Preparation method of fluorine-containing benzidine
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A technology of fluorobenzidine and benzidine, which is applied in the field of preparation of fluorine-containing benzidine, and can solve the problem of high cost
Inactive Publication Date: 2018-07-13
SHANGHAI CHEMSPEC CORP
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This method reduces the reaction steps to one step, which simplifies the process, but still requires the use of palladium catalysts for the reaction, and the cost is still high
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preparation example Construction
[0094] In the preparation method of fluorine-containing benzidine provided by the present invention, it may comprise: preparing the compound of formula I after coupling the compound of formula VI with the compound of formula IV, acidic hydrolysis, and the reaction equation is as follows:
[0095]
[0096] Wherein, Hal is selected from Br, Cl;
[0097] M is selected from Mg, Zn;
[0098] X is selected from Cl, Br, I, preferably Cl;
[0099] R 7 Selected from H, F, C1-C4 alkyl, C1-C4 alkoxy;
[0100] R 8 Selected from H, phenyl, C1-C4 alkyl, preferably H.
[0101] In the preparation method of fluorine-containing benzidine provided by the present invention, coupling reaction is carried out under the condition that catalyst exists usually, and the catalyzer used in coupling reaction can be nickel series catalyst usually, for example, can be nickel salt (for example, Can be a divalent nickel salt, more specifically can be for example NiCl 2 , nickel bromide, Ni(OAc) 2 etc...
Embodiment 1
[0139] Preparation of N-benzylidene-2-chloroaniline:
[0140] Under nitrogen protection, install a water separator in a 2L four-necked bottle, add 127.5g of 2-chloroaniline, 116g of benzaldehyde, 12.7g of p-toluenesulfonic acid and 1L of cyclohexane, reflux for 6 hours of water separation reaction, and there is no The reaction can be stopped when obvious water droplets are produced. After cooling to room temperature, add 100mL of 10% sodium hydroxide aqueous solution to wash, the organic phase is desolvated under reduced pressure, and the resulting residue is distilled under reduced pressure at 10mmHg to obtain 196.6g of the target product, N-benzylidene-2-chloroaniline, with a gas chromatography content of 99.0% , yield 91.2%.
Embodiment 2
[0142] Preparation of N-benzylidene-2-chloro-4-methylaniline:
[0143] Under the protection of nitrogen, install a water separator in a 2L four-neck bottle, add 141.6g of 2-chloro-4-methylaniline, 116g of benzaldehyde, 7.0g of p-toluenesulfonic acid and 1.2L of hexane, reflux for 6h, and separate The reaction can be stopped when there is no obvious water drop in the water container. After cooling to room temperature, 100 mL of 10% aqueous sodium hydroxide solution was added for washing, the organic phase was desolvated under reduced pressure, and the resulting residue was distilled under reduced pressure at 10 mmHg to obtain 206.7 g of the target product N-benzylidene-2-chloro-4-methylaniline. The gas chromatography content is 98.9%, and the yield is 90.0%.
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Abstract
The invention relates to the field of organic synthesis, in particular to a preparation method of fluorine-containing benzidine. The invention provides the preparation method of the fluorine-containing benzidine. The preparation method comprises the following steps: performing a dehydration reaction on a compound shown as a formula II and a compound shown as a formula III to obtain a compound shown as a formula IV; performing a reaction on a compound shown as a formula V and metal magnesium or metal zinc to obtain a compound shown as a formula VI; coupling the compound shown as the formula VIand the compound shown as the formula IV, and performing acidic hydrolysis to obtain a compound shown as a formula I. By a synthesis method of the fluorine-containing benzidine, provided by the invention, the raw material cost is low, a reaction can be performed on a chlorine-containing substrate to synthesize the target fluorine-containing benzidine, and in the synthesis process, use of a precious metal catalyst is not required and preparation of corresponding phenylboronic acid through a metal reagent is also not required, so that the technological production cost is further reduced; in addition, by the preparation method provided by the invention, the condition is mild, the reaction conversion rate is high, the atomic economy is good, and during post-treatment, a high-purity product canbe obtained through simple recrystallization.
Description
technical field [0001] The invention relates to the field of organic synthesis, in particular to a preparation method of fluorine-containing benzidine. Background technique [0002] As a class of important intermediates, fluorine-containing benzidine is widely used in industrial production fields such as pesticides and medicines. For example, 2-amino-3'4'5'-trifluoro-1,1-biphenyl, as a functional biphenyl compound, is an important intermediate in the chemical industry. These compounds can be used as important precursors of aryl or heteroaryl amides, and these amides can be used as important fungicides, such as BASF's amide fungicide Xemium, etc. These compounds are described in WO2006087343, WO2005123690, EP0589301 and There are a large number of reports in patents such as EP0545099. [0003] The methods for synthesizing fluorine-containing 2-aminobiphenyl compounds mainly include: [0004] 1. Suzuki coupling of halogenated nitrobenzene and fluorine-containing phenylboron...
Claims
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