1. A method for synthesizing diclofenac sodium is characterized in that: the method comprises the following steps:

stirring and dripping chloroacetyl chloride into a toluene solution, an aniline solution and a catalyst solution, carrying out heat preservation and reflux for carrying out acylation reaction, then adding 2, 6-dichlorophenol and sodium carbonate, carrying out heat preservation and reflux for carrying out etherification reaction, then extracting with water to obtain an oil layer, adding alkali into the oil layer, carrying out heat preservation for carrying out rearrangement reaction, and carrying out reduced pressure distillation after normal pressure to prepare 2, 6-dichlorodiphenylamine;

heating and melting the 2, 6-dichlorodiphenylamine prepared in the step (1), dripping chloroacetyl chloride, heating, carrying out heat preservation reaction, and crystallizing after hydrolysis to prepare N- (2, 6-dichlorophenyl) -phenyl-chloroacetamide;

heating the N- (2, 6-dichlorophenyl) -phenyl-chloroacetamide prepared in the step (2) to react with aluminum trichloride, transferring the materials into water, stirring, washing with water, and drying to obtain solid 1- (2, 6-dichlorophenyl) -2-indolinone;

and (4) adding the 1- (2, 6-dichlorophenyl) -2-indolinone prepared in the step (3) into an alkali liquor, stirring, heating up, refluxing, cooling and crystallizing to prepare the diclofenac sodium.

2. The method for synthesizing diclofenac sodium according to claim 1, characterized in that: the catalyst in the step (1) is one or more of benzyltriethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium chloride and tetrabutylammonium hydrogen sulfate.

3. The method for synthesizing diclofenac sodium according to claim 1, characterized in that: the base for rearrangement reaction in the step (1) is one or more of triethylamine, sodium methoxide, sodium ethoxide and potassium tert-butoxide.

4. The method for synthesizing diclofenac sodium according to claim 1, characterized in that: in the step (1), the mass ratio of 2, 6-dichlorophenol, aniline, chloroacetyl chloride, catalyst, alkali and toluene is 1: 0.5-0.8: 0.6-1.0: 0.005-0.5: 0.4-2.0: 2 to 8.

5. The method for synthesizing diclofenac sodium according to claim 1, characterized in that: in the step (1), the acylation reaction temperature is 80-100 ℃, the etherification reaction temperature is 80-120 ℃, and the rearrangement reaction temperature is 80-110 ℃.

6. The method for synthesizing diclofenac sodium according to claim 1, characterized in that: the temperature of the reduced pressure distillation in the step (1) is 180-260 ℃.

7. The method for synthesizing diclofenac sodium according to claim 1, characterized in that: in the step (2), the temperature for heating and melting the 2, 6-dichlorodiphenylamine is 50-60 ℃, and the temperature for heat preservation reaction is 120-130 ℃.

8. The method for synthesizing diclofenac sodium according to claim 1, characterized in that: the heat preservation reaction temperature in the step (3) is 140-180 ℃, and the mass ratio of N- (2, 6-dichlorophenyl) -phenyl-chloroacetamide to aluminum trichloride is 1: 0.6 to 1.2.

9. The method for synthesizing diclofenac sodium according to claim 1, characterized in that: in the step (4), the temperature of the heating reflux is 90-105 ℃, and the alkali liquor is NaOH solution with the concentration of 10% -40%.

Background

Diclofenac sodium (diclofenac sodium), chemical name: 2- [ (2, 6-dichlorophenyl) amino ] -sodium phenylacetate, a third-generation potent anti-inflammatory analgesic non-steroidal anti-inflammatory drug developed by Ciba-Geigy Ltd, Switzerland and marketed in 1974. The traditional Chinese medicine composition is clinically used for treating various rheumatoid diseases and osteoarthritis and relieving pain caused by operation, strain and trauma. The effect of the aspirin is 2-2.5 times stronger than that of indomethacin and 26-50 times stronger than that of aspirin. Has obvious pain relieving, inflammation diminishing, antirheumatic and antipyretic effects, unobvious side effects, good tolerance and rapid oral absorption.

Non-steroidal anti-inflammatory analgesics (NSAIDs) are the fastest growing drugs worldwide. Since the market of the coxib drugs is changed and fluctuated after the drugs are successively exposed due to side effects, especially, a plurality of product patents are failed successively, and the drugs with common names become the main bodies of the drugs. The anti-inflammatory analgesic industry in China is mainly characterized by large scale, high yield and complete varieties. In the competition of the best product price, China has become the biggest country in Asia and the second largest anti-inflammatory analgesic production and export country in the world, thereby laying a good foundation for the external trade market of pharmaceutical and chemical industries in China. NSAIDs have become the largest class of drug for hospital use.

The diclofenac sodium is successfully synthesized for the first time in 1975, and then countries such as English, German, Japanese, Fa and the like successively research and produce the diclofenac sodium and successfully put into the market. Up to now, there are dozens of synthetic methods published by domestic and foreign documents, such as: (1) the o-halobenzoic acid method is the earliest process for production in domestic pharmaceutical factories: the o-halobenzoic acid and 2, 6-dichloroaniline are used as raw materials, condensation is carried out to obtain 2- (2, 6-dichlorophenylamino) benzoic acid, acylation and friedel-crafts alkylation reaction are carried out on the benzoic acid and chloroacetyl chloride after high-temperature decarboxylation, and finally, the product diclofenac sodium is obtained through hydrolysis. The method has the advantages of easily available raw materials, complicated steps and low yield. (2) Dutch patent 6604752 and Japanese patent 23418 propose bromobenzene and 2, 6-dichloroaniline as raw materials to be directly subjected to Ullmann condensation to obtain 2, 6-dichlorodiphenylamine, and the product is obtained through chloroacetylation, intramolecular para-gram alkylation and alkaline hydrolysis. The yield is improved, but the generated by-product is difficult to separate and has strong side effect. (3) Chen Fener et al (Chinese patent: CN 1580039A) use cyclohexanone as starting material, chloro-react to obtain 2, 2,6, 6-tetrachlorocyclohexanone, condense with aniline to form corresponding Schiff alkali, generate 2, 6-dichlorodiphenylamine through dehydrochlorination and isomerization reaction, and obtain final product through acylation and Friedel-crafts alkylation hydrolysis. The yield is improved, but the materials used by the method, such as organophosphorus, palladium catalyst and the like, have serious environmental pollution. (4) In 1979, Japanese patents 72152, 87748 and 108844 show a one-step Ullmann condensation of o-halophenylacetic acid with 2, 6-dichloroaniline under the catalysis of cuprous iodide to obtain the product. Chinese scholars have improved the method, but the yield is still generally low, the raw materials are not easy to obtain, the cost is high, and the three wastes are seriously polluted.

Disclosure of Invention

The invention aims to provide a synthetic method of diclofenac sodium, which is convenient to prepare and easy to operate.

In order to achieve the purpose, the invention adopts the technical scheme that:

a synthetic method of diclofenac sodium comprises the following steps:

(1) stirring and dripping chloroacetyl chloride into a toluene solution, an aniline solution and a catalyst solution, carrying out heat preservation and reflux for carrying out acylation reaction, then adding 2, 6-dichlorophenol and sodium carbonate, carrying out heat preservation and reflux for carrying out etherification reaction, then extracting with water to obtain an oil layer, adding alkali into the oil layer, carrying out heat preservation for carrying out rearrangement reaction, and distilling under normal pressure and reduced pressure to prepare 2, 6-dichlorodiphenylamine (compound II);

(2) heating and melting the 2, 6-dichlorodiphenylamine prepared in the step (1), dripping chloroacetyl chloride, heating, carrying out heat preservation reaction, hydrolyzing and crystallizing to prepare N- (2, 6-dichlorophenyl) -phenyl-chloroacetamide (compound III);

(3) heating the N- (2, 6-dichlorophenyl) -phenyl-chloroacetamide prepared in the step (2) to react with aluminum trichloride, transferring the materials into water, stirring, washing with water, and drying to obtain solid 1- (2, 6-dichlorophenyl) -2-indolinone (compound IV);

(4) and (3) adding the 1- (2, 6-dichlorophenyl) -2-indolinone prepared in the step (3) into an alkali liquor, stirring, heating, refluxing, cooling and crystallizing to prepare the diclofenac sodium (compound I).

Further, the catalyst in the step (1) is one or more of benzyltriethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium chloride and tetrabutylammonium hydrogen sulfate.

Further, the base for rearrangement reaction in the step (1) is one or more of triethylamine, sodium methoxide, sodium ethoxide and potassium tert-butoxide.

Further, in the step (1), the mass ratio of the 2, 6-dichlorophenol, the aniline, the chloroacetyl chloride, the catalyst, the alkali and the toluene is 1: 0.5-0.8: 0.6-1.0: 0.005-0.5: 0.4-2.0: 2 to 8.

Further, in the step (1), the acylation reaction temperature is 80-100 ℃, the etherification reaction temperature is 80-120 ℃, and the rearrangement reaction temperature is 80-110 ℃.

Further, the temperature of the reduced pressure distillation in the step (1) is 180-260 ℃.

Further, in the step (2), the temperature for heating and melting the 2, 6-dichlorodiphenylamine is 50-60 ℃, and the temperature for heat preservation reaction is 120-130 ℃.

Further, the temperature of the heat preservation reaction in the step (3) is 140-180 ℃, and the mass ratio of the N- (2, 6-dichlorophenyl) -phenyl-chloroacetamide to the aluminum trichloride is 1: 0.6 to 1.2.

Further, the temperature of the heating reflux in the step (4) is 90-105 ℃, and the alkali liquor is NaOH solution with the concentration of 10% -40%.

Further, a method for synthesizing diclofenac sodium comprises the following steps:

(1) 2-8 parts of toluene, 0.5-0.8 part of aniline and 0.005-0.5 part of catalyst are put into a dry four-necked bottle, the catalyst is one or more of benzyltriethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium chloride and tetrabutylammonium hydrogen sulfate, tail gas absorption is started, 0.6-1.0 part of chloroacetyl chloride is stirred and dripped into the solution, the dripping time is about 1.5h, the temperature is controlled to be 15-25 ℃, the temperature is slowly raised to 80-100 ℃ after dripping is finished, a small amount of toluene is added after reflux and heat preservation is carried out for 4h, and the temperature is reduced to 60-70 ℃. Then adding 1 part of 2, 6-dichlorophenol and 0.6 part of sodium carbonate, heating to 80-120 ℃, preserving heat for 18h, and cooling to 75 ℃. Adding purified water, heating to 80-100 ℃, continuing stirring and preserving heat for 1h, standing, extracting to obtain an oil layer, adding 0.4-2.0 parts of alkali, preserving heat for 6h at 80-110 ℃, wherein the alkali for rearrangement reaction is one or more of triethylamine, sodium methoxide, sodium ethoxide and potassium tert-butoxide. Washing with water, separating an oil layer, distilling under normal pressure and reduced pressure, recovering toluene, distilling under reduced pressure, and collecting 180-260 ℃ fractions to prepare the 2, 6-dichlorodiphenylamine.

(2) Adding the 2, 6-dichlorodiphenylamine prepared in the step (1) into a drying reaction bottle, heating to 50-60 ℃ for melting, dropwise adding 0.5-0.8 part of chloroacetyl chloride, heating to 120-130 ℃, and carrying out heat preservation reaction for 3 hours. Adding the mixture into water after reaction, stirring, crystallizing, cooling, performing suction filtration, draining, washing the material with a small amount of toluene, and drying to obtain the N- (2, 6-dichlorophenyl) -phenyl-chloroacetamide.

(3) And (3) putting the N- (2, 6-dichlorophenyl) -phenyl-chloroacetamide prepared in the step (2) and 0.6-1.2 parts of aluminum trichloride into a dry reaction bottle, connecting an HCl tail gas recovery system, heating, raising the temperature to 140-180 ℃, and carrying out heat preservation reaction for 1.5 hours. Transferring the materials into purified water, stirring, washing with water to make the pH value close to neutral, and pumping to dry to obtain a tan solid 1- (2, 6-dichlorophenyl) -2-indolinone.

(4) And (3) adding the 1- (2, 6-dichlorophenyl) -2-indolinone prepared in the step (3) into 1-4 parts of alkali liquor, wherein the alkali liquor is NaOH solution with the concentration of 10% -40%, stirring and heating to 90-105 ℃, refluxing for 4 hours, then adding 0.005-0.02 part of sodium hydrosulfite, and continuously refluxing for 2 hours. Cooling to room temperature, vacuum filtering, washing with water to pH 7-8, and vacuum drying to obtain diclofenac sodium.

The invention has the advantages that:

(1) the method for synthesizing diclofenac sodium comprises the steps of extracting to obtain an oil layer, and adding one or more of triethylamine, sodium methoxide, sodium ethoxide and potassium tert-butoxide for rearrangement reaction. Firstly, the impurities are removed by extraction, and then the target etherification product is subjected to rearrangement reaction, so that the generation of by-products is reduced, and the product purity is improved.

(2) The method takes the methylbenzene as the solvent in the step (1), does not participate in other organic solvents, is easy to separate the methylbenzene, is simple in post-treatment, can be recycled, reduces the cost and improves the yield.

(3) In the process of obtaining diclofenac sodium by hydrolysis, the method of azeotropic dehydration of a phase transfer catalyst and a NaOH solution in xylene or higher alcohol in the prior art is not adopted, the compound III is refluxed with water and NaOH, sodium hydrosulfite can be added for continuous reflux, and the process monitoring shows that the reaction is complete, and the crude product is obtained by suction filtration, water washing and drying. The method not only saves the solvent, but also shortens the reaction time, simplifies the reaction steps, reduces the cost, is convenient for subsequent treatment and improves the production efficiency.

(4) The invention firstly prepares a compound II by condensation reaction of aniline and 2, 6-dichlorophenol, then prepares a compound III by acyl chlorination reaction of the compound II and chloroacetyl chloride, prepares a compound IV by intramolecular cyclization of the compound III under the catalysis of Lewis acid, and finally prepares the diclofenac sodium (compound I) by hydrolysis ring-opening and salt-forming reaction of the compound IV. The total molar yield is up to 80.2 percent based on 2, 6-dichlorophenol. The invention has the advantages of rich raw material sources, single solvent, simple and convenient operation process, stable synthesis method, low cost and high yield, is suitable for industrial production, and has the following specific reaction mechanism:

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples, and the specific examples described herein are only for explaining the present invention and are not intended to limit the present invention.

Example 1

A synthetic method of diclofenac sodium comprises the following steps:

(1) 2 parts of toluene, 0.5 part of aniline and 0.005 part of benzyltriethylammonium chloride are put into a dry four-necked bottle, tail gas absorption is started, 0.6 part of chloroacetyl chloride is stirred and dripped into the solution, the dripping time is about 1.5h, the temperature is controlled to be 15 ℃, the temperature is slowly increased to 80 ℃ after dripping, a small amount of toluene is added after reflux and heat preservation are carried out for 4h, and the temperature is reduced to 60 ℃. Then adding 1 part of 2, 6-dichlorophenol and 0.6 part of sodium carbonate, heating to 80 ℃, preserving heat for 18 hours, and cooling to 75 ℃. Adding purified water, heating to 80 ℃, continuing stirring and preserving heat for 1h, standing, extracting to obtain an oil layer, adding 0.4 part of triethylamine, and preserving heat for 6h at 80 ℃. Washing with water, separating an oil layer, distilling under normal pressure and reduced pressure, recovering toluene, distilling under reduced pressure, and collecting 180-260 ℃ fractions to prepare the 2, 6-dichlorodiphenylamine.

(2) And (2) adding the 2, 6-dichlorodiphenylamine prepared in the step (1) into a drying reaction bottle, heating to 50-60 ℃ for melting, dropwise adding 0.5 part of chloroacetyl chloride, heating to 120 ℃, and carrying out heat preservation reaction for 3 hours. Adding the mixture into water after reaction, stirring, crystallizing, cooling, performing suction filtration, draining, washing the material with a small amount of toluene, and drying to obtain the N- (2, 6-dichlorophenyl) -phenyl-chloroacetamide.

(3) And (3) putting the N- (2, 6-dichlorophenyl) -phenyl-chloroacetamide prepared in the step (2) and 0.6 part of aluminum trichloride into a drying reaction bottle, connecting an HCl tail gas recovery system, heating, raising the temperature to 140 ℃, and carrying out heat preservation reaction for 1.5 hours. Transferring the materials into purified water, stirring, washing with water to make the pH value close to neutral, and pumping to dry to obtain a tan solid 1- (2, 6-dichlorophenyl) -2-indolinone.

(4) And (3) adding the 1- (2, 6-dichlorophenyl) -2-indolinone prepared in the step (3) into 1 part of 10% NaOH solution, stirring and heating to 90 ℃, refluxing for 4h, then adding 0.005 part of sodium hydrosulfite, and continuously refluxing for 2 h. Cooling to room temperature, vacuum filtering, washing with water to pH 7, and vacuum drying to obtain diclofenac sodium. Through HPLC detection, the content of diclofenac sodium is 99.8%, and the melting point is: 288 ℃ and 290 ℃.

Example 2

(1) 8 parts of toluene, 0.8 part of aniline and 0.5 part of tetrabutylammonium bromide are put into a dry four-necked bottle, tail gas absorption is started, 1.0 part of chloroacetyl chloride is stirred and dripped into the solution, the dripping time is about 1.5h, the temperature is controlled to be 25 ℃, the temperature is slowly increased to 100 ℃ after dripping, a small amount of toluene is added after reflux and heat preservation are carried out for 4h, and the temperature is reduced to 70 ℃. Then adding 1 part of 2, 6-dichlorophenol and 0.6 part of sodium carbonate, heating to 120 ℃, preserving heat for 18 hours, and cooling to 75 ℃. Adding purified water, heating to 100 ℃, continuing stirring and preserving heat for 1h, standing, extracting to obtain an oil layer, adding 2.0 parts of sodium methoxide, heating to 110 ℃, and preserving heat for 6 h. Washing with water, separating an oil layer, distilling under normal pressure and reduced pressure, recovering toluene, distilling under reduced pressure, and collecting 180-260 ℃ fractions to prepare the 2, 6-dichlorodiphenylamine.

(2) And (2) adding the 2, 6-dichlorodiphenylamine prepared in the step (1) into a drying reaction bottle, heating to 50-60 ℃ for melting, dropwise adding 0.8 part of chloroacetyl chloride, heating to 130 ℃, and carrying out heat preservation reaction for 3 hours. Adding the mixture into water after reaction, stirring, crystallizing, cooling, performing suction filtration, draining, washing the material with a small amount of toluene, and drying to obtain the N- (2, 6-dichlorophenyl) -phenyl-chloroacetamide.

(3) And (3) putting the N- (2, 6-dichlorophenyl) -phenyl-chloroacetamide prepared in the step (2) and 1.2 parts of aluminum trichloride into a drying reaction bottle, connecting an HCl tail gas recovery system, heating, raising the temperature to 180 ℃, and carrying out heat preservation reaction for 1.5 hours. Transferring the materials into purified water, stirring, washing with water to make the pH value close to neutral, and pumping to dry to obtain a tan solid 1- (2, 6-dichlorophenyl) -2-indolinone.

(4) And (3) adding the 1- (2, 6-dichlorophenyl) -2-indolinone prepared in the step (3) into 4 parts of 40% NaOH solution, stirring and heating to 105 ℃, refluxing for 4h, then adding 0.02 part of sodium hydrosulfite, and continuously refluxing for 2 h. Cooling to room temperature, vacuum filtering, washing with water to pH 8, and vacuum drying to obtain diclofenac sodium. Through HPLC detection, the content of diclofenac sodium is 99.8%, and the melting point is: 288 ℃ and 290 ℃.

Example 3

(1) 5 parts of toluene, 0.6 part of aniline and 0.25 part of catalyst are put into a dry four-necked bottle, the catalyst is tetrabutylammonium chloride and tetrabutylammonium hydrogen sulfate, tail gas absorption is started, 0.8 part of chloroacetyl chloride is stirred and dripped into the solution, the dripping time is about 1.5h, the temperature is controlled to be 20 ℃, the temperature is slowly increased to 90 ℃ after dripping is finished, a small amount of toluene is added after reflux and heat preservation are carried out for 4h, and the temperature is reduced to 65 ℃. Then adding 1 part of 2, 6-dichlorophenol and 0.6 part of sodium carbonate, heating to 100 ℃, preserving heat for 18 hours, and cooling to 75 ℃. Adding purified water, heating to 90 deg.C, stirring and maintaining for 1h, standing, extracting to obtain oil layer, adding 1.2 parts of sodium ethoxide and tert-butanol, and maintaining at 95 deg.C for 6 h. Washing with water, separating an oil layer, distilling under normal pressure and reduced pressure, recovering toluene, distilling under reduced pressure, and collecting 180-260 ℃ fractions to prepare the 2, 6-dichlorodiphenylamine.

(2) And (2) adding the 2, 6-dichlorodiphenylamine prepared in the step (1) into a drying reaction bottle, heating to 50-60 ℃ for melting, dropwise adding 0.65 part of chloroacetyl chloride, heating to 125 ℃, and carrying out heat preservation reaction for 3 hours. Adding the mixture into water after reaction, stirring, crystallizing, cooling, performing suction filtration, draining, washing the material with a small amount of toluene, and drying to obtain the N- (2, 6-dichlorophenyl) -phenyl-chloroacetamide.

(3) And (3) putting the N- (2, 6-dichlorophenyl) -phenyl-chloroacetamide prepared in the step (2) and 0.9 part of aluminum trichloride into a drying reaction bottle, connecting an HCl tail gas recovery system, heating, raising the temperature to 160 ℃, and carrying out heat preservation reaction for 1.5 hours. Transferring the materials into purified water, stirring, washing with water to make the pH value close to neutral, and pumping to dry to obtain a tan solid 1- (2, 6-dichlorophenyl) -2-indolinone.

(4) And (3) adding the 1- (2, 6-dichlorophenyl) -2-indolinone prepared in the step (3) into 2.5 parts of 25% NaOH solution, stirring and heating to 97 ℃, refluxing for 4 hours, then adding 0.01 part of sodium hydrosulfite, and continuously refluxing for 2 hours. Cooling to room temperature, vacuum filtering, washing with water to pH 7, and vacuum drying to obtain diclofenac sodium. Through HPLC detection, the content of diclofenac sodium is 99.8%, and the melting point is: 288 ℃ and 290 ℃.