阅读说明：本技术 一种可循环的含氮聚碳酸酯塑料的合成方法 (Recyclable nitrogen-containing polycarbonate plastic synthesis method ) 是由 刘野 于艳 吕小兵 于 2020-12-11 设计创作，主要内容包括：本发明提供了一种可循环的含氮聚碳酸酯塑料的合成方法,使用基于联苯的双核钴配合物及季铵盐组成的催化体系应可以实现含氮环氧烷烃与二氧化碳交替共聚反应。此类含氮环氧烷烃是以糠醛为原料制备的生物质单体,之后又在环上引入了不同的氨基甲酸酯的结构,功能基团FG的不同,会显著影响聚合物的降解选择性、结晶性、热力学稳定性等等。同时,这种无毒无害,可生物可降解CO-2基聚碳酸酯,又可以在受热条件下发生化学降解,实现聚碳酸酯到环氧烷烃的循环,是有一种可实现塑料到单体技术的新型聚碳酸酯塑料。(The invention provides a recyclable nitrogen-containing polycarbonate plastic synthesis method, wherein a catalytic system consisting of a binuclear cobalt complex based on biphenyl and quaternary ammonium salt is used for realizing the alternating copolymerization reaction of nitrogen-containing alkylene oxide and carbon dioxide. The nitrogen-containing alkylene oxide is a biomass monomer prepared by taking furfural as a raw material, and then different carbamate structures are introduced on a ring, so that the degradation selectivity, crystallinity, thermodynamic stability and the like of a polymer can be obviously influenced due to different functional groups FG. At the same time, the nontoxic, harmless and biodegradable CO is obtained 2 The polycarbonate can be chemically degraded under the heating condition to realize the circulation from the polycarbonate to the alkylene oxide, and the method has one stepNovel polycarbonate plastics enabling plastics to monomer technology.)

1. A method for synthesizing recyclable nitrogen-containing polycarbonate plastic comprises the following steps: the synthetic route of the nitrogen-containing alkylene oxide is as follows:

in the formula, 5a, R is CH₃、5b:R＝CH₂CH₃、5c:R＝CH₂CH₂CH₃、5d:R＝CH₂CH₂CH₂CH₃、5e:R＝(CH₂)₄CH₃、5f:R＝(CH₂)₅CH₃、5g:R＝CHCH₃CH₂CH₃、5h:R＝C(CH₃)₂CH₂CH₃、5i:R＝CH(CH₃)₂、5j:R＝CH₂CH(CH₃)₂、5k:R＝C(CH₃)₃、5l:R＝CH₂C₆H₅、5m:R＝CPh₃；

The five-membered ring structured alkylene oxide monomer is synthesized by taking 3-pyrroline as a raw material; the 3-pyrroline is formed by hydrolyzing, reducing, halogenating and cyclizing furfural derived from biomass;

(1) synthesis of five-membered ring structure alkylene oxide monomer

(1.1) Synthesis of Compounds 4a-4 b: under the protection of nitrogen, dissolving 3-pyrroline in dichloromethane, wherein the concentration of the 3-pyrroline is 1mol/L, carrying out ice bath to 0 ℃, dropwise adding a compound 2a or a compound 2b, and controlling the molar ratio of the 3-pyrroline to the compound to be 5: 6; then returning to room temperature, stirring for 3h, adding a 2mol/L diluted hydrochloric acid solution with the same volume as dichloromethane, stirring for 0.25h, separating out the organic phase, drying with anhydrous sodium sulfate, spin-drying the solvent, and separating by column chromatography to obtain a colorless liquid;

the synthesis method of the compound 4c-4m comprises the following steps: under the protection of nitrogen, 3-pyrroline is dissolved in dichloromethane, the concentration of the 3-pyrroline is 1mol/L, the mixture is ice-cooled to 0 ℃, added triethylamine is added, and the molar ratio of the triethylamine to the 3-pyrroline is controlled to be 2: dropwise adding one of a compound 2 c-a compound 2m, removing an ice bath after the dropwise adding is completed, reacting at room temperature for 8 hours, and controlling the molar ratio of 3-pyrroline to the compound to be 2: 3; filtering to remove solids, washing the filtrate with saturated saline solution, separating out the organic phase, drying with anhydrous sodium sulfate, removing the solvent, concentrating, and separating by column chromatography to obtain a colorless liquid;

(1.2) method for synthesizing 5a-5 m: under the protection of nitrogen, dissolving one of a compound 4 a-a compound 4m in dichloromethane, controlling the concentration of the compound to be 0.25mol/L, carrying out ice bath to 0 ℃, and then slowly adding m-chloroperoxybenzoic acid, wherein the molar ratio of the compound to the m-chloroperoxybenzoic acid is controlled to be 5: removing the ice bath after 1 hour, reacting for 24 hours at room temperature, adding a saturated sodium thiosulfate solution to make the reaction solution neutral, stirring for 1 hour, separating an organic phase, washing with a saturated sodium bicarbonate solution, separating the organic phase, drying with anhydrous sodium sulfate, concentrating, and separating by column chromatography to obtain a colorless liquid;

(2) preparation of nitrogen-containing polycarbonate plastic by catalyzing reaction of carbon dioxide and alkylene oxide monomer with five-membered ring structure

The adopted catalyst is a double four-tooth or double three-tooth Schiff base complex bimetallic catalyst with two metal centers connected through a biphenyl framework, the reaction temperature is 0-100 ℃, and CO is₂The pressure is 0.1-6.0 MPa, the molar ratio of the catalyst to the alkylene oxide monomer is 1: 1000-1: 200000, and the reaction is carried out for 1-48 hours, so as to obtain the nitrogen-containing polycarbonate plastic.

2. A method for catalytically degrading nitrogen-containing polycarbonate plastics is characterized in that in the catalysis of a chromium complex catalyst containing a Schiff base structure, the nitrogen-containing polycarbonate plastics are catalytically degraded into an alkylene oxide monomer under a heated condition in the presence or absence of a solvent, and the alkylene oxide monomer can be polymerized into polycarbonate again; the molar ratio of the catalyst to the repeating units in the polycarbonate in the catalytic pyrolysis reaction system with the solvent for homogeneous degradation and without the solvent is 1: 10-1: 10000, wherein the concentration of the repeating unit in the homogeneous degradation polycarbonate in the solvent is 0.01-0.1 mol/L, the reaction temperature is 50-150 ℃, and the reaction time is 1-200 hours; the reaction temperature of the solvent-free catalytic pyrolysis is 150-250 ℃, and the reaction time is 0.1-3 hours.

3. A method for directly pyrolyzing nitrogen-containing polycarbonate plastic into alkylene oxide by heating is characterized in that the nitrogen-containing polycarbonate plastic is pyrolyzed into the alkylene oxide monomer under the conditions that the reaction temperature is 200-350 ℃ and the reaction time is 0.5-10 hours.

4. The method according to claim 1, wherein the solvent used comprises: toluene, xylene, tetrahydrofuran, dichloromethane, dioxane, ethylene glycol dimethyl ether.

5. The method according to claim 2, wherein the solvent used comprises: toluene, xylene, tetrahydrofuran, chloroform, o-dichlorobenzene.

Technical Field

The invention relates to a method for synthesizing recyclable nitrogenous polycarbonate plastic, which uses a binuclear cobalt complex based on biphenyl andthe quaternary ammonium salt catalyst system can realize the alternate copolymerization of nitrogen-containing alkylene oxide and carbon dioxide. The nitrogen-containing alkylene oxide is a biomass monomer prepared by taking furfural as a raw material, and then different carbamate structures are introduced on a ring, so that the degradation selectivity, crystallinity, thermodynamic stability and the like of a polymer can be obviously influenced due to different functional groups FG. At the same time, the nontoxic, harmless and biodegradable CO is obtained₂The polycarbonate can be chemically degraded under the heated condition, so that the cycle from polycarbonate to alkylene oxide is realized, and the polycarbonate plastic is a novel polycarbonate plastic capable of realizing the plastic-to-monomer technology.

Background

The synthetic polymer plastic is one of the most important materials invented by human beings since the 20 th century, has the characteristics of light weight, strong toughness, good processability and the like, and is widely applied to various aspects in the production and life of the human society. The plastic production has increased dramatically over the past few decades, and in 2015, mankind has cumulatively produced about 83 hundred million tons of plastic, of which about 63 million tons has become waste, with only 9% being recycled. Plastics mainly come from non-renewable resources such as petroleum, natural gas, the non-renewable nature of this kind of resource has not only brought the problem that the resource consumes almost, and the discarded macromolecular material also can bring serious environmental problem simultaneously, and especially most synthetic polymer all are difficult to degrade. Thus in recent years, like CO₂Renewable resources such as furfural and the like are increasingly applied to the field of polymer synthesis to prepare sustainable materials such as elastomers, hydrogels, resin-based composite polymers and the like.

Research has shown that the advantage of the ring-fused structure of alicyclic alkylene oxide makes it feasible to degrade the polymer at high temperature to obtain the corresponding monomer. 2013, the degradation of the polycyclopentadienyl carbonate by Darensbourg et al was achieved for the first time by CO₂Recovery of the base polycarbonate to monomer, but with the formation of small amounts of cyclic carbonate. In 2017, Sablong and colleagues reported quantitative depolymerization of 1,5, 7-triazabicyclo (4.4.0) dec-5-ene catalyzed poly (limonene carbonate) to the corresponding initial limonene oxide monomer. We use this toA series of alkylene oxide monomers from biomass are designed, furfural is used as a raw material, the cost is low, and chemical degradation can be realized, so that the bio-derived plastic has sustainability and recyclability.

Disclosure of Invention

The invention aims to solve the technical problem of synthesizing and degrading five-membered ring alicyclic polycarbonate from biomass materials.

The technical scheme of the invention is as follows:

a method for synthesizing recyclable nitrogen-containing polycarbonate plastic comprises the following steps:

in the formula, 5a, R is CH₃、5b:R＝CH₂CH₃、5c:R＝CH₂CH₂CH₃、5d:R＝CH₂CH₂CH₂CH₃、 5e:R＝(CH₂)₄CH₃、5f:R＝(CH₂)₅CH₃、5g:R＝CHCH₃CH₂CH₃、5h:R＝C(CH₃)₂CH₂CH₃、 5i:R＝CH(CH₃)₂、5j:R＝CH₂CH(CH₃)₂、5k:R＝C(CH₃)₃、5l:R＝CH₂C₆H₅、5m:R＝ CPh₃；

The five-membered ring structured alkylene oxide monomer is synthesized by taking 3-pyrroline as a raw material; the 3-pyrroline is formed by hydrolyzing, reducing, halogenating and cyclizing furfural derived from biomass;

(1) synthesis of five-membered ring structure alkylene oxide monomer

(1.1) Synthesis of Compounds 4a-4 b: under the protection of nitrogen, dissolving 3-pyrroline in dichloromethane, wherein the concentration of the 3-pyrroline is 1mol/L, carrying out ice bath to 0 ℃, dropwise adding a compound 2a or a compound 2b, and controlling the molar ratio of the 3-pyrroline to the compound to be 5: 6; then returning to room temperature, stirring for 3h, adding a 2mol/L diluted hydrochloric acid solution with the same volume as dichloromethane, stirring for 0.25h, separating out the organic phase, drying with anhydrous sodium sulfate, spin-drying the solvent, and separating by column chromatography to obtain a colorless liquid;

the synthesis method of the compound 4c-4m comprises the following steps: under the protection of nitrogen, 3-pyrroline is dissolved in dichloromethane, the concentration of the 3-pyrroline is 1mol/L, the mixture is ice-cooled to 0 ℃, added triethylamine is added, and the molar ratio of the triethylamine to the 3-pyrroline is controlled to be 2: dropwise adding one of a compound 2 c-a compound 2m, removing an ice bath after the dropwise adding is completed, reacting at room temperature for 8 hours, and controlling the molar ratio of 3-pyrroline to the compound to be 2: 3; filtering to remove solids, washing the filtrate with saturated saline solution, separating out the organic phase, drying with anhydrous sodium sulfate, removing the solvent, concentrating, and separating by column chromatography to obtain a colorless liquid;

(1.2) method for synthesizing 5a-5 m: under the protection of nitrogen, dissolving one of a compound 4 a-a compound 4m in dichloromethane, controlling the concentration of the compound to be 0.25mol/L, carrying out ice bath to 0 ℃, and then slowly adding m-chloroperoxybenzoic acid, wherein the molar ratio of the compound to the m-chloroperoxybenzoic acid is controlled to be 5: removing the ice bath after 1 hour, reacting for 24 hours at room temperature, adding a saturated sodium thiosulfate solution to make the reaction solution neutral, stirring for 1 hour, separating an organic phase, washing with a saturated sodium bicarbonate solution, separating the organic phase, drying with anhydrous sodium sulfate, concentrating, and separating by column chromatography to obtain a colorless liquid;

(2) preparation of nitrogen-containing polycarbonate plastic by catalyzing reaction of carbon dioxide and alkylene oxide monomer with five-membered ring structure

The adopted catalyst is a double four-tooth or double three-tooth Schiff base complex bimetallic catalyst with two metal centers connected through a biphenyl framework, the reaction temperature is 0-100 ℃, and CO is₂The pressure is 0.1-6.0 MPa, the molar ratio of the catalyst to the alkylene oxide monomer is 1: 1000-1: 200000, and the reaction is carried out for 1-48 hours, so as to obtain the nitrogen-containing polycarbonate plastic.

In the catalysis of a chromium complex catalyst containing a Schiff base structure, under the condition of solvent or no solvent, the nitrogen-containing polycarbonate plastic is catalytically degraded into an alkylene oxide monomer under the heated condition, and the alkylene oxide monomer can be polymerized into polycarbonate again; the molar ratio of the catalyst to the repeating units in the polycarbonate in the catalytic pyrolysis reaction system with the solvent for homogeneous degradation and without the solvent is 1: 10-1: 10000, wherein the concentration of the repeating unit in the homogeneous degradation polycarbonate in the solvent is 0.01-0.1 mol/L, the reaction temperature is 50-150 ℃, and the reaction time is 1-200 hours; the reaction temperature of the solvent-free catalytic pyrolysis is 150-250 ℃, and the reaction time is 0.1-3 hours.

A method for directly pyrolyzing nitrogen-containing polycarbonate plastics to obtain alkylene oxide by heating, wherein the nitrogen-containing polycarbonate plastics is pyrolyzed to obtain the alkylene oxide monomer under the conditions that the reaction temperature is 200-350 ℃ and the reaction time is 0.5-10 hours.

Solvents used in the synthesis of the nitrogen-containing polycarbonate plastics include: toluene, xylene, tetrahydrofuran, dichloromethane, dioxane, ethylene glycol dimethyl ether.

Solvents used in the catalytic degradation of nitrogen-containing polycarbonate plastics include: toluene, xylene, tetrahydrofuran, chloroform, o-dichlorobenzene.

The catalyst used in the catalytic degradation of the nitrogen-containing polycarbonate plastic is a chromium complex catalyst 1 containing Schiff base structure. The bimetallic catalyst used in the synthesis of the nitrogen-containing polycarbonate plastic is a double-quadridentate or double-tridentate Schiff base complex bimetallic catalyst 2 which connects two metal centers through a biphenyl framework. Specific structures of the catalyst and cocatalyst are referred to patents reported previously in this group of subjects (CN103102480A, Angew. C hem. int. Ed. DOI: 10.1002/anie.201305154). The degradation and polymerization catalysts were as follows:

the catalytic system consisting of the epoxy alkane binuclear cobalt complex based on biphenyl and quaternary ammonium salt can realize the catalytic system with CO₂Alternating copolymerization of (a):

the invention has the beneficial effects that: the polycarbonate prepared by the method is sustainable and is derived from biomass raw materials; the reaction conditions are relatively mild, and the process is simple and convenient; the catalyst has high activity and the selectivity of the polymerization product is high; the alternating structure in the polycarbonate product is higher than 98%, and the molecular weight distribution is narrow; partial stereoregularity has crystallizability; the polycarbonate can be degraded into an alkylene oxide monomer, and the recycling of the material is realized.

Drawings

FIG. 1 is a nuclear magnetic hydrogen spectrum of monomer N-Me;

FIG. 2 is a nuclear magnetic carbon spectrum of monomer N-Me;

FIG. 3 is a nuclear magnetic hydrogen spectrum of polymer PN-Me;

FIG. 4 is a nuclear magnetic carbon spectrum of polymer PN-Me.

Detailed Description

The following further describes a specific embodiment of the present invention with reference to the drawings and technical solutions.

The polymerization-related reaction was carried out as detailed in Table 1:

in a 100mL stainless steel autoclave, the following were added in the following order at ambient temperature: a certain amount of main catalyst (any one of the binuclear metal complexes described in the second claim), cocatalyst (if necessary), and 20mL of alkylene oxide, adding solvent (if necessary), introducing carbon dioxide gas, rapidly raising to a set temperature, and regulating the carbon dioxide pressure of the reaction system. The autoclave was maintained at the appropriate temperature and pressure and after a regular reaction time, the stirring was stopped and unreacted carbon dioxide was slowly released. Washing the polymerized product with chloroform/methanol precipitate for three times, drying under vacuum to constant weight, and measuring the molecular weight and distribution of the polymer by using gel permeation chromatography; it was determined using Varian INOVA-400MHz¹HNMR, the conversion was calculated.

TABLE 1 trivalent metallic cobalt catalyzed copolymerization of alkylene oxides with carbon dioxide

Note 1: the axial direction of the catalyst is 2, 4-dinitrophenol oxygen anion

Note 2: r¹＝Me，R²＝t-Bu，R³＝-C₆H₁₀-。

Note 3: the cocatalyst is PPNDNP, PPN is bis (triphenyl phosphoranylidene) ammonium cation, and DNP is 2, 4-dinitrophenol oxyanion.

The degradation-related methods of implementation are detailed in table 2:

the three recycling routes for the nitrogen-containing polycarbonate are:

solvent degradation, route 1 (Table 2, entries1-23), in a reaction flask, was added with ambient temperature in the following order: adding a certain amount of main catalyst (if needed), cocatalyst (if needed) and 5g of polymer, adding solvent, quickly raising the temperature to a set temperature, stopping stirring after reacting for a specified time, and measuring by using Varian INOVA-400MHz¹And (4) HNMR, calculating the conversion rate and selectivity of the degradation reaction.

The catalyst was pyrolyzed, route 2 (Table 2, entries24-27), added to the reaction flask in the following order at ambient temperature: a certain amount of main catalyst (if necessary), cocatalyst (if necessary) and polymer 5g, sealing the device, rapidly heating to 200 deg.C, reacting for a specified time, stopping stirring, and measuring with Varian INOVA-400MHz¹And (4) HNMR, calculating the conversion rate and selectivity of the degradation reaction.

Pyrolysis, route 3 (Table 2, entries28-31), in a reaction flask, was added with ambient temperature in the following order: 5g of polymer, sealing the device, rapidly raising the temperature to the set temperature (260 ℃ C.) and 300 ℃ C.), stopping stirring after the reaction is carried out for a specified time, and measuring the polymer by using Varian INOVA-400MHz¹And (4) HNMR, calculating the conversion rate and selectivity of the degradation reaction.

TABLE 2 trivalent chromium metal catalyzed degradation of polycarbonate to monomer

Note 1: r¹，R²t-Bu, entry2-17Of entry18-27

Note 2: PPN is the bis (triphenylphosphoranylidene) ammonium cation and OTs is the p-toluenesulfonic acid anion.

Note 3: the catalyst axis X is chloride.