阅读说明：本技术 一种富氮席夫碱聚合物的合成方法 (Synthetic method of nitrogen-rich Schiff base polymer ) 是由 白赢 余泽浩 彭家建 厉嘉云 于 2021-01-18 设计创作，主要内容包括：本发明公开了一种富氮席夫碱聚合物的合成方法,包括：(1)将对苯二甲醛和三聚氰胺加入到二甲基亚砜溶剂中,再加入甲苯和二甲苯,通入惰性气体,升温至甲苯沸点上下的温度进行分水回流至无水产生；(2)惰性气体下继续升温至二甲苯沸点上下的温度进行反应,分水回流直至无水产生；(3)反应结束后,将反应产物降至室温,抽滤、分离固体、洗涤、干燥后得到富氮席夫碱聚合物。本发明合成方法操作简单、易于控制、收率高,本发明合成的富氮席夫碱聚合物氮含量高、结构稳定、粒径分布均匀。(The invention discloses a synthetic method of a nitrogen-rich Schiff base polymer, which comprises the following steps: (1) adding terephthalaldehyde and melamine into a dimethyl sulfoxide solvent, adding toluene and xylene, introducing inert gas, heating to a temperature above and below the boiling point of toluene, and carrying out water diversion and reflux until no water is generated; (2) continuously heating to the temperature above and below the boiling point of xylene under inert gas to react, and carrying out water diversion and reflux until no water is generated; (3) after the reaction is finished, cooling the reaction product to room temperature, carrying out suction filtration, separating solid, washing and drying to obtain the nitrogen-rich Schiff base polymer. The synthetic method has the advantages of simple operation, easy control and high yield, and the nitrogen-rich Schiff base polymer synthesized by the method has high nitrogen content, stable structure and uniform particle size distribution.)

1. A synthetic method of a nitrogen-rich Schiff base polymer comprises the following steps:

(1) adding terephthalaldehyde and melamine into a dimethyl sulfoxide solvent, adding toluene and xylene, introducing inert gas, heating to a temperature above and below the boiling point of toluene, and carrying out water diversion and reflux until no water is generated;

(2) continuously heating to a temperature above and below the boiling point of xylene under inert gas, reacting, and carrying out water diversion and reflux until no water is generated;

(3) after the reaction is finished, cooling the reaction product to room temperature, carrying out suction filtration, separating solid, washing and drying to obtain the nitrogen-rich Schiff base polymer.

2. The method for synthesizing the nitrogen-rich schiff base polymer according to claim 1, wherein in the step (1), the molar ratio of terephthalaldehyde to melamine to dimethyl sulfoxide is 1: 1-4: 30-40.

3. The method for synthesizing a nitrogen-rich schiff base polymer according to claim 2, wherein in the step (1), the molar ratio of terephthalaldehyde to toluene to xylene is 1: 3-10: 2 to 8.

4. The synthesis method of the nitrogen-rich Schiff base polymer according to claim 1, wherein in the step (1), the temperature is raised to 100-140 ℃ for water diversion and reflux, and the reflux time is 1-4 h.

5. The synthesis method of the nitrogen-rich Schiff base polymer according to claim 4, wherein in the step (1), the temperature is raised to 120-130 ℃ for water diversion and reflux.

6. The method for synthesizing the nitrogen-rich Schiff base polymer according to claim 1, wherein in the step (2), the reaction temperature is 130-160 ℃ and the reaction time is 4-8 h.

7. The method for synthesizing the nitrogen-rich Schiff base polymer according to claim 6, wherein the reaction temperature in the step (2) is 150-160 ℃.

8. The process for synthesizing a nitrogen-rich schiff base polymer according to claim 1, wherein in the step (3), the washing agent is one or more of acetone, tetrahydrofuran, dichloromethane, ethanol and water.

Technical Field

The invention relates to the technical field of synthesis of high polymer materials, in particular to a method for synthesizing a nitrogen-rich Schiff base polymer.

Background

The traditional adsorbing material is limited in large-scale application due to high cost, difficult recovery and poor effect, and the porous organic polymer has the characteristics of high specific surface area, rich gaps, good stability, easy regeneration and the like, so that the porous organic polymer has excellent performance in the fields of ion adsorption, chromatographic separation, catalysis and the like, and becomes a key focus object of development and research of porous materials in recent years. The synthesis method of the polymer mainly comprises the following routes:

(1) patent application with publication number CN107216605A discloses a preparation method of a porous schiff base polymer composite material supported by a nitrogen carbide structure, which comprises the following reaction processes: adding benzene dicarbaldehyde (TA), Melamine (MA) and nitrogen carbide into a dimethyl sulfoxide solvent, magnetically stirring and vacuumizing at 100 ℃, continuously introducing nitrogen for 3 hours, adding toluene into a synthesis system, heating to 180 ℃, condensing and refluxing for 72 hours to obtain brown precipitate, adding acetone into the precipitate, stirring for 3 hours, extracting, centrifugally separating to obtain a crude product, washing the crude product by using acetone, tetrahydrofuran and dichloromethane in sequence, and then drying in vacuum at 100 ℃ for 12 hours to obtain the porous Schiff base polymer composite supported by a hydrogen carbide structure.

The reaction route has high temperature, long reaction time and high energy consumption, and is not suitable for production outside a laboratory.

(2) A periodical high-efficiency porous polymer as an effective catalyst for the Catalysis of carbon compounds with alcohols (published: Molecular Catalysis 451 (2018)) discloses a method for synthesizing a high-efficiency melamine porous organic polymer by microwave assistance, which comprises the following steps: adding Terephthalaldehyde (TA) and Melamine (MA) serving as raw materials into a dimethyl sulfoxide solvent, introducing nitrogen, filling a mixed reaction solution into a polytetrafluoroethylene coating pressure container, placing the container into a microwave reactor for microwave radiation at the reaction temperature of 160 ℃, reacting for 2 hours at the microwave frequency of 400W, filtering and washing the obtained crude product with dichloromethane, water and acetone in sequence, and then drying in vacuum to obtain the Schiff base polymer.

The reaction has the characteristics of simplicity and high efficiency, but the synthesis of the polymer also needs microwave radiation lasting for 2 hours, and the safety is low and difficult to control.

Disclosure of Invention

The invention provides a synthesis method of a nitrogen-rich Schiff base polymer, which is synthesized in one step by using a solvent stage reflux water-splitting method. Compared with the traditional synthetic method, the synthetic method has the advantages of simple process, low cost and high yield, and is suitable for large-scale production.

A synthetic method of a nitrogen-rich Schiff base polymer comprises the following steps:

(1) adding terephthalaldehyde and melamine into a dimethyl sulfoxide solvent, adding toluene and xylene, introducing inert gas, heating to a temperature above and below the boiling point of toluene, and carrying out water diversion and reflux until no water is generated;

(2) continuously heating to the temperature above and below the boiling point of xylene under inert gas to react, and carrying out water diversion and reflux until no water is generated;

(3) after the reaction is finished, cooling the reaction product to room temperature, carrying out suction filtration, separating solid, washing and drying to obtain the nitrogen-rich Schiff base polymer.

In the step (1), the molar ratio of terephthalaldehyde to melamine to dimethyl sulfoxide is 1: 1-4: 30-60.

The solubility between the starting materials directly affects the completeness of the reaction, and the molar ratio of terephthalaldehyde, melamine, and dimethyl sulfoxide affects the solubility between the starting materials.

In the step (1), preferably, the terephthalaldehyde, the melamine, the dimethyl sulfoxide and the benzene-dicarbonyl formaldehyde are mixed in a molar ratio of 1: 1-2: 30-40.

Preferably, the molar ratio of terephthalaldehyde, toluene and xylene is 1: 3-10: 2 to 8. The more the content of the methylbenzene is, the lower the temperature of water diversion reflux is, and the dehydration is facilitated; if the content of the dimethylbenzene is higher, the temperature of water division reflux is higher, which is beneficial to polymerization reaction, but if the temperature is too high, side reaction is easy to occur between the dimethyl sulfoxide and the terephthalaldehyde.

In the step (1), heating to 100-140 ℃ for water diversion and reflux, wherein the reflux time is 1-4 h; toluene and water form an azeotrope, water in the system is separated along with continuous evaporation of toluene, and preferably, the temperature is raised to 120-130 ℃ for water diversion and reflux, and the reflux time is 1-2 h.

In the step (2), the reaction temperature is 130-160 ℃, and the reaction time is 4-8 h; preferably, the reaction temperature is 140-150 ℃, and the reaction time is 2-4 h.

The toluene, the xylene and the water form an azeotrope, the water generated in the reaction system is further separated along with the continuous evaporation of the toluene and the xylene, the forward progress of the polymerization reaction is promoted, and the yield is improved.

In the step (3), the detergent is one or more of acetone, tetrahydrofuran, dichloromethane, ethanol and water; preferably, the detergent is ethanol, water or a mixture of the two.

The invention uses cheap and easily obtained terephthalaldehyde and melamine as raw materials to perform nucleophilic addition reaction under the condition of dimethyl sulfoxide solvent, and the terephthalaldehyde is used as a skeleton for connecting triazine rings to form a polymer.

In the first water dividing reflux stage, toluene is boiled and evaporated to bring out water absorbed in terephthalaldehyde, melamine and dimethyl sulfoxide; in the second heating reaction water separation reflux stage, the mixture of toluene and xylene is boiled to further carry out water produced by the reaction, and the two stages of solvent reflux water separation are favorable for forward reaction.

Compared with the prior art, the invention has the beneficial effects that:

(1) the synthetic method has the advantages of simple operation, easy control and high yield.

(2) The toluene and the xylene are heated and refluxed to separate water adsorbed in the raw materials and water generated by the reaction in two stages, so that reverse reaction is inhibited, the forward reaction is promoted, the reaction time is shortened, the reaction condition is mild, the use amount of an organic solvent is reduced, and the organic solvent can be recycled.

(3) The nitrogen-rich Schiff base polymer synthesized by the method has high nitrogen content, stable structure and uniform particle size distribution.

Drawings

FIG. 1 is an infrared spectrum (FTIR) of a nitrogen-rich Schiff base polymer prepared in example 1;

FIG. 2 is a Scanning Electron Micrograph (SEM) of the nitrogen-rich Schiff base polymer prepared in example 1, wherein a is an original figure, b is a partial enlarged view, and c and d are particle size analysis graphs in different regions of the nitrogen-rich Schiff base polymer;

FIG. 3 is a thermogravimetric analysis (TGA) of the nitrogen-rich Schiff base polymer prepared in example 1.

Detailed Description

The present invention is further illustrated by the following examples, which are given by way of illustration only and are not intended to be limiting of the present invention.

Example 1

Adding 15mmol of Terephthalaldehyde (TA) and 20mmol of Melamine (MA) into a double-mouth round-bottom flask, adding 35ml of dimethyl sulfoxide, 10ml of xylene and 10ml of toluene, connecting a water separator and a condenser pipe, connecting the tail end of the condenser pipe with a bubbler, carrying out magnetic stirring, introducing inert gas for ventilation, continuously introducing gas for protection during the reaction, setting the temperature of an oil bath kettle at 120 ℃, stirring and refluxing for 2 hours, raising the temperature to 150 ℃ after the reflux is finished, carrying out reaction, carrying out water separation and refluxing until no water is generated, wherein the reaction water separation and refluxing time is about 6 hours, stopping heating after the reaction is finished, stopping introducing gas after the temperature is reduced to room temperature, and filtering out solid substances. Extracting the solid substance with water as solvent by Soxhlet extraction for 4h, and oven drying the product in a vacuum drying oven at 80 deg.C for 24h to obtain nitrogen-rich Schiff base polymer 3.04g with yield of 88.4%.

Example 1 analysis of a nitrogen-rich schiff base polymer synthesized as follows:

FIG. 1 is an infrared spectrum of a nitrogen-rich Schiff base polymer prepared in example 1, and the analysis results of FIG. 1 are as follows: in the infrared spectrum, the product is 3400cm^-1NH-in left and right melamine₂The characteristic absorption peak of (A) disappears at 1600cm^-1A small amount of characteristic absorption peaks of aldehyde groups which do not completely participate in the reaction appear, and the absorption peak is 1500cm^-1、1400cm^-1And C & ltN & gt in the triazine ring appears on the left and right, and the comparison of the characteristic group absorption peaks proves that the Schiff base polymer is successfully synthesized.

FIG. 2 is a scanning electron micrograph of the nitrogen-rich Schiff base polymer prepared in example 1, and it can be seen from FIG. 2 that the polymer nanoparticles have the same morphology as reported in the literature, uniform size distribution, and particle size of 40-60 nm.

Fig. 3 is a thermogravimetric analysis (TGA) of the nitrogen-rich schiff base polymer prepared in example 1, and it can be seen from fig. 3 that the thermal weight loss of the nitrogen-rich schiff base polymer can be divided into three stages when the temperature is increased from room temperature to 800 ℃ in a nitrogen atmosphere, and the process of gradual weight loss further proves that the nitrogen-rich schiff base polymer prepared in example 1 is a high molecular polymer.

Elemental analysis test: 1.5mg of the nitrogen-rich Schiff base prepared in example 1 is weighed, burned and decomposed in a catalytic oxidation tube, the content of CHNS element in a sample is detected by a vario EL III element analyzer, and three groups of parallel test experiments show that the test data are shown in Table 1.

Table 1 example 1 preparation of nitrogen-rich schiff base polymer CHNS element content

Sample (I)	C(％)	H(％)	N(％)	S(％)	Sample Mass (mg)
						1	45.26	4.568	34.73	3.474	1.7790
2	46.65	4.677	34.80	3.520	1.4090
						3	45.88	4.592	34.85	3.313	1.6020

As can be seen from table 1, the nitrogen-rich schiff base polymer prepared in example 1 mainly consists of C, H, N, S four elements, wherein the mass fractions of the four elements are respectively C: 45.9%, H: 4.6%, S: 3.4% and N: 34.8%, it can be seen that the nitrogen content of the nitrogen-rich Schiff base polymer prepared in example 1 is higher.

Example 2

Adding 15mmol of Terephthalaldehyde (TA) and 20mmol of Melamine (MA) into a double-mouth round-bottom flask, adding 35ml of dimethyl sulfoxide, 15m of toluene and 5ml of dimethylbenzene, connecting a water separator and a condenser pipe, connecting the tail end of the condenser pipe with a bubbler, carrying out magnetic stirring, introducing inert gas for ventilation, continuously introducing gas for protection during the reaction, setting the temperature of an oil bath kettle at 120 ℃, stirring and refluxing for 2 hours, raising the temperature to 150 ℃ after the reflux is finished, carrying out reaction, carrying out water separation and refluxing until no water is generated, wherein the reaction water separation and refluxing time is about 6 hours, stopping heating after the reaction is finished, stopping introducing gas after the temperature is reduced to room temperature, and filtering out solid substances. Extracting the solid substance with water as solvent by Soxhlet extraction for 4h, placing the product in a vacuum drying oven, and drying at 80 deg.C for 24h to obtain 2.67g of nitrogen-rich Schiff base polymer with yield of 77.6%.

Example 3

Adding 10mmol of Terephthalaldehyde (TA) and 20mmol of Melamine (MA) into a double-mouth round-bottom flask, adding 35ml of dimethyl sulfoxide, 10ml of xylene and 10ml of toluene, connecting a water separator and a condenser pipe, connecting the tail end of the condenser pipe with a bubbler, carrying out magnetic stirring, introducing inert gas for ventilation, continuously introducing gas for protection during the reaction, setting the temperature of an oil bath kettle at 130 ℃, stirring and refluxing for 2 hours, raising the temperature to 150 ℃ after the reflux is finished, carrying out reaction, carrying out water separation and refluxing until no water is generated, wherein the reaction water separation and refluxing time is about 6 hours, stopping heating after the reaction is finished, stopping introducing gas after the temperature is reduced to room temperature, and filtering out solid substances. Extracting the solid substance with water as solvent by Soxhlet extraction for 4h, placing the product in a vacuum drying oven, and drying at 80 deg.C for 24h to obtain 1.77g of nitrogen-rich Schiff base polymer with yield of 78.9%.

Example 4

Adding 15mmol of Terephthalaldehyde (TA) and 20mmol of Melamine (MA) into a double-mouth round-bottom flask, adding 45ml of dimethyl sulfoxide, 10ml of xylene and 10ml of toluene, connecting a water separator and a condenser pipe, connecting the tail end of the condenser pipe with a bubbler, carrying out magnetic stirring, introducing inert gas for ventilation, continuously introducing gas for protection during the reaction, setting the temperature of an oil bath kettle at 120 ℃, stirring and refluxing for 2 hours, raising the temperature to 160 ℃ after the reflux is finished, carrying out reaction, carrying out water separation and refluxing until no water is generated, wherein the reaction water separation and refluxing time is about 6 hours, stopping heating after the reaction is finished, stopping introducing gas after the temperature is reduced to room temperature, and filtering out solid substances. Extracting the solid substance with water as solvent by Soxhlet extraction for 4h, placing the product in a vacuum drying oven, and drying at 80 deg.C for 24h to obtain 2.73g of nitrogen-rich Schiff base polymer with yield of 79.4%.

Example 5

Adding 6mmol of Terephthalaldehyde (TA) and 12mmol of Melamine (MA) into a double-mouth round-bottom flask, adding 35ml of dimethyl sulfoxide, 10ml of toluene and 10ml of xylene, connecting a water separator and a condenser pipe, connecting the tail end of the condenser pipe with a bubbler, carrying out magnetic stirring, introducing inert gas for ventilation, continuously introducing gas for protection during the reaction, setting the temperature of an oil bath kettle at 120 ℃, stirring and refluxing for 2 hours, raising the temperature to 150 ℃ after the reaction is finished, carrying out reaction, carrying out water separation and refluxing until no water is generated, wherein the time of water separation and refluxing for the reaction is about 4 hours, stopping heating after the reaction is finished, stopping introducing gas after the temperature is reduced to room temperature, and filtering out solid substances. Washing twice with 5ml acetone, twice with 5ml absolute ethyl alcohol, twice with 5ml dichloromethane, placing the solid in a vacuum drying oven, drying for 24h at 80 ℃ to obtain 1.26g of nitrogen-rich Schiff base polymer with the yield of 52.8%.