Method for preparing halogenated methyl-benzaldehyde by Grignard reaction
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A technology of halogenated methylbenzaldehyde and Grignard reaction, which is applied in the field of preparation of halogenated benzaldehyde, can solve the problems of slow reaction and difficult industrial application, and achieve the effect of easy-to-obtain raw materials and simple process
Active Publication Date: 2010-05-26
溧阳常大技术转移中心有限公司
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However, this reaction can only proceed smoothly when the arene is replaced by an electron-donating group, and the reaction is slow when the arene is replaced by an electron-withdrawing group, so it is difficult for industrial application
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Embodiment 1
[0020] Put 6.5g (0.27mol) magnesium wire, 50mL tetrahydrofuran, 1g iodine pellets into a 500mL dry and clean device with a drying tube, stir, and add 1 / 10 volume of 51.4g (0.25mol) 3-chloro-4-bromotoluene dropwise Dissolve the mixed solution of 178g (200mL) anhydrous tetrahydrofuran to initiate the reaction, cool down to about 25°C, add dropwise the remaining 9 / 10 volume of 3-chloro-4-bromotoluene in anhydrous tetrahydrofuran solution, dropwise, and react at about 20°C 1h to get the Grignard reagent, lower the temperature to -5°C, add dropwise a mixture of 50mL tetrahydrofuran and 20g (0.27mol) N,N-dimethylformamide to the Grignard reagent, let it rise slowly to 20 ℃, react for 1h, below 20℃, adjust the pH ≤ 2, let it stand, separate the organic phase, use C for the water phase 2 h 4 Cl 2 Extract, combine the organic phases, remove the solvent, and steam distill to obtain 35.62g of 2-chloro-4-methylbenzaldehyde, with a yield of 69.3%.
Embodiment 2
[0022] With the technological operation step of embodiment 1, different conditions are:
[0023] 6.0g (0.25mol) of magnesium wire, 3g of iodine particles, 51.4g (0.25mol) of 3-chloro-4-bromotoluene in 154.2g (173mL) of anhydrous tetrahydrofuran solution, the reaction temperature after initiation is 10°C, -10°C Add N,N-dimethylformamide dropwise, yield 55.2%.
Embodiment 3
[0025] With the technological operation step of embodiment 1, different conditions are:
[0026] 5g iodine pellets, 514g (578mL) anhydrous tetrahydrofuran solution of 51.4g (0.25mol) 3-chloro-4-bromotoluene, the reaction temperature after initiation is 30°C, 18g (0.25mol) N, N-dimethylformaldehyde Amide, yield 64.1%.
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Abstract
The invention relates to a method for preparing halogenated methyl-benzaldehyde by Grignard reaction. The reaction is carried out according to the following reaction formula and the following steps: (1) adding magnesium chips, an organic solvent and an initiating agent into a dry reaction flask with nitrogen protection for stirring to obtain a mixed solution A, then dropwise adding 1/10 volume ofmixed solution B of halogenated benzene and the organic solvent into the mixed solution A for initiating the reaction, and dropwise adding residual 9/10 volume of the mixed solution B of the halogenated benzene and the organic solvent for reacting for 1h to prepare a Grignard reagent, wherein the reaction temperature is 10-80 DEG C, and iodine particles or 1,2-dibromoethane can be used as the initiating agent; and (2) cooling the Grignard reagent to -40-10 DEG C, dropwise adding a mixed solution of N,N-dimethyl formamide and the organic solvent into the Grignard reagent, then slowly heating the mixed solution to 10-45 DEG C for reacting for 0.5-5h, lowering the temperature below 20 DEG C, regulating the pH value to be less than or equal to 2, extracting with CH2Cl2, washing, removing the solvent, and distilling with water vapor to obtain the product. The invention has the advantages of easy acquisition of raw materials and simple processes, the product purity is greater than or equal to 99%, and the product yield is greater than 50%.
Description
technical field [0001] The present invention relates to the preparation method of halogenated benzaldehyde, more specifically, relate to the method for synthesizing chlorobenzaldehyde with halogenated benzene and N,N-dimethylformamide via Bouveault aldehyde. The method of the invention provides a method for preparing halogenated benzaldehyde with easy-to-obtain raw materials, simple operation and industrialization. Background technique [0002] Halogenated benzaldehyde is an important organic intermediate and has a wide range of uses in the fields of medicine, pesticides and dyes. For example, 3-chloro-5-methylbenzaldehyde is the raw material for the synthesis of tachykinin antagonist 1,2,4-trisubstituted piperazine derivatives for the treatment of tachykinin-mediated diseases, including asthma and bronchitis , rhinitis, cough, expectoration, etc.; 2-chloro-4-methylbenzaldehyde is a raw material for the synthesis of pyrazoline and its derivatives with different substituents...
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