Process for the preparation of n-vinyl amides

Abstract

A method for preparing N-olefin amides. The method includes: contacting the compound shown in formula (1) with the compound shown in formula (2-1) under esterification reaction conditions and in the presence of an esterification reaction catalyst to carry out a first reaction, and then subjecting the obtained first reaction product to a pyrolysis reaction; the method is simple to operate, has a high product yield, excellent selectivity, and simple product separation, and the raw materials can be recycled, which can significantly reduce production costs and has good route economy.

Description

Preparation method of N-alkenyl amide

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application 202311542418.0 filed on November 17, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to the technical field of oilfield exploitation, and in particular to a method for preparing N-alkenyl amide. Background Art

[0004] N-alkenyl carboxamides are a new class of functional monomers that have attracted significant attention due to their excellent water solubility, high polymerization activity, and non-toxic properties. Their polymers are widely used in oil extraction, papermaking, water treatment, and other fields. Early production processes mostly utilized high-temperature pyrolysis reactions of precursors to prepare N-alkenyl carboxamides. However, due to the monomer's poor thermal stability, product yields and selectivity were low.

[0005] To address these issues, the Changchun Institute of Applied Chemistry disclosed in CN112047854 A a method for preparing N-alkenylamides from formamide, acetaldehyde, and anhydride. This method significantly reduces the pyrolysis temperature. However, it produces a large amount of acid, making wastewater treatment difficult and costly, making it difficult to commercialize.

[0006] Summary of the Invention

[0007] The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art and to provide a method for preparing N-alkenyl amides. The method is simple to operate, has a high product yield, excellent selectivity, and is easy to separate the product. In particular, the raw materials can be recycled and reused, which can significantly reduce production costs.

[0008] To achieve the above-mentioned object, the present invention provides a method for preparing N-alkenyl amide in a first aspect, comprising: contacting a compound represented by formula (1) with a compound represented by formula (2-1) under esterification reaction conditions and in the presence of an esterification reaction catalyst to cause a first reaction, and then subjecting the obtained first reaction product to a cleavage reaction;

[0009] Among them, in formula (1), R 0 is a C1-C5 alkyl group, R 1 is H or a C1-C8 hydrocarbon group;

[0010] In formula (2-1), R 2 It is H or a C1-C8 hydrocarbon group.

[0011] A second aspect of the present invention provides a method for preparing an N-alkenyl amide, comprising: allowing an aldehyde and an amide to undergo a nucleophilic addition reaction under alkaline conditions to obtain a compound represented by formula (1), and preparing an N-alkenyl amide using the obtained compound represented by formula (1) according to the method described above;

[0012] Among them, in formula (1), R 0 is a C1-C5 alkyl group, R 1 It is H or a C1-C8 hydrocarbon group.

[0013] Through the above technical solution, at least the following beneficial effects are achieved:

[0014] (1) The method for preparing N-alkenylamide of the present invention uses carboxylic acid as one of the raw materials for the reaction, and produces carboxylic acid after a cleavage reaction, thereby not actually consuming the carboxylic acid raw material and not introducing new impurities. After extracting the target product N-alkenylamide from the mixture obtained after the reaction, the remaining material can be directly recycled and used in the next reaction to prepare N-alkenylamide.

[0015] (2) The method of the present invention uses carboxylic acid as a raw material and carboxylate as a catalyst, and has a high product yield and high selectivity.

[0016] (3) While ensuring high yield and selectivity, the product can be obtained at a low cost and simple post-processing, and the carboxylic acid and carboxylate can be recycled, with less waste, waste gas and wastes, which greatly reduces production costs. The method provided by the present invention has more industrial application prospects.

[0017] (4) The preparation method of the present invention does not involve a high-pressure process and has low requirements on the materials of the reaction instruments and equipment. DETAILED DESCRIPTION

[0018] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0019] The present invention provides a method for preparing N-alkenyl amide, which comprises: contacting a compound represented by formula (1) with a compound represented by formula (2-1) under esterification reaction conditions and in the presence of an esterification reaction catalyst to cause a first reaction, and then subjecting the obtained first reaction product to a cleavage reaction;

[0020] Among them, in formula (1), R 0is a C1-C5 alkyl group, R 1 is H or a C1-C8 hydrocarbon group;

[0021] In formula (2-1), R 2 It is H or a C1-C8 hydrocarbon group.

[0022] The inventors of the present invention have found that, through the above method, a carboxylic acid is used as a raw material for the reaction, and carboxylic acid is produced after the cracking reaction. The carboxylic acid raw material is not actually consumed, and no new impurities are introduced. The remaining material after extracting the target product N-alkenyl amide from the mixture obtained after the reaction can be directly recycled for the next reaction of preparing N-alkenyl amide. The reaction can be carried out under mild conditions (for example, not involving high pressure), which can suppress the decomposition of the product, and the product yield is high, the selectivity is high, and the production process safety is also high. In addition, the carboxylic acid shown in formula (2-1) can be recycled, the three wastes are discharged less, and the production cost is reduced; in particular, the product can be separated and obtained in a simple manner after the reaction; the route economy is good. The method provided by the present invention can obtain the product at a lower cost while ensuring a high yield and selectivity. The method provided by the present invention has more industrial application prospects.

[0023] According to the present invention, preferably, R 0 is methyl, R 1 It is H or a C1-C8 hydrocarbon group.

[0024] According to the present invention, preferably, the compound represented by formula (1) is selected from at least one of N-(1-hydroxyethyl)formamide, N-(1-hydroxyethyl)acetamide, N-(1-hydroxyethyl)propionamide, N-(1-hydroxyethyl)butyramide, N-(1-hydroxyethyl)valeramide, N-(1-hydroxyethyl)hexanamide and N-(1-hydroxyethyl)benzamide.

[0025] According to the present invention, preferably, R 2 wherein the C1-C8 hydrocarbon group is selected from a C1-C8 alkyl group, a C2-C8 alkenyl group, a C2-C8 alkynyl group or a benzyl group.

[0026] According to the present invention, preferably, the compound represented by formula (2-1) is at least one selected from formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, cyclohexanoic acid and benzoic acid.

[0027] According to the present invention, preferably, the esterification reaction catalyst includes a compound represented by formula (2-2),

[0028] In formula (2-2), R 3 is H or a C1-C8 hydrocarbon group, preferably selected from C1-C8 alkyl, C2-C8 alkenyl, C2-C8 alkynyl, benzyl, and phenethyl;

[0029] M is a Group IA metal element, preferably selected from Na, K, and Cs.

[0030] R 0 Taking the case of methyl as an example, the synthetic route for preparing N-alkenyl amide by the above method is as follows:

[0031] After the reaction, the carboxylic acid is not consumed, and the carboxylate used as a catalyst is also not consumed. After the reaction, the carboxylic acid and the carboxylate can be recycled, with less discharge of three wastes, and can also be recycled for the next preparation of N-alkenylamide, which can significantly reduce production costs.

[0032] More preferably, the esterification reaction catalyst is the compound represented by the above formula (2-2).

[0033] Preferably, the compound represented by formula (2-2) is selected from at least one of 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.

[0034] According to a particularly preferred embodiment of the present invention, R 2 and R 3 The same. This makes the reaction easier to operate. For example, by adding an appropriate amount of base to the compound represented by formula (2-1) (the metal element in the base is preferably the same as the metal element represented by M in formula (2-2)), compounds of formula (2-1) and formula (2-2) can be obtained simultaneously. It can also further ensure the consistency of the carboxylic acid and carboxylate separated after the reaction with the carboxylic acid and carboxylate initially added, which is more conducive to recycling.

[0035] According to the present invention, preferably, the conditions of the first reaction include: a temperature of 8-45°C, preferably 10-40°C (for example, 10, 12, 15, 18, 20, 23, 25, 28, 30, 32, 35, 38, 40, and any range formed by any two of the above values, and any value within the range); a time of 3-15h, preferably 4-12h (for example, 4, 5, 6, 7, 8, 9, 10, 11, 12, and any range formed by any two of the above values, and any value within the range). The first reaction can be a tank reaction and can be carried out in a flask or a reactor.

[0036] Preferably, the first reaction is carried out under an inert gas purge, wherein the inert gas is selected from nitrogen and / or argon. The inert gas refers to a gas that does not participate in the reaction. The inert gas purge can remove water generated during the reaction. A small amount of acetic acid may also be blown out during the purge.

[0037] According to the present invention, preferably, the first reaction is carried out in the presence of a water scavenger.

[0038] Preferably, the dehydrating agent is selected from At least one of molecular sieve, sodium sulfate, magnesium sulfate and acetaldehyde dimethyl ether, more preferably molecular sieve.

[0039] Preferably, in the first reaction, the mass ratio of the compound represented by formula (1) to the water scavenger is 1:(10-30), preferably 1:(16-25).

[0040] After the first reaction is completed, solid-liquid separation (such as filtration) can be performed to remove the dehydrating agent.

[0041] Preferably, the temperature of the cracking reaction is 80-500° C. The pressure of the cracking reaction can be 0.5-1 kPa (absolute pressure).

[0042] According to the present invention, preferably, the cleavage reaction is carried out in a tubular reactor. The product obtained from the first reaction can be fed into the cleavage reaction container by means of negative pressure, so that the material passes through the cleavage tube quickly.

[0043] Preferably, the temperature of the cracking reaction is 200-350 (for example, it can be 200, 220, 250, 270, 300, 320, 350 and any range formed by any two of the above values ​​and any value within the range) ° C; the time is 0.2-10 (for example, it can be 0.2, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and any range formed by any two of the above values ​​and any value within the range) s. Fillers (such as alumina magnetic balls, silicon carbide, etc.) can also be loaded in the reaction tube to control the residence time of the material in the reaction tube to achieve the above reaction time. The specifications of the reaction tube can be an inner diameter of 30-50 mm and a length of 400-600 mm.

[0044] According to another specific embodiment, the cleavage reaction may also be a tank reaction, wherein the temperature of the tank reaction may be 80-110° C. and the time may be 8-10 hours.

[0045] According to the present invention, preferably, the molar ratio of the compound represented by formula (1), the compound represented by formula (2-1), and the esterification catalyst is 1:(2-25):(0.03-5), preferably 1:(3.5-22):(0.05-0.5). This can further ensure the yield and selectivity of the reaction.

[0046] After the first reaction is completed, part of the carboxylic acid in the obtained solution containing the first reaction product can be removed so that the mass concentration of the first reaction product in the solution is 75-98wt%, which can further inhibit coking in the cracking reaction.

[0047] It can be understood that in the preparation method of the compound shown in the common formula (1), since a catalyst salt is generally required, the compound shown in the obtained formula (1) will be doped with the salt. However, when the method provided by the present invention is used to prepare N-alkenyl amides from the compound shown in the formula (1), it is not necessary to separate the above-mentioned salt. The compound shown in the formula (1) doped with the salt is directly used. After adding carboxylic acid, the salt becomes a carboxylate accordingly, which can play a catalytic role together with the carboxylate added, so that a small amount of the carboxylate added can be saved. Therefore, the method provided by the present invention using carboxylate as a catalyst has a higher tolerance for raw material purity, which further simplifies the operation. The content of the catalyst doped in the compound shown in the obtained formula (1) can be determined by the amount of the catalyst added during the preparation of the compound shown in the formula (1).

[0048] After the reaction is completed, the material can be subjected to reduced pressure distillation, first distilled at 30-33°C until no liquid is distilled out (in this way, the compound represented by formula (2), such as acetic acid, can be isolated), then heated to 60-70°C and distilled again until no liquid is distilled out, thereby obtaining the product N-vinylamide. The pressure of the reduced pressure distillation can be 100-200 Pa.

[0049] According to the present invention, preferably, the method further comprises: isolating N-alkenyl amide from the cleavage reaction product, and recycling the remaining material for contact with the compound shown in formula (1). As mentioned above, after removing N-alkenyl amide from the cleavage reaction product, the remaining material should contain carboxylic acid and carboxylate, and may also contain the compound shown in formula (1) and the first reaction product that are not completely reacted, which can be used in the process for preparing N-alkenyl amide next time. The method provided by the present invention can recycle materials, and the route economy is significantly better.

[0050] In a second aspect, the present invention provides a method for preparing an N-alkenyl amide, comprising: allowing an aldehyde and an amide to undergo a nucleophilic addition reaction under alkaline conditions to obtain a compound represented by formula (1), and preparing an N-alkenyl amide using the obtained compound represented by formula (1) according to the method described above;

[0051] Among them, in formula (1), R 0 is a C1-C5 alkyl group, R 1 It is H or a C1-C8 hydrocarbon group.

[0052] It can be understood that the specific materials and conditions in the first reaction and the cracking reaction have been described in the first aspect and will not be repeated here.

[0053] For example, the compound represented by formula (1) can be synthesized under alkaline conditions by reacting an aldehyde and an amide (the molar ratio of aldehyde to amide can be (1.2-2):1). For example, acetaldehyde and formamide can react to produce N-(1-hydroxyethyl)formamide, and acetaldehyde and acetamide can react to produce N-(1-hydroxyethyl)acetamide. The synthesis of the compound represented by formula (1) can be carried out in the presence of a solvent, which can be toluene, n-hexane, or butanone, and the mass ratio of the solvent to the aldehyde can be (16-25):1. The reaction can be carried out at 10-20°C for 3-6 hours and under nitrogen protection. The alkaline conditions can be provided by a carbonate (such as potassium carbonate), and the molar ratio of the amide to the carbonate can be (50-120):1. For example, potassium carbonate is taken, nitrogen is passed through to remove oxygen, and then the aldehyde and solvent are added. The temperature is then adjusted to the reaction temperature, and the amide is added (for example, dropwise). The reaction is then controlled to complete. After completion, filtration can be performed to obtain the compound represented by formula (1).

[0054] Taking acetaldehyde and formamide as an example, the route of the above reaction can be shown as follows:

[0055] As shown in the above reaction scheme, through the above nucleophilic addition reaction, on the one hand, the compound shown in formula (1) can be obtained. On the other hand, when the alkalinity is provided by carbonate (such as potassium carbonate), the carbonate can react with the raw material R in the next reaction. 2 COOH acid reacts to form carboxylate R 2 COOM, thereby serving as a catalyst for the next reaction. When preparing N-alkenyl amides in this manner, the product obtained from the nucleophilic addition reaction does not require a complex purification step. That is, the process has a high tolerance for the purity of the intermediate product and can also reduce the amount of catalyst added in the next reaction.

[0056] After preparing N-alkenyl amide using the method provided by the present invention, the N-alkenyl amide can also be used to prepare a polymer. The specific method may include: preparing N-alkenyl amide according to the method described above; then mixing the obtained N-alkenyl amide as monomer D' with monomer A', monomer B', monomer C' and an initiator under solution polymerization conditions to carry out a polymerization reaction. The polymer prepared by this method has both aqueous phase viscosifying ability and low-dynamic emulsification of heavy oil performance, can achieve heavy oil viscosity reduction, and is suitable for water-flooding oil reservoir recovery. Wherein, monomer A', the monomer B', the monomer C', initiator, polymerization reaction, etc. are detailed in CN202311522670.5, CN202311522771.2, and CN202311519415.5, which are hereby incorporated by reference in their entirety.

[0057] Preparation Example 1

[0058] Take potassium carbonate (1 mmol), pass nitrogen to deoxygenate, add acetaldehyde (120 mmol) and toluene (150 mL), control the temperature at 15°C, add formamide (100 mmol) dropwise, maintain 15°C for 5 hours after the addition is complete; after the reaction is completed, filter to obtain a solid mixture of N-(1-hydroxyethyl)formamide and potassium carbonate (white).

[0059] In the following examples and comparative examples:

[0060] The instrument used for nuclear magnetic resonance detection is a Bruker 500 MHz nuclear magnetic resonance spectrometer.

[0061] The material obtained from the cracking reaction was subjected to reduced pressure distillation at a pressure of 100 Pa, first distilled at 30° C. until no liquid was distilled out to obtain acetic acid; then distilled at 60° C. until no liquid was distilled out to obtain the product N-alkenylamide.

[0062] In the first reaction, the yield of the first reaction product is calculated as follows: actual yield of the first reaction product / theoretical yield of the first reaction product × 100%, where the theoretical yield of the first reaction product is the yield of the first reaction product when all the charged amount of the compound represented by formula (1) is converted into the first reaction product. The actual yield of the first reaction product is determined by nuclear magnetic resonance peak ratios. Specifically, 50 mg of the reaction solution is added with deuterated dimethyl sulfoxide, followed by nuclear magnetic resonance analysis, and the yield is determined by the peak area ratio of the esterification product to acetic acid and potassium acetate.

[0063] In the cleavage reaction, the conversion rate of the cleavage reaction raw materials is calculated as follows: the consumption of the cleavage reaction raw materials / the input amount of the cleavage reaction raw materials×100%; the selectivity of the cleavage reaction is calculated as the actual output of N-alkenylamide / the theoretical output of N-alkenylamide calculated based on the above cleavage reaction raw materials conversion rate×100%.

[0064] The total yield of N-alkenylamide is calculated as the yield of the first reaction product × the conversion rate of the cleavage reaction raw materials × the selectivity of the cleavage reaction.

[0065] Example 1

[0066] N-(1-hydroxyethyl)formamide (100 mmol, provided by a solid mixture of N-(1-hydroxyethyl)formamide and potassium carbonate obtained in Preparation Example 1) was placed in a 250 mL round-bottom flask, the temperature was adjusted to 10° C., and acetic acid (400 mmol) and potassium acetate (10 mmol) were added. Molecular sieves (200 g) were added and the reaction was maintained at 10°C for 12 hours (tank reaction). After the reaction was complete, the molecular sieves were removed by filtration to obtain a mixture containing N-(1-acetoxyethyl)formamide and acetic acid. A sample was removed by rotary evaporation to remove the acetic acid, and the product structure was characterized by nuclear magnetic resonance. 1 H NMR (500 MHz, DMSO) δ 8.96 (d, J = 7.9 Hz, 1H), 8.61 (t, J = 10.2 Hz, 1H), 8.21 (d, J = 11.0 Hz, 1H), 8.01 (s, 1H), 6.32 (dq, J = 8.9, 6.1 Hz, 1H), 6.01 (dq, J = 12.1, 6.0 Hz, 1H), 2.00 (s, 3H), 1.97 (s, 3H), indicating that the product structure is The product yield was 92.5%.

[0067] To the above-mentioned mixed solution that contains N-(1-acetoxyethyl) methane amide and acetate, remove part acetate, controlling the content of N-(1-acetoxyethyl) methane amide wherein is 75wt%, with this as raw material, adopt negative pressure mode charging, absolute pressure is 500Pa, fills carborundum in the cracking tube, and temperature in the tube keeps 200 ℃, and reaction solution obtains N-vinyl formamide after reaction is finished in pipe residence time 2s (being tubular reaction).The scission reaction raw material conversion rate is 95.7%, and the scission reaction selectivity is 92.9%.

[0068] The total yield of N-vinylformamide was 82.24%.

[0069] Example 2

[0070] N-(1-hydroxyethyl)formamide (100 mmol) was added to a 250 mL round-bottom flask, along with acetic acid (1000 mmol) and potassium acetate (45 mmol). After addition, the temperature was adjusted to 40°C and the reaction was carried out for 4 hours (tank reaction) under a nitrogen purge. After completion of the reaction, a mixture containing N-(1-acetoxyethyl)formamide and acetic acid was obtained. The yield of N-(1-acetoxyethyl)formamide was 90.7%.

[0071] To the above-mentioned mixed solution that contains N-(1-acetoxyethyl) methane amide and acetate, remove part acetate, controlling the content of N-(1-acetoxyethyl) methane amide wherein is 98wt%, with this as raw material, adopt negative pressure mode charging, absolute pressure is 800Pa, fills carborundum in the cracking tube, and tube interior temperature keeps 250 ℃, reaction solution residence time 10s (being tubular reaction) in pipe.Reaction obtains N-vinyl formamide after finishing.The scission reaction raw material conversion rate is 98.8%, and the scission reaction selectivity is 90.3%.

[0072] The total yield of N-vinylformamide was 80.92%.

[0073] Example 3

[0074] Take N-(1-hydroxyethyl)formamide (100mmol) in a 250mL round-bottom flask, add acetic acid (2000mmol) and potassium acetate (10mmol), add Molecular sieves (160 g) were added and reacted at 25°C for 12 hours (autoclave reaction). After completion of the reaction, the molecular sieves were removed by filtration to obtain a mixture containing N-(1-acetoxyethyl)formamide and acetic acid. The yield of N-(1-acetoxyethyl)formamide was 95.2%.

[0075] The above-mentioned mixed solution containing N-(1-acetoxyethyl) formamide and acetic acid was removed with some acetic acid, and the content of N-(1-acetoxyethyl) formamide was controlled to be 90wt%. This was used as a raw material, and negative pressure feeding was adopted. The absolute pressure was 1kPa, and there was no filler in the cracking tube. The temperature in the tube was maintained at 350°C, and the reaction solution was maintained in the tube for 0.5s (i.e., tubular reaction) to obtain N-vinyl formamide. The scission reaction raw material conversion rate was 99.6%, and the scission reaction selectivity was 91.7%. After the reaction was completed, N-vinyl formamide was obtained.

[0076] The total yield of N-vinylformamide was 86.95%.

[0077] Example 4

[0078] The obtained mixture of N-(1-acetoxyethyl) formamide and acetic acid in Example 1 was prepared by removing some acetic acid to control the content of N-(1-acetoxyethyl) formamide to 75wt%. This was used as a raw material and a negative pressure feed was adopted. The absolute pressure was 500 Pa. Alumina balls were filled in the cracking tube. The temperature in the tube was kept at 390°C. The reaction solution was maintained in the tube for 2s (i.e., tubular reaction). After the reaction was completed, N-vinyl formamide was obtained. The cleavage reaction raw material conversion rate was 98%, and the cleavage reaction selectivity was 77.5%.

[0079] The total yield of N-vinylformamide was 70.25%.

[0080] Example 5

[0081] The mixture containing N-(1-acetoxyethyl)formamide and acetic acid obtained in Example 1 was partially removed to control the N-(1-acetoxyethyl)formamide content to 75 wt %. This mixture was used as a raw material and reacted at 1 kPa and 80° C. for 9 h (tank reaction). The raw material conversion rate of the cleavage reaction was 96.1%, and the cleavage reaction selectivity was 85%.

[0082] The total yield of N-vinylformamide was 81.7%.

[0083] Comparative Example 1

[0084] Take N-(1-hydroxyethyl)formamide (100 mmol) in a 250 mL round-bottom flask, adjust the temperature to 10°C, add 410 mmol of acetic anhydride, After the addition of molecular sieves (200 g), the reaction was maintained at 10°C for 12 hours (tank reaction). The yield of N-(1-acetoxyethyl)formamide was 60%.

[0085] Comparative Example 2

[0086] N-(1-hydroxyethyl)formamide (100 mmol) was taken, the temperature was adjusted to 300°C and the reaction was carried out for 10 hours; the conversion rate of N-(1-hydroxyethyl)formamide was 98.7%, the selectivity of N-vinylformamide was 2.8%, and the yield of N-vinylformamide was 2.76%.

[0087] The products of each of the above examples were characterized by NMR. Taking the product obtained in Example 1 as an example, the NMR characterization data of N-vinylformamide are as follows:

[0088] 1 H NMR (500MHz, 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).

[0089] The above results show that the method provided by the present invention is simple to operate, has a high product yield, excellent selectivity, and is easy to separate. In particular, the raw materials can be recycled, which can significantly reduce production costs.

[0090] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing N-alkenyl amide, characterized in that: The method comprises: under esterification reaction conditions and in the presence of an esterification reaction catalyst, contacting a compound represented by formula (1) with a compound represented by formula (2-1) to undergo a first reaction, and then subjecting the obtained first reaction product to a cleavage reaction; Among them, in formula (1), R 0 is a C1-C5 alkyl group, R 1 is H or a C1-C8 hydrocarbon group; In formula (2-1), R 2 It is H or a C1-C8 hydrocarbon group.

2. The method according to claim 1, wherein: R 0 is methyl, R 1 is H or a C1-C8 hydrocarbon group; Preferably, the compound represented by formula (1) is selected from at least one of N-(1-hydroxyethyl)formamide, N-(1-hydroxyethyl)acetamide, N-(1-hydroxyethyl)propionamide, N-(1-hydroxyethyl)butyramide, N-(1-hydroxyethyl)valeramide, N-(1-hydroxyethyl)hexanamide and N-(1-hydroxyethyl)benzamide.

3. The method according to claim 1 or 2, wherein: R 2 wherein the C1-C8 hydrocarbon group is selected from a C1-C8 alkyl group, a C2-C8 alkenyl group, a C2-C8 alkynyl group or a benzyl group; Preferably, the compound represented by formula (2-1) is at least one selected from formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, cyclohexanoic acid and benzoic acid.

4. The method according to any one of claims 1 to 3, wherein: The esterification reaction catalyst includes a compound represented by formula (2-2), In formula (2-2), R 3 is H or a C1-C8 hydrocarbon group, preferably selected from a C1-C8 alkyl group, a C2-C8 alkenyl group, a C2-C8 alkynyl group, a benzyl group or a phenethyl group; M is a Group IA metal element, preferably selected from Na, K or Cs.

5. The method according to claim 4, wherein: The compound represented by formula (2-2) is selected from at least one of 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.

6. The method according to claim 4, wherein: R 2 and R 3 same.

7. The method according to any one of claims 1 to 6, wherein: The conditions of the first reaction include: temperature of 8-45°C, preferably 10-40°C; time of 3-15h, preferably 4-12h.

8. The method according to any one of claims 1 to 7, wherein: The contacting is performed under an inert gas purge, wherein the inert gas is selected from nitrogen and / or argon; Wherein, the first reaction is carried out in the presence of a water scavenger; Preferably, the dewatering agent is selected from At least one of molecular sieve, sodium sulfate, magnesium sulfate and acetaldehyde dimethyl ether, more preferably Molecular sieves; Preferably, in the first reaction, the mass ratio of the compound represented by formula (1) to the water scavenger is 1:(10-30), preferably 1:(16-25).

9. The method according to any one of claims 1 to 8, wherein: The temperature of the cracking reaction is 80-500°C.

10. The method according to any one of claims 1 to 9, wherein: The cleavage reaction is carried out in a tubular reactor; Preferably, the cracking reaction temperature is 200-350°C and the time is 0.2-10s.

11. The method according to any one of claims 1 to 10, wherein: The molar ratio of the compound represented by formula (1), the compound represented by formula (2-1) and the esterification reaction catalyst is 1:(2-25):(0.03-5), preferably 1:(3.5-22):(0.05-0.5).

12. The method according to any one of claims 1 to 11, wherein: The method further comprises: separating N-alkenyl amide from the cleavage reaction product, and recycling the remaining material for contact with the compound represented by formula (1).

13. A method for preparing N-alkenyl amide, characterized in that: The method comprises: under alkaline conditions, allowing an aldehyde and an amide to undergo a nucleophilic addition reaction to obtain a compound represented by formula (1), and preparing N-alkenyl amide using the obtained compound represented by formula (1) according to the method described in any one of claims 1 to 12; Among them, in formula (1), R 0 is a C1-C5 alkyl group, R 1 It is H or a C1-C8 hydrocarbon group.

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