KR830001499B1 - Process for preparing herbicidal pyridine compound - Google Patents

Abstract

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Description

Process for preparing herbicidal pyridine compound

The present invention relates to a method for producing the herbicidal pyridine compound of the general formula (1).

Food,

When R ³ is an alkyl group, an alkyl group having 1-12 carbon atoms is preferable, for example, an alkyl group having 1-4 carbon atoms.

When R ⁷ is an alkyl group, for example, it may be an alkyl group having 1-20 carbon atoms. Examples of alkyl groups within this range include those having 1-12 carbon atoms such as methyl, ethyl, propyl, butyl and dodecyl.

When R ² is an alkoxycarbonyl group, the alkoxy group may contain, for example, 1-20 carbon atoms and may contain, for example, 1-12 carbon atoms. Within this range the alkoxy group may contain, for example, 1-8 carbon atoms. Specific examples of alkoxy groups within this range are methoxy, ethoxy, propoxy, butoxy, isobutoxy, secondary butoxy and octyloxy.

When R ² is a carboxylic acid, the salts of the compounds according to the invention can be prepared by known methods for preparing salts of carboxylic acids. Representative salts include metal salts and ammonium salts. Metal salts include, for example, salts formed with alkali metal cations such as sodium, potassium and lithium and salts formed with alkaline earth cations such as calcium, strontium and magnesium. Ammonium salts include salts formed with ammonium cations or salts formed with mono-, di-, tri-, or tetra substituted ammonium cations whose substituents are, for example, aliphatic groups having 1-6 carbon atoms. Aliphatic groups can be, for example, alkyl groups having 1-6 carbon atoms.

One group of compounds according to the invention includes compounds in which Z is a CF ₃ group, Y is a chlorine atom, R ¹ is a methyl group and R ² is as described above. Within this group, R ² can be, for example, a carboxyl group or in the form of a salt thereof, for example an alkoxycarbonyl group such as an alkoxycarbonyl group having 1-6 carbon atoms.

Another group of compounds according to the invention include compounds in which Z is a CF ₃ group, Y is a chlorine atom, R ¹ is a methyl group and R ² is as described above. R ² in this group may, for example, be a carboxyl group or in the form of a salt thereof, or an alkoxy group may be an alkoxycarbonyl group having 1-6 carbon atoms.

Another group of compounds according to the invention comprises compounds in which Z is a difluoromethyl or chlorodifluoromethyl group, Y is hydrogen or chlorine, R ¹ is methyl group and R ² is as described above. R ² in this group may be for example a carboxyl group or in the form of a salt thereof, or an alkoxy group may be an alkoxycarbonyl group having 1-6 carbon atoms.

In addition to the compound in which R ¹ is a hydrogen atom in the general formula (1), the compound of the present invention contains an asymmetric carbon atom and may exist as two optical isomers. The present invention includes the preferential isomers and the leptomers of each compound of the present invention.

Particular examples of compounds according to the invention are those listed in Table 1.

TABLE 1

General formulas of the two compounds not listed in Table 1 for convenience are as follows.

For many compounds in the above table, physical constants in the form of boiling points or melting points are sometimes obtained by thin layer chromatography, but cannot be obtained because most are viscous oils. The structure of the compound was confirmed by nuclear magnetic resonance spectra, which corresponded to the structure indicated in Table 1.

The compounds of the present invention are generally more effective preparations for grass species than in herbaceous plants. These compounds can be used to control unwanted grass species that grow alone, and can be applied in appropriate proportions to control grass species that grow among broadleaf crops. The compound may be applied to soil before germination of the undesired grass type (pre-germination) or on soil of growing water (post-germination).

Thus, as another feature, the present invention provides a method of inhibiting the growth of unwanted plants, which method adapts the herbicidally effective amount of the compound of the general formula (1) to the plant or to its habitat as described above. It consists of doing.

The amount of compound that can be adapted depends on a variety of factors, such as the particular plant to be inhibited in growth, but generally an amount of 0.025-5 kg / ha is appropriate and 0.1-1.0 kg / ha is preferred. Those skilled in the art will readily be able to determine the appropriate amount for use by routine standard experiments without undue experimentation.

The compound of the present invention is preferably applied in the form of a composition in which the active ingredient is mixed with a carrier containing a solid or liquid diluent. Moreover, it is preferable that a composition contains surfactant.

The solid composition of the present invention may be in powder form, for example, or may be in granule form. Suitable solid diluents include, for example, kaolin, bentonite, diatomaceous earth, dolomite, calcium carbonate, talc, powdered magnesia and clay.

The solid composition may also be in the form of a dispersible powder or granules containing a wetting agent that facilitates the dispersion of the powder or solvent in a liquid in addition to the active ingredient. Such powder or granules may contain fillers, suspending agents and the like.

The liquid composition preferably comprises an aqueous solution, a dispersant and an emulsion containing the active ingredient in the presence of one or more active agent.

Water or organic liquids can be used to prepare solutions, dispersants or emulsions of the active ingredient. The liquid compositions of the present invention may also contain one or more anticorrosion inhibitors such as, for example, lauryl isoquinorium bromide. Surfactants may be in cationic, anionic or nonionic form.

The composition in the form of an aqueous solution, a dispersant or an emulsion is usually applied in the form of a concentrate containing a high proportion of the active ingredient, which is diluted with water before use. In general, it is preferable to contain the concentrate 10-85%, preferably 25-60% based on the weight of the active ingredient. Diluents for use may contain varying amounts of active ingredients depending on the purpose for which they are to be used. However, suitable diluents for various applications contain 0.01-10%, preferably 0.1-1%, based on the weight of the active ingredient.

The compounds of the present invention can be prepared from suitable substituted 2-halogenopyridines of the general formula (2).

Food,

[X is fluorine, chlorine, bromine or iodo, Y and Z are as described above.]

Three methods are useful for converting halogenogenpyridine (2) to a compound of the present invention. These methods are described below as methods A, B, C and.

Method A is summarized as follows.

Method A

In method A, the symbols R ¹ , R ² , Z and Y are as described above, Hal represents halogen, preferably chlorine or bromine and M is a cation such as sodium.

In Method A, the appropriate substituent halogenogen pyridine (2) was reacted with a metal salt of P-methoxyphenol, such as the sodium salt of P-methoxyphenol, for example. The reaction is preferably carried out in a solvent or diluent such as, for example, methylethylketone, tetrahydrofuran, dimethylsulfoxide or dimethylacetamide. The 2-P-methoxy-phenoxy compound (3) thus obtained is subjected to standard processes, such as pyridine hydrochloride or demetallization by heating with hydrogen bromide in acetic acid to give the corresponding P-hydroxy compound (4). Got it.

This was reacted with a suitable halogeno-alkanoic acid derivative (5) in the form of a metal salt thereof to obtain the target compound (1). This reaction is preferably carried out in a solvent or diluent such as methylethylketone.

Method B is summarized as follows.

Method B

In Method B, the appropriately substituted 2-halogeno pyridine (2) was reacted with hydroquinone in the presence of a base to give the P-hydroxy phenoxy compound (4) already mentioned in Method A. The reaction is preferably carried out in a solvent or diluent for the reactants. Examples of suitable solvents are, for example, aprotic solvents such as dimethylformamide. Preferably, the reaction is promoted by heating to a temperature of 50-150 ° C. The base used in the reaction can be, for example, an inorganic base such as sodium carbonate or potassium carbonate.

The second step of Method B is the same as the last step of Method A and will not be explained further.

Method C

A 2-halogenopyridine (2) appropriately substituted according to Method C was reacted with 2-(-P-hydroxy-phenoxy) propionic acid derivative (6) in the presence of a base to directly obtain compound (1) of the present invention. . Derivatives 6 are known per se and can be prepared by known methods. The reaction is preferably carried out in the presence of a solvent or diluent on the reactants. Examples of the solvent include lower ketones such as methyl ethyl ketone. The reaction can be accelerated by heating, for example it is convenient to carry out at reflux temperature of the solvent. Examples of bases used for the reaction include inorganic bases such as anhydrous potassium carbonate.

The starting materials used in Methods A, B and C can be prepared by themselves in several ways. For example, a compound containing a fluorinated alkyl group may be prepared by reacting a corresponding compound with a fluorinating agent to replace all or part of chlorine atoms with fluorine atoms. Thus, 2-chloro-5-trifluoromethyl pyridine can be prepared by reacting 2-chloro-5-trichloro-methylpyridine with, for example, a fluorinating agent such as antimony trifluorolide or liquid hydrogen fluoride. By controlling the amount of the fluorination agent used in the reaction, a compound having an alkyl group containing both fluorine and chlorine atoms can be obtained. For example, 2-chloro-5-trichloro pyridine can be reacted with a limited amount of antimony trifluoride to give 2-chloro-5-chlorodifluoromethyl pyridine and the amount of halogen substituents in the 2-position can be adjusted to Fluorine and compounds can also be obtained. This is not a substantial disadvantage since the halogeno pyridine at the 2-position is substituted with continuous conversion to the compounds of the invention. Any of the chlorinated compounds required as starting materials are considered novel compounds, such as, for example, 2-chloro-5-trichloromethylpyridine and 2,3-dichloro-5-trichloromethylpyridine. In addition to their utility as intermediates in the preparation of the compounds of the present invention, they have several biological activities as pesticides.

It is also possible to prepare 2-chloro-5-trichloromethylpyridine by reacting 3-methylpyridine with chlorine in the liquid phase under irradiation of ultraviolet rays.

The reaction of 3-methylpyridine (in the form of a free base or salt) with chlorine is generally carried out in an inert organic solvent. The solvent is conveniently a halogenated hydrocarbon such as, for example, carbon tetrachloride. However, other solvents may be used if they do not react under the conditions used and leave unnecessary by-products above acceptable values (e.g. hydrocarbons or ethers). The reaction is conveniently facilitated by heating since the reaction is carried out slowly at or below room temperature. Convenient reaction temperatures are, for example, in the range 50-130 ° C. The solution can be heated to reflux. Preference is given to using anhydrous reactants and solvents. It may be deposited in the reaction mixture to obtain the greatest effect of supplying ultraviolet light to the reaction from a suitable electric lamp. In general, a mixture of products is obtained by the reaction. From this the desired 2-chloro-5-trichloromethylpyridine can be liberated by conventional methods such as distillation.

As another method for preparing 2-halogeno-3-or-5-trifluoromethylpyridine, 2-halogeno-3- or-5-carboxypyridine is reacted with sulfur tetrafluoride in the presence of hydrogen fluoride to 2-chloro-5-trifluoromethylpyridine as can be obtained.

Compounds containing difluoromethyl groups can be prepared by treating pyridine aldehyde with sulfur tetrafluoride as described below.

The invention is illustrated by the following examples. Unless otherwise noted, all parts in the examples are by weight and all temperatures are in degrees Celsius.

Example 1

This example describes a method for preparing 2-chloro-5-trichloromethylpyridine by chlorination of 3-methylpyridine under the influence of ultraviolet light.

3-methylpyridine (10 ml) was dissolved in anhydrous carbon tetrachloride (300 ml). The solution was heated to reflux (about 80 ° C.), and then irradiated with 100 watts of ultraviolet light generating 185 nm of light while passing anhydrous chlorine gas through the mixture for 3 hours. The thin layer chromatography (silica, chloroform / cyclohexane) isolated on the evaporated feed of the solution thus obtained gave three main products as 10-15%. Most of these were identical to the desired 2-chloro-5-trichloromethylpyridine by nuclear magnetic resonance spectroscopy. This was confirmed by mass spectrometry analysis of the obtained solution. The other two main products were 2-chloro-3-trichloromethylpyridine and di (trichloromethyl) pyridine, present in amounts of 1/2 and 1/10 of the main product, respectively.

Example 2

This example relates to the preparation of 2-chloro-5-trichloromethylpyridine from salts of 3-methylpyridine.

3-methylpyridine (15 g) in anhydrous carbon tetrachloride was treated with anhydrous gas to obtain hydrogen chloride. The oil mixture obtained was stirred and then heated to reflux. Anhydrous chlorine gas was bubbled into the reflux mixture for 4 hours, and the inside was irradiated with ultraviolet light installed in the reaction flask. After cooling the reaction mixture, the solution and oily solids were separated accordingly. The oily solid was purified and contained unreacted 3-methylpyridine salt. The solution was evaporated to give an oily semi-solid, which was characterized by thin layer chromatography with the properties of 2-chloro-5-trichloromethylpyridine.

Example 3

This example relates to a process for preparing 2-chloro-5-trifluorotomethylpyridine.

6-chloronicotinic acid (23.6 g), sulfur tetrafluoride (37.4 g) and anhydrous hydrogen fluoride (18.7 g) were heated in a pressure cooker with stirring at 120 ° C. for 8 hours. The mixture was cooled, poured into ice and neutralized with concentrated sodium hydroxide at 0 ° C. The mixture was extracted with ether and then the extract was washed with water, dried and evaporated. The residue was distilled off and the fractions boiling at 140-150 ° C. were collected. The analysis showed that this consisted of 2-chloro-5-trifluoromethylpyridine with some 2-fluoro-5-trifluoromethylpyridine.

Example 4

This example relates to another method of preparing 2-chloro-5-trifluorotomethylpyridine.

2-chloro-5-trichloromethyl pyridine (30.8 g) and anhydrous hydrogen fluoride (80 g) were heated at 200 ° C. for 10 hours with stirring in an autoclave. The mixture was cooled and poured ice and neutralized at 0 ° C. The mixture was filtered and the residue and filtrate extracted with ether. The ether extract was washed with water, dried and evaporated to give an oil. This was distilled off and the fractions boiling at 140-154 ° C. were collected. The analysis consisted of 2-chloro-5-trifluoromethylpyridine with some 2-fluoro-5-trifluoromethylpyridine.

Example 5

This example relates to a method for preparing 2,3-dichloro-5-trifluoromethylpyridine by fluorination of 2,3-dichloro-5-trichloromethylpyridine.

2,3-dichloro-5-trichloromethylpyridine (35 g) was heated with anhydrous hydrogen fluoride (100 g) in a pressure cooker at 200 ° C. for 10 hours with stirring. The cooled reaction mixture was poured into ice and neutralized with sodium hydroxide at 0 ° C. The mixture was extracted with methylene chloride (750 ml). The extract was washed in the order of water (500 ml), sodium carbonate solution (500 ml) and water (500 ml), then dried and evaporated. The remaining oil was distilled off and the fraction (boiling point: 77-83 ° C./25 Torr) was collected, which was the same as the desired pyridine derivative.

Example 6

In addition, the present invention relates to a method for producing 2,3-dichloro-5-trifluoromethylpyridine.

Antimony trifluoride (61 g) is melted in vacuo to remove moisture. The cooled material was crushed and then heated to 65-70 ° C. with dropwise addition of antimony entachloride (6.6 g). 2,3-dichloro-5-trichloro methylpyridine (40 g) was added dropwise to the mixture and the whole was heated to 160 ° C. for at least 45 minutes. The mixture was cooled and then steam distilled off. The oil to be distilled was extracted with ether (2 x 100 ml). The ether extract was washed with a tin solution, followed by water, sodium bicarbonate and water in that order and dried. The remaining oil was distilled off. The fraction (boiling point: 71-80 ° C./18 Torr) was identical to the desired pyridine derivative.

Example 7

This example relates to the preparation of ethyl 2 [4 (3-chloro-5-trifluoromethylpyridyl-2-oxy) phenoxy] propionate (compound number 30 in Table 1).

3-chloro-5-trifluoromethyl-2-P-hydroxy phenoxy pyridine (1.0 g) was dissolved in methyl ethyl ketone (25 ml) potassium carbonate (0.5 g) and ethyl 2-bromo-propionate (1.0 g). heated under reflux for 4 h with g). The mixture was cooled, filtered and the filtrate was evaporated to remove the oil, which was then extracted on two 2 ml plates (20 x 20 cm each) using a mixture of 20 volumes of ether and 100 volumes of hexane as eluent. Purified. The product was extracted with ethanol. Evaporation with ethanol resulted in colorless oil, which was the same as compound number 30 by nuclear magnetic resonance spectrum.

Example 8

According to the method described in Example 7, compound numbers 29, 31-39, 41 and 42 in Table 1 were prepared using the appropriate esters of 2-bromo propionic acid, respectively.

Example 9

This example shows 2 [4 (3-chloro-5-trifluoromethyl pyridyl-2-oxy) phenoxy] propionic acid (Compound No. 28 in Table 1).

Compound No. 31 (2.19 g) in Table 1 in isopropanol (20 ml) was appropriately treated with a solution of sodium hydroxide (0.23 g) in water (20 ml) at room temperature. The mixture was stirred at room temperature for 4 hours and then diluted to 300 ml with water. The solution was extracted with methylene dichloride (2 x 50 ml) and acidified with 2-mol hydrochloric acid. The acidified solution was extracted with methylene dichloride (2 x 150 ml) and the extract was dried and evaporated to give an oil. It was left to stand, solidified and dried at 85 ° C. in vacuo to give compound No. 28. Melting point: 104-107 ° C.

Example 10

This example relates to the preparation of compounds Nos. 43-45 and 48-51 in Table 1.

(a) 2 [4 (3-chloro-5-trifluoromethyl pyridyl-2-oxy) phenoxy] propionyl chloride

The carboxylic acid (16.5 g) prepared by the method of Example 9 was dissolved in excess thionyl chloride (200 ml) and then heated at reflux for 2 hours. Excess thionyl chloride was removed under reduced pressure to give acid chloride as a yellow oil. This was taken up in anhydrous ether (220 ml) and the solution was used to prepare compounds Nos. 40,43-45,48-51 and 77 as follows. Since the process is conventional, only a summary is briefly shown in the following table.

* TLC stands for Thin Layer Chromatography.

Example 11

This example relates to a method of preparing Compound 46 of Table 1.

The solution (20 ml) prepared in Example 10 (a) was added to a solution of phenylhydrazine (0.95 g) in anhydrous ether (20 ml) at room temperature, and the mixture was stirred overnight. The mixture was diluted with water and then acidified with 2-mol hydrochloric acid. The ether layer was separated, washed with water and dried. Evaporation of the ether gave phenyl hydrazide as a solid. Melting Point: 109-110 ℃

Example 12

This example relates to the preparation of compound number 47 in Table 1.

The solution (20 ml) prepared in Example 10 (a) was added to a solution of propargyl alcohol (0.25 g) in ether (20 ml) containing potassium carbonate (0.75 g). The mixture was stirred overnight at room temperature. Chromatography indicates that no reaction occurs. The mixture was filtered and the filtrate was evaporated to yield an oil. Propargyl alcohol (5 ml) was added and the mixture was heated at 100 ° C. for 2 hours. After cooling the mixture, excess propargyl alcohol was removed under reduced pressure. The residue was purified by thin layer chromatography using silica gel and a mixture of ether (1 volume of petroleum (60-80 ° C .; 5 volumes) as eluent in solid phase. The product liberated by this method was colorless oil, which was stored. Compound No. 47 was obtained by solidifying the mixture, and the melting point was 57.5-58.5 ° C.

Example 13

This example relates to the preparation of ethyl 2 [4 (3-chloro-5-chlorodifluoromethylpyridine-2-oxy) phenoxy] propionate (Compound No. 53 in Table 1) by Method C. .

Methyl ethyl ketone containing sodium carbonate (0.1 g) containing 2,3-dichloro-5-chlorodifluoromethylpyriline (0.1 g) and ethyl 2- (4-hydroxyphenoxy) propionate (0.1 g) Stir at (10 g) then heat to reflux for 3 hours. The mixture was cooled and then filtered. The residue was washed with methyl ethyl ketone and the filtrate and washings were evaporated under reduced pressure to give an oil. The oil was purified by thin layer chromatography using silica gel and a mixture of ether (1 volume) and petroleum (boiling point: 60-80 ° C., 4 volumes) as solids. The product was colorless oil, which was stored and circulated to give compound number 53. Melting point: 61-62 ° C.

Example 14

This example relates to the preparation of compound numbers 54-58 of Table 1.

(a) Propyl 2 [4 (3-chloro-5-chloro-difluoromethyl pyridyl-2-oxy) phenoxy] propionate

2,3-dichloro-5-chloro difluoropyridine was reacted with propyl 2 (4-hydroxyphenoxy) propionate in methylethylketone as described above for the corresponding ethyl ester in Example 13. The propyl ester thus obtained was dissolved in a mixture of ether (1 volume) and petroleum (boiling point: 60-80 ° C., 4 volumes) and then passed through silica gel kelum.

(b) Preparation of Carboxylic Acid from (a)

The propyl ester was dissolved in isopropanol and then slowly treated with sodium hydroxide solution as described in Example 9. The carboxylic acid was liberated as described in Example 9.

(c) Preparation of Acid Chloride from (b)

2 [[4 (3-chloro-5-chlorodifluoromethylpyridyl-2-oxy) phenoxy] priponic acid prepared in (b) was heated at 100 ° C. for 2 hours with excess thionyl chloride. Excess thionyl chloride was then removed under reduced pressure. Acid chloride was used to prepare compounds 54-58 as follows. Since the process is conventional, only a summary is given in the table below.

Example 15

This example relates to the preparation of 3-bromo-2-chloro-5-trifluoromethylpyridine.

(a) Preparation of 3-bromo-2-chloro-5-pyridinecarboxylic acid

시간 더 교반하였다. 혼합물을 스팀-증류하여 변하지 않은 출발물질을 제거한 다음 가열하면서 여과하였다. 여액의 세척액을 냉각시킨 다음 농염산으로 산성화시켰다. 분리된 고체를 에테르로 추출하였다. 에테르 추출물을 건조시킨 다음 증발시킨 결과 3-브로모-2-클로로피리딘-5-카복실산이 얻어졌다.3-bromo-2-chloro-5-methylpyridine (30 g) was stirred in water (650 ml) containing potassium permanganate (60 g) and then heated under reflux for 3 hours. Add more potassium permanganate (20 g), then heat the mixture

Stir for more time. The mixture was steam-distilled to remove unchanged starting material and then filtered while heating. The wash of the filtrate was cooled and then acidified with concentrated hydrochloric acid. The separated solid was extracted with ether. The ether extract was dried and then evaporated to afford 3-bromo-2-chloropyridine-5-carboxylic acid.

(b) Preparation of 3-bromo-2-chloro-5-trifluoromethylpyridine

The product from (a) (12 g), sulfur tetrafluoride (20 g) and hydrogen fluoride anhydrous (10 g) were stirred and then heated to 120 ° C. for 8 hours in a pressure cooker. The product was poured into ice and then neutralized with sodium hydroxide at 0 ° C. The mixture was extracted with ether (3 × 100 ml) and then the extract was washed with water and then with sodium bicarbonate solution and again with water. The extract was dried and distilled to give a brown oil. This was distilled off and the oil (boiling point: 88-93 ° C.) was collected. This was identical to 3-bromo-2-fluoro-5-fluoromethylpyridine.

The product of (b) was used as starting material to prepare compounds No. 59 and 60 in Table 1 according to Method C.

Example 16

This example relates to the preparation of 2,5-dichloro-3-trifluoromethylpyridine and 2,5-dichloro-3-difluoromethylpyridine.

(a) Preparation of 2,5-dichloro-3-trichloromethyl pyridine and 2,5-dichloro-3-dichloromethyl pyridine

시간 염소화를 계속한 다음 용액을 증발시킨 결과 오일상 고체를 얻었다. 이것을 석유(비점 : 30-40℃)로 세척하였다. 잔사는 주로 2,5-디클로로-3-트리클로로메틸피리딘으로 구성된 것으로 확인되었다. 여액을 증발시킨 결과 주로 2,5-디클로로-3-트리클로로메틸피리딘으로 구성된 것으로 확인된 오일이 얻어졌다.2,5-dichloro-3-methylpyridine (37 g) in anhydrous carbon tetrachloride (500 ml) was treated with sufficient anhydrous hydrogen chloride to precipitate the pyridine as its hydrochloride. The mixture was heated under reflux while passing through anhydrous chlorine while stirring and the solution was irradiated with ultraviolet light inside.

Continued time chlorination and the solution was evaporated to give an oily solid. It was washed with petroleum (boiling point: 30-40 ° C.). The residue was found to consist mainly of 2,5-dichloro-3-trichloromethylpyridine. Evaporation of the filtrate yielded an oil which was found to consist mainly of 2,5-dichloro-3-trichloromethylpyridine.

(b) Preparation of 2,5-dichloro-3-trifluoromethylpyridine

2,5-dichloro-3-trichloromethylpyridine (30 g) prepared from (a) described above in anhydrous hydrogen fluoride (90 g) was stirred and then heated to 200 ° C. in a pressure cooker for 10 hours. The contents were cooled and then injected into Earl and neutralized with concentrated sodium hydroxide at 0 ° C. The aqueous layer was separated from the oil organic layer and the oil organic layer was then treated appropriately with methylene chloride (layer 750 ml). The methylene chloride extract was dried and then evaporated to give an oil. This was distilled off and the oil (boiling point: 70-76 ° C./20 Torr) was collected. Analysis showed that the material consisted of 2,5-dichloro-3-trifluoromethylpyridine containing about 5% by weight of 5-chloro-2-fluoro-3-trifluro-methylpyridine.

(c) Preparation of 2,5-dichloro-3-difluoromethylpyridine

2,5-dichloro-3-dichloromethylpyridine (20 g) in anhydrous hydrogen fluoride (60 g) was stirred and then heated in a pressure cooker at 200 ° C. for 10 hours. The mixture was cooled and then poured into ice and neutralized with sodium hydroxide solution at 0 ° C. The aqueous layer was removed from the organic layer and then the organic layer was dissolved in methylene chloride. This methylene chloride solution was used to extract the aqueous layer. This methylene chloride extract was washed in the order of water, sodium carbonate solution and water, then dried and evaporated. The remaining oil was distilled off. The fraction (boiling point: 85-98 ° C./22 Torr) was collected and re-distilled in a micro spinning band device. The fraction (boiling point: 87-87.5 ° C./25 Torr) was identified as 95% pure 2,5-dichloro-3-difluoromethylpyridine.

2,5-dichloro-3-trifluoro methylpyridine obtained as described above was converted to Compound Nos. 61 and 62 in Table 1 by Method C, and 2,5-dichloro-3-difluoromethylpyridine was obtained. Compound C was converted by method C.

Example 17

This example relates to the preparation of ethyl 2 [4 (5-difluoromethylpyridyl-2-oxy) phenoxy] propionate (compound 68 in Table 1).

(a) Preparation of 2-chloro-5-formyl pyridine

시간동안 교반한 다음 가열용액을 여과하였다. 잔사를 가열 에탄올(25ml씩)로 세척한 다음 여액을 합친다음 물로 600ml까지 희석시켰다. 용액을 에테르(3×250ml)로 추출하였다. 에테르추출물을 탄산나트륨용액 및 물로 세척한 다음 건조시킨 후 증발시킨결과 2-클로로-5-포르밀피리딘으로 확인된 연황색 고체가 얻어졌다.2-chloro-5-cyanopyridine (15 g) in 90% formic acid (60 ml) and water (15 ml) was stirred at 55 ° C. and then treated with a nickel nickel aluminum alloy (15 g). The mixture at 55 ° C.

After stirring for an hour, the heating solution was filtered. The residue was washed with heated ethanol (25 ml each), then the filtrates were combined and diluted to 600 ml with water. The solution was extracted with ether (3 × 250 ml). The ether extract was washed with sodium carbonate solution and water, dried and evaporated to yield a pale yellow solid identified as 2-chloro-5-formylpyridine.

(b) Preparation of 2-chloro-5-difluoromethylpyridine

The product from (a) (9.9 g) and sulfur tetrafluoride (15.5 g) were heated in a pressure cooker at 153-155 ° C. for 6 hours. The pressure cooker was cooled and then vented. The mixture was made basic with sodium carbonate solution and then extracted with methylene dichloride. Methylene dichloride was dried and then evaporated and the remaining oil was distilled off. The fraction (boiling point: 156-164 ° C.) was collected and identified as 2-chloro-5-difluoromethylpyridine containing some 2-fluoro-5-difluoro methylpyridine.

(c) Preparation of Compound No. 68

시간동안 환류하에 가열하였다. 혼합물을 냉각시킨 다음 여과하고 여액을 증발시켰다. 잔존하는 오일을 고체상으로 실리카겔 및 액체상으로서 클로로포름(75 용량부), 석유(비점 : 60-80℃, 25부) 및 에틸아세테이트(5부)의 혼합물을 사용하여 크로마토그라피에 의하여 정제시켰다. 이렇게하여 얻어진 생성물은 오일이었다.In methyl ethyl ketone (10 ml) containing potassium carbonate (0.5 g) was stirred the product from (b) (0.44 g) and ethyl 2- (4-hexifenoxy) propionate (0.63 g)

Heated under reflux for hours. The mixture was cooled and then filtered and the filtrate was evaporated. The remaining oil was purified by chromatography using a mixture of chloroform (75 parts by volume), petroleum (boiling point: 60-80 ° C., 25 parts) and ethyl acetate (5 parts) as silica gel and liquid phase in solid phase. The product thus obtained was an oil.

Example 18

This example relates to the preparation of ethyl 2 [4 (3-bromo-4-difluoromethylpyridyl-2-oxy) phenoxy] propionate (compound no. 70 in Table 1).

(a) Preparation of 3-bromo-2-chloro-5-propylpyridine

Treat 90% formic acid (40 ml) and 3-bromo-2-chloro-5-cyanopyridine (8.6 g) in water (10 ml) with a Ranickel / Aluminum alloy (8.0 g), then stir the mixture and Heated to 55-60 ° C. for hours. The mixture was left for 2 days and then extracted with ether (2 × 2500 ml). The ether extract was treated with sodium carbonate solution, dried and evaporated to give an oil. The oil was diluted with toluene and then toluene was removed under reduced pressure. The residue was diluted with a small amount of ether, the solution was filtered and the filtrate was evaporated to yield the oil identified as the desired aldehyde.

(b) Preparation of 3-bromo-2-chloro-5-difluoromethylpyridine

The product from (a) (5.6 g) and sulfur tetrafluoride (9 g) were heated in an autoclave at 150 ° C. for 6 hours. The autoclave was cooled and then ventilated and the contents were treated with sodium carbonate solution. The solution was extracted with methylene dichloride and the methylene dichloride extract was dried and evaporated to give an oil which was distilled off under reduced pressure. Collecting an oil fraction (boiling point: 85-95 ° C./15 Torr) resulted in 3- containing a small amount of 2-chloro-3-fluoro-5-difluoromethylpyridine or 2-fluoro-3-chloro isomer thereof. Bromo-2-chloro-5-difluoro methylpyridine was identified.

(c) Preparation of Compound No. 70

시간동안 환류하에서 가열하였다. 혼합물을 여과한 다음 증발시킨 결과 황색오일이 얻어졌다. 이것을 고체상으로 실리카겔 및 액상으로서 실시예 (C)에 기술된 혼합물을 사용하여 박층크로마토그라피에 의하여 정제시켰다. 주요흡수대를 에탄올로 추출하고 에탄올을 증발시킨 결과 오일이 얻어졌으며, 이것을 기체-액체 크로마토그라피한 결과 주성분을 96% 함유한 것으로 화합물 70으로 확인되었다.The product from (b) (0.5 g), ethyl 2- (4-hydroxy-phenoxy) propionate (0.465 g) and potassium carbonate (0.5 g) were stirred in methyl ethyl ketone (10 ml) and then

Heated under reflux for hours. The mixture was filtered and then evaporated to give yellow oil. This was purified by thin layer chromatography using silica gel in the solid phase and the mixture described in Example (C) as a liquid phase. Extraction of the main absorption zone with ethanol and evaporation of ethanol yielded an oil, which was identified as compound 70 by gas-liquid chromatography, containing 96% of the main component.

Example 19

This example relates to the preparation of ethyl 2 [4 (3-chloro-5-difluoromethylpyridyl-2-oxy) phenoxy] propionate (compound 69 in Table 1) by method C.

(a) Preparation of 2,3-dichloro-5-difluoromethyl

A mixture of 2,3-dichloro-5-propylpyridine (3 g) containing a small amount of 2,3,5-trichloropyridine was treated with sulfur terafluoride (4.5 g) in a pressure cooker for 6 hours.

The cooled reaction mixture was treated with sodium carbonate solution and then extracted with methylene dichloride. The extract was dried and then evaporated and the residue was distilled on a micro spinning band device. An oil fraction (boiling point: 65-100 ° C.) was collected. It was gas-liquid chromatographed and this was a mixture of about 60% 3-chloro-2-fluoropyridine and 40% of the desired 2,3-dichloro-5-difluoromethylpyridine.

(b) Preparation of Compound No. 69

시간동안 교반하면서 메틸에틸케톤(10ml)중에서 환류하에 가열하였다. 용액을 여과한 다음 여액을 증발시킨 결과 오일이 얻어졌다. 고체상으로 실리카겔 및 용리제로서 클로로포름(75용량부), 석유(비점 : 60-80℃, 25부) 및 에틸아세테이트(5부)의 혼합물을 사용하여 박층 크로마토그라피에 의하여 오일을 정제시켰다. 이것을 용리제로서 에테르(1용량부) 및 석유(비점 : 60-80℃, 2부)의 혼합물을 사용하여 다시 크로마토그라피하였다. 두개의 흡수대가 전개되었다. 빨리 이동하는 흡수대를 에탄올로 추출한 다음 에탄올 추출물을 증발시켰다. 잔존하는 오일은 핵자기 공명 스펙트럼에 의하여 화합물 69로서 확인되었다.The product from (a) (0.65 g) and ethyl 2 (4-hydroxyphenoxy) propionate (1.0 g)

Heated under reflux in methylethylketone (10 ml) with stirring for hours. The solution was filtered and the filtrate was evaporated to yield an oil. The oil was purified by thin layer chromatography using silica gel and a mixture of chloroform (75 parts by volume), petroleum (boiling point: 60-80 ° C., 25 parts) and ethyl acetate (5 parts) as solid phase. This was chromatographed again using a mixture of ether (1 part by volume) and petroleum (boiling point: 60-80 ° C., 2 parts) as eluent. Two sinks were developed. The fast moving absorption zone was extracted with ethanol and the ethanol extract was evaporated. The remaining oil was identified as compound 69 by nuclear magnetic resonance spectra.

Example 20

This example relates to the preparation of 2-chloro-3,5-bistrifluoromethylpyridine.

(a) Preparation of 3,5-bis-trifluoromethyl pyridine

3,5-pyridine-dicarboxylic acid (17.5 g) containing a portion of pyridine 2,5-dicarboxylic acid, together with sulfur tetrafluoride (72 g) and hydrogen fluoride (40 g) in an autoclave at 150-151 ° C. for 8 hours. Heated. The cooled reaction mixture was neutralized with potassium hydroxide solution at 0 ° C., then the mixture was extracted with methylene dichloride and the extract was dried and evaporated. The residue was distilled off and the oil (boiling point: 119-128 ° C.) collected. This was shown as a mixture of 3,5- and 2,5-bis-trifluoromethylpyridine by NMR spectrum.

(b) Preparation of 2-chloro-3,5-bis-trifluoromethylpyridine

시간후 사염화탄소를 증류 제거한 다음 잔사를 스피닝 밴드장치에서 증류시켰다. 유분(비점 : 75-85℃)을 수집한 결과 이것은 소량의 2,5-및 3,5-비스-트리플루오로메틸피리미딘을 함유하는 2-클로로-3,5-비스-트리플루오로메틸피리미딘으로 확인되었다.The product (3.0 g) described above was heated to reflux with chlorine (dried) slowly passing through the solution while stirring in anhydrous carbon tetrachloride (250 ml), and the solution was irradiated with ultraviolet light.

After time carbon tetrachloride was distilled off and the residue was distilled off in a spinning band device. Collection of oil (boiling point: 75-85 ° C.) resulted in 2-chloro-3,5-bis-trifluoromethyl containing small amounts of 2,5- and 3,5-bis-trifluoromethylpyrimidine It was identified as pyrimidine.

The 2-chloro-bis-trifluoromethypyridine thus obtained was converted to compound 71 of Table 1 according to Method C.

Example 21

This example illustrates the herbicidal properties of the compounds of the present invention. Each compound was mixed with 5 ml of an emulsion prepared by diluting 100 ml of a solution containing 21.8 g of Span 80 per liter and 78.2 g of Tween 20 per liter in methyl cyclohexane to 500 ml with water. Test formulations were made. Span 80 is a registered trademark of surfactants containing sorbitan monolaurate. Tween 20 is a trademark for a surfactant containing a concentrate of 20 moles of ethylene oxide concentrated with sorbitan monooleate. The mixture of compound and emulsion was shaken with glass beads and then diluted to 12 ml with water.

The spray composition thus prepared was sprayed on potted young plants (post-germination test) of the kind named in Table 2 below at a rate corresponding to 1000 liters per hectare. Damage to plants was assessed 14 days after spraying compared to untreated plants. The damage level is 0-3, 0 means no effect, and 3 means 75-100% damage. In tests for pre-germination herbicides, seeds of the test plants were placed on the surface of the soil fiber trays and sprayed at a rate of 1000 l per hectare (ha). The seeds were then covered with other soil. Three weeks after spraying, the damage rating was 0-3 compared to the seedlings in the non-sprayed control trays. (-) In the table means not tested, the results are as described in Table 2 below.

TABLE 2

Test plant names are as follows.

Lt: lettuce

To: Tomato

Ot / Av: Cultivated Oats and Wild Oats (Avena Patua) Wild oats were used for post-germination tests and cultivated oats were used for pre-germination tests.

Ll: Loririum Perene (perennial rye)

Cn: Cypherus Rotunders

St; Setaria Viridis

The results in Table 2 clearly illustrate the selectivity of the compounds of the present invention, whereas the dicots were inherently harmless, whereas the type of grass used in the test was significantly damaged or killed.

Example 22

This example illustrates the herbicidal properties of the compounds of Table 1. The test was performed as described in Example 21. The compound was formulated by mixing an appropriate amount of compound with 5 ml of an emulsion prepared by diluting 160 ml of a solution containing 21.8 g per l of span 80 and 78.2 g per l of tween 20 to 500 ml in methylcyclohexane. The mixture of compound and emulsion was shaken with glass beads and then diluted to 40 ml with water. The damage rating was evaluated as 0-5, with 0 being 0-20% damage and 5 means complete death. (-) In the table means not tested, the results are shown in Table 3 below.

TABLE 3

Test plant names are as follows.

Sb: Beet Ip: Ipomoea purpurea

Rp: Flat Am: Amaranthus Retroplexus

Ct: Cotton Pi: Polygonium Abicolorase

Sy: Soy Ca: Chenoporium Album

Mz: millet Po: Fortraca Oleracea

Ww: Winter wheat Xs: Xantium Spino Island

Rc: Rice Ab: Abtiron Deoplaster

Sn: Senesio Bulgaris Cv: Convervalus Arvensis

Ot / Av: Wild oats and wild oats (Avena Patua) wild oats were used in the post-germination test, and cultivated oats were used in the pre-germination test.

Dg: Digitarian Sanquinaris Sh: Sorhum Halefense

Pu: Poua Anua Ag: Aggropyleanes

St: Setaria Viridis Cn: Cypherus Rotunders

Ec: Echinocro cros-Gali

Example 23

This example illustrates the selective herbicidal action of the compounds of the invention. Tests were conducted on cereals and weeds. Here, the compound was applied to cereals at 10 times the rate applied to weeds. The test process is similar to the process described in Example 21. The damage was evaluated after 20 days of spraying and was expressed as 0-10, where 0 means no effect and 10 means complete test. Each result listed in the table below is an average value of damage to three plants. Although there is little or no damage to the grains despite the fact that the compounds were applied to cereals at 10 times the rate of causing severe damage to weeds, the selectivity properties of the herbicidal compounds of the present invention can be easily seen from the results in the table. will be.

The abbreviation for the test plant name has the meaning given in Example 22 except for Al. Al means Allopecurus myosuroides.

Example 24

This example illustrates the later herbicidal action on perennial grasses, which is an example compared to previously known herbicidal compounds.

Known compounds are the following compounds (A).

Compounds 5 and 31 in Table 1 were compared with Compound A. In the test, a piece of rhizome of 5-8 cm sorb gum halfens with 2-3 nodes was buried in compost in a plastic tray in a greenhouse. Compounds were formulated for testing as described in Example 22. In the pre-germination test, the Japanese compound was sprayed on compost after the root piece was applied, and then the surface was covered with more compost and watered. In the germination bone experiment, the root pieces were sprayed when the sprouts with 2-4 leaves were left for 20 days. Weed damage was assessed on 3 weeks of treatment.

In the test, three replicates were used for each treatment. The results are expressed as% damage to plants, which is the average of two separate tests. The numerical values for% damage are as listed in the following table.

Results before germination

Result after germination

As can be seen from the above table, the compound of the present invention has a superior herbicidal effect than Compound A at a low ratio.

Example 25

This example illustrates the herbicidal properties of other compounds of the invention. This compound was tested by the process described in Example 21 and the results were shown by the same method. The results are shown in the following table, which may be considered as a continuation of Table 2.

Claims (1)

A process for preparing the herbicidal pyridine compound of formula (1) characterized by reacting the compound of formula (2) with the compound of formula (6) in the presence of a base.

Wherein Z is a trifluoromethyl group, Y is hydrogen or chlorine, R ¹ is a methyl group, R ² is cyano, carboxyl, a carbox amido of the formula-CONR ³ R ⁴ , a group of the formula-COSR ⁷ , an alkoxy carbonyl substituted with a hydroxy or halogen salt, formula-CO (OCH ₂ CH ₂ ) _{a group of} OR ⁸ , cyclohexyloxycarbonyl optionally substituted with halogen or methyl, (C _3-6 alkenyl) oxycarbonyl, phenoxycarbonyl optionally substituted with halogen or methyl, or a phenyl group by a halogen or methyl group Optionally substituted benzyl oxy carbonyl group. [R ³ is hydrogen or an alkyl group, R ⁴ is hydrogen, phenyl, C _1-4 alkyl, C _1-4 alkoxy or —NR ⁵ R ^{6 a group of the} general formula, [R ⁵ is hydrogen or C _1-4 alkyl R ⁶ is Hydrogen or C _1-4 alkyl or phenyl] R ⁷ is an alkyl or phenyl group, R ⁸ is a C _1-4 alkyl group, n is an integer of 1 to 5. X is fluorine, chlorine, bromine or iodine.]