Method for preparing 2-hydroxyl 3,6-dichlorobenzoic acid

A technology of dichlorobenzoic acid and dichlorobenzaldehyde, which is applied in the direction of oxidation to prepare carboxylic acid, hydrolysis to prepare carbonyl compounds, organic chemistry, etc., can solve the problems of expensive raw materials, low total reaction yield, long reaction steps, etc., and achieve the goal of reaction The conditions are easy to realize, the reaction raw materials are easy to obtain, and the effect of simple operation

Inactive Publication Date: 2015-03-25
SHANGHAI OCEAN UNIV
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  • Abstract
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AI Technical Summary

Problems solved by technology

Although this method avoids the use of high-pressure reactors in traditional methods, its reaction steps are long, which will inevitably lead to low overall yields, and Grignard reagents or organolithium reagents will be used, which makes the reaction still have certain shortcomings.
[0009] In a word, all the above-mentioned methods, either the raw materials are expensive, so that the production cost is higher, or the particularity of the reaction process requires the use of high-pressure equipment and must be able to react under very high pressure, making its industrialization difficult to realize, or the use of special and unreasonable materials in the reaction. Stable reagents such as organolithium reagents make industrial production difficult, or the reaction steps are too long, making the overall yield of the reaction lower

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] The preparation of embodiment 1 2-hydroxyl 3,6-dichlorobenzaldehyde (1)

[0033] Add 10.5g (0.14mol) of calcium hydroxide, 11.5g (0.11mol) of sodium carbonate, 5.216g (0.032mol) of 2,5-dichlorophenol and 80ml of water into the reactor, and heat the system to maintain the temperature at 65 Within -75°C, at this temperature, slowly add 12g (0.10mol) trichloromethane dropwise to the reaction system, the drop rate should be slow, and the drop will be completed within one hour. Then, the reaction was stirred overnight at 65-75°C. The temperature was lowered, and the reaction mixture was acidified with concentrated hydrochloric acid to pH 2, extracted with methyl tert-butyl ether, and the residue after removing the solvent was separated by column chromatography, and the developing solvent was petroleum ether: ethyl acetate = 15:1 to obtain 2 -Hydroxy 3,6-dichlorobenzaldehyde 3.85g, the yield rate is 63%, and the by-product 4-hydroxy 2,5-dichlorobenzaldehyde 1.83g can also be...

Embodiment 2

[0035] Embodiment 2 The preparation of 2-hydroxyl 3,6-dichlorobenzaldehyde (2)

[0036]Dissolve 5.216g (0.032mol) of 2,5-dichlorophenol in 15ml of ethanol solution and add it to the reactor, add 10.4g (0.26mol) of sodium hydroxide in 15ml of aqueous solution to the reaction system, and heat to maintain the temperature of the system Within 65-75°C, at this temperature, slowly add 12g (0.10mol) trichloromethane dropwise to the reaction system, the drop rate should be slow, and the drop will be completed within one hour. Then, the reaction was stirred overnight at 65-75°C. The temperature was lowered, and the reaction mixture was acidified with concentrated hydrochloric acid to pH 2, extracted with methyl tert-butyl, and the residue after removing the solvent was separated by column chromatography, and the developer was petroleum ether: ethyl acetate = 15: 1 to obtain 2- Hydroxyl 3,6-dichlorobenzaldehyde 3.36g, the yield rate is 55%, in addition, 2.44g of the by-product 4-hydrox...

Embodiment 3

[0038] Example 3 Preparation of 2-hydroxyl 3,6-dichlorobenzoic acid (1)

[0039] Under ice-water bath cooling, 2-hydroxyl 3,6-dichlorobenzaldehyde, 50ml water, 100ml toluene, 0.5g tetrabutylammonium iodide (1.36mmol) prepared by 3.4g (17.8mmol) embodiment 1 or 2 Added in the reactor, 8.7g (55mmol) potassium permanganate was added to the above-mentioned reaction system in three hours within 3 hours, the reaction system was naturally warmed up to room temperature, then stirred and reacted for 8 hours, and 5.2g (50mmol) of sulfurous acid was added Quench the reaction with sodium hydrogen, acidify to pH=2 with concentrated hydrochloric acid, separate the liquids, take the organic phase and dry it with anhydrous sodium sulfate, remove the solvent to obtain the crude product, and use 5ml of the sodium hydroxide solution alkali with a molar concentration of 4mol / L for the crude product After purification, the mixed solution is extracted with an organic solvent such as toluene, methyl...

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PUM

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Abstract

The invention belongs to the technical field of organic synthesis and aims at providing a method for preparing 2-hydroxyl 3,6-dichlorobenzoic acid. The method comprises the following two steps: by using marketed 2,5-dichlorophenol and trichloromethane as raw materials, inorganic bases such as sodium hydroxide, potassium hydroxide, calcium hydroxide, potassium carbonate and the like as bases and water or alcohol or an alcohol and water mixed solvent as a solvent, carrying out Reimer-Tiemann reaction to obtain 2-hydroxyl 3,6-dichlorobenzaldehyde; by using potassium permanganate as an oxidizing agent, oxidizing the obtained 2-hydroxyl 3,6-dichlorobenzaldehyde to obtain 2-hydroxyl 3,6-dichlorobenzoic acid in the presence of a phase transfer catalyst. The method is few in reaction steps (just two steps), a high pressure reaction kettle is not required for reaction, the reaction condition is easy to achieve, and the method is simple to operate and low in cost.

Description

technical field [0001] The invention belongs to the field of organic chemistry, in particular to a method for preparing a pesticide intermediate, in particular to a method for preparing 2-hydroxyl 3,6-dichlorobenzoic acid. Background technique [0002] 2-Hydroxy 3,6-dichlorobenzoic acid (I), also known as 3,6-dichlorosalicylic acid, English name is 3,6-dichloro-2-hydroxybenzoic acid, the structure is shown in formula (I), The pure product is white needle-like crystal, m.p.188~191℃, insoluble in water, soluble in alkali and organic solvent. It is an important pesticide intermediate and can be used to synthesize dicamba, a low-toxicity, high-efficiency and high-selectivity herbicide in upland fields. Dicamba is a benzoic acid herbicide with systemic conduction effect, and has a significant control effect on annual and perennial broad-leaved weeds, and is relatively safe on grass crops such as wheat, corn, millet, and rice. Due to its good performance, it is widely used at ho...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C65/05C07C51/16
CPCC07C45/43C07C51/16C07C47/565C07C65/05
Inventor 黄宏吴江涛李圆杏赵旭温博
Owner SHANGHAI OCEAN UNIV
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