Preparation method of 2-sulfydryl-6-chlorobenzoic acid

Abstract

The invention relates to the technical field of chemical synthesis, in particular to a preparation method of 2-sulfydryl-6-chlorobenzoic acid, which comprises the following steps: dissolving chlorobenzoic acid in dimethyl sulfoxide, adding sodium hydrogen sulfite, and stirring at room temperature; the preparation method comprises the following steps: dissolving mercaptobenzoate in dimethyl sulfoxide, adding sodium carbonate and dimethylamino, and reacting at high temperature; cooling to room temperature, and adjusting the pH value to be neutral by using dilute acid; adding into diethyl ether, uniformly mixing, adding into dilute acid, and standing for layering to obtain 2-sulfydryl-6-chlorobenzoic acid; the preparation method of the chlorobenzoic acid comprises the following steps: mixing parachlorotoluene with water, adding a supported catalyst, stirring and heating; after the temperature rises to 80 DEG C, adding potassium permanganate in batches for reaction; and filtering, adjusting the pH value to be acidic by using dilute acid, and then carrying out suction filtration and drying to obtain the chlorobenzoic acid. According to the preparation method disclosed by the invention, chlorobenzoic acid and mercaptobenzoate are subjected to a reaction to obtain 2-mercapto-6-chlorobenzoic acid with high yield; the method has the characteristics of simplified operation, energy consumption reduction, shortened production period and low production cost.

Description

Technical Field

[0001] The invention relates to the technical field of chemical synthesis, in particular to a method for preparing 2-mercapto-6-chlorobenzoic acid. Background Art

[0002] 2-Mercapto-6-chlorobenzoic acid is a light yellow solid with a density of 1.49. It is a key intermediate of the new generation of broad-spectrum herbicides, pyrimidine sulfoxide. It is an acetolactate synthase inhibitor that prevents weeds by preventing the biosynthesis of amino acids. It can prevent annual and perennial grass weeds and most broad-leaved weeds. It has a good control effect on difficult-to-control weeds such as various morning glories, Xanthium sibiricum, Abutilon, Prickly Yellow Grass, Amaranthus chinensis, Arab sorghum, etc., so it has a wide range of applications and huge market prospects. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a preparation method of 2-mercapto-6-chlorobenzoic acid to solve the above problems.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing 2-mercapto-6-chlorobenzoic acid, the specific steps are as follows: Step 1, dissolving chlorobenzoic acid in dimethyl sulfoxide, adding sodium bisulfite, and stirring at room temperature; Step 2, dissolving mercaptobenzoate in dimethyl sulfoxide, adding sodium carbonate and dimethylamino, and then adding the product of step 1, and reacting at high temperature; Step 3, cooling to room temperature, and adjusting the pH value to neutral with dilute acid; Step 4, add ether and mix well, then add dilute acid and let stand for stratification to obtain 2-mercapto-6-chlorobenzoic acid; The specific steps of the preparation method of the chlorobenzoic acid are as follows: S1, mixing para-chlorotoluene and water, adding a supported catalyst, stirring and heating; S2, after the temperature rises to 80°C, potassium permanganate is added in batches to react; S3, filter, adjust the pH value to acidic with dilute acid, then filter and dry to obtain chlorobenzoic acid.

[0005] As a further solution of the present invention, in the step 1, the stirring temperature is 20-26° C., and the stirring is performed for 6-8 hours.

[0006] As a further solution of the present invention, the reaction temperature in step 2 is 75-85°C and the reaction time is 3-5h.

[0007] As a further solution of the present invention, the dilute acid is dilute hydrochloric acid, and the concentration is 4-7 mol / L.

[0008] As a further solution of the present invention, the dilute acid in step 4 is dilute hydrochloric acid, and the concentration is 4-7 mol / L.

[0009] As a further embodiment of the present invention, the supported catalyst in S1 is quaternary ammonium salt A-1.

[0010] As a further embodiment of the present invention, the supported catalyst is benzyltriethylammonium salt.

[0011] As a further solution of the present invention, potassium permanganate is added to S2 in batches to react for 2-3 hours.

[0012] As a further solution of the present invention, the S3 dilute acid is dilute hydrochloric acid, and has a concentration of 4-7 mol / L; and a pH value of 2-3.

[0013] As a further embodiment of the present invention, the mass ratio of p-chlorotoluene: water: supported catalyst: potassium permanganate is 1: (250-400): (2.4-2.8): (0.02-0.06) Since the present invention adopts the above technical scheme, the present invention has the advantages and positive effects of: obtaining a high yield of 2-mercapto-6-chlorobenzoic acid by reacting chlorobenzoic acid and mercaptobenzoic acid ester; and having the characteristics of simplified operation, energy saving, shortened production cycle and low production cost. DETAILED DESCRIPTION

[0014] Example 1 The present invention provides a method for preparing 2-mercapto-6-chlorobenzoic acid, which comprises the following specific steps: Step 1, dissolve chlorobenzoic acid in dimethyl sulfoxide, add sodium bisulfite, and stir at 20°C for 6 hours; Step 2, dissolving mercaptobenzoate in dimethyl sulfoxide, adding sodium carbonate and dimethylamino, and then adding the product of step 1, reacting at 75° C. for 3 h; Step 3, cooling to room temperature, and adjusting the pH value to neutral with 4 mol / L dilute hydrochloric acid; Step 4, add ether and mix well, then add 4 mol / L dilute hydrochloric acid and let stand for stratification to obtain 2-mercapto-6-chlorobenzoic acid with a yield of 87.7%; The specific steps of the preparation method of the chlorobenzoic acid are as follows: S1, after mixing p-chlorotoluene and water, adding benzyltriethylammonium salt, stirring and heating; S2, after the temperature rises to 80°C, potassium permanganate is added in batches to react for 2h; S3, filtering, adjusting the pH value to 2 with 4 mol / L dilute hydrochloric acid, then filtering and drying to obtain chlorobenzoic acid; Wherein, the mass ratio of p-chlorotoluene: water: supported catalyst: potassium permanganate is 1:250:2.4:0.02.

[0015] Example 2 The present invention provides a method for preparing 2-mercapto-6-chlorobenzoic acid, which comprises the following specific steps: Step 1, dissolve chlorobenzoic acid in dimethyl sulfoxide, add sodium bisulfite, and stir at 22°C for 6.5h; Step 2, dissolving mercaptobenzoate in dimethyl sulfoxide, adding sodium carbonate and dimethylamino, and then adding the product of step 1, reacting at 78°C for 3.5h; Step 3, cooling to room temperature, and adjusting the pH value to neutral with 5 mol / L dilute hydrochloric acid; Step 4, add ether and mix well, then add 5 mol / L dilute hydrochloric acid and let stand for stratification to obtain 2-mercapto-6-chlorobenzoic acid with a yield of 87.8%; The specific steps of the preparation method of the chlorobenzoic acid are as follows: S1, after mixing p-chlorotoluene and water, adding benzyltriethylammonium salt, stirring and heating; S2, after the temperature rises to 80°C, potassium permanganate is added in batches to react for 2.2h; S3, filtering, adjusting the pH value to 2.4 with 5 mol / L dilute hydrochloric acid, then filtering and drying to obtain chlorobenzoic acid; Wherein, the mass ratio of p-chlorotoluene: water: supported catalyst: potassium permanganate is 1:300:2.5:0.04.

[0016] Example 3 The present invention provides a method for preparing 2-mercapto-6-chlorobenzoic acid, which comprises the following specific steps: Step 1, dissolve chlorobenzoic acid in dimethyl sulfoxide, add sodium bisulfite, and stir at 24°C for 7 hours; Step 2, dissolving mercaptobenzoate in dimethyl sulfoxide, adding sodium carbonate and dimethylamino, and then adding the product of step 1, reacting at 81° C. for 4 hours; Step 3, cooling to room temperature, and adjusting the pH value to neutral with 6 mol / L dilute hydrochloric acid; Step 4, add ether and mix well, then add 6 mol / L dilute hydrochloric acid and let stand for stratification to obtain 2-mercapto-6-chlorobenzoic acid with a yield of 87.6%; The specific steps of the preparation method of the chlorobenzoic acid are as follows: S1, after mixing p-chlorotoluene and water, adding benzyltriethylammonium salt, stirring and heating; S2, after the temperature rises to 80°C, potassium permanganate is added in batches to react for 2.5 hours; S3, filtering, adjusting the pH value to 2.8 with 6 mol / L dilute hydrochloric acid, then filtering by suction and drying to obtain chlorobenzoic acid; Wherein, the mass ratio of p-chlorotoluene: water: supported catalyst: potassium permanganate is 1:350:2.7:0.05.

[0017] Example 4 The present invention provides a method for preparing 2-mercapto-6-chlorobenzoic acid, which comprises the following specific steps: Step 1, dissolve chlorobenzoic acid in dimethyl sulfoxide, add sodium bisulfite, and stir at 26°C for 8 hours; Step 2, dissolving mercaptobenzoate in dimethyl sulfoxide, adding sodium carbonate and dimethylamino, and then adding the product of step 1, reacting at 85° C. for 5 hours; Step 3, cooling to room temperature, and adjusting the pH value to neutral with 7 mol / L dilute hydrochloric acid; Step 4, add ether and mix well, then add 7 mol / L dilute hydrochloric acid and let stand for stratification to obtain 2-mercapto-6-chlorobenzoic acid with a yield of 87.9%; The specific steps of the preparation method of the chlorobenzoic acid are as follows: S1, after mixing p-chlorotoluene and water, adding benzyltriethylammonium salt, stirring and heating; S2, after the temperature rises to 80°C, potassium permanganate is added in batches to react for 3 hours; S3, filtering, adjusting the pH value to 3 with 7 mol / L dilute hydrochloric acid, then filtering and drying to obtain chlorobenzoic acid; Wherein, the mass ratio of p-chlorotoluene: water: supported catalyst: potassium permanganate is 1:400:2.8:0.06.

[0018] Although specific embodiments of the present invention are described above, those skilled in the art should understand that these are merely examples and that various changes or modifications may be made to the embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is limited only by the appended claims.

Claims

1. A method for preparing 2-mercapto-6-chlorobenzoic acid, characterized in that: Specific steps as follows: Step 1, dissolving chlorobenzoic acid in dimethyl sulfoxide, adding sodium bisulfite, and stirring at room temperature; Step 2, dissolving mercaptobenzoate in dimethyl sulfoxide, adding sodium carbonate and dimethylamino, and then adding the product of step 1, and reacting at high temperature; Step 3, cooling to room temperature, and adjusting the pH value to neutral with dilute acid; Step 4, add ether and mix well, then add dilute acid and let stand for stratification to obtain 2-mercapto-6-chlorobenzoic acid; The specific steps of the preparation method of the chlorobenzoic acid are as follows: S1, mixing para-chlorotoluene and water, adding a supported catalyst, stirring and heating; S2, after the temperature rises to 80°C, potassium permanganate is added in batches to react; S3, filter, adjust the pH value to acidic with dilute acid, then filter and dry to obtain chlorobenzoic acid.

2. The method for preparing 2-mercapto-6-chlorobenzoic acid according to claim 1, wherein: In the step 1, the stirring temperature is 20-26° C. and the stirring is performed for 6-8 hours.

3. A method for preparing 2-mercapto-6-chlorobenzoic acid according to claim 1, characterized in that: In the step 2, the reaction temperature is 75-85° C. and the reaction time is 3-5 h.

4. A method for preparing 2-mercapto-6-chlorobenzoic acid according to claim 1, characterized in that: The dilute acid is dilute hydrochloric acid, and has a concentration of 4-7 mol / L.

5. A method for preparing 2-mercapto-6-chlorobenzoic acid according to claim 1, characterized in that: The dilute acid in step 4 is dilute hydrochloric acid, and the concentration is 4-7 mol / L.

6. A method for preparing 2-mercapto-6-chlorobenzoic acid according to claim 1, characterized in that: The supported catalyst in S1 is quaternary ammonium salt A-1.

7. A method for preparing 2-mercapto-6-chlorobenzoic acid according to claim 6, characterized in that: The supported catalyst is benzyltriethylammonium salt.

8. A method for preparing 2-mercapto-6-chlorobenzoic acid according to claim 1, characterized in that: The S2 is added with potassium permanganate in batches to react for 2-3 hours.

9. A method for preparing 2-mercapto-6-chlorobenzoic acid according to claim 1, characterized in that: The S3 dilute acid is dilute hydrochloric acid, and has a concentration of 4-7 mol / L; and a pH value of 2-3.

10. A method for preparing 2-mercapto-6-chlorobenzoic acid according to claim 1, characterized in that: The mass ratio of p-chlorotoluene: water: supported catalyst: potassium permanganate is 1: (250-400): (2.4-2.8): (0.02-0.06).