Preparation process of o-nitrobenzaldehyde
By using tetrabutyl ammonium bromide and manganese dioxide as catalysts and water as solvents under nitrogen protection, direct oxidation reaction converts o-nitrotoluene to o-nitrobenzaldehyde, solving the problems of low yield and wastewater pollution in the prior art, and achieving efficient and low-cost synthesis effect.
Patent Information
- Application Number
- CN202411724786.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-28
- Publication Date
- 2025-03-04
AI Technical Summary
In the prior art, the synthesis method of orthon-nitrobenzaldehyde has problems such as low yield, wastewater pollution, equipment corrosion and high preparation costs.
The phase transfer catalyst tetrabutyl ammonium bromide and the catalyst manganese dioxide were used, and under nitrogen protection, water was used as a solvent to convert o-nitrotoluene to ortho-nitrobenzaldehyde through direct oxidation reaction.
It has achieved efficient and low-cost synthesis, with yields increased to 81.0%, product purity reached 99.0%, and significantly reduced wastewater pollution, gentle process temperature and easy to control.
Smart Images
Figure BDA0005158930440000011
Abstract
Description
Technical Field
[0001] The invention relates to a preparation process of o-nitrobenzaldehyde and belongs to the technical field of organic synthesis. Background Art
[0002] o-Nitrobenzaldehyde is an important chemical intermediate, which is widely used in the fields of medicine, pesticides, etc. In medicine, it is mainly used to synthesize drugs for the treatment of cardiovascular diseases, such as nitropyridine, nisoldipine, encainamide, etc. Its nitro-reduction product, o-aminobenzaldehyde, is an important intermediate for the synthesis of quinoline ring drugs and an important organic synthesis raw material, which is widely used in the chemical industry.
[0003] In recent years, the industrial demand for o-nitrobenzaldehyde is very large. Although there are many methods for its synthesis, most of them are synthesized by indirect methods. The reaction steps are cumbersome, and oxides such as bromine salts, chromates, nitrates, and chlorates are used as oxidants, which cause serious wastewater generation, environmental pollution, and equipment corrosion. For example, o-nitrotoluene is brominated with bromine to generate o-nitrobenzyl bromide, which is then hydrolyzed to generate o-nitrobenzyl alcohol, and then oxidized with nitric acid to obtain the target product. This process has a low yield of about 45%, and a large amount of bromine-containing wastewater is generated, which is difficult to treat and easily causes serious environmental pollution. Moreover, the price of bromine is high and its preparation cost is high; in addition, benzaldehyde is used as a raw material, benzyl diacetic anhydride is added dropwise to obtain an intermediate, and then nitrated with fuming nitric acid to obtain a yellow block solid and separate o-nitrobenzaldehyde. This method has the problem of complex separation of ortho-para products, and low yield and purity.
[0004] In view of the above problems, it is very urgent to design a synthesis method of o-nitrobenzaldehyde with simple synthesis route, mild conditions, low cost, no pollution or less pollution to the environment, high efficiency and high selectivity. Summary of the invention
[0005] The invention provides a preparation process of o-nitrobenzaldehyde. In the process, o-nitrobenzaldehyde is directly oxidized to o-nitrotoluene under the action of tetrabutylammonium bromide and manganese dioxide as phase transfer catalysts to obtain o-nitrobenzaldehyde. The process uses water as a solvent, does not use bromine, does not contain wastewater containing bromine, chromium, etc., is simple to operate, has a mild process temperature that is easy to control, has stable product quality, low impurity content, and significant environmental benefits.
[0006] The present invention adopts the following technical solutions:
[0007] Under nitrogen protection, with o-nitrotoluene as the starting material and water as the solvent, under the action of phase transfer catalyst and catalyst manganese dioxide, o-nitrotoluene and hydrogen peroxide undergo oxidation reaction to obtain o-nitrobenzaldehyde. The reaction equation is:
[0008]
[0009] The specific steps are:
[0010] (1) Under nitrogen protection, with o-nitrotoluene as the starting material and water as the solvent, o-nitrotoluene and hydrogen peroxide undergo an oxidation reaction under the action of a phase transfer catalyst and manganese dioxide;
[0011] (2) After the reaction is completed, the reaction is filtered, and the filtrate is adjusted to pH = 13 by adding liquid alkali to quench the hydrogen peroxide. The aqueous phase is extracted with anhydrous ethanol, and the organic phase is dried with anhydrous magnesium sulfate;
[0012] (3) After the dried organic phase is heated to 50° C., activated carbon is added, stirred for 0.5 h, filtered, concentrated, cooled, filtered, and dried to obtain the product o-nitrobenzaldehyde.
[0013] The phase transfer catalyst is tetrabutylammonium bromide.
[0014] The reaction temperature of the oxidation reaction is 30-45°C.
[0015] The oxidation reaction time is 2 to 4 hours.
[0016] The feed ratio, calculated by molar ratio, is o-nitrotoluene: hydrogen peroxide: tetrabutylammonium bromide: manganese dioxide = 1: 1.3-1.5: 0.03-0.05: 0.02-0.03.
[0018] The manganese dioxide described in the present invention is newly prepared manganese dioxide.
[0019] The mass ratio of the added solvent water to the mass ratio of the o-nitrotoluene is 1:0.6-0.8.
[0020] The content of the hydrogen peroxide is 27.5%, and the addition method is batch dropwise addition.
[0021] The preparation process of o-nitrobenzaldehyde of the present invention uses o-nitrotoluene as a starting material and water as a solvent. Under the action of a phase transfer catalyst, tetrabutylammonium bromide, and a catalyst, manganese dioxide, o-nitrotoluene is subjected to a hydrogen peroxide oxidation reaction to obtain o-nitrobenzaldehyde. The process uses water as a solvent, does not use bromine, does not contain wastewater containing bromine, chromium, etc., is simple to operate, has a mild process temperature that is easy to control, has stable quality of the obtained product, has a low impurity content, has significant environmental benefits, has a GC purity of 99.0%, and has a total process yield of up to 81.0%. DETAILED DESCRIPTION
[0022] The present invention is further described below in conjunction with embodiments. It should be noted that the following description is only for explaining the present invention and does not limit its contents.
[0023] Example 1
[0024] In a three-necked flask, under nitrogen protection, 20.6g of o-nitrotoluene, 16.4g of water, 2.42g of tetrabutylammonium bromide and 0.39g of manganese dioxide were added in sequence. At 45°C, 27.8g of 27.5% hydrogen peroxide was slowly added dropwise within 1h. After the addition was completed, the reaction was stirred for 2.5h and the temperature was controlled at 40-45°C. After the reaction was completed, the reaction solution was filtered, and the filtrate was added with liquid alkali to adjust the pH to 13 for quenching. The aqueous phase was extracted with 15ml*3 anhydrous ethanol, and the organic phase was dried over anhydrous magnesium sulfate. After the organic phase was heated to 50°C, 2g of activated carbon was added, and the mixture was stirred for 0.5h and filtered. The product o-nitrobenzaldehyde (18.81g) was obtained after concentration, cooling, filtering and drying. The GC purity was 99.9% and the total process yield could reach 82.9%.
[0025] Example 2
[0026] In a three-necked flask, under nitrogen protection, 20.6g of o-nitrotoluene, 16.4g of water, 2.42g of tetrabutylammonium bromide and 0.39g of manganese dioxide were added in sequence. At 30°C, 27.8g of 27.5% hydrogen peroxide was slowly added dropwise within 1h. After the addition was completed, the reaction was stirred for 2.5h and the temperature was controlled at 30-35°C. After the reaction was completed, the reaction solution was filtered, and the filtrate was added with liquid alkali to adjust the pH to 13 for quenching. The aqueous phase was extracted with 15ml*3 anhydrous ethanol, and the organic phase was dried over anhydrous magnesium sulfate. After the organic phase was heated to 50°C, 2g of activated carbon was added, and the mixture was stirred for 0.5h and filtered. The product o-nitrobenzaldehyde (18.77g) was obtained after concentration, cooling, filtering and drying. The GC purity was 99.9% and the total process yield could reach 82.7%.
[0027] Example 3
[0028] In a three-necked flask, under nitrogen protection, 20.6g of o-nitrotoluene, 16.4g of water, 2.42g of tetrabutylammonium bromide and 0.26g of manganese dioxide were added in sequence. At 45°C, 24.2g of 27.5% hydrogen peroxide was slowly added dropwise within 1h. After the addition was completed, the reaction was stirred for 2.5h and the temperature was controlled at 40-45°C. After the reaction was completed, the reaction solution was filtered, and the filtrate was added with liquid alkali to adjust the pH to 13 for quenching. The aqueous phase was extracted with 15ml*3 anhydrous ethanol, and the organic phase was dried over anhydrous magnesium sulfate. After the organic phase was heated to 50°C, 2g of activated carbon was added, and the mixture was stirred for 0.5h and filtered. The product o-nitrobenzaldehyde (18.52g) was obtained after concentration, cooling, filtering and drying. The GC purity was 99.8%, and the total process yield could reach 81.6%.
[0029] Example 4
[0030] In a three-necked flask, under nitrogen protection, 20.6g of o-nitrotoluene, 12.4g of water, 1.46g of tetrabutylammonium bromide and 0.39g of manganese dioxide were added in sequence. At 45°C, 27.8g of 27.5% hydrogen peroxide was slowly added dropwise within 0.5h. After the addition was completed, the reaction was stirred for 3h and the temperature was controlled at 40-45°C. After the reaction was completed, the reaction solution was filtered, and the filtrate was added with liquid alkali to adjust the pH to 13 for quenching. The aqueous phase was extracted with 15ml*3 anhydrous ethanol, and the organic phase was dried over anhydrous magnesium sulfate. After the organic phase was heated to 50°C, 2g of activated carbon was added, and the mixture was stirred for 0.5h and filtered. The product o-nitrobenzaldehyde (18.45g) was obtained after concentration, cooling, filtering and drying. The GC purity was 99.5%, and the total process yield could reach 81.3%.
[0031] Example 5
[0032] In a three-necked flask, under nitrogen protection, 20.6g of o-nitrotoluene, 12.4g of water, 1.46g of tetrabutylammonium bromide and 0.26g of manganese dioxide were added in sequence. At 45°C, 27.8g of 27.5% hydrogen peroxide was slowly added dropwise within 0.5h. After the addition was completed, the reaction was stirred for 3h and the temperature was controlled at 40-45°C. After the reaction was completed, the reaction solution was filtered, and the filtrate was added with liquid alkali to adjust the pH to 13 for quenching. The aqueous phase was extracted with 15ml*3 anhydrous ethanol, and the organic phase was dried over anhydrous magnesium sulfate. After the organic phase was heated to 50°C, 2g of activated carbon was added, and the mixture was stirred for 0.5h and filtered. The product o-nitrobenzaldehyde (18.41g) was obtained after concentration, cooling, filtering and drying. The GC purity was 99.0%, and the total process yield could reach 81.1%.
[0033] Although the above describes the specific implementation methods of the present invention, it does not limit the scope of protection of the present invention. Based on the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present invention.
Claims
1. A process for preparing o-nitrobenzaldehyde, characterized in that: Under nitrogen protection, with o-nitrotoluene as the starting material and water as the solvent, an oxidation reaction was carried out to obtain o-nitrobenzaldehyde.
2. The preparation process of o-nitrobenzaldehyde according to claim 1, characterized in that: The specific steps are: (1) Under nitrogen protection, using o-nitrotoluene as a starting material and water as a solvent, under the action of a phase transfer catalyst and manganese dioxide, o-nitrotoluene and hydrogen peroxide undergo an oxidation reaction; (2) After the reaction is completed, filtering is performed, and the filtrate is adjusted to pH=13 by adding liquid alkali to quench the hydrogen peroxide, the aqueous phase is extracted with anhydrous ethanol, and the organic phase is dried over anhydrous magnesium sulfate; (3) After the dried organic phase is heated to 50° C., activated carbon is added, stirred for 0.5 h, filtered, concentrated, cooled, filtered, and dried to obtain the product o-nitrobenzaldehyde.
3. The preparation process of o-nitrobenzaldehyde according to claim 2, characterized in that: The phase transfer catalyst is tetrabutylammonium bromide.
4. The preparation process of o-nitrobenzaldehyde according to claim 2, characterized in that: The reaction temperature of the oxidation reaction is 30-45°C.
5. The preparation process of o-nitrobenzaldehyde according to claim 2, characterized in that: The oxidation reaction time is 2 to 4 hours.
6. The process for preparing o-nitrobenzaldehyde according to claim 2, characterized in that: In terms of molar ratio, o-nitrotoluene: hydrogen peroxide: tetrabutylammonium bromide: manganese dioxide = 1: 1.3-1.5: 0.03-0.05: 0.02-0.
03.
7. The process for preparing o-nitrobenzaldehyde according to claim 2, characterized in that: The mass ratio of the added solvent water to the mass ratio of the o-nitrotoluene is 1:0.6-0.
8.
8. The process for preparing o-nitrobenzaldehyde according to claim 2, characterized in that: The content of the hydrogen peroxide is 27.5%, and the addition method is batch dropwise addition.