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Method for preparing purified 2-methyl-4-chloropropionic acid

A technology of chloropropionic acid and chloropropionic acid, applied in the field of preparation of refined 2-methyl-4 chloropropionic acid, can solve the problems of large optical loss, low optical content of refined 2-methyl-4 chloropropionic acid, etc., and achieves low optical loss, Simple process and high yield

Inactive Publication Date: 2015-03-25
SHANDONG WEIFANG RAINBOW CHEM
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Problems solved by technology

The preparation method of this pure 2-methyl-4-chloropropionic acid provided by the prior art has a mature and stable process, but the optical loss is relatively large in the process of preparing pure 2-methyl-4-chloro-propionic acid, so that the prepared refined 2-methyl-4-chloropropionic acid The optical content is low and needs to be purified to reach 95%

Method used

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  • Method for preparing purified 2-methyl-4-chloropropionic acid
  • Method for preparing purified 2-methyl-4-chloropropionic acid
  • Method for preparing purified 2-methyl-4-chloropropionic acid

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preparation example Construction

[0026] The invention provides a kind of preparation method of refined 2-methyl-4-chloropropionic acid, comprising:

[0027] performing a first reaction with o-cresol and a first basic compound to obtain an o-cresol salt;

[0028] S-2 chloropropionic acid and the second basic compound are subjected to a second reaction to obtain chloropropionate;

[0029] Carrying out the third reaction of the o-formate and the chloropropionate in toluene to obtain o-tolyloxypropionic acid;

[0030] Under the action of amine compounds, the fourth reaction is carried out between hypochlorite and the o-tolyloxypropionic acid to obtain refined 2-methyl-4-chloropropionic acid.

[0031] The method provided by the present invention adopts o-cresol and chloropropionic acid to prepare o-cresyloxypropionic acid under alkaline conditions, and then chlorates the obtained o-cresyloxypropionic acid with hypochlorite to prepare refined 2,4 Chloropropionic acid. The optical content of the refined 2-methyl-...

Embodiment 1

[0075] Add 70.5g o-cresol and 82.5g mass concentration of 32.5% sodium hydroxide aqueous solution to a 250mL four-necked flask and carry out the first reaction at 40° C. for 1 hour to obtain sodium o-cresol.

[0076] Add 60.03g of S-2-chloropropionic acid and 66.5g of 32.5% sodium hydroxide aqueous solution to a 250mL four-necked flask at 30°C for 2 hours to obtain sodium chloropropionate.

[0077] Add 765 g of toluene to 153 g of the above-mentioned sodium o-cresolate for azeotropic dehydration to obtain a dehydrated product; add 50.6 g of the above-mentioned sodium chloropropionate dropwise to the dehydrated product, then raise the temperature to 130 ° C, and continue to drop The third reaction was carried out for 10 hours by adding 75.9 g of the above-mentioned sodium chloropropionate.

[0078] After the third reaction is completed, dilute the obtained third reaction product with 450g of water to obtain the material; transfer the material to a double-layer glass extraction ...

Embodiment 2

[0095] Add 70.4g of o-cresol and 82.3g of 32.5% sodium hydroxide aqueous solution to a 250mL four-necked flask at 40°C for 1 hour of the first reaction to obtain sodium o-cresol.

[0096] Add 60.04g of S-2-chloropropionic acid and 66.5g of 32.5% sodium hydroxide aqueous solution to a 250mL four-necked flask at 30°C for 2 hours to obtain sodium chloropropionate.

[0097] Add 758g of toluene to 152.7g of the above-mentioned sodium o-cresol and heat up to 100°C for dehydration to obtain a dehydrated product; add 43g of the above-mentioned sodium chloropropionate dropwise to the dehydrated product, and then raise the temperature to 128°C, Continue to dropwise add 83.5 g of the above-mentioned sodium chloropropionate to carry out the third reaction for 10 hours.

[0098] After the third reaction is completed, the obtained third reaction product is subjected to heat preservation treatment at 128° C. for 1 hour; the third reaction product after heat preservation treatment is diluted ...

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Abstract

The invention provides a method for preparing purified 2-methyl-4-chloropropionic acid. The method comprises the following steps: carrying out a first reaction on o-cresol and a first alkaline compound to obtain an o-cresol salt; carrying out a second reaction on S-2 chloropropionic acid and a second alkaline compound to obtain a chloropropionic acid salt; carrying out a third reaction on the o-cresol salt and the chloropropionic acid salt in methylbenzene to obtain o-toluene oxypropionate; and under the action of an alkaline compound, carrying out a fourth reaction on a pypocholoride and the o-toluene oxypropionate to obtain the purified 2-methyl-4-chloropropionic acid. The optical content of the purified 2-methyl-4-chloropropionic acid prepared by the method provided by the invention is higher. In addition, the optical loss of the method provided by the invention in a preparation process of the purified 2-methyl-4-chloropropionic acid is smaller; moreover, the method provided by the invention can be used for preventing the generation of dioxin, to ensure a higher yield of the purified 2-methyl-4-chloropropionic acid; and the method for preparing purified 2-methyl-4-chloropropionic acid provided by the invention is simple in process and smaller in environmental pollution.

Description

technical field [0001] The invention relates to the technical field of compound synthesis, in particular to a preparation method of refined 2-methyl-4-chloropropionic acid. Background technique [0002] 2-methyl-4-chloropropionic acid, referred to as MCPP, is a phenoxycarboxylic acid herbicide, which is mainly used in cereal crops to control weeds such as quinoa, pigtails and chickweed. MCPP has a chiral structure, and usually the prepared MCPP product is a racemic mixture, that is, a mixture of the right-handed R-body and its enantiomer, the left-handed S-body, but the herbicidally active structure in MCPP is almost all concentrated in the R-body In general, the S-body has almost no herbicidal activity, and the degradation rate of the S-body in the environment is relatively slow, so the market prospect for the production of R-body of 2-methyl-4-chloropropionic acid is broader. [0003] The R-body of 2-methyl-4-chloropropionic acid is also called refined 2-methyl-4-chloropr...

Claims

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Application Information

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IPC IPC(8): C07C59/68C07C51/363
CPCC07C51/363C07C37/66C07C51/367C07C51/41
Inventor 孙国庆侯永生李宗清朱小猛黄效鹏邱潇杨
Owner SHANDONG WEIFANG RAINBOW CHEM
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