Metal-free catalytic dehalogenation reaction method for iodo-containing aromatic compounds

Abstract

The invention belongs to the technical field of organic synthetic chemistry, discloses a metal-free catalytic dehalogenation reaction method for an iodo-containing aromatic compound, and particularly relates to a method for preparing an aromatic compound through dehalogenation of the iodo-containing aromatic compound without the action of a catalyst. Under the combined action of the organic solvent N, N-dimethyl amide and water, the dehalogenation reaction of the iodo-containing aromatic compound is realized, and the aromatic compound is prepared. The synthesis method is simple in condition, a target product can be efficiently synthesized without using a metal catalyst, and a novel synthesis method is provided for dehalogenation reaction.

Description

Technical Field

[0001] The invention belongs to the technical field of dehalogenation chemistry, and specifically relates to a dehalogenation reaction using an iodine-containing aromatic compound as a substrate under the combined action of water and N,N-dimethylformamide. Background Art

[0002] The dehalogenation of organic halides is not only a strategy for the synthesis of drugs, but also beneficial to environmental protection.

[0003] Halogenated aromatic compounds are widely used in agriculture and can be used as herbicides, fungicides and insecticides, but the use of halogenated aromatic compounds can lead to environmental pollution problems. Because halogens are strong electron-withdrawing group substitutions, not only do they make the compounds difficult to degrade, but they also increase the risk of the compounds forming toxic intermediates. Therefore, dehalogenation of halogenated aromatic pesticides is the key to removing the toxicity of aromatic hydrocarbons and degrading the compounds.

[0004] At present, various dehalogenation reaction methods for aromatic compounds have been developed, including catalytic hydrogenation dehalogenation and chemical reduction dehalogenation. Catalytic hydrogenation dehalogenation is a commonly used method, usually using supported catalysts such as Pd / C, Pd-Fe / C, etc. Although these catalysts have high activity and stability under appropriate reaction conditions, these catalysts are expensive and costly. For example, dichlorophthalic acid is treated with a bimetallic catalyst Pd-Fe / C. Chemical reduction dehalogenation usually uses alcohol as a hydrogen source and is carried out under the action of a supported catalyst. For example, halogenated aromatic compounds are currently used as raw materials, water is used as a solvent, and alcohol is used as a hydrogen source. Under the action of a supported catalyst (such as Rh, Pd, Pt, and Ni, etc.), the reaction is carried out at 30-260°C and a pressure of 1-10MPa for 5-50 hours to achieve dehalogenation degradation. In the prior art, dehalogenation in the absence of a dehalogenation or conversion catalyst must be carried out in the presence of inorganic anions and at a low pH value, that is, under strongly acidic conditions, requiring the addition of strong acids such as HCl, H3PO4 and H2SO4. Strong acidic substances have oxidants, and the oxidants are added to the acidic solution, and the reaction conditions are harsh.

[0005] Therefore, it is very necessary to develop a universal and mild dehalogenation reaction with high conversion rate, no catalyst and good stability. The reaction system is simple and has no side reactions. It is a good method for hydrogenation and dehalogenation of halogenated hydrocarbons and has broad application prospects in organic industry and environmental protection. Summary of the invention

[0006] The present invention aims at the shortcomings in the dehalogenation process of iodinated aromatic compounds, and performs dehalogenation. Under the reaction conditions that do not require the participation of a catalyst or an oxidant, the present invention directly performs a dehalogenation reaction of the iodinated aromatic compound without generating any byproducts. The method of the present invention is simple to operate, environmentally friendly, free of byproducts, high in yield, and the catalyst is easy to separate and recycle.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] The dehalogenation reaction steps of the present invention are as follows: adding an iodinated aromatic compound as a substrate into a reaction device, then adding H2O and DMF, putting into a heater, heating and stirring for reaction, and after the reaction is completed, removing water, filtering, collecting the solution, and obtaining a dehalogenated product.

[0009] The reaction involved is:

[0010]

[0011] The halogenated position (CI) in iodinated aromatic compounds undergoes dehalogenation.

[0012] R is selected from one of iodine, alkyl, hydrogen, and aromatic groups; R can be independently selected from ortho, meta, and para positions; R is one or two substituents. Further, R is one or two of hydrogen, 3-methyl, 4-methyl, 5-methyl, and benzene ring.

[0013] The position of iodine in the iodine-substituted aromatic compound is one or both of 1-iodine and 4-iodine.

[0014] The heating reaction temperature in the present invention is 150°C to 160°C.

[0015] The heating reaction time in the present invention is 8 to 24 hours.

[0016] Furthermore, the molar ratio of the iodinated aromatic compound to the molar ratio of H2O is 1:50 to 1:280, preferably 1:110 to 150.

[0017] The molar ratio of the iodinated aromatic compound to the molar ratio of DMF is 1:15 to 1:64, preferably 1:22 to 40.

[0018] Compared with the prior art, the technical advantages of the present invention are:

[0019] The invention provides a simple and convenient dehalogenation reaction without side reactions, the reaction state is stable, no catalyst is required, no special gas environment is required, no alkali or acid needs to be added to promote the reaction, the preparation process is simple, the product is easy to separate, the post-treatment is simple, and it is environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the NMR image of toluene, the target product of Example 1.

[0021] Figure 2 This is the NMR image of the target product naphthalene in Example 3.

[0022] Figure 3 This is the NMR image of the target product iodobenzene in Example 4. DETAILED DESCRIPTION

[0023] The following specific examples are used to describe the technical solution of the present invention in detail, but are not intended to limit the scope thereof. Unless otherwise specified, the reagents and instruments used in the following examples are all commercially available products.

[0024] Embodiment 1:

[0025]

[0026] 4-iodotoluene (0.2mmol, 43.6mg), DMF (0.4mL), and H2O (0.5mL) were added to a 10mL glass tube in sequence, and the reaction was placed in a reaction plate after the operation was completed. The reaction temperature was controlled at 150°C and stirred for 12 hours. After the reaction was completed, it was cooled to room temperature, the reaction system was dehydrated, filtered, and the solution was collected to obtain toluene. The conversion rate was 98%, the selectivity was 100%, and the yield of the product was 98% as determined by GC.

[0027] Embodiment a

[0028] If the temperature of Example 1 is lowered to 140° C. and other conditions remain unchanged, the conversion rate is 0% and the yield of the product is 0% as determined by GC.

[0029] Embodiment b

[0030] If the reaction time of Example 1 is reduced to 9 h and other conditions remain unchanged, the conversion rate is 10.7%, the selectivity is 100%, and the yield of the product is 10.7% as determined by GC.

[0031] Embodiment c:

[0032] 4-iodotoluene (0.2mmol, 43.6mg), DMF (0.5mL), and H2O (0.5mL) were added to a 10mL glass tube in sequence, and the reaction was placed in a reaction plate after the operation was completed. The reaction temperature was controlled at 150°C and stirred for 12 hours. After the reaction was completed, it was cooled to room temperature, the reaction system was dehydrated, filtered, and the solution was collected to obtain toluene. The conversion rate was 92% and the selectivity was 100% using GC, and the yield of the product was 92%.

[0033] Embodiment d:

[0034] 4-iodotoluene (0.2mmol, 43.6mg), DMF (0.5mL), and H2O (0.4mL) were added to a 10mL glass tube in sequence, and the reaction was placed in a reaction plate after the operation was completed. The reaction temperature was controlled at 150°C and stirred for 12 hours. After the reaction was completed, it was cooled to room temperature, the reaction system was dehydrated, filtered, and the solution was collected to obtain toluene. The conversion rate was 84.2% and the selectivity was 100% using GC. The yield of the product was 84.2%.

[0035] Embodiment e:

[0036] 4-iodotoluene (0.2mmol, 43.6mg), DMF (0.5mL), and H2O (0.2mL) were added to a 10mL glass tube in sequence, and the reaction was placed in a reaction plate after the operation was completed. The reaction temperature was controlled at 150°C and stirred for 12 hours. After the reaction was completed, it was cooled to room temperature, the reaction system was dehydrated, filtered, and the solution was collected to obtain toluene. The conversion rate was 26.4% and the selectivity was 100% using GC. The yield of the product was 26.4%.

[0037] Embodiment 2:

[0038]

[0039] 3-iodotoluene (0.2mmol, 26μL), DMF (0.4mL), and H2O (0.5mL) were added to a 10mL glass tube in sequence, and the reaction was placed in a reaction plate after the operation was completed. The reaction temperature was controlled at 150°C and stirred for 12h. After the reaction was completed, it was cooled to room temperature, the reaction system was dehydrated, filtered, and the solution was collected to obtain toluene. The conversion rate was 91.1% and the selectivity was 100% using GC. The yield of the product was 91.1%.

[0040] Embodiment 3:

[0041]

[0042] 1-Iodonaphthalene (0.2mmol, 29μL), DMF (0.4mL), and H2O (0.5mL) were added to a 10mL glass tube in sequence, and the reaction was placed in a reaction plate after the operation was completed. The reaction temperature was controlled at 150°C and stirred for 12h. After the reaction was completed, it was cooled to room temperature, the reaction system was dehydrated, filtered, and the solution was collected to obtain naphthalene. The conversion rate was 82.8% and the selectivity was 100% using GC. The yield of the product was 82.8%.

[0043] Embodiment 4:

[0044]

[0045] 1,4-diiodobenzene (0.2mmol, 65.98mg), DMF (0.4mL), and H2O (0.5mL) were added to a 10mL glass tube in sequence. After the operation was completed, the mixture was placed in a reaction plate, the reaction temperature was controlled at 150°C, and the reaction was stirred for 12 hours. After the reaction was completed, the mixture was cooled to room temperature, the reaction system was dehydrated, filtered, and the solution was collected to obtain iodobenzene. The conversion rate was 100%, the selectivity was 100%, and the yield of the product was 100% as determined by GC.

[0046] Embodiment 5:

[0047]

[0048] 3,5-dimethyliodobenzene (0.2mmol, 29μL), DMF (0.4mL), and H2O (0.5mL) were added to a 10mL glass tube in sequence. After the operation was completed, the mixture was placed in a reaction plate, the reaction temperature was controlled at 150°C, and the reaction was stirred for 12 hours. After the reaction was completed, the mixture was cooled to room temperature, the reaction system was dehydrated, filtered, and the solution was collected to obtain meta-xylene. The conversion rate was 100%, the selectivity was 100%, and the yield of the product was 100% as determined by GC.

[0049] Comparative Example 1:

[0050] 4-Iodotole (0.2mmol, 43.6mg) and DMF (1mL) were added to a 10mL glass tube in sequence, and after the operation was completed, the mixture was placed in a reaction plate, the reaction temperature was controlled at 150°C, and the reaction was stirred for 12h. After the reaction was completed, the mixture was cooled to room temperature, and the solution was collected to obtain toluene. The conversion rate was 1%, the selectivity was 100%, and the yield of the product was 1% as determined by GC.

[0051] Comparative Example 2:

[0052] 4-Iodotole (0.2 mmol, 43.6 mg) and H2O (1 mL) were added to a 10 mL glass tube in sequence, and after the operation was completed, the reaction was placed in a reaction plate, the reaction temperature was controlled at 150°C, and the reaction was stirred for 12 hours. After the reaction was completed, the reaction was cooled to room temperature, the solution was collected, and the toluene conversion rate was 0% and the product yield was 0% as determined by LC.

[0053] Comparative Example 3:

[0054] 4-iodotoluene (0.2mmol, 43.6mg), tert-amyl alcohol (0.4mL), and H2O (0.5mL) were added to a 10mL glass tube in sequence, and the reaction was placed in a reaction plate after the operation was completed. The reaction temperature was controlled at 150°C and stirred for 12h. After the reaction was completed, it was cooled to room temperature, the reaction system was dehydrated, filtered, and the solution was collected. No target product toluene was generated by GC determination.

[0055] Comparative Example 4:

[0056] 4-Iodotole (0.2mmol, 43.6mg), DMSO (0.4mL), and H2O (0.5mL) were added to a 10mL glass tube in sequence, and the reaction was placed in a reaction plate after the operation was completed. The reaction temperature was controlled at 150°C and stirred for 12h. After the reaction was completed, it was cooled to room temperature, the reaction system was dehydrated, filtered, and the solution was collected. No target product toluene was generated by GC determination.

[0057] Comparative Example 5:

[0058] 4-iodotoluene (0.2mmol, 43.6mg), ethyl acetate (0.4mL), and H2O (0.5mL) were added to a 10mL glass tube in sequence, and the reaction was placed in a reaction plate after the operation was completed. The reaction temperature was controlled at 150°C and stirred for 12h. After the reaction was completed, it was cooled to room temperature, the reaction system was dehydrated, filtered, and the solution was collected. No target product toluene was generated by GC determination.

[0059] The above describes the optional embodiments of the present invention to teach those skilled in the art how to implement and reproduce the present invention. The raw materials and equipment used in the present invention, unless otherwise specified, are all commonly used raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are all conventional methods in the art. In order to teach the scheme of the present invention, some conventional technical aspects have been simplified and omitted. Those skilled in the art should understand that variations arising from this aspect are all within the scope of protection of the present invention.

Claims

1. A method for dehalogenation of iodine-containing aromatic compounds without metal catalysis, characterized in that: Using an iodinated aromatic compound as a reaction raw material, adding a solvent N,N-dimethylamide and water into a reaction device, performing a dehalogenation reaction under heating conditions, and then removing water from the reaction mixture, filtering, and collecting the solution to obtain a deiodinated aromatic compound; 2. The method for dehalogenation of iodine-containing aromatic compounds without metal catalysis according to claim 1, characterized in that: R is one or more of an alkyl group, a hydrogen group, and an aromatic group.

3. The method for dehalogenation of iodine-containing aromatic compounds without metal catalysis according to claim 1, characterized in that: The heating conditions are 150°C to 160°C, and the reaction time is 8 to 24 hours.

4. The method for dehalogenation of iodine-containing aromatic compounds without metal catalysis according to claim 1, characterized in that: The ratio of the molar amount of the iodinated aromatic compound to the molar amount of H2O is 1:50 to 1:

280.

5. The method for dehalogenation of iodine-containing aromatic compounds without metal catalysis according to claim 4, characterized in that: The ratio of the molar amount of the iodinated aromatic compound to the molar amount of H2O is 1:110-150.

6. The method for dehalogenation of iodine-containing aromatic compounds without metal catalysis according to claim 1, characterized in that: The molar ratio of the iodinated aromatic compound to the molar ratio of N,N-dimethylamide is 1:15 to 1:

64.

7. The method for dehalogenation of iodine-containing aromatic compounds without metal catalysis according to claim 6, characterized in that: The molar ratio of the iodinated aromatic compound to the molar ratio of N,N-dimethylamide is 1:22-40.

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