A method for the simultaneous synthesis of tetraaryl manganese porphyrins by condensation of aldehyde and pyrrole and oxidative insertion reaction of divalent manganese salt

Abstract

The application discloses a method for synthesizing tetraaryl manganese porphyrin by simultaneously condensing aldehyde and pyrrole and oxidizing and inserting manganese salt, which comprises the following steps: adding anhydrous aluminum chloride, aromatic aldehyde, pyrrole and manganese dichloride into DMF in sequence under stirring, heating and refluxing the reaction for a certain time, stopping the reaction, cooling, and placing overnight near 273K, and then filtering to obtain manganese porphyrin purple-black crystals. The method directly uses aromatic aldehyde, pyrrole and manganese dichloride as raw materials, does not need to use porphine, and does not use strong corrosive organic acid as a solvent. High-purity tetraaryl manganese porphyrin is obtained in high yield without using complex separation means, and industrial production is easy to realize.

Description

Technical Field

[0001] This invention relates to a method for the simultaneous synthesis of tetraarylmanganese porphyrin via condensation of aldehydes and pyrroles and oxidative insertion of divalent manganese salts. In particular, it relates to a method for the one-step synthesis of tetraarylmanganese porphyrins using aromatic aldehydes, pyrroles, and divalent manganese salts as raw materials in DMF solvent with anhydrous aluminum trichloride as a catalyst, which belongs to the field of organic synthesis. Background Technology

[0002] Manganese porphyrins are organometallic compounds with a macrocyclic conjugated structure. The ligand porphyrin, porphyrin, is a large cyclic molecule composed of 20 carbon atoms and 4 nitrogen atoms, possessing a stable conjugated system with 4n+2 electrons and aromaticity. In industrial production and daily life, manganese porphyrins are mainly used as catalysts for chemical oxidation and electro- and photo-oxidation. The commonly used manganese porphyrin catalyst is tetraarylporphyrin manganese. Currently, the chemical synthesis methods for tetraarylporphyrin manganese reported in literature and patents are generally based on the basic reaction of tetraarylporphyrin as a raw material with manganese salts reported by Adler et al. (J. Inorg. Nucl. Chem., 1970, 32, 2443). The chemical processes involved are as follows:

[0003]

[0004] During the reaction, divalent manganese ions coordinate with tetraarylporphyrin to form an unstable divalent manganese porphyrin intermediate, which then rapidly transforms into a stable trivalent manganese porphyrin. Patent CN103880851B discloses a method for the industrial-scale production of manganese porphyrin using tetraarylporphyrin as a raw material and reacting it with manganese salt via a continuous process. The biggest drawback of this reaction is that the tetraarylporphyrin used in the synthesis of manganese porphyrin is expensive. Furthermore, even a trace amount of water in a neutral or slightly alkaline environment can cause manganese porphyrin to transform into a coordination product with oxygen, affecting the purity of the resulting manganese porphyrin.

[0005] Existing literature also reports one-step synthesis of zinc porphyrins from aryl aldehydes, pyrroles, and zinc salts. Badger et al. reported a one-step synthesis of zinc porphyrins from aryl aldehydes, pyrroles, and zinc salts in an autoclave (Australian J Chem, 1964, 19, 1028).

[0006]

[0007] However, this reaction condition cannot be used to prepare manganese porphyrin. In propionic acid solvent, manganese salts cannot form manganese porphyrin with porphyrin.

[0008] Given that zinc porphyrin can be replaced by manganese salt to obtain manganese 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 porphyrin is obtained from aryl aldehydes, pyrroles, and zinc salts without the use of an autoclave, and then the mixture of zinc porphyrin and porphyrin is reacted with manganese dichloride to synthesize manganese porphyrin.

[0009]

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

[0011] To address the shortcomings of existing technologies that lack a one-step synthesis of tetraarylzinc porphyrin from aryl aldehydes, pyrroles, and manganese salts, instead requiring the metallization reaction of expensive tetraarylporphyrin with manganese salts or the metal substitution reaction of expensive tetraarylzinc porphyrin with divalent manganese salts to synthesize tetraarylmanganese porphyrin, the present invention aims to provide a method for simultaneously generating tetraarylmanganese porphyrin through the condensation of aldehydes and pyrroles and the oxidative insertion reaction of divalent manganese salts using readily available aryl aldehydes, pyrroles, and divalent manganese salts, and obtaining high-purity tetraarylmanganese porphyrin in high yield without the need for complex separation methods. This method is easily scalable for industrial production.

[0012] The reaction raw materials selected for this invention are simple organic raw materials aromatic aldehydes and pyrroles, as well as the inorganic salt manganese dichloride. The reaction solvent is DMF, and the catalyst is the aprotic inorganic acid anhydrous aluminum trichloride.

[0013] The chemical reaction underlying this invention is as follows:

[0014]

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

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

[0017] The operation process for implementing this invention is as follows: DMF is added to a commonly used reflux stirred reactor and brought to a boil. Anhydrous aluminum trichloride, aryl aldehyde, pyrrole and manganese salt are added sequentially under stirring. After a certain reaction time, the reaction is stopped, the temperature is lowered, and the mixture is placed at around 273K overnight. Porphyrin manganese purple-black crystals are obtained by filtration.

[0018] The molar ratio of aryl aldehyde, pyrrole, manganese salt and anhydrous AlCl3 is 1-1.5:1-1.5:1-5:1-5, with a preferred ratio of 1:1:3:1.5.

[0019] The molar ratio of pyrrole to DMF is 1:300-2000, with a preferred ratio of 1:500;

[0020] The reaction time is 0.5-4 hours, with the preferred reaction time being 2 hours.

[0021] The reaction requires adding all reactants at room temperature before heating to reflux. If the reactants are added after reflux, or if the divalent manganese salt is added after reflux, the desired product will not be obtained, or the product yield will be reduced.

[0022] The technical solution of this invention involves the simultaneous occurrence of the condensation of aromatic aldehydes and pyrrole, and the oxidation and metallization of the condensation product with divalent manganese ions. This transforms the two-step reaction of the existing technology for synthesizing tetraarylmanganese porphyrin from aromatic aldehydes and pyrrole into a one-step reaction. Simultaneously, the divalent manganese ions also act as a template in the condensation process of aromatic aldehydes and pyrrole, thereby increasing the condensation yield. Anhydrous AlCl3, an aprotic acid, is used as an acidic catalyst, which promotes the condensation of aromatic aldehydes and pyrrole while avoiding the defect of divalent ions transforming into tetravalent manganese ions, which cannot undergo metallization with porphyrin. The use of DMF as a solvent dissolves anhydrous AlCl3, which is beneficial for leveraging the catalytic performance of AlCl3 in the condensation of aromatic aldehydes and pyrrole. Furthermore, the difference in solubility of DMF for organic hydrocarbons and metal compounds allows tetraarylmanganese porphyrin to crystallize at low temperatures. During the reaction, various intermediate impurities formed by the condensation of aromatic aldehydes and pyrrole do not precipitate with the product, simplifying the separation of the tetraarylmanganese porphyrin product.

[0023] Compared with the prior art, the technical solution of the present invention brings the following beneficial technical effects:

[0024] 1) Compared with the existing technology of synthesizing tetraarylmanganese porphyrin using porphyrin as raw material, the aromatic aldehydes and pyrroles used in this invention are more economical and readily available than porphyrin, and can also effectively avoid the further formation of oxygen-coordinated manganese porphyrin byproducts in the product tetraarylmanganese porphyrin, thereby improving product purity and simplifying the separation process.

[0025] 2) Compared with the existing technology of synthesizing tetraarylmanganese porphyrin from aromatic aldehydes and pyrroles, the present invention only requires one reaction step, does not require special equipment, reduces reaction steps, and the product yield can reach up to 50% under preferred conditions. At the same time, it can avoid the large-scale use of corrosive organic acids and has good environmental benefits.

[0026] 3) The technical solution of the present invention has simple steps and is easy to operate, meeting the requirements of industrial production. Example

[0027] The following examples are intended to further illustrate the content of the present invention, rather than to limit the scope of protection of the claims. Unless otherwise specified, the raw materials involved in the examples are all commercially available conventional raw materials.

[0028] Example 1:

[0029] 250 mL of DMF was added to a stirred reactor equipped with a reflux condenser. Then, 0.75 mol of anhydrous aluminum trichloride, 0.5 mol of benzaldehyde, 0.5 mol of pyrrole and 1.5 mol of manganese dichloride were added sequentially with stirring. The reaction mixture was heated to reflux and maintained for 2 hours before the reaction was stopped. The mixture was then cooled and placed at 273 K overnight. The mixture was filtered to obtain tetraphenylporphyrin manganese purple-black crystals with a yield of 50%.

[0030] Example 2:

[0031] 240 mL of DMF was added to a stirred reactor equipped with a reflux condenser. Then, 1 mol of anhydrous aluminum trichloride, 0.8 mol of 3-bromopyridine carboxaldehyde, 0.6 mol of pyrrole, and 1.5 mol of manganese dichloride were added sequentially with stirring. The reaction mixture was heated to reflux and maintained for 1 hour before the reaction was stopped. The mixture was then cooled and placed at 273 K overnight. The mixture was filtered to obtain tetra(3-bromopyridine)porphyrin manganese purple-black crystals with a yield of 35%.

[0032] Example 3:

[0033] 210 mL of DMF was added to a stirred reactor equipped with a reflux condenser. Then, 1.2 mol of anhydrous aluminum trichloride, 0.8 mol of 2-ethylpyrrole carbaldehyde, 0.7 mol of pyrrole, and 2 mol of manganese dichloride were added sequentially with stirring. The reaction mixture was heated to reflux and maintained for 2 hours before the reaction was stopped. The mixture was then cooled and placed at 273 K overnight. The mixture was filtered to obtain tetra(2-ethylpyrrole)porphyrin manganese purple-black crystals with a yield of 30%.

[0034] Example 4:

[0035] 1000 mL of DMF was added to a stirred reactor equipped with a reflux condenser. Then, 0.75 mol of anhydrous aluminum trichloride, 0.75 mol of 5-hydroxy-1-naphthaldehyde, 0.75 mol of pyrrole, and 2 mol of manganese dichloride were added sequentially with stirring. The reaction mixture was heated to reflux and maintained for 1.5 hours before the reaction was stopped. The mixture was then cooled and placed at 273 K overnight. The solution was filtered to obtain tetra(5-hydroxy-1-naphthylpyridine)porphyrin manganese pale green crystals in 25% yield.

[0036] Example 5:

[0037] 300 mL of DMF was added to a stirred reactor equipped with a reflux condenser. Then, 1 mol of anhydrous aluminum trichloride, 0.6 mol of 3-methylfuran carbaldehyde, 0.5 mol of pyrrole, and 1.8 mol of manganese dichloride were added sequentially with stirring. The reaction mixture was heated to reflux and maintained for 1.8 hours before the reaction was stopped. The mixture was then cooled and placed at 273 K overnight. The mixture was filtered to obtain tetra(3-methylfuran)porphyrin manganese purple-black crystals with a yield of 35%.

[0038] Example 6:

[0039] 500 mL of DMF was added to a stirred reactor equipped with a reflux condenser. Then, 0.5 mol of anhydrous aluminum trichloride, 0.7 mol of 5-methoxy-2-quinoline carbaldehyde, 0.5 mol of pyrrole, and 1.2 mol of manganese dichloride were added sequentially with stirring. The reaction mixture was heated to reflux and maintained for 3 hours before the reaction was stopped. The mixture was then cooled and placed at 273 K overnight. The mixture was filtered to obtain tetra(5-methoxy-2-quinoline)porphyrin manganese purple crystals, with a yield of 25%.

[0040] Example 7:

[0041] 2500 mL of DMF was added to a stirred reactor equipped with a reflux condenser. Then, 2 mol of anhydrous aluminum trichloride, 0.75 mol of 4-chlorobenzaldehyde, 0.5 mol of pyrrole, and 2 mol of manganese dichloride were added sequentially with stirring. The reaction mixture was heated to reflux and maintained for 2.5 hours before the reaction was stopped. The mixture was then cooled and placed at 273 K overnight. The mixture was filtered to obtain tetra(4-chlorophenyl)porphyrin manganese purple-black crystals with a yield of 48%.

[0042] Example 8:

[0043] 1000 mL of DMF was added to a stirred reactor equipped with a reflux condenser. Then, 2.5 mol of anhydrous aluminum trichloride, 0.5 mol of 3-aminobenzaldehyde, 0.5 mol of pyrrole, and 1.5 mol of manganese dichloride were added sequentially with stirring. The reaction mixture was heated to reflux and maintained for 2 hours before the reaction was stopped. The mixture was then cooled and placed at 273 K overnight. The mixture was filtered to obtain tetra(3-aminophenyl)porphyrin manganese blue-violet crystals, with a yield of 20%.

[0044] Example 9:

[0045] 2000 mL of DMF was added to a stirred reactor equipped with a reflux condenser. Then, 2 mol of anhydrous aluminum trichloride, 0.6 mol of 4-carboxybenzaldehyde, 0.5 mol of pyrrole, and 2.2 mol of manganese dichloride were added sequentially with stirring. The reaction mixture was heated to reflux and maintained for 1.5 hours before the reaction was stopped. The mixture was then cooled and placed at 273 K overnight. The mixture was filtered to obtain tetra(4-carboxyphenyl)porphyrin manganese purple-black crystals with a yield of 23%.

[0046] Example 10:

[0047] 1500 mL of DMF was added to a stirred reactor equipped with a reflux condenser. Then, 0.8 mol of anhydrous aluminum trichloride, 0.6 mol of 4-nitrobenzaldehyde, 0.5 mol of pyrrole, and 2.5 mol of manganese dichloride were added sequentially with stirring. The reaction mixture was heated to reflux and maintained for 0.5 hours before the reaction was stopped. The mixture was then cooled and placed at 273 K overnight. The solution was filtered to obtain tetra(4-nitrophenyl)porphyrin manganese purple-black crystals, with a yield of 20%.

Claims

1. A method for the simultaneous synthesis of tetraarylmanganese porphyrin via condensation of aldehyde and pyrrole and oxidative insertion reaction of divalent manganese salt, characterized in that: Using anhydrous aluminum trichloride as a catalyst and DMF as a solvent, the condensation reaction of aromatic aldehydes and pyrroles and the oxidative insertion reaction of divalent manganese salts were completed simultaneously to generate tetraarylmanganese porphyrin. The reaction process was as follows: DMF was added to a reflux stirred reactor at room temperature, stirring was started, and anhydrous aluminum trichloride, aryl aldehydes, pyrroles and divalent manganese salts were added in sequence. The reaction mixture was heated to reflux, and the reaction was stopped after a certain period of time. The mixture was cooled and placed at around 273K overnight. The tetraarylmanganese porphyrin purple crystals were obtained by filtration. The synthesized product, tetraarylmanganese porphyrin, has the structure shown in Figure 1: ; The aryl Ar group can be a benzene ring, pyridine, pyrrole, furan, naphthalene, or quinoline; The substituent R on the aryl Ar is methyl, ethyl, or propyl, or chlorinated, bromine, or iodine substituent, or methoxy, ethoxy, hydroxy, or carboxyl, or amino, dimethylamino, or nitro.

2. The method for simultaneously synthesizing tetraarylmanganese porphyrin by condensation of aldehyde and pyrrole and oxidative insertion reaction of divalent manganese salt according to claim 1, characterized in that: The molar ratio of aryl aldehyde, pyrrole, manganese dichloride and anhydrous AlCl3 is 1-1.5:1-1.5:1-5:1-5.

3. The method for simultaneously synthesizing tetraarylmanganese porphyrin by condensation of aldehyde and pyrrole and oxidative insertion reaction of divalent manganese salt according to claim 2, characterized in that: The molar ratio of aryl aldehyde, pyrrole, manganese dichloride and anhydrous AlCl3 is 1:1:3:1.

5.

4. The method for simultaneously synthesizing tetraarylmanganese porphyrin by condensation of aldehyde and pyrrole and oxidative insertion reaction of divalent manganese salt according to claim 1, characterized in that: The molar concentration of pyrrole in DMF is 1 / 300-1 / 2000.

5. The method for simultaneously synthesizing tetraarylmanganese porphyrin by condensation of aldehyde and pyrrole and oxidative insertion reaction of divalent manganese salt according to claim 4, characterized in that: The molar concentration of pyrrole in DMF is 1 / 500.

6. The method for simultaneously synthesizing tetraarylmanganese porphyrin by condensation of aldehyde and pyrrole and oxidative insertion reaction of divalent manganese salt according to claim 1, characterized in that: The reaction time is 0.5-4 hours.

7. The method for simultaneously synthesizing tetraarylmanganese porphyrin by condensation of aldehyde and pyrrole and oxidative insertion reaction of divalent manganese salt according to claim 6, characterized in that: The reaction time is 2 hours.

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