A method for synthesizing tetraarylcobalt porphyrin via simultaneous cyclization and metallation reactions

Abstract

The invention discloses a method for synthesizing tetraaryl cobalt porphyrin through synchronous cyclization and metalation reaction. Aromatic aldehyde, pyrrole and cobalt salt are catalyzed by anhydrous aluminum chloride, and cyclization and metalation reaction are synchronously carried out in DMF solvent and nitrogen atmosphere to generate tetraaryl cobalt porphyrin. The reaction process is: anhydrous aluminum chloride, aromatic aldehyde, pyrrole and cobalt salt are sequentially added to DMF under stirring, and the reaction is stopped after heating and reflux reaction for a certain period of time, and the temperature is lowered, and the mixture is placed at about 273K overnight, and cobalt porphyrin crystals are obtained by suction filtration. The method directly uses aromatic aldehyde, pyrrole and cobalt salt as raw materials, does not need to use porphyrin, does not use highly corrosive organic acid as solvent, obtains high-purity tetraaryl cobalt porphyrin with high yield without using complex separation means, and is easy to realize industrial production.

Description

Technical Field

[0001] The invention relates to a method for synthesizing tetraarylcobalt porphyrin through synchronous cyclization and metalation reaction, and particularly relates to a method for synthesizing tetraarylcobalt porphyrin in a DMF solvent by utilizing simple and readily available basic chemical raw materials of aromatic aldehyde, pyrrole and cobalt salt and catalyzing anhydrous aluminum chloride, and belongs to the field of metal organic synthesis. Background Art

[0002] Cobalt porphyrin is a metal organic compound with a macrocyclic conjugated structure. The ligand porphin of cobalt porphyrin is a large cyclic molecule composed of 20 carbon atoms and 4 nitrogen atoms, with a stable conjugated system of 4n+2 electrons and aromaticity. In industrial production and life, cobalt porphyrin is mainly used as a catalyst for chemical oxidation and electrical and photooxidation. The cobalt porphyrin commonly used as a catalyst is tetraaryl cobalt porphyrin. The chemical synthesis method of tetraaryl cobalt porphyrin reported in the literature and patents is generally based on the basic reaction of tetraaryl porphyrin as raw material and cobalt salt reported by Adler et al. (J. Inorg. Nucl. Chem., 1970, 32, 2443). The chemical process involved is:

[0003]

[0004] During the reaction, the divalent cobalt ion coordinates with the tetraaryl porphine to form a stable divalent cobalt porphyrin. Patent CN103880851B discloses a method for producing cobalt porphyrin on an industrial scale by reacting the tetraaryl porphine as a raw material with a cobalt salt through a continuous process. The biggest disadvantage of this reaction is that the raw material tetraaryl porphyrin used in the synthesis of cobalt porphyrin is expensive, and in a neutral or slightly alkaline environment, the presence of a very small amount of water and air will also cause the cobalt porphyrin to be further converted into a trivalent cobalt porphyrin product and affect the product purity of the divalent cobalt porphyrin.

[0005] From the existing literature, there are also reports on the one-step synthesis of zinc porphyrin using aromatic aldehydes, pyrrole and zinc salts as raw materials. Badger et al. reported the one-step synthesis of zinc porphyrin using aromatic aldehydes, pyrrole and zinc salts as raw materials in an autoclave (Australian J Chem, 1964, 19, 1028).

[0006]

[0007] However, this reaction condition cannot be used to prepare cobalt porphyrin. In propionic acid solvent, cobalt salt cannot react with porphyrin to form cobalt porphyrin with poor stability.

[0008] In view of the fact that zinc porphyrin can be replaced with cobalt salt to obtain cobalt porphyrin (Chemical Technology, 2000, 8, 1; Journal of Shenyang University of Technology, 2010, 60; Chemical Research and Application, 2012, 24, 154), patent CN1238355C discloses a reaction in which a mixture of zinc porphyrin and porphine is obtained by using aromatic aldehyde, pyrrole and zinc salt as raw materials without using an autoclave, and then the mixture of zinc porphyrin and porphine is reacted with cobalt acetate to synthesize cobalt porphyrin.

[0009]

[0010] In the above process, the intermediate products porphyrin zinc and porphine need to be obtained through a separation process, and the propionic acid solvent used in the first step is an organic acid with strong corrosiveness. In addition, if cobalt salt is directly added to the propionic acid system, divalent cobalt ions cannot coordinate with porphine to obtain cobalt porphyrin. Summary of the invention

[0011] In view of the defect that the prior art cannot synthesize tetraarylcobalt porphyrin through the synchronous reaction of cyclization and metalation between aldehyde, pyrrole and cobalt salt, but needs to firstly perform cyclization from aldehyde and pyrrole, and then perform multi-step reaction of metalation between the cyclization product tetraarylporphyrin and cobalt salt, or synthesize tetraarylcobalt porphyrin through metal replacement reaction between expensive tetraarylzinc porphyrin and cobalt salt, the purpose of the present invention is to provide a method for synthesizing tetraarylcobalt porphyrin in one step through the reaction of basic organic raw materials aryl aldehyde, pyrrole and cobalt salt through the synchronous reaction of cyclization and metalation between aldehyde, pyrrole and cobalt salt, and obtain high-purity tetraarylcobalt porphyrin with high yield without using complicated separation means, and the method is easy to realize industrial production.

[0012] The reaction raw materials used to realize the present invention are simple organic raw materials, aromatic aldehyde and pyrrole, and inorganic cobalt salt, the reaction solvent is DMF, and the catalyst is a non-protonic inorganic acid, anhydrous aluminum chloride.

[0013] The chemical reaction on which the present invention is based is as follows:

[0014]

[0015] The aromatic group Ar can be a benzene ring or an aromatic heterocycle such as pyridine, pyrrole, furan, naphthalene, quinoline, etc.;

[0016] The substituent R on the aryl group Ar may be an alkyl substituent such as methyl, ethyl, propyl or a halogen substituent such as chlorine, bromine or iodine, or an oxygen-containing substituent such as methoxy, ethoxy, hydroxyl or carboxyl or a nitrogen-containing substituent such as amino, dimethylamino or nitro;

[0017] The cobalt salt used in the reaction can be cobalt acetate, cobalt chloride, cobalt bromide, cobalt nitrate, or cobalt sulfate.

[0018] The operation process of the present invention is as follows: DMF is added to a reflux stirring reactor at room temperature, anhydrous aluminum chloride, aromatic aldehyde, pyrrole and cobalt salt are added in sequence under stirring, the reaction mixture is heated to reflux, the reaction is continued for a certain period of time, and then the reaction is stopped, the temperature is lowered, the reaction mixture is placed at about 273K overnight, and cobalt porphyrin crystals are obtained by suction filtration.

[0019] The input ratio (molar ratio) of aromatic aldehyde, pyrrole, cobalt salt and anhydrous AlCl3 is: 1-1.5:1-1.5:1-5:1-5, and the preferred ratio is 1:1:3:1.5;

[0020] The molar ratio of pyrrole to DMF is 1:500-2000, preferably 1:1200;

[0021] The reaction time is 0.5-4 hours, preferably 2.5 hours.

[0022] The reaction requires that all reactants are added at room temperature and then heated to reflux. If reactants are added after reflux, or cobalt salt is added after reflux, the desired product will not be obtained, or the product yield will be reduced.

[0023] In an air environment, the reaction product divalent cobalt porphyrin can be partially converted into trivalent cobalt porphyrin. The introduction of nitrogen can avoid the conversion of divalent cobalt porphyrin into trivalent cobalt porphyrin, thereby simplifying the separation of the product divalent cobalt porphyrin.

[0024] According to the technical solution of the present invention, the condensation of aromatic aldehyde and pyrrole and the metalation of the condensation product with divalent cobalt ions occur simultaneously, so that the two-step reaction of the prior art of synthesizing tetraarylcobalt porphyrin using aromatic aldehyde and pyrrole as raw materials is transformed into a one-step reaction. At the same time, the divalent cobalt ions also play a template role in the condensation process of aromatic aldehyde and pyrrole to improve the condensation yield; non-protonic acid anhydrous AlCl3 is used as an acidic catalyst, which can not only promote the condensation of aromatic aldehyde and pyrrole, but also prevent the divalent ions from being converted into a catalyst that cannot undergo a metalation reaction with porphyrin. The defects of trivalent cobalt ions can be eliminated; the introduction of nitrogen can avoid the conversion of divalent cobalt porphyrin to trivalent cobalt porphyrin; the use of DMF as a solvent can dissolve anhydrous AlCl3, which is beneficial to the catalytic performance of AlCl3 on the condensation of aromatic aldehydes and pyrrole, and the difference in the solubility of DMF for organic hydrocarbons and metal compounds allows tetraarylcobalt porphyrin to crystallize at low temperatures, and various intermediate impurities formed by the condensation of aromatic aldehydes and pyrrole during the reaction will not precipitate with the product, making the separation of the product tetraarylcobalt porphyrin simple.

[0025] Compared with the prior art, the technical solution of the present invention brings the following beneficial technical effects:

[0026] 1) Compared with the prior art of synthesizing tetraarylcobalt porphyrin using porphine as raw material, the raw materials aromatic aldehyde and pyrrole used in the present invention are more economical and readily available than porphyrin, and can effectively avoid the product tetraarylcobalt porphyrin from further forming trivalent cobalt porphyrin byproduct, thereby improving the purity of the product and simplifying the separation process;

[0027] 2) Compared with the prior art of synthesizing tetraarylcobalt porphyrin using aromatic aldehyde and pyrrole as raw materials, the present invention only requires one step of reaction and does not require the use of special equipment, thus reducing the number of reaction steps. The product yield under optimal conditions can reach up to 50%. At the same time, the large-scale use of corrosive organic acids can be avoided, thus having good environmental benefits.

[0028] 3) The technical solution of the present invention has simple steps and strong operability, and meets the requirements of industrial production. Example

[0029] The following examples are intended to further illustrate the present invention rather than to limit the scope of protection of the claims. The raw materials involved in the examples are all commercially available conventional raw materials unless otherwise specified.

[0030] Embodiment 1:

[0031] 600 mL of DMF was added to a stirred reactor equipped with a reflux condenser, and 0.75 mol of anhydrous aluminum chloride, 0.5 mol of benzaldehyde, 0.5 mol of pyrrole and 1.5 mol of cobalt acetate were added in sequence under stirring. After nitrogen was introduced, the reaction mixture was heated to reflux and the reaction was maintained for 2.5 hours, then the reaction was stopped, the temperature was lowered, and the mixture was placed at 273 K overnight. Orange-red crystals of tetraphenylcobalt porphyrin were obtained by suction filtration with a yield of 50%.

[0032] Embodiment 2:

[0033] 1800 mL of DMF was added to a stirred reactor equipped with a reflux condenser, and 1 mol of anhydrous aluminum chloride, 0.8 mol of 3-bromopyridinecarboxaldehyde, 0.6 mol of pyrrole and 1.5 mol of cobalt chloride were added in sequence under stirring. After nitrogen was introduced, the reaction mixture was heated to reflux and the reaction was maintained for 1 hour, then the reaction was stopped, the temperature was lowered, and the mixture was placed at 273 K overnight. Orange-red crystals of tetra(3-bromopyridine)cobaltporphyrin were obtained by suction filtration with a yield of 40%.

[0034] Embodiment three:

[0035] 2800 mL of DMF was added to a stirred reactor equipped with a reflux condenser, and 1.2 mol of anhydrous aluminum chloride, 0.8 mol of 2-ethylpyrrole carboxaldehyde, 0.7 mol of pyrrole and 2 mol of cobalt bromide were added in sequence under stirring. After nitrogen was introduced, the reaction mixture was heated to reflux and the reaction was maintained for 2 hours, then the reaction was stopped, the temperature was lowered, and the mixture was placed at 273 K overnight. Orange-red crystals of tetra(2-ethylpyrrole)cobalt porphyrin were obtained by suction filtration with a yield of 35%.

[0036] Embodiment 4:

[0037] 1500 mL of DMF was added to a stirred reactor equipped with a reflux condenser, and 0.75 mol of anhydrous aluminum chloride, 0.75 mol of 5-hydroxy-1-naphthaldehyde, 0.75 mol of pyrrole and 2 mol of cobalt nitrate were added in sequence under stirring. After nitrogen was introduced, the reaction mixture was heated to reflux and the reaction was maintained for 1.5 hours before stopping the reaction, cooling, and leaving at 273 K overnight. Tetrakis(5-hydroxy-1-naphthylpyridine)cobaltporphyrin was obtained by suction filtration with a yield of 28%.

[0038] Embodiment five:

[0039] 1000 mL of DMF was added to a stirred reactor equipped with a reflux condenser, and 1 mol of anhydrous aluminum chloride, 0.6 mol of 3-methylfuraldehyde, 0.5 mol of pyrrole and 1.8 mol of cobalt sulfate were added in sequence under stirring. After nitrogen was introduced, the reaction mixture was heated to reflux and the reaction was maintained for 1.8 hours, and then the reaction was stopped, the temperature was lowered, and the mixture was placed at 273 K overnight. Orange-red crystals of tetra(3-methylfuran)cobaltporphyrin were obtained by suction filtration with a yield of 38%.

[0040] Embodiment six:

[0041] 1500 mL of DMF was added to a stirred reactor equipped with a reflux condenser, and 0.5 mol of anhydrous aluminum chloride, 0.7 mol of 5-methoxy-2-quinolinecarboxaldehyde, 0.5 mol of pyrrole and 1.2 mol of cobalt acetate were added in sequence under stirring. After nitrogen was introduced, the reaction mixture was heated to reflux and the reaction was maintained for 3 hours, and then the reaction was stopped, the temperature was lowered, and the mixture was placed at 273 K overnight. Orange-red crystals of tetrakis(5-methoxy-2-quinoline)cobaltporphyrin were obtained by suction filtration, with a yield of 30%.

[0042] Embodiment seven:

[0043] 2500 mL of DMF was added to a stirred reactor equipped with a reflux condenser, and 2 mol of anhydrous aluminum chloride, 0.75 mol of 4-chlorobenzaldehyde, 0.5 mol of pyrrole and 2 mol of cobalt acetate were added in sequence under stirring. After nitrogen was introduced, the reaction mixture was heated to reflux and the reaction was maintained for 2.5 hours, and then the reaction was stopped, the temperature was lowered, and the mixture was placed at 273 K overnight. Orange-red crystals of tetra(4-chlorophenyl)cobaltporphyrin were obtained by suction filtration with a yield of 48%.

[0044] Embodiment eight:

[0045] 2000 mL of DMF was added to a stirred reactor equipped with a reflux condenser, and 2.5 mol of anhydrous aluminum chloride, 0.5 mol of 3-aminobenzaldehyde, 0.5 mol of pyrrole and 1.5 mol of cobalt acetate were added in sequence under stirring. After nitrogen was introduced, the reaction mixture was heated to reflux and the reaction was maintained for 2 hours, and then the reaction was stopped, the temperature was lowered, and the mixture was placed at 273 K overnight. The tetrakis(3-aminophenyl)cobaltporphyrin purple-red crystals were obtained by suction filtration with a yield of 20%.

[0046] Embodiment nine:

[0047] 2000 mL of DMF was added to a stirred reactor with a reflux condenser, and 2 mol of anhydrous aluminum chloride, 0.6 mol of 4-carboxybenzaldehyde, 0.5 mol of pyrrole and 2.2 mol of cobalt acetate were added in sequence under stirring. After nitrogen was introduced, the reaction mixture was heated to reflux and the reaction was maintained for 1.5 hours, and then the reaction was stopped, the temperature was lowered, and the mixture was placed at 273 K overnight. Orange-red crystals of tetrakis(4-carboxyphenyl)cobaltporphyrin were obtained by suction filtration with a yield of 20%.

[0048] Embodiment ten:

[0049] 1500 mL of DMF was added to a stirred reactor equipped with a reflux condenser, and 0.8 mol of anhydrous aluminum chloride, 0.6 mol of 4-nitrobenzaldehyde, 0.5 mol of pyrrole and 2.5 mol of cobalt acetate were added in sequence under stirring. After nitrogen was introduced, the reaction mixture was heated to reflux and the reaction was maintained for 0.5 hour, then the reaction was stopped, the temperature was lowered, and the mixture was placed at 273 K overnight. Orange-red crystals of tetrakis(4-nitrophenyl)cobaltporphyrin were obtained by suction filtration with a yield of 18%.

Claims

1. A method for synthesizing tetraarylcobalt porphyrin by simultaneous cyclization and metallation reaction, characterized in that: Anhydrous aluminum chloride catalyzes the synchronous cyclization and metalation reaction between aromatic aldehyde, pyrrole and cobalt salt in DMF solvent to generate tetraaryl cobalt porphyrin; the reaction process is: add DMF into a reflux stirring reactor at room temperature, start stirring, and add anhydrous aluminum chloride, aromatic aldehyde, pyrrole and cobalt salt in sequence; after nitrogen is introduced, heat the reaction mixture to reflux, continue the reaction for a certain period of time and then stop the reaction; cool down, place it at about 273K overnight, and filter to obtain porphyrin cobalt crystals; wherein the input molar ratio of aromatic aldehyde, pyrrole, cobalt salt and anhydrous AlCl3 is: 1-1.5:1-1.5:1-5:1-5; the molar concentration of pyrrole in DMF is 1 / 500-1 / 2000; The structure of the aromatic aldehyde is as follows: ； The tetraarylcobalt porphyrin has the following structure: ; Ar is a benzene ring, pyridine, pyrrole, furan, naphthalene or quinoline; The substituent R on Ar is methyl, ethyl, propyl, chloro, bromo, iodo, methoxy, ethoxy, hydroxy, carboxyl, amino, dimethylamino or nitro.

2. The method for synthesizing tetraarylcobalt porphyrin by simultaneous cyclization and metalation according to claim 1, characterized in that: The reaction time is 0.5-4 hours.

3. The method for synthesizing tetraarylcobalt porphyrin by simultaneous cyclization and metalation according to claim 1, characterized in that: The reaction was carried out under refluxing DMF.

4. The method for synthesizing tetraarylcobalt porphyrin by simultaneous cyclization and metalation according to claim 1, characterized in that: The cobalt salt used in the reaction is cobalt acetate, cobalt chloride, cobalt bromide, cobalt nitrate or cobalt sulfate.

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