阅读说明：本技术 以配体聚合物为载体的高负载量单原子催化剂的制备方法 (Preparation method of high-load monatomic catalyst taking ligand polymer as carrier ) 是由 唐海涛 潘英明 任世丞 庞丽萍 黄文雍 李文豪 于 2020-05-27 设计创作，主要内容包括：本发明公开了一种以配体聚合物为载体的高负载量单原子催化剂的制备方法,所述方法为：通过各类官能团取代的溴代苯甲醛与甲基三苯基溴化膦的witting反应合成溴代乙烯基苯,再利用三氯化磷与溴代乙烯基苯反应制备出各种乙烯基取代三苯基膦单体,然后采用均相-异相配体交换法负载金属后,得到高负载量单原子催化剂。该方法具有成本低、操作简便、易于大量合成等优点,制备出的单原子金属化多孔有机聚合物催化剂结构稳定,离散性好,同时能够继承均相金属/配体催化体系的高反应性和选择性,相较于其他气相沉淀法合成的单原子催化剂,此催化剂在需要特殊结构配体的区域选择性反应中有着极高的应用价值。(The invention discloses a preparation method of a high-load monatomic catalyst taking a ligand polymer as a carrier, which comprises the following steps: bromo-vinylbenzene is synthesized through a witting reaction of various functional group substituted bromo-benzaldehyde and methyl triphenyl phosphonium bromide, various vinyl substituted triphenylphosphine monomers are prepared through a reaction of phosphorus trichloride and bromo-vinylbenzene, and then a high-load monatomic catalyst is obtained after a homogeneous phase-heterogeneous ligand exchange method is adopted to load metals. The method has the advantages of low cost, simple and convenient operation, easy mass synthesis and the like, the prepared monatomic metallized porous organic polymer catalyst has stable structure and good discreteness, and can inherit the high reactivity and selectivity of a homogeneous metal/ligand catalytic system, and compared with monatomic catalysts synthesized by other gas-phase precipitation methods, the catalyst has extremely high application value in regioselective reaction needing ligands with special structures.)

1. The preparation method of the high-load monatomic catalyst taking the ligand polymer as the carrier is characterized in that the general formula of the preparation method is as follows:

in the general formula, R is alkyl, alkoxy or fluorine; x ═ chlorine, bromine, or iodine; m ═ cobalt, rhodium, or palladium.

2. The method for preparing a high-load monatomic catalyst with a ligand polymer as a carrier according to claim 1, characterized by comprising the steps of:

(1) adding methyl triphenyl phosphonium bromide (1eq.) into a round-bottom flask, putting into cold hydrazine at 0 ℃ under the atmosphere of argon, adding 40ml of tetrahydrofuran solution, slowly dropwise adding n-butyl lithium, reacting in the cold hydrazine for half an hour, slowly dropwise adding the compound A (1eq.) into the mixture, stirring the mixture to react for 4 to 5 hours, then quenching the mixture by using a saturated ammonium chloride solution, extracting and drying the mixture, evaporating the solvent, and performing fast column chromatography separation to obtain a purified compound B;

(2) putting magnesium particles (1.1eq.) into a round-bottom flask, adding a tetrahydrofuran solution dissolved with iodine into the round-bottom flask under the argon atmosphere, heating, adding a compound B (1eq.) into the tetrahydrofuran solution for dilution when the liquid color gradually turns white, slowly dropping the compound B into a reaction bottle, and reacting for 30 minutes;

(3) putting a reaction bottle into cold hydrazine at 0 ℃, adding a phosphorus trichloride solution into tetrahydrofuran for dilution, slowly dripping into a reaction solution, reacting for 30 minutes, reacting at room temperature for 4-5 hours, then quenching with a saturated ammonium chloride solution, evaporating a solvent after extraction, and performing flash column chromatography separation to obtain a pure compound C;

(4) and adding a tetrahydrofuran solution into the compound C and azodiisobutyronitrile under the protection of argon, carrying out copolymerization reaction for 24 hours at 100 ℃, carrying out suction filtration, washing for 3 times by using ethyl acetate, carrying out vacuum drying to obtain a substituted triphenylphosphine porous polymer, and carrying with different types of metals according to requirements to prepare the high-load-capacity monatomic catalyst taking the triphenylphosphine porous organic polymer containing the substituent as a carrier.

Technical Field

The invention relates to chemical synthesis, and particularly provides a preparation method of a high-load monatomic catalyst taking a ligand polymer as a carrier.

Background

Monatomic catalysis has been favored by many scientific researchers as a popular field in recent years. Monatomic metal catalysts have a number of advantages over traditional supported metal catalysts, one of which is: the metal in the single-atom state can be completely dispersed on the carrier in the atomic state, so that the metal utilization rate is one hundred percent, and the effect of 'one to ten' can be achieved on the catalytic efficiency; the second step is as follows: when the metal catalytic centers in the catalyst are dispersed to an atomic level, different from the traditional large-particle nano catalyst, the single-atom catalyst has uniform and clearly-defined catalytic sites, and therefore, the single-atom catalyst often has high selectivity which is difficult to have in the traditional nano catalyst. However, the preparation of monatomic catalysts still presents some core challenges, mainly manifested by a sharp increase in the specific surface area of the metal when the active centers of the metal are scattered to the monatomic level, leading to a sharp increase in the free energy of the metal surface, which in turn agglomerates to form clusters during the reaction, eventually leading to catalyst deactivation. In the past, the preparation of monatomic catalysts has often been achieved with very low metal loadings (<0.1 wt%), while methods for preparing functionalized monatomic catalysts with high loadings (>2 wt%) have been less common to date. The method for preparing the high-load monatomic catalyst taking the triphenylphosphine porous organic polymer containing the substituent as the carrier is developed by combining a homogeneous-heterogeneous ligand exchange method which utilizes abundant coordination units in the microstructure of the porous organic ligand polymer material to provide enough coordination sites for metal and resist the agglomeration tendency of metal atoms and can easily obtain the high-load monatomic metal catalyst.

Since the traditional metal-supported triphenylphosphine is most commonly used as a ligand to catalyze reactions among numerous ligands, for example: zhan et al realized amination reaction Of chloromethyl naphthalene and chloromethyl anthracene derivatives with various amines using palladium tetratriphenylphosphine as a catalyst (Zhang, S.; Wang, Y.; Feng, X. -J.; Bao, M.; Journal Of American Chemical Society,2012,134: 5492-5495); wang Haining and the like realize regioselective hydrogenation esterification of alkenylphenol and benzoic acid into lactone by utilizing a catalyst obtained by coordinating triphenylphosphine and palladium acetate (Wang, H. -N.; Dong, B.; Wang, Y.; Li, J. -F.; Shi, Y.; Organic Letters,2014,16: 186-189); the Liuyuan red topic group also utilizes a catalyst in which triphenylphosphine and palladium acetate are coordinated to realize a cyclization reaction of a carbon-carbon bond (Chen, J. -J.; Li, Y. -X.; Gao, H. -J.; Liu, Y. -H.; Organometallics,2008,27: 5619-. Triphenylphosphine polymers may act as ligands for the metal, for example: the jamangping problem group achieved highly selective reactions of hydrosilation using triphenylphosphine polymers as ligands (r.h.li.; x.m.an.; y.yang.; d.c.li.; z.l.hu.; z.p.zhan.; org.lett.2018,20,5023). The triphenylphosphine serving as a ligand has the main effect of coordinating and combining the P at the center and metal, so that catalytic reaction is realized, if the electrical property of the P at the center can be changed, the electrical property of the metal catalytic center can be changed, further the regioselective reaction is influenced, and even a result different from the original reaction result can be generated, so that the limitation of a homogeneous triphenylphosphine catalyst can be broken through when the high-load monatomic catalyst taking the triphenylphosphine porous organic polymer containing the substituent as a carrier is prepared to realize the catalytic reaction, and the reaction universality is greatly enhanced.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a preparation method of a high-load monatomic catalyst taking a ligand polymer as a carrier. The method has the advantages of low cost, simple and convenient operation and easy mass synthesis, the monatomic metallized porous organic polymer catalyst prepared by the method has stable structure and good discreteness, and simultaneously can inherit the high reactivity and selectivity of a homogeneous metal/ligand catalytic system, and compared with monatomic catalysts synthesized by other gas-phase precipitation methods, the catalyst has extremely high application value in regioselective reaction needing ligands with special structures.

The technical scheme for realizing the purpose of the invention is as follows:

the difference of the preparation method of the high-load monatomic catalyst taking the ligand polymer as the carrier with the prior art is that the preparation method has the following general formula:

in the general formula, R is alkyl, alkoxy or fluorine; x ═ chlorine, bromine, or iodine; m ═ cobalt, rhodium, or palladium.

The preparation of the high-load monatomic catalyst taking the ligand polymer as the carrier comprises the following steps:

(1) adding methyl triphenyl phosphonium bromide (1eq.) into a round-bottom flask, putting into cold hydrazine at 0 ℃ under the atmosphere of argon, adding 40ml of tetrahydrofuran solution, slowly dropwise adding n-butyl lithium, reacting in the cold hydrazine for half an hour, slowly dropwise adding the compound A (1eq.) into the mixture, stirring the mixture to react for 4 to 5 hours, then quenching the mixture by using a saturated ammonium chloride solution, extracting and drying the mixture, evaporating the solvent, and performing fast column chromatography separation to obtain a purified compound B;

(2) putting magnesium particles (1.1eq.) into a round-bottom flask, adding a tetrahydrofuran solution dissolved with iodine into the round-bottom flask under the argon atmosphere, heating, adding a compound B (1eq.) into the tetrahydrofuran solution for dilution when the liquid color gradually turns white, slowly dropping the compound B into a reaction bottle, and reacting for 30 minutes;

(3) putting a reaction bottle into cold hydrazine at 0 ℃, adding a phosphorus trichloride solution into tetrahydrofuran for dilution, slowly dripping into a reaction solution, reacting for 30 minutes, reacting at room temperature for 4-5 hours, then quenching with a saturated ammonium chloride solution, evaporating a solvent after extraction, and performing flash column chromatography separation to obtain a pure compound C;

(4) and adding a tetrahydrofuran solution into the compound C and azodiisobutyronitrile under the protection of argon, carrying out copolymerization reaction for 24 hours at 100 ℃, carrying out suction filtration, washing for 3 times by using ethyl acetate, carrying out vacuum drying to obtain a substituted triphenylphosphine porous polymer, and carrying with different types of metals according to requirements to prepare the high-load-capacity monatomic catalyst taking the triphenylphosphine porous organic polymer containing the substituent as a carrier.

According to the technical scheme, bromovinylbenzene is synthesized through a witting reaction of various functional group substituted bromobenzaldehydes and methyl triphenyl phosphine bromide, various vinyl substituted triphenylphosphine monomers are prepared through a reaction of phosphorus trichloride and bromovinylbenzene, and after simple radical polymerization, a high-load-capacity monatomic catalyst taking a stable substituent-containing triphenylphosphine porous organic polymer as a carrier can be obtained after a homogeneous phase-heterogeneous ligand exchange method is used for loading metal.

The method has the advantages of low cost, simple and convenient operation and easy mass synthesis, the monatomic metallized porous organic polymer catalyst prepared by the method has stable structure and good discreteness, and simultaneously can inherit the high reactivity and selectivity of a homogeneous metal/ligand catalytic system, and compared with monatomic catalysts synthesized by other gas-phase precipitation methods, the catalyst has extremely high application value in regioselective reaction needing ligands with special structures.

Drawings

FIG. 1 is a graph of HADDF-STEM of a high loading monoatomic palladium-substituted tris (2-methoxy) phenylphosphine porous polymer in examples;

FIG. 2 is an SEM image of a high loading of monatomic palladium-substituted tris (2-methoxy) phenylphosphine porous polymer in examples.

Detailed Description

The present invention will be further illustrated with reference to the following examples, but is not limited thereto.

Example 1:

preparation of a tris (2-methoxy) phenylphosphine porous Polymer:

the synthetic route of the tri (2-methoxy) phenylphosphine porous polymer is as follows:

the synthesis steps of the tri (2-methoxy) phenylphosphine porous polymer are as follows:

(a) adding 16mmol of methyl triphenyl phosphonium bromide into a 100ml round-bottom flask, putting into cold hydrazine at 0 ℃ under the atmosphere of argon, adding 40ml of tetrahydrofuran solution, slowly dropwise adding 10ml of n-butyl lithium, reacting in the cold hydrazine for half an hour, and slowly dropwise adding 16mmol of 3-bromo-4-methoxybenzaldehyde A₁Stirring for reaction for 4.5 hours, then quenching with 20ml of saturated ammonium chloride solution, extracting with dichloromethane for 3 times, combining organic phases, drying with anhydrous sodium sulfate, decompressing, filtering, performing rotary evaporation to remove a solvent, and performing rapid column chromatography separation to obtain a pure compound 3-bromo-4-methoxystyrene B₁；

(b) Putting 28mmol magnesium particles into a round-bottom flask, adding 2ml tetrahydrofuran solution dissolved with iodine simple substance into the flask under argon atmosphere, heating, and when the liquid color gradually turns white, adding 25mmol 3-bromo-4-methoxystyrene B₁Adding 20ml of ultra-dry tetrahydrofuran solution for dilution treatment, slowly dropping into a reaction bottle, and reacting for 30 minutes;

(c) putting a reaction bottle into cold hydrazine at 0 ℃, adding 8.6mmol of phosphorus trichloride solution into tetrahydrofuran for dilution, slowly dripping into reaction liquid, reacting for 30 minutes, reacting for 4-5 hours at room temperature, then quenching with 20ml of saturated ammonium chloride solution, extracting for 3 times with dichloromethane, combining organic phases, drying with anhydrous sodium sulfate, decompressing, filtering, performing rotary evaporation to remove the solvent, and performing rapid column chromatography separation to obtain a monomer tri (2-methoxy-5-vinyl) phenylphosphine C₁：C₁Is characterized in that:¹H NMR(400MHz,CDCl₃)δ＝7.39(3H,dd,J＝8.4Hz,2.1Hz),6.86(3H,dd,J＝8.4Hz,4.9Hz),6.80(3H,dd,J＝4.6Hz,2.2Hz),6.51(3H,dd,J＝17.6Hz,10.9Hz),6.36(3H,d,J＝17.5Hz),4.99(3H,d,J＝10.9Hz),3.74(9H,s).¹³C NMR(100MHz,CDCl₃)δ＝161.4,136.4,131.9,130.3,127.8,124.2,111.2,110.1,55.8.³¹P NMR(400MHz,CDCl₃)δ＝-36.9；

(d)100mg of tris (2-methoxy-5-vinyl) phenylphosphine C₁With 10mg of azobisisobutyronitrile under the protection of argon gasAdding 1ml dichloromethane solution, carrying out copolymerization reaction in a sealed tube at 100 ℃, carrying out suction filtration after 24h, washing 3 times with ethyl acetate, and carrying out vacuum drying to obtain the tri (2-methoxy) phenylphosphine porous polymer.

Example 2:

preparation of a tris (4-fluoro) phenylphosphine porous Polymer:

the synthesis route of the tri (4-fluoro) phenylphosphine porous polymer is as follows:

the synthesis steps of the tri (4-fluoro) phenylphosphine porous polymer are as follows:

(a) adding 16mmol of methyl triphenyl phosphonium bromide into a round-bottom flask, putting the round-bottom flask into cold hydrazine at 0 ℃ under the argon atmosphere, adding 40ml of tetrahydrofuran solution, slowly dropwise adding 10ml of n-butyl lithium, reacting in the cold hydrazine for half an hour, and slowly dropwise adding 16mmol of 5-iodine-2-fluorobenzaldehyde A₂Stirring for reaction for 4-5 hr, quenching with 20ml saturated ammonium chloride solution, extracting with dichloromethane for 3 times, mixing organic phases, drying with anhydrous sodium sulfate, vacuum filtering, rotary evaporating to remove solvent, and separating by flash column chromatography to obtain 5-iodo-2-fluorostyrene B₂；

(b) Putting 28mmol magnesium particles into a round-bottom flask, adding 2ml tetrahydrofuran solution dissolved with iodine into the flask under argon atmosphere, heating, and adding 25mmol 5-iodine-2-fluorostyrene B when the liquid color gradually turns white₂Adding 20ml of ultra-dry tetrahydrofuran solution for dilution treatment, slowly dropping into a reaction bottle, and reacting for 30 minutes;

(c) putting a reaction bottle into cold hydrazine at 0 ℃, adding 8.6mmol of phosphorus trichloride solution into 5mmol of tetrahydrofuran for dilution, slowly dripping into the reaction solution, reacting for 30 minutes, reacting at room temperature for 4-5 hours, then quenching with 20ml of saturated ammonium chloride solution, extracting with dichloromethane for 3 times, combining organic phases, drying with anhydrous sodium sulfate, decompressing, filtering, performing rotary evaporation to remove the solvent, and performing rapid column chromatography separation to obtain a monomer III (4-Fluoro-3-vinyl) phenylphosphine C₂，C₂Is characterized in that:¹H NMR(400MHz,CDCl₃)δ＝7.36(3H,td,J₁＝15.74Hz,J₂＝1.96Hz)，7.05-6.95(3H,m),6.92-6.84(3H,m),6.66(3H,dd,J₁＝29.11Hz,J₂＝11.26Hz),5.58(3H,d,J＝17.68Hz),5.19(3H,d,J＝11.64Hz).³C NMR(100MHz,CDCl₃)δ＝161.9,133.9(q,J＝26.05),132.6(d,J＝23.47),132.2(d,J＝11.29),128.6,117.0(d,J＝4.93),116.0(dd,J₁＝28.75,J₂＝6.53).³¹P NMR(400MHz,CDCl₃)δ＝-8.09；

(d)100mg of tris (4-fluoro-3-vinyl) phenylphosphine C₂Adding 1ml tetrahydrofuran solution into 10mg azodiisobutyronitrile under the protection of argon, carrying out copolymerization reaction for 24h at 100 ℃, carrying out suction filtration, washing for 3 times by using ethyl acetate, and carrying out vacuum drying to obtain the tris (4-fluoro) phenylphosphine porous polymer.

Example 3: 2.3 preparation of porous Polymer of tris (3, 5-dimethyl) phenylphosphine:

the synthesis route of the 2.3 tri (3, 5-dimethyl) phenylphosphine porous polymer is as follows:

the 2.3 tris (3, 5-dimethyl) phenylphosphine porous polymer is synthesized by the following steps:

(a) adding 16mmol of methyl triphenyl phosphonium bromide into a round-bottom flask, putting the round-bottom flask into cold hydrazine at 0 ℃ under the argon atmosphere, adding 40ml of tetrahydrofuran solution, slowly dropwise adding 10ml of n-butyl lithium, reacting in the cold hydrazine for half an hour, and slowly dropwise adding 16mmol of 2, 6-dimethyl-4-chlorobenzaldehyde A₃Stirring for reaction for 4-5 hr, quenching with 20ml saturated ammonium chloride solution, extracting with dichloromethane for 3 times, mixing organic phases, drying with anhydrous sodium sulfate, vacuum filtering, rotary evaporating to remove solvent, and separating by flash column chromatography to obtain 2, 6-dimethyl-4-chlorostyrene B₃；

(b) 28mmol of magnesium particles are put into a round-bottom flask, and 2ml of iodine simple substance is dissolved in the round-bottom flask under the argon atmosphereAdding tetrahydrofuran solution into bottle, heating, observing liquid color gradually turning white, adding 25mmol 2, 6-dimethyl-4-chlorostyrene B₃Adding 20ml of tetrahydrofuran solution for dilution treatment, slowly dropping the tetrahydrofuran solution into a reaction bottle, and reacting for 30 minutes;

(c) putting a reaction bottle into cold hydrazine at 0 ℃, adding 8.6mmol of phosphorus trichloride solution into 5mmol of tetrahydrofuran for dilution, slowly dripping into the reaction solution, reacting for 30 minutes, reacting at room temperature for 4-5 hours, then quenching with 20ml of saturated ammonium chloride solution, extracting with dichloromethane for 3 times, combining organic phases, drying with anhydrous sodium sulfate, decompressing, filtering, performing rotary evaporation to remove the solvent, and performing rapid column chromatography to obtain a monomer tri (3, 5-dimethyl-4-vinyl) phenylphosphine C₃，C₃Is characterized in that:¹H NMR(400MHz,CDCl₃)δ＝7.05(6H,d,J＝8.10Hz),6.70(3H,dd,J₁＝28.57Hz,J₂＝11.58Hz),5.56(3H,dd,J₁＝13.55Hz,J₂＝1.90Hz),5.31(3H,dd,J₁＝19.93Hz,J₂＝1.92Hz),2.28(18H,s).¹³C NMR(100MHz,CDCl₃)δ＝138.0,135.7(d,J＝7.22),135.2(d,J＝9.60),134.8,133.0(d,J＝19.65),119.60.³¹P NMR(400MHz,CDCl₃)δ＝-6.3；

(d) adding 1ml tetrahydrofuran solution into 100mg tris (4-fluoro-3-vinyl) phenylphosphine and 10mg azobisisobutyronitrile under the protection of argon, carrying out copolymerization reaction for 24h at 100 ℃, carrying out suction filtration, washing for 3 times by using ethyl acetate, and carrying out vacuum drying to obtain the tris (3, 5-dimethyl) phenylphosphine porous polymer.

The specific preparation method of the high-load monatomic catalyst taking the triphenylphosphine porous organic polymer containing the substituent group as the carrier comprises the following steps: the synthesized substituted triphenylphosphine porous organic polymer can be subjected to ligand exchange with most of the existing homogeneous metal catalysts, so as to synthesize a high-load monatomic catalyst, wherein the method comprises the following steps: the high-load monatomic catalyst prepared by the method has greatly improved reaction efficiency and regioselectivity in the reaction, and specifically comprises the following components:

1. the preparation method of the high-load monatomic palladium substituted tri (2-methoxy) phenylphosphine porous organic polymer comprises the following steps:

placing the tri (2-methoxy) phenylphosphine porous polymer obtained by the method in a flask, adding a small amount of tetrahydrofuran under the atmosphere of argon, stirring, fully dissolving a catalyst containing metal palladium, in this case, triphenylphosphine palladium dichloride in a tetrahydrofuran solution, slowly dripping the solution into the flask, stirring for 12 hours, and performing suction filtration to obtain a high-load monatomic palladium metal substituted tri (2-methoxy) phenylphosphine porous organic polymer;

2. the preparation method of the high-load monatomic rhodium substituted tri (4-fluoro) phenylphosphine porous polymer comprises the following steps:

placing the tri (4-fluoro) phenylphosphine porous polymer obtained by the method in a flask, adding a small amount of tetrahydrofuran under the argon atmosphere, stirring, adding a catalyst containing metal rhodium, namely bis (1, 5-cyclooctadiene rhodium chloride in the example of being fully dissolved in a tetrahydrofuran solution, slowly dripping into the flask, stirring for 12 hours, and performing suction filtration to obtain a high-load monatomic rhodium substituted tri (4-fluoro) phenylphosphine porous organic polymer;

3. the preparation method of the high-load monatomic cobalt-substituted tri (3, 5-dimethyl) phenylphosphine porous polymer comprises the following steps:

placing the tri (3, 5-dimethyl) phenylphosphine porous polymer obtained by the method in a flask, adding a small amount of tetrahydrofuran under the argon atmosphere, stirring, fully dissolving a catalyst containing metal cobalt, in this case cobalt acetylacetonate, in a tetrahydrofuran solution, slowly dropping the solution into the flask, stirring for 12 hours, and performing suction filtration to obtain the monatomic cobalt-substituted tri (3, 5-dimethyl) phenylphosphine porous organic polymer with high load capacity.

Referring to fig. 1 and fig. 2, in various physical characterization diagrams, no metal agglomeration phenomenon is seen, all metals are uniformly distributed on the polymer, and it can be seen that the preparation of the high-load monatomic catalyst using the substituent-containing triphenylphosphine porous organic polymer as a carrier is successfully realized.

The high-load monatomic metallized catalyst prepared by the method overcomes the defect that monatomic metal of the monatomic catalyst is unstable and is agglomerated, is beneficial to regulating and controlling the steric hindrance and the electronic effect of a phosphorus ligand due to the addition of various different substituents, ensures that the reaction is not limited to the limitation of triphenylphosphine, can inherit the high reactivity and selectivity of a homogeneous metal/ligand catalytic system, has extremely high application value in catalyzing a regioselective reaction needing a ligand with a special structure, and has extremely high research significance in the field of heterogeneous catalysis.