CN109369414B - Method for preparing teflubenzuron intermediate 3, 5-dichloro-2, 4-difluoroaniline - Google Patents
Method for preparing teflubenzuron intermediate 3, 5-dichloro-2, 4-difluoroaniline Download PDFInfo
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- C07C209/30—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds
- C07C209/32—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds by reduction of nitro groups
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Abstract
The invention discloses a method for preparing a teflubenzuron intermediate 3, 5-dichloro-2, 4-difluoroaniline, which comprises the following steps: the raw material 3, 5-dichloro-2, 4-difluoronitrobenzene (II) is subjected to hydrogen reduction in the presence of a dehalogenation inhibitor and a catalyst to prepare high-content 3, 5-dichloro-2, 4-difluoroaniline (I). The synthesis method has the advantages of mild reaction conditions, easy control, high selectivity, less three wastes, good product purity and high yield, meets the development requirements of clean processes, and is very suitable for industrial production.
Description
Technical Field
The invention belongs to the field of synthesis of pesticides, and particularly relates to a method for preparing a teflubenzuron intermediate 3, 5-dichloro-2, 4-difluoroaniline.
Background
3, 5-dichloro-2, 4-difluoroaniline is a key intermediate of insecticide fluazuron, which is a benzoylurea insecticide discovered by Jelaiv Ferok company belonging to Bayer corporation in Germany and developed and independently operated to produce and sell by Mitsubishi chemical corporation in Japan, and is registered in 1990, 11 months and 7 days;
the pesticide has effect in preventing 30-150g (a.i.) per ha against larvae of Trialepidoptera, Diptera, Octoptera, Hymenoptera, Lepidoptera and Carpesidae. Can be used for cabbage, mandarin orange, cotton, grape, pome fruit, potato, stone fruit, sorghum, soybean, tree, tobacco, and vegetable. It can inhibit the growth of young insects and prevent desquamation. A suspension concentrate (150g/L) had no effect on many parasitic insects, predatory insects and arachnids. The product can also be used for preventing and treating locusta migratoria in most of young stages.
The toxicity of the flufenoxuron to human and livestock is extremely low, and the HLD of the original drug to large and small mice is more than 5000 mg/Kg; acute percutaneous LD for rats50More than 2000 mg/Kg; the amount of inhaled La in the rat was 5038 mg/M; the medicament has slight stimulation to rabbit eyes and skin, and the non-action dosage in a two-year feeding test is as follows: rat 5.38mg/Kg/d, dog 3.15 mg/Kg/d. The tests of chronic toxicity, carcinogenicity and mutagenicity show that the teflubenzuron is very safe to human and animals, and is used for LC of carp and trout50More than 500 mg/L.
The fluazuron is a novel benzoyl urea insecticide, and benzoyl urea compounds are used as a most main chitin synthesis inhibitor of insects, have excellent effect on crop protection by using the unique insecticidal activity, and particularly have better effect on controlling pests with resistance to organophosphorus, paraway-worm bacteria ester and carbamate 3 insecticides.
The research on the key intermediate 3, 5-dichloro-2, 4-difluoroaniline of the teflubenzuron develops a catalytic hydrogenation reduction process with high product content, good quality, high yield and environmental friendliness, and is a clean production technology which is currently spotlighted. Has positive significance for further developing a preparation method of the teflubenzuron.
For the preparation of 3, 5-dichloro-2, 4-difluoroaniline, the main synthetic methods reported in the literature are as follows:
iron powder reduction method under acidic condition
Patent EP052833 discloses the preparation of 2, 4-difluoro-3, 5-dichloroaniline from 3, 5-dichloro-2, 4-difluoronitrobenzene by iron powder reduction at 95-100 ℃ in a water/acetic acid mixed solvent, alkali neutralization, steam distillation, extraction with dichloromethane and concentration;
patent CN105801429A discloses a synthesis method of 3, 5-dichloro-2, 4-difluoroaniline obtained by using 1,2, 3-trichlorobenzene as a starting material to prepare 3, 5-dichloro-2, 4-difluoronitrobenzene, and then reducing the difluoronitrobenzene with iron powder/ammonium chloride, wherein the synthesis method comprises the following steps:
patent CN1683318A discloses that 3, 5-dichloro-2, 4-difluoroaniline is obtained by reducing 3, 5-dichloro-2, 4-difluoronitrobenzene with iron powder in ethanol \ water mixed solvent in the presence of acetic acid and ammonium chloride;
luyang and the like are also prepared by reducing 3, 5-dichloro-2, 4-difluoronitrobenzene by using iron powder in a mixed solvent of ethanol and water in the presence of acetic acid and ammonium acetate to prepare 3, 5-dichloro-2, 4-difluoroaniline;
liuchang et al report that 3, 5-dichloro-2, 4-difluoronitrobenzene is also reduced in water with iron powder as a reducing agent in the presence of ammonium chloride to obtain a compound of formula I;
the iron powder reduction method under the acidic condition is a main method for producing 3, 5-dichloro-2, 4-difluoroaniline at home and abroad at present; although the method has the advantages of easy production control, less side reaction, high selectivity and good product quality, most of the products are separated by adopting an organic solvent extraction or steam distillation mode, the steam distillation separation can consume a large amount of energy and generate a large amount of wastewater, a large amount of tar is generated in the distillation process, the product loss is large, and the actual yield is low; the organic solvent extraction causes severe operation environment, needs activated carbon for decolorization and recrystallization, and also causes environmental pollution; in a word, the iron powder reduction method has the defects of serious environmental pollution, more three wastes, long flow path, difficult treatment of a large amount of iron mud, extremely high treatment cost of the three wastes, harsh operation environment and the like, and is not beneficial to industrial production.
Catalytic hydrogenation process
Patent CN102617360A discloses that 2, 4-dichloro-3-fluoronitrobenzene distillation residue is used as starting material, and is first chlorinated and fluorinated to prepare 3, 5-dichloro-2, 4-difluoronitrobenzene, then 5% palladium carbon is used as catalyst, ammonium formate is used as hydrogen source in methanol, and 3, 5-dichloro-2, 4-difluoroaniline is prepared by reduction, yield is 95.4%; 3, 5-dichloro-2, 4-difluoronitrobenzene is hydrogenated and reduced in DMF by taking raney nickel and 5% palladium carbon as catalysts respectively to prepare 3, 5-dichloro-2, 4-difluoroaniline, the yield is 93% and 95% respectively, and the product content and the content of dehalogenation byproducts are not reported;
practical experiments show that the method has poor actual selectivity, more side reactions, a large amount of dehalogenation products, poor product color, low purity, low yield and is not beneficial to industrial production.
Patent CN1683318A discloses that 2, 4-difluoronitrobenzene is used as the starting material to prepare 3, 5-dichloro-2, 4-difluoronitrobenzene, and 3, 5-dichloro-2, 4-difluoroaniline is prepared by hydrogenation in solvent DMF in the presence of raney nickel or palladium carbon catalyst, the yield is 90.6% and 93.2%, and the product content and dehalogenation byproduct content are not reported. The synthetic route is as follows:
in the hydrogenation reduction process, a large amount of dehalogenation byproducts are generated, so that equipment corrosion and product purity are reduced, the yield is low, the product color is poor, and the industrial production is not facilitated.
Patent CN1310162A discloses that 3, 5-dichloro-2, 4-difluoronitrobenzene is directly hydrogenated and reduced by taking Pd/C as a catalyst at the temperature of 60 ℃ under the pressure of 3MPa to prepare 3, 5-dichloro-2, 4-difluoroaniline, the yield is 95.1 percent, and the product content and the content of dehalogenation byproducts are not reported; according to the principle of the reaction, a large amount of dehalogenation byproducts are inevitably generated in the reduction process, the purity of the product is greatly reduced, inconvenience is brought to product separation, and the industrial production is not facilitated.
The catalytic hydrogenation process has obvious advantages in the aspect of three wastes; but the catalytic hydrogenation process has poor selectivity, more side reactions and easy dehalogenation, especially nitro compounds containing multiple nitro groups in the same molecule or multiple halogens in the molecule, such as 3, 5-dichloro-2, 4-difluoronitrobenzene, which is the compound of the invention;
in view of this, the methods for reducing 3, 5-dichloro-2, 4-difluoronitrobenzene to 3, 5-dichloro-2, 4-difluoroaniline reported in the above-mentioned documents all have some drawbacks, and although the yield can be made higher, no product content is reported, and the actual product purity and color are poor, especially, the dehalogenation byproducts are more.
In order to improve the selectivity of the catalyst to the reaction and prevent the generation of byproducts, the invention screens 3% of platinum carbon as a hydrogenation catalyst through research, and simultaneously adds a small amount of specific cocatalyst to inhibit dehalogenation byproducts, thereby greatly improving the purity of the product 3, 5-dichloro-2, 4-difluoroaniline, not requiring purification and being convenient for industrial production.
Disclosure of Invention
The invention mainly aims to solve the technical problems of high three-waste pollution, difficult dehalogenation and purification, high production cost, color difference of products, incapability of large-scale production and the like in the conventional method for synthesizing 3, 5-dichloro-2, 4-difluoroaniline by reducing 3, 5-dichloro-2, 4-difluoronitrobenzene, and provides a novel method for synthesizing 3, 5-dichloro-2, 4-difluoroaniline.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a method for preparing a teflubenzuron intermediate 3, 5-dichloro-2, 4-difluoroaniline comprises the following steps:
carrying out hydrogenation reduction reaction on 3, 5-dichloro-2, 4-difluoronitrobenzene at 0-100 ℃ in the presence of a dehalogenation inhibitor and a hydrogenation catalyst to obtain a reduction product, filtering, washing with water, extracting and concentrating to obtain 3, 5-dichloro-2, 4-difluoroaniline; the above reaction formula is as follows:
preferably, the dehalogenation inhibitor is phosphoric acid; further, the concentration of the phosphoric acid is 0.1-85%; furthermore, the concentration of the phosphoric acid is 75-85%.
Preferably, the catalyst is Pt/C; further, the concentration of the Pt/C is 1-10%.
Preferably, the molar ratio of the 3, 5-dichloro-2, 4-difluoronitrobenzene to the dehalogenation inhibitor is 1: 0.01 to 0.2; further, the molar ratio of the 3, 5-dichloro-2, 4-difluoronitrobenzene to the dehalogenation inhibitor is 1: 0.05 to 0.1.
Preferably, the molar ratio of the 3, 5-dichloro-2, 4-difluoronitrobenzene to the catalyst is 1: 0.0001 to 0.01; further, the molar ratio of the 3, 5-dichloro-2, 4-difluoronitrobenzene to the catalyst is 1: 0.0005 to 0.001.
Preferably, the temperature of the hydrogenation reduction reaction is 20-100 ℃; further, the temperature of the hydrogenation reduction reaction is 75-80 ℃.
Preferably, the hydrogenation reduction reaction time is 0.5-24 hours; further, the hydrogenation reduction reaction time is 4-6 hours;
preferably, the reaction solvent in the hydrogenation reduction reaction is methanol, ethanol or isopropanol; the mass ratio of the 3, 5-dichloro-2, 4-difluoronitrobenzene to the reaction solvent is 1: 7 to 10.
Preferably, the hydrogenation reduction reaction pressure is 1.0 to 2.5MPa, preferably 1.0 to 1.5 MPa.
The method for preparing the 3, 5-dichloro-2, 4-difluoroaniline serving as the teflubenzuron intermediate has the advantages of mild reaction conditions, easiness in control, high selectivity, less three wastes, good product purity and high yield, meets the development requirement of a clean process, and is very suitable for industrial production.
Detailed Description
Example 1
Adding 160g of methanol and 22.8g (0.1mol) of compound (II)3, 5-dichloro-2, 4-difluoronitrobenzene into a 500ml stainless steel autoclave provided with a hydrogen inlet, cooling circulating water, a pressure gauge and an electric heating device, stirring, adding 0.80g of 3% platinum carbon and 0.85g (0.007mol) of 85% phosphoric acid, flushing a pipeline with 20g of methanol, and closing the autoclave; wherein the molar amount of platinum carbon is calculated in the manner of 0.80 (1-60% water) 3% dry basis platinum content/195.078 platinum molecular weight 0.0000492 mol;
introducing hydrogen to the internal pressure of 0.2-0.4MPa for 2-3 times, introducing the hydrogen to the internal pressure of 1.0-1.5MPa, controlling the temperature to be 75-80 ℃, stirring and reacting, and replenishing the hydrogen until the pressure does not drop any more. HPLC monitoring substantial disappearance or less than 0.5% of starting material (II); reacting for 6h, carrying out suction filtration on the reaction solution, and washing filter residues with methanol for 2 times, wherein 10ml of the filter residues are obtained each time; recycling solid platinum carbon;
recovering methanol from the filtrate under reduced pressure until a large amount of light yellow solid is separated out and dried completely; stirring and dripping 50g of water, quickly stirring for 30 minutes, slowly cooling to 0-5 ℃ for crystallization for 1 hour, filtering, draining, digging and washing the solid to be neutral by water, rinsing by 10g of water, and drying at 50 ℃ under normal pressure to obtain white-like to white powdery solid, wherein the weight is as follows: 19.0g, content 97.2%; the yield thereof was found to be 96.0%.
1HNMR(400MHz，CDCl3)δppm：6.70-6.75(m,1H),3.74(s,2H)。
Example 2
Adding 230g of ethanol and 22.8g (0.1mol) of compound (II)3, 5-dichloro-2, 4-difluoronitrobenzene into a 500ml stainless steel autoclave provided with a hydrogen inlet, cooling circulating water, a pressure gauge and an electric heating device, stirring, adding 0.80g (0.0000492mol) of 3% platinum carbon and 1.31g (0.01mol) of 75% phosphoric acid, flushing a pipeline with 20g of ethanol, and closing the autoclave;
introducing hydrogen to the internal pressure of 0.2-0.4MPa for 2-3 times, introducing the hydrogen to the internal pressure of 1.5-2.0 MPa, controlling the temperature to 75-80 ℃, stirring and reacting, and replenishing the hydrogen until the pressure does not drop. HPLC monitoring substantial disappearance or less than 0.5% of starting material (II); reacting for 4h, filtering the reaction solution, and washing filter residue with 10ml of methanol for 2 times; recycling solid platinum carbon;
recovering ethanol from the filtrate under reduced pressure until a large amount of light yellow solid is separated out and dried completely; stirring and dripping 50g of water, quickly stirring for 30 minutes, slowly cooling to 0-5 ℃ for crystallization for 1 hour, filtering, draining, digging and washing the solid to be neutral by water, rinsing by 10g of water, and drying at 50 ℃ under normal pressure to obtain white-like to white powdery solid, wherein the weight is as follows: 19.0g, content 96.9%; the yield thereof was found to be 95.9%.
1HNMR(400MHz，CDCl3)δppm：6.70-6.75(m,1H),3.74(s,2H)。
Example 3:
adding 160g of methanol and 22.8g (0.1mol) of compound (II)3, 5-dichloro-2, 4-difluoronitrobenzene into a 500ml stainless steel autoclave provided with a hydrogen inlet, cooling circulating water, a pressure gauge and an electric heating device, stirring, adding 1.62g (0.001mol) of 3% platinum carbon, flushing a pipeline by 20g of methanol, and closing the autoclave;
introducing hydrogen to the internal pressure of 0.2-0.4MPa for 2-3 times, introducing hydrogen to the internal pressure of 1.0-1.5MPa, controlling the temperature to 75-80 ℃, stirring and reacting, and replenishing hydrogen until the pressure is not reduced. HPLC monitoring substantial disappearance or less than 0.5% of starting material (II); the reaction is carried out for 15h, the reaction solution is filtered by suction, and the filter residue is washed by methanol for 2 times, 10ml each time. Recycling solid platinum carbon;
recovering methanol from the filtrate under reduced pressure until a large amount of light yellow solid is separated out and dried completely; stirring and dripping 50g of water, quickly stirring for 30 minutes, slowly cooling to 0-5 ℃ for crystallization for 1 hour, filtering, draining, digging and washing the solid to be neutral by water, rinsing by 10g of water, and drying at 50 ℃ under normal pressure to obtain light brown yellow powdery solid, wherein the weight is as follows: 18.0g, content 91.8% and yield 90.9%.
Comparative tests were carried out under the conditions of the production process of the present invention, with the other reaction conditions being unchanged, and the results obtained are shown in the following table:
from the above table, it can be seen that: according to the technical scheme, 3% of Pt/C is selected as a main hydrogenation catalyst, and when 85% of phosphoric acid is adopted as a dehalogenation inhibitor, the obtained compound I is good in purity and color; when other dehalogenation inhibitors are adopted, the product I needs to be further separated and purified, the operation is complicated, the color is poor, the content is reduced, the production cost is greatly improved, the large-scale industrial production is not facilitated, and the yield is also greatly reduced; when other hydrogenation catalysts are used for reduction, other byproducts are generated due to dehalogenation, so that the yield and purity of the product can slide down, and the product is not generated easily.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the inventive concept of the present invention, and these changes and modifications are all within the scope of the present invention.
Claims (7)
1. A method for preparing a teflubenzuron intermediate 3, 5-dichloro-2, 4-difluoroaniline is characterized by comprising the following steps:
carrying out hydrogenation reduction reaction on 3, 5-dichloro-2, 4-difluoronitrobenzene at 0-100 ℃ in the presence of a dehalogenation inhibitor and a hydrogenation catalyst to obtain a reduction product, filtering, washing with water, extracting and concentrating to obtain 3, 5-dichloro-2, 4-difluoroaniline; the above reaction formula is as follows:
the dehalogenation inhibitor is phosphoric acid; the molar ratio of the 3, 5-dichloro-2, 4-difluoronitrobenzene to the dehalogenation inhibitor is 1: 0.05 to 0.1;
the catalyst is Pt/C; the molar ratio of the 3, 5-dichloro-2, 4-difluoronitrobenzene to the catalyst is as follows: 0.0001-0.01.
2. The method for preparing the teflubenzuron intermediate 3, 5-dichloro-2, 4-difluoroaniline as claimed in claim 1, wherein the concentration of the phosphoric acid is 75-85%.
3. The method for preparing the teflubenzuron intermediate 3, 5-dichloro-2, 4-difluoroaniline as claimed in claim 1, wherein the temperature of the hydrogenation reduction reaction is 20-100 ℃.
4. The method for preparing the teflubenzuron intermediate 3, 5-dichloro-2, 4-difluoroaniline as claimed in claim 1, wherein the hydrogenation reduction reaction time is 0.5-24 hours.
5. The process for preparing teflubenzuron intermediate 3, 5-dichloro-2, 4-difluoroaniline as claimed in claim 1, wherein the reaction solvent in the hydrogenation reduction reaction is methanol, ethanol or isopropanol.
6. The method for preparing the teflubenzuron intermediate 3, 5-dichloro-2, 4-difluoroaniline as claimed in claim 5, wherein the mass ratio of the 3, 5-dichloro-2, 4-difluoronitrobenzene to the reaction solvent is 1: 7 to 10.
7. The method for preparing the teflubenzuron intermediate 3, 5-dichloro-2, 4-difluoroaniline as claimed in claim 1, wherein the pressure of the hydrogenation reduction reaction is 1.0-2.5 Mpa.
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