JPH05221986A - Production of substituted pyridine derivative - Google Patents

Abstract

PURPOSE:To enable simple and easy production of the subject compound which is useful as an intermediate for agrochemicals and medicines from readily available starting substances by reducing a substituted trichloropyridine derivative with a specific proton donor and a specific reducing agent. CONSTITUTION:A substituted trichloromethylpyridine derivative of formula I (R<1> to R<4> are H, halogen, alkyl) is reduced using a proton donor such as acetic acid or sulfuric acid and a reducing agent such as zinc or tin, preferably at -20 to +100 deg.C for 0.5 to 20 hours to give the objective compound of the formula II (m is 1 to 3), for example, 2-chloro-5-chloromethylpyridine. By the way, sulfuric acid is preferred as a proton donor, while zinc is preferred as a reducing agent. Further, it is preferred to feed the proton donor or reducing agent in portions.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a substituted pyridine derivative represented by the following general formula (II) which is useful as an intermediate raw material for agricultural chemicals, pharmaceuticals, etc., such as 2-chloro-5-chloromethylpyridine (hereinafter abbreviated as CCMP). , 2-chloro-5-dichloromethylpyridine (hereinafter abbreviated as CDCP) and the like. General formula (II)

[0002]

[Chemical 3]

(In the formula, m is an integer of 1 to 3, R ¹ ,
R ² , R ³ and R ⁴ are hydrogen atoms, halogen atoms or alkyl groups).

[0004]

2. Description of the Related Art There have been many proposals for a method for producing a substituted pyridine derivative represented by the general formula (II). For example, as a method for producing CCMP, Japanese Patent Laid-Open No.
-68565, JP-A-2-212475, 2-2
Although proposed in each publication of 18666, this method has drawbacks such as difficulty in industrially obtaining raw materials or long reaction steps. Further, as a method for producing CDCP, there are disclosed in JP-A-54-115381 and JP-A-5-
Nos. 5-43017, JP-A-3-58972, and U.S. Pat. No. 4,497,955 are proposed, but these methods also have a low yield and a long reaction step,
Alternatively, it is difficult to separate the produced by-product from CDCP, and this method also has various problems in industrial practice. On the other hand, in recent years, CCMP, CDCP and the like have become more important as a production intermediate for the production of nitromethylene derivative insecticides, and therefore, the production of those production methods suitable for industrial implementation is desired.

[0005]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted various studies on a method for producing a substituted pyridine derivative represented by the general formula (II) containing CCMP and CDCP, and found that the following general formula (I ), The substituted trichloromethylpyridine derivative is selectively reduced by using a specific proton donor and a reducing agent to selectively give CCM.
The present invention has been completed based on the finding that each compound of the substituted pyridine derivative represented by the general formula (II) containing P, CDCP and the like can be obtained. That is, the present invention has the general formula (I)

[0006]

[Chemical 4]

A substituted trichloromethylpyridine derivative represented by the formula (wherein R ¹ , R ² , R ³ and R ⁴ are a hydrogen atom, a halogen atom or an alkyl group) and acetic acid, hydrochloric acid or sulfuric acid is used as a proton donor. General formula (II), characterized in that it is used and reduced using zinc, tin or mixtures thereof as reducing agent.

[0008]

[Chemical 5]

(In the formula, m is an integer of 1 to 3, and R ¹ ,
R ² , R ³ or R ⁴ is as described above).

R ¹ in the above general formulas (I) and (II),
As the halogen atom contained in R ² , R ³ or R ⁴ ,
Fluorine atom, chlorine atom, bromine atom, iodine atom can be mentioned,
The alkyl group has 1 to 6 carbon atoms, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group,
A hexyl group and the like can be mentioned, and each of these groups also includes structural isomers of linear or branched fatty chains.

Examples of the substituted trichloromethylpyridine derivative represented by the general formula (I) which is a starting material for the production method of the present invention include 3-trichloromethylpyridine; 2-chloro-3-trichloromethylpyridine, 2 or 3 -Chloro-5-trichloromethylpyridine, 2-chloro-3-fluoro-5-trichloromethylpyridine,
2,5-dichloro-3-trichloromethylpyridine,
2,6-dichloro-3-trichloromethylpyridine,
2,3-difluoro-5-trichloromethylpyridine,
2,3-dichloro-5-trichloromethylpyridine, 2
-Bromo-3-fluoro-5-trichloromethylpyridine, 2-fluoro-5-trichloromethylpyridine,
Halogen-substituted trichloromethylpyridines such as 2,3,6-trichloro-5-trichloromethylpyridine; 2
Examples include alkyl-substituted trichloromethylpyridines such as -methyl-3-trichloromethylpyridine, 3-methyl-5-trichloromethylpyridine, and 2-methyl-5-trichloromethylpyridine.

These derivatives can be obtained by a conventionally known method, for example, JP-A-55-22617 and JP-A-55-76860.
No. 56-1157776, No. 58-177973.
No. 61-30665 and 61-34414
No., Japanese Patent Publication No. 2-49304, etc., Journal of Medicinal Chemistry (J. Med. C)
hem. ) 13: 1124-1130 (1970),
Chemical and Pharmaceutical Bulletin (Chem. Pharm. Bull.) Volume 38, 22
It can be easily produced according to the methods described in the literature such as pages 46-2258 (1990), combinations of these methods or these methods.

The compound obtained by the production method of the present invention, that is, the substituted pyridine derivative represented by the general formula (II) is, for example, 3-dichloromethylpyridine, 3-chloromethylpyridine, 3-methylpyridine, 2 -Chloro-3-dichloromethylpyridine; 2 or 3-chloro-5-dichloromethylpyridine; 2-chloro-3-fluoro-5-dichloromethylpyridine, 2,5
-Dichloro-3-dichloromethylpyridine, 2,6-dichloro-3-dichloromethylpyridine, 2,3-difluoro-5-dichloromethylpyridine, 2,3-dichloro-5-dichloromethylpyridine, 2-fluoro-5 -Dichloromethylpyridine, 2-bromo-3-fluoro-5
-Dichloromethylpyridine, 2,3,6-trichloro-
Halogen-substituted dichloromethylpyridines such as 5-dichloromethylpyridine; 2-chloro-3-chloromethylpyridine; 2 or 3-chloro-5-chloromethylpyridine; 2-chloro-3-fluoro-5-chloromethylpyridine, 2,5-dichloro-3-chloromethylpyridine,
2,6-dichloro-3-chloromethylpyridine, 2,3
-Difluoro-5-chloromethylpyridine, 2-bromo-3-fluoro-5-chloromethylpyridine, 2-fluoro-5-chloromethylpyridine, 2,3-dichloro-
5-chloromethylpyridine, 2,3,6-trichloro-
Halogen-substituted chloromethylpyridines such as 5-chloromethylpyridine; 2-chloro-3-methylpyridine, 2
Or 3-chloro-5-methylpyridine; 2-chloro-3
-Fluoro-5-methylpyridine, 2,5-dichloro-
3-methylpyridine, 2,6-dichloro-3-methylpyridine, 2,3-difluoro-5-methylpyridine,
2,3-dichloro-5-methylpyridine, 2-fluoro-5-methylpyridine, 2-bromo-3-fluoro-5
-Halogen-substituted methylpyridines such as -methylpyridine and 2,3,6-trichloro-5-methylpyridine; 5-
Dichloromethyl-2-methylpyridine, 5-dichloromethyl-3-methylpyridine, 3-dichloromethyl-2-
Alkyl-substituted dichloromethylpyridines such as methylpyridine; 5-chloromethyl-2-methylpyridine, 5-
Alkyl-substituted chloromethylpyridines such as chloromethyl-3-methylpyridine and 3-chloromethyl-2-methylpyridine; Alkyl-substituted such as 2,3-dimethylpyridine, 2,5-dimethylpyridine and 3,5-dimethylpyridine Methyl pyridines etc. are mentioned.

Examples of the proton donor used in the production method of the present invention include acetic acid, hydrochloric acid and sulfuric acid, but sulfuric acid or acetic acid is preferable, and sulfuric acid is more preferable. Examples of the reducing agent include zinc, tin or a mixture thereof,
Zinc is preferred. In addition, the shape of zinc or tin as a reducing agent is appropriately selected at the time of implementation, and examples thereof include powder, sand, shaving, granule, granule, flower, plate and rod.

In the reduction reaction of the present invention, the product may contain substances having different degrees of progress in the reduction reaction. That is,
The substance in which the trichloromethyl group of the substituted trichloromethylpyridine derivative of the raw material is converted into a dichloromethyl group, a chloromethyl group or a methyl group may be contained in the product at the same time in two or three species. Therefore, in the production method of the present invention, the amounts of the proton donor and the reducing agent to be used for the substituted trichloromethylpyridine derivative as the raw material are those when the reaction product contains a large amount of the target substance. It is difficult to specify. However, if it is strong, the proton donor is 1 to 1 for the substituted trichloromethylpyridine derivative which is a normal raw material.
20 equivalents and the reducing agent are 1 to 20 equivalents. Since the amount of each of them varies depending on the target substance, it will be described for each target substance.
After setting the amount used according to the reaction conditions, it is transferred to industrial practice. When the target substance is dichloromethylpyridines (when m is 1 in the general formula (II)), the proton donor is 1 to 10 equivalents, preferably 1 to 3 equivalents,
The reducing agent is 1 to 10 equivalents, preferably 1 to 3 equivalents.
When the target compound is a chloromethylpyridine (when m is 2 in the general formula (II)), the number of proton donors is 2 to
15 equivalents, preferably 2 to 4 equivalents, the reducing agent is 2 to
It is 15 equivalents, preferably 2 to 4 equivalents. The target product is methylpyridines (when m is 3 in the general formula (II))
In the case of, the proton donor is 3 to 20 equivalents, preferably 3 to 6 equivalents, and the reducing agent is 3 to 20 equivalents, preferably 3 to 6 equivalents. If the amount of the proton donor or the reducing agent deviates greatly from the above range, the desired reaction may not proceed, the amount used may exceed the necessary amount, resulting in economical loss, and the amount of by-products may increase, resulting in low yield. Or the cost becomes high, which is not desirable.

In the reduction reaction of the present invention, a solvent may or may not be present. Examples of the solvent used include alcohols, nitriles, ethers, halogenated hydrocarbons, ketones, Examples include esters and aprotic polar solvents, such as methanol, ethanol,
Alcohols such as propanol are preferable, and methanol is particularly preferable. The amount of them used is 0 to 100 parts by weight, preferably 0.5 to 50 parts by weight, relative to 1 mol of the substituted trichloromethylpyridine derivative as a raw material. If the amount of the solvent used exceeds the above range, the cost becomes high, which is not desirable. When sulfuric acid is used as the proton donor, it is generally preferable to use the above alcohols, preferably methanol.

The reaction temperature in the reduction reaction of the present invention depends on the types of raw material, target substance, reducing agent, proton donor, solvent,
It may vary depending on other reaction conditions and the like and cannot be specified unconditionally, but is usually -78 ° to + 200 ° C, preferably -20 °.
The reaction time is 0.1 to 50 hours, preferably 0.5 to 20 hours. In addition, various methods such as splitting and batching may be appropriately adopted as a method of adding the raw material, the proton donor and the reducing agent in the present invention, but it is desirable to add the proton donor or the reducing agent in portions.

In the reduction step of the present invention, the reaction product is subjected to usual purification,
The target can be easily obtained by the separating means. For example, put the reaction product in water, and if necessary, extract the target product with a solvent,
The desired product is separated by distillation. In addition, after separating the target product from the reaction product, the intermediate product of the reduction reaction and the unreacted raw material can be recycled and used again in the reduction reaction.

[0019]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited thereto.

Example 1 2-chloro-5-trichloromethylpyridine (hereinafter CT
C) 2.31 g (0.01 mol) was dissolved in 15 ml of concentrated hydrochloric acid, and then 2.85 g (2.4 equivalents) of tin powder was added,
The reaction was carried out at room temperature for 30 minutes and further at 70 ° C. for 50 minutes with stirring. After completion of the reaction, the reaction product was analyzed by gas chromatography to find that 2-chloro-5-chloromethylpyridine (CCMP) 74.3%, 2-chloro-5-
The composition was 21.3% of dichloromethylpyridine (hereinafter CDCP) and 4.4% of others. The total amount of the reaction product is water 1
Pour into 00 ml and add 3 ml with 100 ml of diethyl ether.
It was extracted twice, and the extracted layer was dried over anhydrous Glauber's salt. The dried reaction product was purified by silica gel column chromatography (developing solvent; n-hexane: ethyl acetate = 15: 1) to obtain 0.49 g of CCMP having a melting point of 37 to 38 ° C. NMR (60 MHz, δ value of CDCl ₃ ) 8.42 (1H, d, J = 3 Hz), 7.67 (1H,
dd, J = 8, 3 Hz), 7.33 (1H, d, J = 8)
Hz), 4.58 (2H, s)

Example 2 30.7 g (3 equivalents) of concentrated sulfuric acid was added to 400 ml of methanol, and then 46.2 g (0.2 mol) of CTC was added and well stirred to obtain a uniform solution. Then zinc powder 31.4
g (2.4 equivalents) was reacted at 10 to 25 [deg.] C. for 12 hours dividedly over 3 hours and 15 minutes, and after the addition was completed, the reaction was continued at room temperature for 40 minutes with stirring. After completion of the reaction, methanol was distilled off from the reaction product under reduced pressure, and 200 ml of water was added.
And 200 ml of methylene chloride were added for liquid separation. After that, the aqueous layer was extracted twice with 100 ml of methylene chloride, and the extracted layer was dried with 46.2 g of anhydrous sodium sulfate. The dried reaction product was analyzed by gas chromatography and found to be CCMP8.
It contained 4.3%, CDCP 3.8% and 2-chloro-5-methylpyridine (hereinafter CMP) 11.4%. After distilling off methylene chloride, the residue was distilled under reduced pressure to obtain 21.47 g of white crystals of CCMP (purity by gas chromatography: 85.0%).

Example 3 CTC 2.31 g (0.01 mol), zinc powder 1.57
g (2.4 equivalents) and methanol (20 ml) in a mixed solution of 3.0 g (5 equivalents) of acetic acid at 20 to 33 ° C. for 15 minutes to allow the reaction to proceed, and after the completion of the reaction, the mixture is stirred at the same temperature for 30 minutes. To react. After the reaction is completed, the reaction product is treated with 100 m of water.
1 ml, extracted twice with 100 ml of methylene chloride,
It was washed with 100 ml of water, and then the extract layer was dried over anhydrous sodium sulfate. The dried reaction product was analyzed by gas chromatography to find that CCMP was 69.0% and CDCP was 12.7.
%, CMP 16.3%, CTC 0.5% and others 1.
It contained 5%. Distill off the methylene chloride to remove CCMP1.
46 g (69% purity by gas chromatography) were obtained.

Examples 4 to 13 Tables 1 to 4 show Examples 4 to 13 carried out according to the above Examples 1 to 3.

[0024]

[Table 1]

In Table 1 above, Examples 4 to 10 are methods of finally adding a reducing agent, and Examples 11 to 13 are methods of finally adding or dropping a proton donor. In Example 11, the proton donor was added all at once, and in Examples 12 and 13, the proton donor was dropped for about 15 minutes. In Table 1, the composition of the reaction product is a value measured by gas chromatography of the reaction product, and * is a crude oil taken out by post-treatment after completion of the reaction.
Is the value measured by gas chromatography. CCM
In the column of P, the value in [] is the isolated yield of CCMP by silica gel column chromatography.

Example 14 2,6-Dichloro-3-trichloromethylpyridine 3
Concentrated sulfuric acid 2 was added to a suspension of 9.9 g of methanol in 300 ml.
3.0 g was added, and at room temperature, 19.68 g of zinc powder was added to 2.5 g.
It took time, and the reaction was carried out while the addition was repeated 6 times. After the addition was completed, the reaction was further carried out at room temperature for 2 hours with stirring. After completion of the reaction, the reaction product was analyzed by gas chromatography, and as a result, 2,6-dichloro-3-chloromethylpyridine 80.8%, 2,6-dichloro-3-dichloromethylpyridine 0.9% and 2, The composition was 6-dichloro-3-methylpyridine 12.5%. The reaction product is water 3
The mixture was poured into 00 ml and extracted with 300 ml of methylene chloride three times, and the extract layer was dried over anhydrous sodium sulfate. After removing methylene chloride from the dried reaction product, silica gel column chromatography (developing solvent; n-hexane: ethyl acetate =)
30: 1) and purified to give 2,6-
16.16 g of dichloro-3-chloromethylpyridine was obtained.

Example 15 2,3-Dichloro-5-trichloromethylpyridine 9.
5.69 g of concentrated sulfuric acid was added dropwise to 75 ml of 87 g of a methanol solution. At 5 to 30 ° C in an ice bath, 6.1 g of zinc powder was added.
It took 5 hours, and the reaction was carried out while the addition was repeated 5 times. After the addition was completed, the reaction was further continued at room temperature for 1 hour with stirring. After completion of the reaction, the reaction product was put into 120 ml of water, extracted with 200 ml of methylene chloride three times, and the extract layer was dried over anhydrous sodium sulfate. As a result of analysis by gas chromatography, the dried reaction product contained 84.1% of 2,3-dichloro-5-chloromethylpyridine and 12.0% of 2,3-dichloro-5-methylpyridine. After distilling off methylene chloride, the product was purified by silica gel column chromatography (developing solvent; n-hexane: ethyl acetate = 15: 1) and melted at 39-41 ° C. to give 2,3-dichloro-5-chloromethylpyridine (4.65 g). Got

Example 16 37.9 g of 2-chloro-3-trichloromethylpyridine
25.2 g of concentrated sulfuric acid was added to 170 ml of a methanol solution of (0.164 mol), and zinc powder 25.7 was added at 20 to 30 ° C.
g was required for 1 hour, and the reaction was carried out while adding it in portions over multiple times. After the addition was completed, the reaction was further carried out at 20 to 30 ° C. for 0.5 hour with stirring. After the completion of the reaction, the reaction product was analyzed by gas chromatography. As a result, 2-chloro-3-chloromethylpyridine 83.2%, 2-chloro-3-dichloromethylpyridine 2.3% and 2-chloro-3- The composition was 11.9% of methylpyridine. Pour all the reactants into 300 ml of water and add 2 ml with 400 ml of methylene chloride.
It was extracted twice, and the extracted layer was dried over anhydrous Glauber's salt. After distilling off methylene chloride, the dried reaction product was purified by silica gel column chromatography (developing solvent; n-hexane: ethyl acetate = 15: 1 to 5: 1) to give 2-chloro having a melting point of 35 to 36 ° C. -3-dichloromethylpyridine 17.06 g
Got

Example 17 13.3 g (1.3 equivalents) of concentrated sulfuric acid was added to 200 m of methanol.
Then, 23.1 g (0.1 mol) of CTC was added thereto and well stirred to obtain a uniform solution. Then, 7.85 g (1.2 equivalents) of zinc powder was reacted at −5 ° to + 4 ° C. for 1 hour at 12 times in divided addition, and after the addition was completed, the reaction was continued at room temperature for 15 minutes with stirring. Let
After completion of the reaction, 300 ml of water and 300 ml of methylene chloride
Was added to separate the layers. After that, the aqueous layer is methylene chloride 20
The extract was extracted twice with 0 ml, and the extract layer was dried over anhydrous sodium sulfate. The dried reaction product was analyzed by gas chromatography and found to have CDCP of 83.9%, CCMP of 3.4% and CTC.
It contained 7.7%. After distilling off methylene chloride, the product was purified by silica gel column chromatography (developing solvent; n-hexane: ethyl acetate = 15: 1) to obtain 15.69 g of 2-chloro-5-dichloromethylpyridine.

Examples 18 to 24 Example 18 carried out according to Examples 16 and 17 above.
-24 are listed in Table 2.

[0031]

[Table 2]

In Table 2 above, the composition of the reaction product is the value measured by gas chromatography, and * is the value measured by gas chromatography of crude oil taken out after post-treatment after completion of the reaction. In the column of CDCP, [] is the isolated yield of CDCP by silica gel column chromatography.

Example 25 4.62 g of CTC, 4.59 g of sulfuric acid and 40 of methanol
20% to 33% of zinc powder 4.71 g was added to the mixed solution of ml.
It took 0.7 hours at 0 ° C., and the reaction was carried out while adding it in multiple portions in multiple portions, and further at room temperature for 1 hour and at 50 ° C. for 2.5 hours with stirring. After completion of the reaction, the reaction product was analyzed by gas chromatography to find that the composition was 96.8% CMP and 3.1% CCMP. The reaction product is 100 m of water
It was put in 1 and extracted three times with 70 ml of methylene chloride, and the extract layer was dried over anhydrous sodium sulfate. After distilling off methylene chloride, the product was purified by silica gel column chromatography (developing solvent; n-hexane: ethyl acetate = 15: 1) to perform CMP.
1.72 g was obtained.

Examples 26 and 27 Examples 26 and 27 performed according to Example 25 above.
Are listed in Table 3.

[0035]

[Table 3]

In Table 3, the composition of the reaction product is a value measured by gas chromatography.

[0037]

The substituted pyridine derivative represented by the general formula (II) obtained by the production method of the present invention is a pesticide,
It is useful as an intermediate raw material for medicines. For example, 2-chloro-
5-Chloromethylpyridine is disclosed in JP-A-62-81382.
No. 64-70468, EP Publication No. 302346,
No. 210647, No. 375907, No. 383091
No. 376279, No. 302389, No. 3660
Nos. 85 and 163855 can be used for the production of active ingredient compounds for insecticides, and 2-chloro-5-dichloromethylpyridine is disclosed in JP-A-60-218.
It can be used for producing an active ingredient compound of an insecticide disclosed in JP-A No. 386 and JP-A-3-58972.

Claims (10)

[Claims] 1. A compound represented by the general formula (I): (Wherein R ¹ , R ² , R ³ and R ⁴ are a hydrogen atom, a halogen atom or an alkyl group), using acetic acid, hydrochloric acid or sulfuric acid as a proton donor, and Characterized by reducing with zinc, tin or a mixture thereof as a reducing agent,
General formula (II): (In the formula, m is an integer of 1 to 3, and R ¹ , R ² , R ³ and R ⁴ are as described above). 2. The general formula (I) or (II) of the substituted trichloromethylpyridine derivative or the substituted pyridine derivative.
The method according to claim 1, wherein R ¹ , R ² , R ³ or R ⁴ is a hydrogen atom or a halogen atom. 3. The substituted trichloromethylpyridine derivative is 3-trichloromethylpyridine, 2-chloro-3-
Trichloromethylpyridine, 2-chloro-5-trichloromethylpyridine, 2,3-dichloro-5-trichloromethylpyridine or 2,6-dichloro-3-trichloromethylpyridine, wherein the substituted pyridine derivative is 3-
Chloromethyl, 3-dichloromethyl or 3-methylpyridine: 2-chloro-3-chloromethyl, 2-chloro-3
-Dichloromethyl or 2-chloro-3-methylpyridine: 2-chloro-5-chloromethyl, 2-chloro-5-
Dichloromethyl or 2-chloro-5-methylpyridine:
2,3-dichloro-5-chloromethyl, 2,3-dichloro-5-dichloromethyl or 2,3-dichloro-5-methylpyridine: or 2,6-dichloro-3-chloromethyl, 2,6- Dichloro-3-dichloromethyl or 2,6
-Dichloro-3-methylpyridine. 4. The substituted trichloromethylpyridine derivative is 2-chloro-5-trichloromethylpyridine, and the substituted pyridine derivative is 2-chloro-5-chloromethyl, 2-chloro-5-dichloromethyl or 2-chloro. The method of claim 1, which is -5-methylpyridine. 5. The reduction reaction is carried out at a reaction temperature of −78 ° C. to +2.
The method according to claim 1, which is carried out at 00 ° C in the presence of a solvent. 6. The method according to claim 1, wherein the reduction reaction is carried out using 1 to 20 equivalents of a proton donor and a reducing agent, respectively, with respect to the trichloromethylpyridine derivative. 7. The method of claim 1, wherein the proton donor is sulfuric acid and the reducing agent is zinc. 8. Sulfuric acid is used in an amount of 2 to 15 equivalents and zinc is used in an amount of 2 to 15 equivalents based on 2-chloro-5-trichloromethylpyridine, and 0.5 mol of methanol is added to 1 mol of 2-chloro-5-trichloromethylpyridine. The method according to claim 1, wherein 2-chloro-5-trichloromethylpyridine is reduced at a reaction temperature of -20 to + 100 ° C to prepare 2-chloro-5-chloromethylpyridine by using -50 parts by weight. 9. Sulfuric acid is used in an amount of 1 to 10 equivalents and zinc is used in an amount of 1 to 10 equivalents based on 2-chloro-5-trichloromethylpyridine, and 0.5 mol of methanol is added to 1 mol of 2-chloro-5-trichloromethylpyridine. The method according to claim 1, wherein 2-chloro-5-trichloromethylpyridine is reduced at a reaction temperature of -20 to + 100 ° C to prepare 2-chloro-5-dichloromethylpyridine by using -50% by weight. 10. Sulfuric acid in an amount of 3 to 20 equivalents and zinc in an amount of 3 to 20 relative to 2-chloro-5-trichloromethylpyridine.
2-chloro-5-trichloromethylpyridine is used in an equivalent amount and 0.5-50 parts by weight of methanol is used for 1 mol of 2-chloro-5-trichloromethylpyridine to reduce 2-chloro-5-trichloromethylpyridine at a reaction temperature of -20 to + 100 ° C. The method of claim 1 for producing 2-chloro-5-methylpyridine.