Preparation method of N-vinyl amide

Abstract

The invention relates to the technical field of oilfield exploitation, and discloses a preparation method of N-vinyl amide. The method comprises the following steps: under a heating condition, enabling a structure as shown in a formula (1) and a structure as shown in a formula (2) to be in contact and react, wherein in the formula (1), R1 is H or alkyl of C1-C8, and R2 is hydrogen or alkyl of C1-C4; in the formula (2), R3 is H or C1-C8 alkyl, and M is H, Na, K or Cs. The method has the advantages of low reaction temperature, simplicity in operation, small corrosion to equipment, high product yield and excellent purity.

Description

Technical Field

[0001] The present invention relates to the technical field of oilfield exploitation, and particularly relates to a preparation method of N-vinylamide. Background Art

[0002] N-vinylalkylamide is a new type of functional monomer, which has attracted much attention due to its advantages such as good water solubility, high polymerization activity, non-toxic and harmless. Its polymers are widely used in fields such as oil exploitation, papermaking, and hydrogels. Only BASF in Germany and Mitsubishi Chemical in Japan in the world master the synthesis process of N-vinylformamide. Existing production processes all use the high-temperature cracking reaction of precursors to prepare N-vinylformamide. Due to the poor thermal stability of this monomer, the product yield and purity of existing processes are relatively low.

[0003] In view of the above problems, the Changchun Institute of Applied Chemistry disclosed a method for preparing N-vinylalkylamide from formamide, acetaldehyde and acid anhydride. This method can significantly reduce the cracking temperature. However, a large amount of acid by-products will be generated in this process, which causes great corrosion to the equipment and is difficult to treat the waste liquid.

[0004] Therefore, it is still necessary to develop a synthesis process of N-vinylamide with mild reaction conditions, simple operation, low corrosion to equipment, and high product yield and excellent purity. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above problems existing in the prior art, and provide a preparation method of N-vinylamide, which has the advantages of low reaction temperature, simple operation, low corrosion to equipment, high product yield and excellent purity.

[0006] In order to achieve the above purpose, the present invention provides a preparation method of N-vinylamide, which includes: under heating conditions, contacting and reacting the structure shown in formula (1) with the structure shown in formula (2);

[0007]

[0008] Wherein, in formula (1), R 1 is H or a C1-C8 hydrocarbon group, and R 2 is hydrogen or a C1-C4 alkyl group;

[0009] In formula (2), R 3 is H or a C1-C8 hydrocarbon group, and M is H, Na, K or Cs.

[0010] Through the above technical solutions, at least the following beneficial effects are obtained:

[0011] (1) The preparation method of N-vinylamide of the present invention has a low reaction temperature, can significantly inhibit the decomposition of N-vinylalkylamide during the reaction, and has a high product yield, high purity, and relatively high polymerization performance.

[0012] (2) In the preparation method of the present invention, the simultaneous reaction may not involve high temperature and high pressure processes, and has low requirements for the material of the reaction instrument and equipment.

[0013] (3) In the preparation method disclosed by the present invention, the carboxylic acid or carboxylate can be recycled, with less three wastes, and the production cost is greatly reduced. Detailed implementation mode

[0014] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values and individual point values of each range, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0015] The present invention provides a preparation method of N-vinylamide, which includes: under heating conditions, bringing the structure shown in formula (1) into contact with the structure shown in formula (2) and reacting;

[0016]

[0017] Wherein, in formula (1), R 1 is H or a C1-C8 hydrocarbon group, and R 2 is hydrogen or a C1-C4 alkyl group;

[0018] In formula (2), R 3 is H or a C1-C8 hydrocarbon group, and M is H, Na, K or Cs.

[0019] The inventors of the present invention have found through research that by preparing N-vinylamide according to the method described above, the reaction can be carried out under mild conditions, and the decomposition of the product during the reaction can be significantly inhibited, obtaining a high-yield and high-purity product; at the same time, it has little corrosion to the reaction equipment and high production process safety. In addition, the structure shown in formula (2) can be a carboxylic acid or carboxylate catalyst, which can be recycled, with less three-waste emissions and reduced production costs.

[0020] In the present invention, the reaction conditions can be the reaction conditions commonly used by those skilled in the art. Preferably, the heating conditions include: the temperature is 50-130 °C, preferably 60-110 (for example, it can be 60, 70, 80, 90, 100, 110 and the values within the ranges formed by any two of the above values) °C.

[0021] Preferably, the reaction time is 6 - 11 h, preferably 8 - 10 (for example, it can be 8, 9, 10) h.

[0022] Under the above conditions, it is possible to further ensure a better yield and purity.

[0023] According to the present invention, preferably, the reaction conditions further include: the pressure is 0.5 - 100 (for example, it can be 0.5, 1, 2, 3, 4, 5, 6, 10, 20, 40, 50, 60, 70, 80, 90, 100 and the ranges and values within the ranges formed by any two of the above values) kPa, more preferably 3 - 100 kPa. Under this condition, the conditions are relatively mild, and it is also possible to further ensure the yield and purity of the reaction. The above pressure values are all absolute pressures.

[0024] In the present invention, the amounts of the respective raw materials in the preparation process of the compound are not particularly limited. Preferably, relative to 1 mol of the structure shown in formula (1), the amount of the structure shown in formula (2) is 0.1 - 10 mol, more preferably 0.4 - 5 (for example, it can be 0.4, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 and the ranges and values within the ranges formed by any two of the above values) mol.

[0025] According to the present invention, preferably, R 1 Among them, the C1 - C8 hydrocarbon group is selected from a C1 - C6 alkyl group or a phenyl group.

[0026] Preferably, R 2 is selected from hydrogen, a methyl group or an ethyl group.

[0027] Preferably, R 3 Among them, the C1 - C8 hydrocarbon group is selected from a C1 - C6 alkyl group or a benzyl group.

[0028] According to the present invention, preferably, the structure shown in formula (1) is selected from one of N-(1-hydroxyethyl)formamide, N-(1-methoxyethyl)formamide, N-(1-ethoxyethyl)formamide, N-(1-hydroxyethyl)acetamide, N-(1-methoxyethyl)acetamide, N-(1-ethoxyethyl)acetamide, N-(1-hydroxyethyl)propanamide, N-(1-methoxyethyl)propanamide, N-(1-ethoxyethyl)propanamide, N-(1-hydroxyethyl)butyramide, N-(1-methoxyethyl)butyramide, N-(1-ethoxyethyl)butyramide, N-(1-hydroxyethyl)valeramide, N-(1-methoxyethyl)valeramide, N-(1-ethoxyethyl)valeramide, N-(1-hydroxyethyl)hexanamide, N-(1-methoxyethyl)hexanamide, N-(1-ethoxyethyl)hexanamide, N-(1-hydroxyethyl)benzamide, N-(1-methoxyethyl)benzamide, N-(1-ethoxyethyl)benzamide. The N-vinylamide can be N-vinylformamide, N-vinylacetamide, N-vinylpropanamide, N-vinylbutyramide, N-vinylvaleramide, N-vinylhexanamide, N-vinylbenzamide, etc.

[0029] According to the present invention, preferably, the structure shown in formula (2) is selected from at least one of formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, cyclohexane carboxylic acid, benzoic acid, sodium formate, sodium acetate, sodium propionate, sodium butyrate, sodium valerate, sodium caproate, sodium cyclohexanecarboxylate, sodium benzoate, potassium formate, potassium acetate, potassium propionate, potassium butyrate, potassium valerate, potassium caproate, potassium cyclohexanecarboxylate, potassium benzoate, cesium formate, cesium acetate, cesium propionate, cesium butyrate, cesium valerate, cesium caproate, cesium cyclohexanecarboxylate, cesium benzoate.

[0030] After the reaction is completed, the material can be subjected to vacuum distillation to obtain the product N-vinylamide. The conditions for vacuum distillation can include: 100 - 200 Pa, temperature 20 - 120 °C.

[0031] Among them, the present invention does not particularly limit the source of the structure shown in formula (1), which can be commercially purchased or prepared by itself. For example, the structure in which R 2 in formula (1) is H (which can also be called a precursor), that is, OR 2 in formula (1) is a hydroxyl group, and then the hydroxyl group can be subjected to hydroxyalkylation with an alcohol to obtain the structure in which R 2 is an alkyl group.

[0032] The synthesis method of the above-mentioned precursor is not particularly limited either. For example, under alkaline conditions, the precursor can be synthesized through the reaction of an aldehyde and an amide (the molar ratio of the aldehyde to the amide can be (1.2 - 2):1). For example, acetaldehyde and formamide can react to obtain N-(1-hydroxyethyl)formamide, and acetaldehyde and acetamide can react to obtain N-(1-hydroxyethyl)acetamide. The synthesis of the precursor can be carried out in the presence of a solvent, and the solvent can be toluene and / or n-hexane. The mass ratio of the solvent to the aldehyde can be (16 - 25):1. It can be carried out at 10 - 20 °C for 3 - 6 h and can be carried out under nitrogen protection. The alkaline condition can be provided by a carbonate (such as potassium carbonate), and the molar ratio of the amide to the carbonate can be (80 - 120):1. For example, take potassium carbonate, after purging with nitrogen to remove oxygen, add the aldehyde and the solvent, then adjust the temperature to the reaction temperature, slowly dropwise add the amide, and then control the temperature to react until the end. After the reaction, filtration can be carried out to obtain the precursor.

[0033] The above-mentioned operation of hydroxyalkylating the hydroxyl group can be carried out under nitrogen protection. For example, take the precursor, after purging with nitrogen to remove oxygen, add an alcohol (the molar ratio of the alcohol to the precursor can be 5 - 10:1), cool down (to about 3 - 7 °C), and slowly dropwise add concentrated sulfuric acid (the molar ratio of the concentrated sulfuric acid to the precursor can be 0.01 - 0.2:1). After the addition is complete, raise the temperature to the reaction temperature (10 - 20 °C) and react for 4 - 6 h; then add a sodium hydroxide solution (in the sodium hydroxide solution, the mass concentration of sodium hydroxide can be 20 - 30 wt%), until the pH is 7; then filter to obtain the liquid phase, and subject the liquid phase to vacuum distillation (the conditions can include 100 - 200 Pa and a temperature of 20 - 120 °C) to obtain the structure shown in formula (1).

[0034] It can be understood that the synthetic route for preparing N-alkenylamide provided by the present invention is as follows:

[0035]

[0036] The present invention also relates to a method for preparing a polymer, which includes: preparing N-alkenylamide according to the method as described above; then mixing the obtained N-alkenylamide as monomer D’ with monomer A’, monomer B’, monomer C’ and an initiator and carrying out a polymerization reaction under solution polymerization reaction conditions. The polymer prepared by this method has both the ability to thicken in the aqueous phase and the performance of emulsifying heavy oil with low dynamic viscosity, can achieve viscosity reduction of heavy oil, and is suitable for waterflood reservoir exploitation. Among them, monomer A′, monomer B′, monomer C′, the initiator, the polymerization reaction, etc. are detailed in CN202311522670.5, CN202311522771.2, CN202311519415.5, which are hereby incorporated herein by reference in their entirety.

[0037] The present invention will be described in detail below by way of preparation examples (for preparing the structure shown in formula (1)) and examples.

[0038] In the following preparation examples, the calculation method for the yield of the structure shown in formula (1) is the molar ratio of the product in step (2) to the amide reactant in step (2), and the determination method for purity is the internal standard method of 1H NMR. The structures of the products were verified by NMR characterization and were indeed the products described in each preparation example.

[0039] Preparation Example 1

[0040] (1) Potassium carbonate (1 mmol) was taken, deoxygenated by passing nitrogen, then acetaldehyde (120 mmol) and toluene (150 mL) were added. After cooling to 15 °C, formamide (100 mmol) was slowly added dropwise. After the addition was complete, the reaction was carried out at 15 °C for 5 h. After the reaction was completed, filtration was carried out to obtain N-(1-hydroxyethyl)formamide;

[0041] (2) N-(1-hydroxyethyl)formamide (97 mmol) was taken, deoxygenated by passing nitrogen, then methanol (30 mL) was added. After cooling to 5 °C, concentrated sulfuric acid (2 mmol) was slowly added dropwise. After the addition was complete, the temperature was raised to 15 °C and the reaction was carried out for 5 h. After the reaction was completed, 25 wt% sodium hydroxide solution was added to neutralize to pH 7, and then the solid was filtered off. The filtrate was subjected to vacuum distillation (200 Pa, 20 °C) to obtain N-(1-methoxyethyl)formamide. The yield of the obtained product N-(1-methoxyethyl)formamide was 94.9%, and the purity was 95.1%.

[0042] Preparation Example 2

[0043] (1) Potassium carbonate (1 mmol) was taken, deoxygenated by passing nitrogen, then acetaldehyde (120 mmol) and toluene (150 mL) were added. After cooling to 15 °C, formamide (100 mmol) was slowly added dropwise. After the addition was complete, the reaction was carried out at 15 °C for 5 h. After the reaction was completed, filtration was carried out to obtain N-(1-hydroxyethyl)formamide;

[0044] (2) N-(1-hydroxyethyl)formamide (97 mmol) was taken, deoxygenated by passing nitrogen, then ethanol (35 mL) was added. After cooling to 5 °C, concentrated sulfuric acid (2 mmol) was slowly added dropwise. After the addition was complete, the temperature was raised to 15 °C and the reaction was carried out for 5 h. After the reaction was completed, 25 wt% sodium hydroxide solution was added to neutralize to pH 7, and then the solid was filtered off. The filtrate was subjected to vacuum distillation (200 Pa, 40 °C) to obtain N-(1-ethoxyethyl)formamide. The yield of the obtained product N-(1-ethoxyethyl)formamide was 90.4%, and the purity was 93.1%.

[0045] Preparation Example 3

[0046] (1) Take potassium carbonate (1 mmol). After purging with nitrogen to remove oxygen, add acetaldehyde (120 mmol) and n - hexane (150 mL). Then cool the mixture to 15 °C and slowly add acetamide (100 mmol). After the addition is complete, maintain the reaction at 15 °C for 5 h. After the reaction is completed, filter to obtain N - (1 - hydroxyethyl) acetamide;

[0047] (2) Take N - (1 - hydroxyethyl) acetamide (95 mmol). After purging with nitrogen to remove oxygen, add methanol (30 mL). Then cool the mixture to 5 °C and slowly add concentrated sulfuric acid (2 mmol). After the addition is complete, heat the mixture to 15 °C and react for 5 h. After the reaction is completed, add 25 wt% sodium hydroxide solution to neutralize to pH 7, then filter the solid. The filtrate is subjected to vacuum distillation (200 Pa, 20 °C) to obtain N - (1 - methoxyethyl) acetamide. The yield of the obtained product N - (1 - ethoxyethyl) acetamide is 91.5%, and the purity is 95.3%.

[0048] In the following examples, the calculation method for the yield of N - vinylamide is the actual yield of the target product / the theoretical production amount of the target product × 100%, and the purity determination method is the internal standard method of nuclear magnetic resonance hydrogen spectrum.

[0049] The structures of the products were verified by nuclear magnetic resonance hydrogen spectrum characterization, and they were indeed the products described in each example and comparative example.

[0050] Example 1

[0051] Take N - (1 - hydroxyethyl) formamide (100 mmol), add acetic acid (500 mmol). After the addition is complete, heat the mixture to 70 °C and react at atmospheric pressure for 9 h. After the reaction is completed, perform vacuum distillation (100 Pa, 60 °C) to obtain N - vinylformamide.

[0052] Examples 2 - 8

[0053] The operation processes of Examples 2 - 8 are generally similar to those of Example 1. The specific operating conditions, materials, and their dosages are shown in Table 1.

[0054] Comparative Example 1

[0055] Take N - (1 - methoxyethyl) formamide (100 mmol), heat it to 70 °C and react for 10 h. After the reaction is completed, perform vacuum distillation (100 Pa, 60 °C) to obtain N - vinylformamide. The yield of the obtained product N - vinylformamide is 9.2%, and the purity is 31.5%.

[0056] Comparative Example 2

[0057] Take N-(1-ethoxyethyl)formamide (100 mmol), and then heat it to 70 °C for reaction for 10 h; after the reaction is completed, distill it under reduced pressure (100 Pa, 60 °C) to obtain N-vinylformamide. The yield of the obtained product N-vinylformamide is 7.4%, and the purity is 34.9%.

[0058] Comparative Example 3

[0059] Carry out according to the method of Example 2, except that sodium formate is replaced with sodium chloride. The yield of the obtained product N-vinylformamide is 5.7%, and the purity is 22.3%.

[0060] Table 1

[0061]

[0062]

[0063] The products of the above examples were characterized by NMR for the product structure. Taking the product obtained in Example 1 as an example, the NMR characterization data of N-vinylformamide are as follows:

[0064] 1 H NMR(400MHz,DMSO)δ10.13–9.81(m,2H),8.29(d,J=10.9Hz,1H),8.02(s,1H),6.93–6.78(m,1H),6.74–6.59(m,1H),4.71(d,J=16.0Hz,1H),4.52(d,J=15.5Hz,1H),4.40–4.36(m,1H),4.19(t,J=9.6Hz,1H).

[0065] It can be seen from the results in Table 1 that by using the method provided by the present invention, the reaction can be carried out at a lower temperature, which can significantly inhibit the decomposition of monomer products during the reaction, so as to obtain N-vinylalkylamide with excellent yield and purity. And the operation is simple, and the corrosion to equipment is small. In addition, the carboxylic acid or carboxylate can be recycled after the reaction process, reducing the emission of three wastes and lowering the cost.

[0066] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for preparing N-vinyl amide, characterized in that: The method comprises: under heating conditions, bringing the structure represented by formula (1) into contact with the structure represented by formula (2) and reacting them; Among them, in formula (1), R 1 is H or a C1-C8 hydrocarbon group, R 2 is hydrogen or a C1-C4 alkyl group; In formula (2), R 3 is H or a C1-C8 hydrocarbon group, and M is H, Na, K or Cs.

2. The method according to claim 1, wherein: The heating conditions include: a temperature of 50-130°C.

3. The method according to claim 1 or 2, wherein: The reaction time is 6-11h.

4. The method according to claim 1, wherein: The heating conditions include: a temperature of 60-110°C; And / or, the reaction time is 8-10 hours.

5. The method according to claim 1 or 4, wherein: The reaction conditions also include: pressure of 0.5-100 kPa.

6. The method according to claim 1 or 4, wherein: The amount of the structure represented by formula (2) used is 0.1-10 mol relative to 1 mol of the structure represented by formula (1).

7. The method according to claim 1, wherein: The amount of the structure represented by formula (2) is 0.4-5 mol relative to 1 mol of the structure represented by formula (1).

8. The method according to claim 1 or 7, wherein: R 1 wherein the C1-C8 hydrocarbon group is selected from a C1-C6 alkyl group or a phenyl group; and / or, R 2 is selected from hydrogen, methyl or ethyl; and / or, R 3 In the above, the C1-C8 hydrocarbon group is selected from a C1-C6 alkyl group or a benzyl group.

9. The method according to claim 1 or 8, wherein: The structure represented by formula (1) is selected from N-(1-hydroxyethyl)formamide, N-(1-methoxyethyl)formamide, N-(1-ethoxyethyl)formamide, N-(1-hydroxyethyl)acetamide, N-(1-methoxyethyl)acetamide, N-(1-ethoxyethyl)acetamide, N-(1-hydroxyethyl)propionamide, N-(1-methoxyethyl)propionamide, N-(1-ethoxyethyl)propionamide, N-(1-hydroxyethyl)butanamide, N-(1-methoxyethyl)propionamide, N-(1-ethoxyethyl)propionamide, One of N-(1-hydroxyethyl)butyramide, N-(1-ethoxyethyl)butyramide, N-(1-hydroxyethyl)valeramide, N-(1-methoxyethyl)valeramide, N-(1-ethoxyethyl)valeramide, N-(1-hydroxyethyl)hexanamide, N-(1-methoxyethyl)hexanamide, N-(1-ethoxyethyl)hexanamide, N-(1-hydroxyethyl)benzamide, N-(1-methoxyethyl)benzamide and N-(1-ethoxyethyl)benzamide.

10. The method according to claim 1 or 8, wherein: The structure represented by formula (2) is selected from at least one of formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, cyclohexanoic acid, benzoic acid, sodium formate, sodium acetate, sodium propionate, sodium butyrate, sodium valerate, sodium hexanoate, sodium cyclohexanoate, sodium benzoate, potassium formate, potassium acetate, potassium propionate, potassium butyrate, potassium valerate, potassium hexanoate, potassium cyclohexanoate, potassium benzoate, cesium formate, cesium acetate, cesium propionate, cesium butyrate, cesium valerate, cesium hexanoate, cesium cyclohexanoate, and cesium benzoate.

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