CN116836110A - Preparation method of 2-aminoethyl-3-chloro-5-trifluoromethyl pyridine hydrochloride - Google Patents

Preparation method of 2-aminoethyl-3-chloro-5-trifluoromethyl pyridine hydrochloride Download PDF

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CN116836110A
CN116836110A CN202310794562.7A CN202310794562A CN116836110A CN 116836110 A CN116836110 A CN 116836110A CN 202310794562 A CN202310794562 A CN 202310794562A CN 116836110 A CN116836110 A CN 116836110A
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栗晓东
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Tianjin Junkai Agricultural Technology Co ltd
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    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D213/00—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members
    • C07D213/02—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members
    • C07D213/04—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom
    • C07D213/60—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
    • C07D213/61—Halogen atoms or nitro radicals

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Abstract

The invention provides a preparation method of 2-aminoethyl-3-chloro-5-trifluoromethyl pyridine hydrochloride, which comprises the following steps: s1: 2-acetyl-3-chloro-5-trifluoromethyl pyridine reacts with hydroxylamine in a solution under alkaline conditions to obtain 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethylamino p-toluenesulfonate; s2: reacting 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethylamino p-toluenesulfonate in a solution at low temperature under alkaline conditions to obtain 2-amino-1- (3-chloro-5-trifluoromethyl) pyridin-2-yl) ethanone; s3: 2-amino-1- (3-chloro-5-trifluoromethyl pyridine-2-yl) ethanone is reduced by a reducing agent under the action of a catalyst in solution, and finally salified to obtain 2-aminoethyl-3-chloro-5-trifluoromethyl pyridine hydrochloride. The invention has the beneficial effects that: the total yield of the three steps is 82%, the purity of the product is more than 99%, the used solvent can be recycled, the reaction route is short, the reaction yield is high, the purity of the product is high, no special process is needed, and the industrial popularization can be carried out.

Description

Preparation method of 2-aminoethyl-3-chloro-5-trifluoromethyl pyridine hydrochloride
Technical Field
The invention belongs to the field of organic synthesis and fine chemicals, and particularly relates to a preparation method of fluopyram intermediate 2-aminoethyl-3-chloro-5-trifluoromethyl pyridine hydrochloride.
Background
Fluopyram is a pyridine ethyl benzamide fungicide discovered and developed by bayer and first reported in 2009. The bayer market in 2012 has been registered and marketed in countries including china, united states, european union, australia, turkish, roman, chile, mexico, etc. worldwide, and has been mainly applied to a variety of crop fields such as field crops, vegetables, flowers, lawns, melons, fruits, tobacco, etc. In 2003, bayer crop science corporation applied for compound patents on fluopyram, which was protected in china to 2023, 8, 7.
The synthesis method of 2-aminoethyl-3-chloro-5-trifluoromethyl pyridine hydrochloride in the current literature mainly comprises the following steps:
the patent document WO2004016088 takes 2, 3-dichloro-5-trifluoromethyl pyridine and ethyl cyanoacetate as starting materials and prepares 2-ethylamino-3-chloro-5-trifluoromethyl pyridine hydrochloride through four-step chemical reaction. The reaction route is long, and the cyano-group reduction hydrolysis is not thorough, so that impurities are not easy to remove, and the product quality is lower than 95%. The above equation is:
disclosure of Invention
In view of the above, the invention aims to provide a preparation method of 2-aminoethyl-3-chloro-5-trifluoromethyl pyridine hydrochloride, which has the advantages of simple preparation process, high reaction yield and high product purity.
In order to achieve the above purpose, the technical scheme of the invention is realized as follows:
a method for preparing 2-aminoethyl-3-chloro-5-trifluoromethyl pyridine hydrochloride, comprising the following steps: s1: 2-acetyl-3-chloro-5-trifluoromethyl pyridine reacts with hydroxylamine in a solution under alkaline conditions to obtain 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethylamino p-toluenesulfonate;
s2: reacting 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethylamino p-toluenesulfonate in a solution at low temperature under alkaline conditions to obtain 2-amino-1- (3-chloro-5-trifluoromethyl) pyridin-2-yl) ethanone;
s3: the reaction formula of the three steps is that 2-amino-1- (3-chloro-5-trifluoromethyl pyridine-2-yl) ethanone is reduced by a reducing agent under the action of a catalyst, and finally salified to obtain 2-aminoethyl-3-chloro-5-trifluoromethyl pyridine hydrochloride:
the step S1 also comprises 2-acetyl-3-chloro-5-trifluoromethyl pyridine and hydroxylamine, stirring with a first-stage alkaline substance in a first-stage solvent for a period of time at room temperature, heating to reflux reaction, filtering, washing a filter cake with water to obtain 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethanol oxime, adding a second-stage solvent and a second-stage alkaline substance, adding water after the reaction with p-toluenesulfonyl chloride is completed under heating condition, recovering the solvent from an organic phase, cooling, filtering and vacuum drying to obtain 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethylamino p-toluenesulfonate;
the step S2 also comprises the steps of cooling the 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethylamino p-toluenesulfonate obtained in the step S1 in a solvent, adding methylene dichloride after the reaction with alkaline substances is finished, washing an organic phase with an acetic acid aqueous solution, recovering the solvent, cooling, filtering and vacuum drying to obtain 2-amino-1- (3-chloro-5-trifluoromethyl) pyridin-2-yl) ethanone;
the step S3 also comprises the step S2 of reacting 2-amino-1- (3-chloro-5-trifluoromethyl-pyridin-2-yl) ethanone with a reducing agent in a solvent at a certain temperature in the presence of a catalyst, dripping sodium bisulfate aqueous solution and ethyl acetate, adding an organic phase into hydrochloric acid, and filtering to obtain 2-aminoethyl-3-chloro-5-trifluoromethyl-pyridine hydrochloride.
The hydroxylamine in the step S1 includes one of hydroxylamine hydrochloride, hydroxylamine sulfate, aqueous hydroxylamine solution, hydroxylamine nitrate and hydroxylamine phosphate, and preferably, the hydroxylamine is hydroxylamine hydrochloride.
The first-stage solvent and the second-stage solvent in the step S1 comprise one or more of alcohols, esters, haloalkanes, ethers and amides;
the first stage solvent is preferably an alcohol, preferably an aqueous ethanol solution;
the second stage solvent is preferably an alkyl halide, preferably methylene chloride.
The first-stage alkaline substance and the second-stage alkaline substance in the step S1 comprise one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, triethylamine, isopropylamine and methylamine water solution, and preferably, the first-stage alkaline substance is sodium hydroxide; the second stage alkaline substance is aqueous methylamine solution, preferably 40% aqueous methylamine solution.
The molar ratio of the raw materials in the step S1 is as follows: 2-acetyl-3-chloro-5-trifluoromethylpyridine: hydroxylamine: first stage alkaline substance: first stage solvent: p-toluenesulfonyl chloride: second stage alkaline substance: second stage solvent = 1 (1-2): 1-2: (20-40): (1-1.5): (1-1.5): (30-50);
the optimal proportion is as follows: 2-acetyl-3-chloro-5-trifluoromethylpyridine: hydroxylamine: sodium hydroxide: ethanol water: p-toluenesulfonyl chloride: aqueous methylamine solution: second stage solvent = 1:1.5:1.6:30:1.2:1.3:41;
in the step S2, the solvent includes one or two of methanol, ethanol, isopropanol, butanol, dichloromethane, ethyl acetate and dimethylacetamide; preferably, the solvent is isopropanol;
the alkaline substances in the step S2 comprise one or two of sodium hydroxide, potassium hydroxide, sodium ethoxide, potassium ethoxide, sodium isopropoxide and potassium isopropoxide;
preferably, the alkaline substance is potassium isopropoxide;
in the step S2, the temperature is reduced to-5 ℃ in a solvent;
in the step S2, the molar ratio of the raw materials is: 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethylamino p-toluenesulfonate: alkaline substance: solvent=1 (1-2): 15-30, preferred ratio is: 1:1.5:20.
The solvent in the step S3 includes one or more of diethyl ether, tetrahydrofuran, dichloromethane, chloroform, dichloroethane and toluene, and preferably, the solvent is dichloromethane.
The reducing agent in the step S3 comprises one or more of sodium borohydride, lithium aluminum hydride, trimethylchlorosilane, hydrogen and zinc amalgam, and preferably, the reducing agent is trimethylchlorosilane;
in the step S3, the catalyst includes one of trifluoroacetic acid, acetic acid, palladium carbon, acetic anhydride, trifluoropropionic acid, boron trifluoride diethyl ether, boron trifluoride butyl ether and the like, and preferably, the catalyst is boron trifluoride diethyl ether.
In the step S3, the molar ratio of the raw materials is: 2-amino-1- (3-chloro-5-trifluoromethylpyridin-2-yl) ethanone: trimethylchlorosilane: boron trifluoride etherate: solvent = 1 (1-5): 1-4): 20-40; preferably, 2-amino-1- (3-chloro-5-trifluoromethylpyridin-2-yl) ethanone: trimethylchlorosilane: boron trifluoride etherate: solvent = 1:3:2:30;
preferably, 2-amino-1- (3-chloro-5-trifluoromethylpyridin-2-yl) ethanone in step S4 is reacted completely in a solvent with a reducing agent at 10-25℃in the presence of a catalyst.
Compared with the prior art, the preparation method of the 2-aminoethyl-3-chloro-5-trifluoromethyl pyridine hydrochloride has the following advantages:
the invention provides a novel method for synthesizing fluopyram intermediate 2-aminoethyl-3-chloro-5-trifluoromethyl pyridine hydrochloride. The method takes commercial 2-acetyl-3-chloro-5-trifluoromethylpyridine as a raw material, and the product is prepared by three steps of reaction, the total yield of the three steps is 82%, the product purity is more than 99%, the used solvent can be recycled, the reaction route is short, the reaction yield is high, the product purity is high, no special process exists, and the industrialized popularization can be carried out.
Detailed Description
It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other.
The present invention will be described in detail with reference to examples.
Example 1
Step 1 to the reaction flask at room temperature was added 22.3g of 2-acetyl-3-chloro-5-trifluoromethylpyridine, 10.4g of hydroxylamine hydrochloride, 156g of 90% ethanol aqueous solution, then 6.4g of sodium hydroxide was added in two portions, stirring was carried out at room temperature for 1 hour, and then the mixture was heated to reflux reaction to precipitate a white solid. Filtering, and recycling filtrate. Washing the filter cake with water, washing with 50% ethanol water, pumping to obtain 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethanol oxime, directly adding into a three-port bottle, adding 350g of dichloromethane 10.3g of 40% methylamine water solution, heating to 50 ℃, adding 22.8g of p-toluenesulfonyl chloride in two batches until the raw materials react completely, adding 300ml of water, layering, washing 100ml of water for three times, taking an organic phase, recovering 50% of solvent, cooling to 0 ℃, precipitating solid, stirring for 1h, filtering, washing the filter cake with a small amount of solvent, and vacuum drying to obtain 37.9g of 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethylaminop-toluenesulfonate, wherein the yield is 96.68%.
Step 2 35g of 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethylamino p-toluenesulfonate were added to a three-necked flask, 107g of isopropanol were added, the temperature was lowered to-5℃and 3 batches of 13g of potassium isopropoxide were added in portions, maintaining the reaction temperature at no more than 10 ℃. After the reaction was completed, 500ml of methylene chloride was added to the reaction solution, after stirring for 1 hour, the mixture was separated, a methylene chloride layer was taken, and washed twice with 100ml of a 10% aqueous acetic acid solution, and the organic phase was dried over anhydrous magnesium sulfate, filtered, and 50% of the solvent was distilled off, cooled, filtered and dried under vacuum to obtain 19.5g of 2-amino-1- (3-chloro-5-trifluoromethylpyridin-2-yl) ethanone, with a yield of 91.85%.
Step 3 19g of 2-amino-1- (3-chloro-5-trifluoromethylpyridin-2-yl) ethanone are added into a three-necked flask, 200g of dichloromethane and 27.9g of trimethylchlorosilane are added, 22.7g of boron trifluoride diethyl ether solution are dropwise added at 10-25 ℃, the reaction is kept at the temperature until the raw materials react completely after the dropwise addition, 50g of 10% sodium bisulfate aqueous solution is dropwise added, 400ml of ethyl acetate is added after the dropwise addition, an organic phase is extracted, 20ml of hydrochloric acid is added, and the ethyl acetate is filtered to flush 19.3g of 2-aminoethyl-3-chloro-5-trifluoromethylpyridin hydrochloride, the yield is 92.34%, and the liquid phase content is 99.57%.
Example 2
Step 1 to the reaction flask at room temperature was added 22.3g of 2-acetyl-3-chloro-5-trifluoromethylpyridine, 13.8g of hydroxylamine hydrochloride, 173g of 90% ethanol aqueous solution, then 8g of sodium hydroxide was added in two portions, stirring was carried out at room temperature for 1 hour, and after stirring at room temperature, the mixture was warmed to reflux for reaction, and a white solid was precipitated. Filtering, and recycling filtrate. Washing the filter cake with water, washing with 50% ethanol water, pumping to obtain 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethanol oxime, directly adding into a three-port bottle, adding 350g of methylene dichloride 12g of 40% methylamine water solution, heating to 50 ℃, adding 20.9g of p-toluenesulfonyl chloride in two batches, adding 300ml of water after the raw materials react completely, layering, washing 100ml of water for three times, taking an organic phase, recovering 50% of solvent, cooling to 0 ℃, precipitating solid, stirring for 1h, filtering, washing the filter cake with a small amount of solvent, and vacuum drying to obtain 36.9g of 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethylamino p-toluenesulfonate with a yield of 94.13%.
Step 2 35g of 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethylamino p-toluenesulfonate were added to a three-necked flask, 140g of isopropanol were added, the temperature was lowered to-5℃and 3 batches of 18g of potassium isopropoxide were added in portions, maintaining the reaction temperature at no more than 10 ℃. After the reaction was completed, 500ml of methylene chloride was added to the reaction solution, after stirring for 1 hour, the mixture was separated, a methylene chloride layer was taken, and washed twice with 130 ml of a 10% aqueous acetic acid solution, and the organic phase was dried over anhydrous magnesium sulfate, filtered, and 50% of the solvent was distilled off, cooled, filtered and dried under vacuum to obtain 18.7g of 2-amino-1- (3-chloro-5-trifluoromethylpyridin-2-yl) ethanone, with a yield of 88.08%.
Step 3, 18g of 2-amino-1- (3-chloro-5-trifluoromethylpyridin-2-yl) ethanone is added into a three-necked flask, 190g of dichloromethane and 26g of trimethylchlorosilane are added, 34g of boron trifluoride diethyl etherate solution is dropwise added at the temperature of 10-25 ℃ and is reacted until the raw materials react completely, 63g of 10% sodium bisulfate aqueous solution is dropwise added, 350ml of ethyl acetate is added after the dropwise addition, an organic phase is extracted, 18ml of hydrochloric acid is added, and then the ethyl acetate is filtered and washed with 18.6g of 2-aminoethyl-3-chloro-5-trifluoromethylpyridin hydrochloride, the yield is 88.57%, and the liquid phase content is 99.12%.
Example 3
Step 1 to the reaction flask at room temperature, 22.3g of 2-acetyl-3-chloro-5-trifluoromethylpyridine, 14.5g of hydroxylamine nitrate, 180g of 90% ethanol aqueous solution, then 8g of sodium hydroxide was added in two portions, stirring was carried out at room temperature for 1h, and then the mixture was heated to reflux reaction to precipitate a white solid. Filtering, and recycling filtrate. Washing the filter cake with water, washing with 50% ethanol water, pumping to obtain 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethanol oxime, directly adding into a three-port bottle, adding 400g of methylene chloride 11g of 40% aqueous methylamine solution, heating to 50 ℃, adding 21g of p-toluenesulfonyl chloride in two batches, adding 300ml of water after the raw materials react completely, dividing into 100ml of water, washing with three times, taking an organic phase, recovering 50% solvent, cooling to 0 ℃, precipitating solid, stirring for 1h, filtering, washing the filter cake with a small amount of solvent, and vacuum drying to obtain 36.8g of 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethylaminop-toluenesulfonate, wherein the yield is 93.87%.
Step 2 35g of 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethylamino p-toluenesulfonate are added to a three-necked flask, 107g of ethanol are added, the temperature is reduced to-5 ℃,3 batches of 12g of potassium ethoxide are added in batches, and the reaction temperature is kept at not more than 5 ℃. After the reaction was completed, 500ml of methylene chloride was added to the reaction solution, after stirring for 1 hour, the mixture was separated, a methylene chloride layer was taken, and washed twice with 100ml of a 10% aqueous acetic acid solution, and the organic phase was dried over anhydrous magnesium sulfate, filtered, and 50% of the solvent was distilled off, cooled, filtered and dried under vacuum to give 16.4g of 2-amino-1- (3-chloro-5-trifluoromethylpyridin-2-yl) ethanone, with a yield of 77.25%.
Step 3, 80g of tetrahydrofuran is added into a three-port bottle, 4g of lithium aluminum hydride is added after cooling to 0 ℃ in an ice bath, 16g of 2-amino-1- (3-chloro-5-trifluoromethyl pyridine-2-yl) ethanone is added into the reaction liquid in 4 batches, the reaction temperature is maintained to be no more than 5 ℃, the raw materials are completely reacted, the reaction liquid is dripped into 500mL of ice water, the dripping is completed, filtration is carried out, a filter cake is added into 50mL of ethyl acetate, 9g of hydrochloric acid is dripped, stirring is carried out for 2h below 10 ℃, 12.5g of 2-aminoethyl-3-chloro-5-trifluoromethyl pyridine hydrochloride is obtained after filtration, the yield is 71.47%, and the liquid phase content is 98.35%.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.

Claims (10)

1. A preparation method of 2-aminoethyl-3-chloro-5-trifluoromethyl pyridine hydrochloride is characterized by comprising the following steps: the method comprises the following steps:
s1: 2-acetyl-3-chloro-5-trifluoromethyl pyridine reacts with hydroxylamine in a solution under alkaline conditions to obtain 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethylamino p-toluenesulfonate;
s2: reacting 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethylamino p-toluenesulfonate in a solution at low temperature under alkaline conditions to obtain 2-amino-1- (3-chloro-5-trifluoromethyl) pyridin-2-yl) ethanone;
s3: 2-amino-1- (3-chloro-5-trifluoromethyl pyridine-2-yl) ethanone is reduced by a reducing agent under the action of a catalyst in solution, and finally salified to obtain 2-aminoethyl-3-chloro-5-trifluoromethyl pyridine hydrochloride.
2. A process for the preparation of 2-aminoethyl-3-chloro-5-trifluoromethylpyridine hydrochloride according to claim 1, characterized in that:
the step S1 also comprises 2-acetyl-3-chloro-5-trifluoromethyl pyridine and hydroxylamine, stirring with a first-stage alkaline substance in a first-stage solvent for a period of time at room temperature, heating to reflux reaction, filtering, washing a filter cake with water to obtain 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethanol oxime, adding a second-stage solvent and a second-stage alkaline substance, adding water after the reaction with p-toluenesulfonyl chloride is completed under heating condition, recovering the solvent from an organic phase, cooling, filtering and vacuum drying to obtain 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethylamino p-toluenesulfonate;
the step S2 also comprises the steps of cooling the 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethylamino p-toluenesulfonate obtained in the step S1 in a solvent, adding methylene dichloride after the reaction with alkaline substances is finished, washing an organic phase with an acetic acid aqueous solution, recovering the solvent, cooling, filtering and vacuum drying to obtain 2-amino-1- (3-chloro-5-trifluoromethyl) pyridin-2-yl) ethanone;
the step S3 also comprises the step S2 of reacting 2-amino-1- (3-chloro-5-trifluoromethyl-pyridin-2-yl) ethanone with a reducing agent in a solvent at a certain temperature in the presence of a catalyst, dripping sodium bisulfate aqueous solution and ethyl acetate, adding an organic phase into hydrochloric acid, and filtering to obtain 2-aminoethyl-3-chloro-5-trifluoromethyl-pyridine hydrochloride.
3. A process for the preparation of 2-aminoethyl-3-chloro-5-trifluoromethylpyridine hydrochloride according to any one of claims 1 or 2, characterized in that: the hydroxylamine in the step S1 includes one of hydroxylamine hydrochloride, hydroxylamine sulfate, aqueous hydroxylamine solution, hydroxylamine nitrate and hydroxylamine phosphate, and preferably, the hydroxylamine is hydroxylamine hydrochloride.
4. A process for the preparation of 2-aminoethyl-3-chloro-5-trifluoromethylpyridine hydrochloride according to claim 2, characterized in that: the first-stage solvent and the second-stage solvent in the step S1 comprise one or more of alcohols, esters, haloalkanes, ethers and amides;
the first stage solvent is preferably an alcohol, preferably an aqueous ethanol solution;
the second stage solvent is preferably an alkyl halide, preferably methylene chloride.
5. A process for the preparation of 2-aminoethyl-3-chloro-5-trifluoromethylpyridine hydrochloride according to claim 1 or 2, characterized in that: the first-stage alkaline substance and the second-stage alkaline substance in the step S1 comprise one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, triethylamine, isopropylamine and methylamine water solution;
preferably, the first stage alkaline substance is sodium hydroxide; the second stage alkaline substance is aqueous methylamine solution, preferably 40% aqueous methylamine solution.
6. A process for the preparation of 2-aminoethyl-3-chloro-5-trifluoromethylpyridine hydrochloride according to claim 2, characterized in that: the molar ratio of the raw materials in the step S1 is as follows: 2-acetyl-3-chloro-5-trifluoromethylpyridine: hydroxylamine: first stage alkaline substance: first stage solvent: p-toluenesulfonyl chloride: second stage alkaline substance: second stage solvent = 1 (1-2): 1-2: (20-40): (1-1.5): (1-1.5): (30-50);
the optimal proportion is as follows: 2-acetyl-3-chloro-5-trifluoromethylpyridine: hydroxylamine: sodium hydroxide: ethanol water; p-toluenesulfonyl chloride: aqueous methylamine solution: dichloromethane=1:1.5:1.6:30:1.2:1.3:41.
7. A process for the preparation of 2-aminoethyl-3-chloro-5-trifluoromethylpyridine hydrochloride according to claim 2, characterized in that: in the step S2, the solvent includes one or two of methanol, ethanol, isopropanol, butanol, dichloromethane, ethyl acetate and dimethylacetamide;
preferably, the solvent is isopropanol;
the alkaline substances in the step S2 comprise one or two of sodium hydroxide, potassium hydroxide, sodium ethoxide, potassium ethoxide, sodium isopropoxide and potassium isopropoxide;
preferably, the alkaline substance is potassium isopropoxide;
in the step S2, the temperature is reduced to-5 ℃ in a solvent;
in the step S2, the molar ratio of the raw materials is: 1- (3-chloro-5- (trifluoromethyl) pyridin-2-yl) ethylamino p-toluenesulfonate: alkaline substance: solvent=1 (1-2): 15-30, preferred ratio is: 1:1.5:20.
8. A process for the preparation of 2-aminoethyl-3-chloro-5-trifluoromethylpyridine hydrochloride according to claim 2, characterized in that: the solvent in the step S3 includes one or more of diethyl ether, tetrahydrofuran, dichloromethane, chloroform, dichloroethane and toluene, and preferably, the solvent is dichloromethane.
9. A process for the preparation of 2-aminoethyl-3-chloro-5-trifluoromethylpyridine hydrochloride according to claim 2, characterized in that: the reducing agent in the step S3 comprises one or more of sodium borohydride, lithium aluminum hydride, trimethylchlorosilane, hydrogen and zinc amalgam, and preferably, the reducing agent is trimethylchlorosilane;
in the step S3, the catalyst includes one of trifluoroacetic acid, acetic acid, palladium carbon, acetic anhydride, trifluoropropionic acid, boron trifluoride diethyl ether, boron trifluoride butyl ether and the like, and preferably, the catalyst is boron trifluoride diethyl ether.
10. A process for the preparation of 2-aminoethyl-3-chloro-5-trifluoromethylpyridine hydrochloride according to claim 2, characterized in that: in the step S3, the molar ratio of the raw materials is: 2-amino-1- (3-chloro-5-trifluoromethylpyridin-2-yl) ethanone: reducing agent: catalyst solvent=1 (1-5): 1-4): 20-40,
preferably, 2-amino-1- (3-chloro-5-trifluoromethylpyridin-2-yl) ethanone: trimethylchlorosilane: boron trifluoride etherate: solvent = 1:3:2:30;
preferably, 2-amino-1- (3-chloro-5-trifluoromethylpyridin-2-yl) ethanone in step S4 is reacted completely in a solvent with a reducing agent at 10-25℃in the presence of a catalyst.
CN202310794562.7A 2023-06-30 2023-06-30 Preparation method of 2-aminoethyl-3-chloro-5-trifluoromethyl pyridine hydrochloride Pending CN116836110A (en)

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