned membrane material was soaked in a 5 wt% organic acid buffer solution (10 mg / mL formic acid + 50 mM sodium formate aqueous solution, pH 4.4) and soaked and reacted at 35 °C for 12 h to construct a polyorganic acid-mediated layer on the surface of the base membrane.

[0136] At 60 °C, the base film for constructing the polyorganic acid-mediated layer was immersed in ethyl acetate containing 3 wt% of dechlorinating agent - 2 for 6 h to load the dechlorinating agent.

[0137] Finally, the base film loaded with the dechlorinating agent was soaked in diethylamine at room temperature for 6 h for the capping reaction to obtain the dechlorinating agent-loaded membrane - 2.

[0138]

Example 5

[0139] Specific application of the dechlorinating agent-loaded membrane in toluene diisocyanate

[0140] The crude TDI was prepared by the conventional two-step phosgenation method of cold and heat. After the crude TDI was de-tarred, the dechlorinating agent-loaded membrane 1 was installed at the gas-phase outlet of TDI. Under the working conditions of 1 - 10 kPaG and 120 - 180 °C, the gas-phase TDI was treated through the membrane to remove organic chlorine impurities. After further purification of the product, the hydrolyzable chlorine content of the produced TDI was less than 1 ppm, and the dechlorination rate was 99%.

[0141] Repeat the above steps, replace the dechlorinating agent-loaded membrane 1 with the dechlorinating agent-loaded membrane 2, the hydrolyzable chlorine content of the produced TDI is less than 1 ppm, and the dechlorination rate is 99%.

[0142]

Comparative Example 1

[0143] Prepare the intermediate A-2-loaded membrane. The loading method is the same as that in Example 4 for preparing the dechlorinating agent-loaded membrane - Example 3, only replace the diethyl phthalate containing 1 wt% of dechlorinating agent - 2 with the diethyl phthalate containing 1 wt% of intermediate A-2.

[0144] Repeat the steps of Example 5, the hydrolyzable chlorine content of the produced TDI is about 90 ppm, and there is basically no dechlorination rate.

[0145]

Comparative Example 2

[0146] Prepare the intermediate B-loaded membrane. The loading method is the same as that in Example 4 for preparing the dechlorinating agent-loaded membrane - Example 4, only replace the ethyl acetate containing 3 wt% of dechlorinating agent - 2 with the ethyl acetate containing 3 wt% of intermediate B.

[0147] Repeat the steps of Example 5, the hydrolyzable chlorine content of the produced TDI is about 50 ppm, and the dechlorination rate is about 45%.

Claims

1. A dechlorinating agent, characterized in that, The structure is as shown in Formula 1: In Formula 1, R is selected from C1-C5 alkyl, C6-C9 alkaryl, preferably C1-C3 alkyl, phenyl.

2. The preparation method of the dechlorination agent according to claim 1, characterized in that It includes the following steps: 1) React N-R group-3-oxo-3-phenylpropanamide shown in Formula 2 and a fluorine reagent as raw materials to prepare intermediate A shown in Formula 3; 2) React N-chlorosuccinimide (NCS) and thiocyanate as raw materials to prepare intermediate B described in Formula 4; 3) Use intermediate A prepared in step 1) and intermediate B prepared in step 2) as raw materials, and use a chiral bis-nitrogen-oxygen ligand as a catalyst to react to prepare the dechlorinating agent shown in Formula 1; Among them, the N-R group-3-oxo-3-phenylpropanamide shown in Formula 2, intermediate A shown in Formula 3, and intermediate B described in Formula 4 have the following structures: In Formulas 2 and 3, the definition of R is the same as that in Formula 1.

3. The preparation method according to claim 2, characterized in that, The N-R group-3-oxo-3-phenylpropanamide in step 1) is selected from at least one of N-(C1-C5 alkyl)-3-oxo-phenylpropanamide, N-(C6-C9 alkaryl)-3-oxo-phenylpropanamide, preferably at least one of N-methyl-3-oxo-phenylpropanamide, N-phenyl-3-oxo-phenylpropanamide; and / or The fluorine reagent in step 1) is 1-chloromethyl-4-fluoro-1,4-diazabicyclo[2.2.2]octane bis(tetrafluoroborate); and / or The molar ratio of the N-R group-3-oxo-3-phenylpropanamide to the fluorine reagent in step 1) is 1:0.5 to 1:4, preferably 1:0.8 to 1:1.2; and / or For the reaction in step 1), the system may further contain an optional solvent, and the solvent is selected from at least one of an acetonitrile-water mixture, an N-methylformamide-water mixture, an N-methylpyrrolidone-water mixture, preferably an acetonitrile-water mixture with a volume ratio of 1:2 to 2:1; Preferably, the solvent dosage is 150-250 ml / mol of N-R group-3-oxo-phenylpropanamide; and / or For the reaction in step 1), the temperature is 20-40°C, preferably 25-30°C, and the time is 2-8 h, preferably 3-6 h.

4. The preparation method according to claim 2, characterized in that, The thiocyanate in step 2) is selected from at least one of potassium thiocyanate, sodium thiocyanate, ammonium thiocyanate; and / or The molar ratio of N-chlorosuccinimide to thiocyanate in step 2) is 1:1 to 1:4, preferably 1:2 to 1:3; and / or For the reaction in step 2), the system may further contain an optional solvent, and the solvent is selected from at least one of N-methylformamide, N-methylpyrrolidone, acetonitrile, preferably acetonitrile; Preferably, the solvent dosage is 150-250 ml / mol of N-chlorosuccinimide; and / or For the reaction in step 2), the temperature is 20-40°C, preferably 25-30°C, and the time is 15-60 min, preferably 30-45 min.

5. The preparation method according to claim 2, characterized in that, The molar ratio of intermediate A to intermediate B in step 3) is 2:1 to 1:4, preferably 1:1 to 1:1.5; and / or The chiral bis-nitrogen-oxygen ligand in step 3) is selected from at least one of 2,3-bipyridine dioxide, 2,5-dimethylpyrazine dioxide, phenazine dioxide; Preferably, the dosage of the chiral bis(oxime) ligand catalyst is 1-10% of the total mass of Intermediate A and Intermediate B, preferably 3-7%; and / or For the reaction in step 3), the system may further contain an optional solvent, which is selected from at least one of petroleum ether, dichloromethane, chloroform, and dichloroethane, preferably chloroform; Preferably, the dosage of the solvent is 150-250 ml / mol (Intermediate A + Intermediate B); and / or For the reaction in step 3), the temperature is 25-50°C, preferably 25-35°C, and the time is 0.5-8 h, preferably 1-3 h.

6. A preparation method of a dechlorinating agent-loaded membrane, characterized in that, The raw material contains the dechlorinating agent supported by the base film as claimed in claim 1 or the dechlorinating agent prepared by the method according to any one of claims 2-5, and the steps include: (1) Cleaning the base film with a solvent and then air-drying it naturally; (2) Immersing the air-dried base film from step (1) in an organic acid buffer solution for reaction to construct an organic acid-mediated layer on the film surface; (3) Immersing the base film with the mediated layer constructed in (2) into an organic solution of the dechlorinating agent shown in Formula 1 to obtain a base film loaded with the dechlorinating agent; (4) Immersing the base film loaded with the dechlorinating agent in (3) in a capping agent for capping reaction to obtain a dechlorinating agent-loaded membrane.

7. The preparation method according to claim 6, characterized in that, The base film in step (1) is selected from membranes formed by polymers, preferably at least one of polyvinylidene fluoride membrane (PVDF) and polytetrafluoroethylene membrane (PTFE); and / or The solvent in step (1) is selected from at least one of alkyl alcohols, acetone, and water, preferably at least one of methanol and acetone, more preferably acetone; and / or The pH value of the organic acid buffer solution in step (2) is 3-10; Among them, the organic acid is selected from at least one of formic acid, acetic acid, salicylic acid, and maleic acid, preferably acetic acid-ammonium acetate buffer system; Preferably, in the organic acid buffer solution, the concentration of the organic acid is 1-5 wt%; and / or For the reaction in step (2), the reaction temperature is 30-60°C, preferably 35-45°C, and the reaction time is 8-24 h, preferably 10-12 h.

8. The preparation method according to claim 6, characterized in that, For the organic solution of the dechlorinating agent in step (3), the organic solvent is selected from at least one of benzene, toluene, acetone, cyclohexane, ethyl acetate, and diethyl isophthalate, preferably diethyl isophthalate; Preferably, the concentration of the dechlorinating agent in the organic solution of the dechlorinating agent is 0.5-3 wt%; and / or For the immersion in step (3), the time is 4-8 h, preferably 5-6 h, and the temperature is 40-80°C, preferably 50-60°C; and / or The capping agent in step (4) is selected from at least one of basic amine substances, preferably at least one of trimethylamine, diethylamine, and triethylamine, more preferably triethylamine; and / or For the capping reaction in step (4), the time is 4-8 h, preferably 5-6 h.

9. A dechlorinating agent-loaded membrane prepared by the method according to any one of claims 6-8.

10. Use of the dechlorinating agent-loaded membrane prepared by the method according to any one of claims 6-8 or the dechlorinating agent-loaded membrane according to claim 9 in the preparation of TDI; Preferably, the dechlorination agent-loaded membrane is applied to the gas-phase extraction material port after the crude toluene diisocyanate is de-tarred. After the material passes through the loaded membrane, a toluene diisocyanate product with a hydrolyzable chlorine content of less than 1 ppm is obtained; More preferably, the operating temperature of passing the material through the dechlorination agent-loaded membrane is 120-180 °C, and the pressure is 1-10 kPa.

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