Preparation method of bis(3-methoxypropyl)methylamine

Abstract

The invention belongs to the field of organic synthesis, and specifically discloses a method for preparing bis(3-methoxypropyl)methylamine, comprising the following steps: 1), using acrylonitrile and methanol as raw materials, and using alkali as an addition catalyst to perform Michael addition reaction; 2), first adding acid to the obtained reaction solution containing 3-methoxypropionitrile, and then filtering, adding an auxiliary agent and a hydrogenation catalyst to the filtrate for catalytic hydrogenation reaction; post-treating the reaction product, recovering the hydrogenation catalyst, and obtaining bis(3-methoxypropyl)amine, etc.; 3), dissolving paraformaldehyde in the methanol fraction, and then adding the hydrogenation catalyst recovered in step 2) and bis(3-methoxypropyl)amine for hydrogenation methylation reaction; post-treating the reaction product to obtain bis(3-methoxypropyl)methylamine. Bis(3-methoxypropyl)methylamine can be used as a novel polyurethane foaming catalyst.

Description

Technical Field

[0001] The invention belongs to the field of organic synthesis, and particularly relates to a method for preparing bis(3-methoxypropyl)methylamine. Background Art

[0002] Bis(3-methoxypropyl)methylamine, whose molecular formula is C9H 21 NO2, molecular weight is 175.26, CAS number is 2361631-67-4, and the structural formula is shown in Formula 1. In the synthesis process of polyurethane foam plastics, the foaming catalyst plays an important role, and bis(3-methoxypropyl)methylamine can be used as an important amine ether polyurethane foaming catalyst. Amine ether catalysts have high catalytic activity for foaming reactions, and the prepared products have excellent performance. In addition, a major advantage of amine ether catalysts is that they can cooperate with organic tin catalysts to act on the foaming reaction. When they are used in coordination, they can obtain polyurethane foam products with excellent performance at a lower addition amount.

[0003]

[0004] Formula 1, structural formula of bis(3-methoxypropyl)methylamine

[0005] Currently, there is no literature report on the preparation method of bis(3-methoxypropyl)methylamine.

[0006] Patent CN109456204A discloses a method for preparing 3-methoxypropylamine, comprising the following steps: preparing 3-methoxypropionitrile with acrylonitrile and sodium methoxide as raw materials; reducing 3-methoxypropionitrile with 3-methoxypropionitrile as raw material in the presence of ammonia water, nickel catalyst and silver nitrate to prepare 3-methoxypropylamine. In this preparation method, ammonia is introduced into the reactor, and a side reaction occurs to generate n-propylamine; and the ammonia gas in the system is difficult to post-process and difficult to recycle, and a large amount of ammonia-containing wastewater is generated.

[0007] Patent CN113004171A discloses a method for preparing 3-methoxypropylamine, wherein a crude 3-methoxypropionitrile product is prepared by addition of methanol and acrylonitrile, and then the crude product is hydrogenated under the action of a Raney catalyst to prepare 3-methoxypropylamine. The addition reaction of the method is controlled by air protection and gradient temperature, which is beneficial to improving the conversion rate of acrylonitrile in the addition reaction. However, since the reaction system contains a strong base in the first step of the addition reaction during catalytic hydrogenation, more reverse reactions occur, which is not conducive to subsequent separation and treatment, and the product yield is reduced.

[0008] Patent CN101328129B discloses a method for preparing an intermediate bis(3-methoxypropyl)amine, wherein 3-methoxypropanol is used as a raw material and Cu-Co / Al2O3-diatomaceous earth is used as a catalyst. Under certain pressure and temperature conditions, 3-methoxypropanol is pumped into a preheater and mixed with ammonia and hydrogen for preheating and vaporization, and then enters a fixed bed reactor for reaction. After the reaction, the material is condensed and cooled, and the gas and liquid are separated. 3-methoxypropylamine is extracted as a product, and bis(3-methoxypropyl)amine is also generated. However, bis(3-methoxypropyl)amine is a by-product generated under this process route, and this method does not continue to explore the application related to bis(3-methoxypropyl)amine. Summary of the invention

[0009] The technical problem to be solved by the present invention is to provide a method for preparing bis(3-methoxypropyl)methylamine.

[0010] In order to solve the above technical problems, the present invention provides a method for preparing bis(3-methoxypropyl)methylamine, which uses acrylonitrile and methanol as raw materials and comprises Michael addition reaction, catalytic hydrogenation reaction and hydrogenation methylation reaction, so as to obtain bis(3-methoxypropyl)methylamine.

[0011] As an improvement of the preparation method of bis(3-methoxypropyl)methylamine of the present invention, the method comprises the following steps:

[0012] 1) Michael addition reaction:

[0013] Using acrylonitrile and methanol as raw materials and alkali as addition catalyst;

[0014] Firstly, dissolve the alkali in methanol to obtain a methanol solution of the alkali; heat the solution to 20-100° C. (preferably 35±5° C.), then drop acrylonitrile into the methanol solution of the alkali for reaction for 2-5 hours; after the dropwise addition is completed, continue to keep the temperature for reaction for 1-4 hours to obtain a reaction solution containing 3-methoxypropionitrile;

[0015] Methanol: acrylonitrile = 1.1-3.0:1 (preferably 1.5:1) molar ratio; alkali is 0.1%-5.0% (preferably 0.3%-0.4%) of the mass of acrylonitrile;

[0016] Note: Methanol also serves as the solvent;

[0017] 2) Catalytic hydrogenation reaction:

[0018] First, add an acid (the acid and the base auxiliary agent are equivalent) to the reaction solution containing 3-methoxypropionitrile obtained in step 1) to neutralize the base in the reaction solution, and then filter, transfer the obtained filtrate to an autoclave, add 3-methoxypropylamine as an auxiliary agent and a hydrogenation catalyst to the autoclave, replace the gas in the autoclave (replace the air in the autoclave with nitrogen and hydrogen respectively), introduce hydrogen into the autoclave, and react for 3 to 6 hours under the conditions of a hydrogen pressure of 1.0 to 5.0 MPa (preferably 2 to 4 MPa) and a reaction temperature of 30° C. to 150° C. (preferably 50 to 100° C.);

[0019] The hydrogenation catalyst is 1%-20% (preferably 10-20%) of the mass of the acrylonitrile in step 1), and the 3-methoxypropylamine is 20%-400% (preferably 100%-400%) of the mass of the acrylonitrile in step 1);

[0020] The reaction product is post-treated to recover the hydrogenation catalyst, as well as the methanol fraction, the 3-methoxypropylamine fraction and the bis(3-methoxypropyl)amine; the methanol is used as the methylation reaction solvent in the following step 3), and the bis(3-methoxypropyl)amine is used as the hydrogenation methylation reaction raw material in the following step 3);

[0021] Note: Since methanol is excessive in step 1), the reaction solution containing 3-methoxypropionitrile obtained in step 1) also contains methanol. Therefore, step 2) actually uses crude 3-methoxypropionitrile as a raw material, and hydrogenates it in the presence of a methanol solvent, a hydrogenation catalyst, and an auxiliary agent to react, thereby obtaining bis(3-methoxypropyl)amine as an intermediate;

[0022] 3) Hydromethylation reaction:

[0023] Add all the methanol fractions dissolved with paraformaldehyde in step 2) into the autoclave, then add all the hydrogenation catalysts recovered in step 2) and all the bis(3-methoxypropyl)amine obtained in step 2); after replacing the gas in the autoclave (replacing the air in the autoclave with nitrogen and hydrogen respectively), introduce hydrogen into the autoclave, and react for 2.5 to 5 hours under the conditions of hydrogen pressure of 1.0 to 5.0 MPa (preferably 2 to 4 MPa) and reaction temperature of 30° C. to 150° C. (preferably 80 to 120° C.);

[0024] Paraformaldehyde: acrylonitrile in step 1) = 0.2-2.0:1 (preferably 0.5:1) in molar ratio;

[0025] The reaction product is post-treated to recover the hydrogenation catalyst; the reaction liquid is subjected to vacuum distillation to obtain bis(3-methoxypropyl)methylamine (as a product) and methanol.

[0026] Description: In this step 3), bis(3-methoxypropyl)amine and polyformaldehyde are used as raw materials, and bis(3-methoxypropyl)methylamine is prepared by catalytic hydrogenation and methylation in the presence of recovered methanol solvent and a hydrogenation catalyst.

[0027] As a further improvement of the preparation method of bis(3-methoxypropyl)methylamine of the present invention: the base in step 1) is at least any one of sodium hydroxide, potassium hydroxide, sodium methoxide and sodium ethoxide (ie, one or more combinations).

[0028] As a further improvement of the preparation method of bis(3-methoxypropyl)methylamine of the present invention: the hydrogenation catalyst in step 2) is any one of the following: Raney Ni, Raney Co, Pd / C (5wt% Pd), Pt / C (5wt% Pt).

[0029] As a further improvement of the preparation method of bis(3-methoxypropyl)methylamine of the present invention: in step 3):

[0030] The recovered hydrogenation catalyst can be recycled and used in step 2);

[0031] Since the amount of catalyst is lost during the recovery process, new catalyst needs to be added to the set amount when the catalyst is recycled. The added amount is about 5%-10% of the set amount.

[0032] The obtained methanol can be recycled and used in step 1).

[0033] As a further improvement of the preparation method of bis(3-methoxypropyl)methylamine of the present invention: the 3-methoxypropylamine fraction obtained in step 2) can be recycled and used in step 2) as an auxiliary agent.

[0034] In the present invention:

[0035] The post-treatment of step 2) is as follows: venting the gas in the kettle, opening the kettle and letting it stand, filtering, and obtaining a filtrate and a filter cake, respectively. The filtrate is a reaction liquid containing bis(3-methoxypropyl)amine; and the filter cake is a Raney Ni catalyst. The Raney Ni catalyst is washed and continued to be used in the next step of the reaction. The above reaction liquid is subjected to vacuum distillation to obtain a methanol fraction, a 3-methoxypropylamine fraction, and a bis(3-methoxypropyl)amine fraction, respectively.

[0036] The post-treatment of step 3) is as follows: venting the gas in the kettle, opening the kettle and letting it stand, filtering, and obtaining a filtrate and a filter cake respectively, wherein the filtrate is a reaction liquid containing bis(3-methoxypropyl)methylamine; and the filter cake is a Raney Ni catalyst. The catalyst is washed and recovered and can be used for recycling; the reaction liquid is subjected to vacuum distillation to obtain a methanol fraction and bis(3-methoxypropyl)methylamine respectively.

[0037] The invention combines the existing amine ether polyurethane foaming catalyst production process and proposes to use methanol and acrylonitrile as raw materials to prepare a novel high-activity, non-irritating odor polyurethane foaming catalyst, bis(3-methoxypropyl)methylamine, through the steps of Michael addition, catalytic hydrogenation and hydrogenation methylation.

[0038] The synthetic route of the present invention is as follows:

[0039]

[0040] Formula 2, Synthesis route of bis(3-methoxypropyl)methylamine

[0041] The bis(3-methoxypropyl)methylamine and its precursor bis(3-methoxypropyl)amine of the present invention are good polyurethane foaming catalysts as shown by tests, but the synthesis method thereof has not been reported in the literature.

[0042] The prior art mainly focuses on synthesizing 3-methoxypropylamine, and bis(3-methoxypropyl)amine is a by-product in the reaction process. This type of method suppresses the occurrence of side reactions by adding strong bases such as sodium hydroxide during the catalytic hydrogenation reaction, but the presence of strong bases will also cause some reverse reactions to occur. The present invention finds that the methylation product of the by-product (bis(3-methoxypropyl)amine) described in the above prior art has good application effects, so an auxiliary agent is added during the hydrogenation reaction in step 2) to achieve the effect of promoting the generation of bis(3-methoxypropyl)amine. That is, the present invention selects a suitable hydrogenation catalyst and changes the process conditions to generate bis(3-methoxypropyl)amine with high selectivity, and continuously performs N-methylation reaction to prepare a new polyurethane foaming catalyst with excellent application effects-bis(3-methoxypropyl)methylamine.

[0043] The present invention prepares bis(3-methoxypropyl)methylamine by the above-mentioned synthetic route, which has the following technical advantages:

[0044] 1. Step 2) by adding 3-methoxypropylamine as an auxiliary agent, the generation of bis(3-methoxypropyl)amine is promoted, while other undesirable side reactions are inhibited, and the introduction of new components into the system is avoided;

[0045] 2. The excess raw material methanol in step 1) can be used in the subsequent steps, and the hydrogenation catalyst in step 2) can be used in the subsequent steps;

[0046] Moreover, both methanol and hydrogenation catalyst can be recycled and reused;

[0047] 3. The bis(3-methoxypropyl)methylamine of the present invention has the advantages of high activity and no irritating odor, and can be applied to many fields related to polyurethane materials;

[0048] 4. The entire synthesis route can be carried out under relatively mild conditions, and the operation is simple; the reaction pressure is low, which reduces the requirements for reaction equipment; no inhibitors are used, which reduces the difficulty of post-processing and reduces wastewater discharge.

[0049] In summary, this synthetic route has the characteristics of simple process, less wastewater discharge and excellent product performance, so it has good application prospects and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings.

[0051] Figure 1 For the intermediate bis (3-methoxypropyl) amine 1 H NMR spectrum;

[0052] 1 H NMR (500MHz, CDCl3) δ = 3.32 (t, J = 6.3Hz, 4H), 3.21 (s, 6H), 2.57 (t, J = 7.0Hz, 4H), 1.64 (p, J = 6.6Hz, 4H), 1.30 (s, 1H).

[0053] Figure 2 The product is bis(3-methoxypropyl)methylamine 1 H NMR spectrum.

[0054] 1 H NMR (500MHz, CDCl3) δ = 3.30 (t, J = 6.5Hz, 4H), 3.22 (s, 6H), 2.34–2.27 (m, 4H), 2.11 (s, 3H), 1.68–1.58 (m, 4H). DETAILED DESCRIPTION

[0055] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto:

[0056] Note: The products obtained in the following cases have been 1 The H NMR spectrum confirmed that the obtained product was indeed bis(3-methoxypropyl)methylamine.

[0057] Steps 1) to 3) are all carried out under conventional stirring conditions.

[0058] Example 1: A method for preparing bis(3-methoxypropyl)methylamine, comprising the following steps:

[0059] 1) Michael addition reaction:

[0060] 144 g (4.5 mol) of methanol was added to a reactor, and 0.6 g (0.015 mol) of sodium hydroxide was added thereto, stirred to dissolve and heated to a reaction temperature of 35°C, 159 g (3.0 mol) of acrylonitrile was added dropwise to the reactor within 2 h, and after the addition was completed, stirring was maintained and the reaction was kept warm for 1 h to obtain a reaction solution containing about 303 g of 3-methoxypropionitrile, of which 254 g of 3-methoxypropionitrile was contained.

[0061] 2) Catalytic hydrogenation reaction:

[0062] 0.74 g (0.0075 mol) of sulfuric acid was added to the reaction solution obtained in step 1) to neutralize the sodium hydroxide. The mixture was filtered to obtain a filtrate and a filter cake, wherein the filter cake was sodium sulfate and was treated as solid waste.

[0063] The obtained filtrate was transferred to an autoclave, and 159 g of 3-methoxypropylamine and 15.9 g of Raney Ni catalyst (as a hydrogenation catalyst) were added. The autoclave was then closed, and the gas in the autoclave was replaced with nitrogen 3 times, and the gas in the autoclave was replaced with hydrogen 3 times. After the replacement was completed, the autoclave was pressurized with hydrogen to an initial pressure of 1.5 MPa, and the temperature was slowly raised to a reaction temperature of 50°C, and hydrogen was added to a pressure of 2.0 MPa, and then the pressure was kept constant, and the reaction was kept at 50°C for 6 hours.

[0064] After the reaction was completed, the autoclave was taken out, the gas in the autoclave was vented, the autoclave was opened and left to stand for 1 hour, and then filtered to obtain a filtrate and a filter cake, respectively. The filtrate was a reaction liquid containing bis(3-methoxypropyl)amine; and the filter cake was a Raney Ni catalyst.

[0065] The Raney Ni catalyst was washed with methanol for 3 times and then continued to be used in the next reaction. The reaction solution was subjected to vacuum distillation. The fraction at 65°C was collected under normal pressure, and 45g of methanol fraction was collected, which was used as the solvent for the next methylation reaction; the fraction at 45°C was collected under a pressure of 25 mmHg, and 167g of 3-methoxypropylamine fraction was collected and recycled; the fraction at 100°C was collected under a pressure of 25 mmHg, and 207g of bis(3-methoxypropyl)amine (purity ≥ 99.5%) was collected, with a yield of 85.7%, which was used as the raw material for the next methylation reaction.

[0066] 3) Hydromethylation reaction:

[0067] The whole methanol fraction recovered in step 2) in which 45 g (1.5 mol) of polyformaldehyde is dissolved is added to the reaction kettle, and the whole Raney Ni catalyst obtained in step 2) and the whole bis(3-methoxypropyl)amine obtained in step 2) are added to the reaction kettle, and then the kettle is closed, and the gas in the kettle is replaced with nitrogen 3 times, and the gas in the kettle is replaced with hydrogen 3 times. After the replacement is completed, the pressure is filled with hydrogen to an initial pressure of 1.5 MPa, and the temperature is slowly increased to a reaction temperature of 80° C., and hydrogen is added to a pressure of 2.0 MPa, and then the pressure is kept constant, and the reaction is kept at 80° C. for a reaction time of 5 hours, thereby obtaining a reaction solution containing bis(3-methoxypropyl)methylamine.

[0068] After the reaction was completed, the reactor was taken out, the gas in the reactor was vented, the reactor was opened and left to stand for 1 hour, and then filtered to obtain a filtrate and a filter cake, respectively. The filtrate was a reaction liquid containing bis(3-methoxypropyl)methylamine; and the filter cake was a Raney Ni catalyst.

[0069] The catalyst was washed with methanol three times and then recovered and can be used for recycling;

[0070] The reaction solution was subjected to vacuum distillation, and the methanol fraction at 65°C was collected under normal pressure, and the fraction at 110°C was collected under a pressure of 25 mmHg as bis(3-methoxypropyl)methylamine;

[0071] Therefore, 220 g of bis(3-methoxypropyl)methylamine with a purity of 99.5% (purity ≥ 99.5%) was obtained as a product, and the final product yield was 84.0%; 43 g of methanol and 15 g of Raney Ni catalyst were recovered.

[0072] Embodiment 2-1, with respect to embodiment 1, makes the following changes:

[0073] The catalyst in step 2) was changed from Raney Ni to Pd / C (5 wt % Pd), and the weight remained unchanged at 15.9 g; the rest was the same as in Example 1.

[0074] The yield of bis(3-methoxypropyl)amine obtained in step 2) is 53.6%;

[0075] The yield of bis(3-methoxypropyl)methylamine obtained in step 3) is 50.1%.

[0076] Embodiment 2-2, with respect to embodiment 1, makes the following changes:

[0077] The catalyst in step 2) was changed from Raney Ni to Pt / C (5 wt % Pt), and the weight remained unchanged at 15.9 g; the rest was the same as in Example 1.

[0078] The yield of bis(3-methoxypropyl)amine obtained in step 2) is 50.5%;

[0079] The yield of the bis(3-methoxypropyl)methylamine product obtained in step 3) is 48.3%.

[0080] Embodiment 2-3, relative to embodiment 1, makes the following changes:

[0081] The catalyst in step 2) was changed from Raney Ni to Raney Co, and the weight remained unchanged, still 15.9 g; the rest was the same as in Example 1.

[0082] The yield of bis(3-methoxypropyl)amine obtained in step 2) is 45.9%;

[0083] The yield of the bis(3-methoxypropyl)methylamine product obtained in step 3) is 44.0%.

[0084] Embodiment 3: Compared with Embodiment 1, the following changes are made:

[0085] The amount of catalyst in step 2) was changed from 15.9 g to 31.8 g, and the rest was the same as in Example 1.

[0086] The yield of bis(3-methoxypropyl)amine obtained in step 2) is 84.5%; the yield of bis(3-methoxypropyl)methylamine obtained in step 3) is 82.9%.

[0087] Embodiment 4: With respect to Embodiment 1, the following changes are made:

[0088] The reaction pressure of step 2) was changed from 2.0 MPa to 4.0 MPa, and the reaction time was changed to 5 h; and the reaction pressure of step 3) was changed from 2.0 MPa to 4.0 MPa, and the reaction time was changed to 4 h; the rest was the same as Example 1.

[0089] The yield of bis(3-methoxypropyl)amine obtained in step 2) is 86.0%; the yield of bis(3-methoxypropyl)methylamine obtained in step 3) is 84.9%.

[0090] Embodiment 5: With respect to Embodiment 1, the following changes are made:

[0091] The reaction temperature of step 2) was changed from 50°C to 100°C, and the reaction time was changed to 3h; the reaction temperature of step 3) was changed from 80°C to 120°C, and the reaction time was changed to 2.5h; the rest was the same as Example 1.

[0092] The yield of bis(3-methoxypropyl)amine obtained in step 2) is 81.8%; the yield of bis(3-methoxypropyl)methylamine obtained in step 3) is 80.2%.

[0093] Examples 6 to 12, when other reaction conditions remain unchanged, compared with Example 1, the amount of the auxiliary agent 3-methoxypropylamine added is changed to obtain Examples 6 to 12 respectively. The yields of the intermediate bis(3-methoxypropyl)amine and the product bis(3-methoxypropyl)methylamine are shown in Table 1 below.

[0094] Table 1. Experimental results of different amounts of additive 3-methoxypropylamine

[0095]

[0096]

[0097] Example 13: Compared with Example 1, the "15.9 g Raney Ni catalyst" in step 2) is changed to "15 g Raney Ni catalyst recovered in step 3) of Example 1 and supplemented with 0.9 g fresh Raney Ni catalyst". The rest is the same as Example 1.

[0098] The corresponding relationship between the number of times the catalyst is recycled and the results obtained is shown in Table 2 below.

[0099] Table 2 Experimental results of catalyst recycling times

[0100]

[0101] Comparative Example 1: Compared with Example 1, the following changes were made:

[0102] The steps of "adding sulfuric acid to neutralize the sodium hydroxide, filtering and taking the filtrate" in step 2) of Example 1 are cancelled and replaced with "directly transferring the reaction solution obtained in step 1) to an autoclave", and the rest are the same as Example 1.

[0103] The yield of bis(3-methoxypropyl)amine obtained in step 2) is 61.6%; the yield of bis(3-methoxypropyl)methylamine obtained in step 3) is 59.3%.

[0104] Comparative Example 2: Compared with Example 1, the following changes were made:

[0105] In step 2) of Example 1, "adding 3-methoxypropylamine as an auxiliary agent" is cancelled and replaced with "introducing 5.0 g of ammonia gas after the gas is replaced", and the rest is the same as Example 1.

[0106] The yield of bis(3-methoxypropyl)amine obtained in step 2) is 30.5%; the yield of bis(3-methoxypropyl)methylamine obtained in step 3) is 28.9%.

[0107] Experiment 1: Use of the bis(3-methoxypropyl)methylamine and the intermediate bis(3-methoxypropyl)amine of the present invention as a catalyst

[0108] Bis(3-methoxypropyl)methylamine and intermediate bis(3-methoxypropyl)amine are used as part of the polyurethane foaming catalyst system to prepare polyurethane materials, namely polyurethane foams. The details are as follows:

[0109] Table 3 Foam preparation formula

[0110]

[0111] Note: Amine catalyst A33 (33% triethylenediamine solution, solvent is dipropylene glycol) is a commonly used commercial amine catalyst.

[0112] PPG-2000, methane, flame retardant TPP, water, silicone oil 815H, stannous octoate, and amine catalyst in the above table are added to the mixing barrel in sequence, mixed and stirred for 8s with a mixer at a speed of 3500r / min, and then left to stand for 2min, and then toluene diisocyanate (TDI-80) with a 2,4-body content of 80% is poured into the mold, the temperature is controlled at about room temperature, the timing is started, and after rapid stirring for 3s, the mixed material is poured into a foaming box for foaming, and cut into the required size after ripening for performance testing. Under the same conditions, the foaming effects of amine catalyst A33, bis(3-methoxypropyl)amine of the present invention, and bis(3-methoxypropyl)methylamine are compared, and the corresponding foaming data obtained are listed in Table 4.

[0113] Table 4 Comparison of polyurethane foaming data obtained under different amine catalysts

[0114] Experiment No. Experimental group ① Experimental group ② Experimental group ③ Experimental group ④ Start time 78s 138s 80s 76s Ripening time 7.0min 12.0min 8.0min 6.9min Foam smell No irritating smell No irritating smell No irritating smell No irritating smell Foam height 20cm 17cm 20cm 20cm density <![CDATA[15g / cm 3 ]]> <![CDATA[17g / cm 3 ]]> <![CDATA[16g / cm 3 ]]> <![CDATA[15g / cm 3 ]]> Tensile Strength 0.35MPa 0.15MPa 0.38MPa 0.34MPa Rebound rate 40％ 17％ 42％ 39％

[0115] From the foaming data in Table 4, it can be concluded that the bis(3-methoxypropyl)methylamine of the present invention has a more excellent catalytic activity than the commercially commonly used amine catalyst A33, and can be used alone for the catalysis of polyurethane foaming, and the prepared foam has a normal color without color difference and no irritating odor. The intermediate bis(3-methoxypropyl)amine of the present invention has a poor catalytic effect when used alone for polyurethane foaming, but it can be seen from the results in the table that it can be used as an auxiliary catalyst, and the A33 catalyst with bis(3-methoxypropyl)amine added in a corresponding proportion can achieve the catalytic activity of A33 when used alone.

[0116] Finally, it should be noted that the above examples are only some specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and there are many variations. All variations that can be directly derived or associated with the content disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. A method for preparing bis(3-methoxypropyl)methylamine, characterized in that: Using acrylonitrile and methanol as raw materials, including Michael addition reaction, catalytic hydrogenation reaction and hydrogenation methylation reaction, thereby obtaining bis(3-methoxypropyl)methylamine; 1) Michael addition reaction: Using acrylonitrile and methanol as raw materials and alkali as addition catalyst; Firstly, dissolve the alkali in methanol to obtain a methanol solution of the alkali; heat it to 20-100°C, then drop acrylonitrile into the methanol solution of the alkali for reaction, the drop adding time is 2-5 hours, and after the drop adding is completed, keep the temperature for reaction for 1-4 hours to obtain a reaction solution containing 3-methoxypropionitrile; Methanol: acrylonitrile = 1.1~3.0:1 molar ratio; alkali is 0.1%~5.0% of the mass of acrylonitrile; 2) Catalytic hydrogenation reaction: First, an acid is added to the reaction solution containing 3-methoxypropionitrile obtained in step 1) to neutralize the alkali in the reaction solution, and then the filtrate is filtered, and the obtained filtrate is transferred to an autoclave, and then 3-methoxypropylamine as an auxiliary agent and a hydrogenation catalyst are added to the autoclave, and after gas replacement in the autoclave, hydrogen is introduced into the autoclave, and the reaction is carried out for 3 to 6 hours under the conditions of a pressure of 2 to 4 MPa and a reaction temperature of 50 to 100° C.; The hydrogenation catalyst is 10-20% of the mass of acrylonitrile in step 1), and the 3-methoxypropylamine is 100-400% of the mass of acrylonitrile in step 1); The reaction product is post-treated to recover the hydrogenation catalyst, as well as a methanol fraction, a 3-methoxypropylamine fraction and bis(3-methoxypropyl)amine; the methanol fraction is used as a methylation reaction solvent in the following step 3), and the bis(3-methoxypropyl)amine is used as a raw material for the hydrogenation methylation reaction in the following step 3); The hydrogenation catalyst is Raney Ni; 3) Hydrogenation methylation reaction: Add the methanol fraction dissolved with paraformaldehyde in step 2) into the autoclave, then add the hydrogenation catalyst recovered in step 2) and the bis(3-methoxypropyl)amine obtained in step 2); after replacing the gas in the autoclave, introduce hydrogen into the autoclave, and react for 2.5 to 5 hours at a pressure of 2 to 4 MPa and a reaction temperature of 80 to 120° C.; Paraformaldehyde: acrylonitrile in step 1) = 0.2~2.0:1 molar ratio; The reaction product is post-treated to recover the hydrogenation catalyst; the reaction liquid is subjected to vacuum distillation to obtain bis(3-methoxypropyl)methylamine and methanol respectively.

2. The method for preparing bis(3-methoxypropyl)methylamine according to claim 1, characterized in that: The base in step 1) is at least any one of sodium hydroxide, potassium hydroxide, sodium methoxide and sodium ethoxide.

3. The method for preparing bis(3-methoxypropyl)methylamine according to claim 2, characterized in that In the step 3): The recovered hydrogenation catalyst can be recycled and used in step 2); The obtained methanol can be recycled and used in step 1).

4. The method for preparing bis(3-methoxypropyl)methylamine according to claim 3, characterized in that The 3-methoxypropylamine fraction obtained in step 2) can be recycled and used in step 2) as an auxiliary agent.

5. Use of bis(3-methoxypropyl)methylamine prepared by any of the methods of claims 1 to 4 in the preparation of polyurethane materials, characterized in that The recipe is: PPG-2000 92kg Methane 10 kg Flame retardant TPP 4 kg Water 5 kg Silicone oil 815H 0.8 kg Stannous octoate 0.4 kg Bis(3-methoxypropyl)methylamine 0.4 kg.

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