JPH0433788B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to novel pyridine derivatives having herbicidal properties and weeding methods using them. According to the first invention, a herbicidal pyridine compound represented by the following formula (), that is, the following formula () {In the formula, Z and Y each represent a chlorine or hydrogen atom, or a trifluoromethyl group, provided that at least one of Z and Y is a trifluoromethyl group, and R ² is (1) carboxamide group

[Formula] [However, R ³ is hydrogen, R ⁴ is a phenyl group or a chlorophenyl group,
or the group ^-NR5R6 ( ^R5 is hydrogen and ^R6 is a phenyl group or chlorophenyl group), or the group ^-NR3R4 in the carboxamide group as ^{R2 is} a morpholino group ^. ], or R ² is (2) group

[Formula] (R ⁷ is a phenyl group), or R ² is (3) a haloalkoxycarbonyl group or (4) a phenoxycarbonyl group (however, this phenoxycarbonyl group has a halogen or methyl substituent. ), provided that when Z is a trifluoromethyl group, R ² is of the formula

Carboxamide group of [Formula] (where R ³ is hydrogen and R ⁴ is a phenyl group or chlorophenyl group), the formula

It is not a group of [Formula] or a phenoxycarbonyl group (however, this phenoxycarbonyl group may have a halogen or methyl substituent), and
When R ² is _a haloalkoxycarbonyl group, a pyridine derivative represented by _the following formula is provided. One group of compounds of general formula () according to the invention includes those in which Z is a CF ₃ group, Y is a hydrogen atom, and R ² has the same meaning as above. A second group of compounds according to the invention includes Z
CF ₃ group, Y is a chlorine atom, and R ² has the same meaning as above. The compounds of the invention have asymmetric carbon atoms and can therefore exist in two optically isomeric forms. The invention includes the dextrorotatory and levorotatory isomers of each compound of the invention and mixtures thereof in any proportion. Particular examples of compounds according to the invention include those listed in Table 1 below.

【table】

【formula】

【formula】

[Formula] For many of the compounds in the table above, physical constants in terms of boiling or melting points are not available because these compounds are often isolated by thin layer chromatography and a high proportion are viscous oils. . The structures of the compounds were confirmed by testing their nuclear magnetic resonance spectra, which corresponded to the structures specified in Table 1. The compounds of this invention are generally substantially more effective herbicides against grass species than against broadleaf species of plants. They can be used to control undesirable grass species growing singly or, at appropriate application rates, to control weeds growing between broadleaf crop plants. The compound can be applied to the soil before the emergence of undesirable grass species (pre-emergence application) or to the portion of the growing grass plant above the soil (post-emergence application). Therefore, according to a second aspect of the invention, the invention consists of applying a herbicidally effective amount of a pyridine derivative of the formula () as defined above to undesired herbaceous plants, in particular to grass species or to their growing areas. A method for suppressing the growth of undesirable plants is provided. The amount of compound of formula () to be applied will depend on a number of factors, such as the particular plant species whose growth is to be inhibited, but 0.025-5 Kg/ha is usually suitable, preferably 0.1-1.0 Kg/ha. /ha.
Those skilled in the art can determine the appropriate amount to use by routine, standardized tests without undue experimentation. The compounds of the invention are preferably applied in the form of compositions, in which the active ingredient is mixed with a carrier consisting of a solid or liquid diluent. Preferably the composition further comprises a surfactant. The solid compositions of the invention may be in the form of powders or granules, for example. Suitable solid diluents include, for example, kaolin, bennite, diatomaceous earth, dolomite, calcium carbonate, talc, powdered magnesia and fuller's earth. The solid compositions may also be in the form of dispersible powders or granules containing, in addition to the active ingredient, wetting agents to facilitate the dispersion of the powder or granules in the liquid. Such powders or granules contain fillers,
This includes prevention of sedimentation, etc. Liquid compositions include aqueous solutions, dispersions and emulsions containing the active ingredient, preferably in the presence of one or more surfactants; Can be used to make emulsions. The liquid compositions of the invention may also contain one or more corrosion inhibitors, such as laurylisoquinolinium bromide. The surfactant may be cationic, anionic or nonionic. Suitable cationic type activators include, for example, quaternary ammonium compounds such as cetyltrimethylammonium bromide.
Suitable anionic active agents are, for example, soaps, salts of aliphatic monoesters of sulfonic acids, such as sodium lauryl sulfonate, and salts of sulfonated aromatic compounds, such as dodecylbenzenesulfonate, sodium lignosulfonate, calcium and ammonium, butylnaphthalene sulfonate and diisopropyl- and triisopropyl-
Contains a mixture of sodium salts of naphthalene sulfonic acid. Suitable nonionic activators include other nonionic activators including, for example, condensates of ethylene oxide with aliphatic alcohols such as oleyl alcohol and cetyl alcohol or with alkylphenols such as octylphenol, nonylphenol and octylcresol. are partial esters derived from long-chain fatty acids and hexitol anhydride, such as sorbitol monourate, condensates of such partial esters with ethylene oxide, and lecithin. Compositions to be used in the form of aqueous solutions, dispersions or emulsions are usually presented in the form of concentrates containing a high proportion of the active ingredient, which concentrates are diluted with water before use. These concentrates usually withstand long periods of storage and, after such storage, require the ability to be diluted with water to produce an aqueous preparation that remains homogeneous long enough to be applied with conventional spray equipment. Ru. Generally the concentrate is 10-85% by weight, preferably 25%
Advantageously, it contains ~65% by weight of active ingredient. Dilute preparations ready for use can contain different amounts of active ingredient depending on the purpose for which they are used, but dilute preparations suitable for many uses contain between 0.01 and 10% by weight, preferably between 0.1 and 1% by weight. % active ingredient by weight. The compounds of the present invention, i.e. pyridine derivatives of the general formula (), are of the formula () (In the formula, X represents a fluorine, chlorine, bromine or iodine atom, and Y and Z have the same meanings as in the above formula ()). Three routes are possible for converting this halogenopyridine () into a compound of the invention, and these are described below as routes A, B and C. Route A is summarized in the following reaction equation. In route A, R ² , Z, Y and X have the meanings specified for them above, Hal means halogen, preferably chlorine or bromine, M
is a cation, for example sodium. In Route A, a suitably substituted halogenopyridine () is reacted with a metal salt of p-methoxyphenol, such as the sodium salt of p-methoxyphenol. The reaction is preferably carried out in a solvent or diluent such as methyl ethyl ketone, tetrahydrofuran, dimethyl sulfoxide or dimethyl acetamide. Thus obtained 2
The -p-methoxyphenoxy compound () is then demethylated to give the corresponding p-hydroxy compound by standard methods, for example by heating with pyridine hydrochloride or with hydrogen bromide in acetic acid. This is then reacted in the form of its metal salt (eg sodium or potassium salt) with a suitable halogenoalkanoic acid derivative () to give the desired compound (). Preferably, this reaction is carried out in a solvent or diluent, such as methyl ethyl ketone. Route B is summarized in the following reaction equation. According to Route B, a suitably substituted 2-halogenopyridine () is reacted with hydroquinone in the presence of a base to give the p-hydroxyphenoxy compound () already mentioned in Route A. The reaction is preferably carried out in a solvent or diluent for the reactants. Examples of suitable solvents include aprotic solvents such as dimethylformamide. The reaction is preferably accelerated by heating to a temperature of, for example, 50-150°C. The base used in the reaction can be, for example, an inorganic base, such as sodium or potassium carbonate. The second stage of route B is the same as the final stage of route A and does not require further explanation. According to Route C, a suitably substituted 2-halogenopyridine () is reacted with a 2-(p-hydroxy)propionic acid derivative () in the presence of a base directly to give a compound of the invention. Derivatives () are known per se and can be produced by conventional methods. The reaction is preferably carried out in the presence of a solvent or diluent for the reactants. Examples of solvents include:
Included are lower ketones such as methyl ethyl ketone. The reaction can be accelerated by heating, for example conveniently carried out at the reflux temperature of the solvent. Examples of bases used in the reaction include inorganic bases such as anhydrous potassium carbonate. The starting materials () used in routes A, B and C can themselves be prepared in various ways. For example, compounds containing fluorinated alkyl groups can be prepared by reacting a reacting chlorinated compound with a fluorinating agent to exchange some or all of the chlorine atoms for fluorine atoms. Thus, 2-chloro-5-trifluoromethylpyridine converts 2-chloro-5-trichloromethylpyridine into a fluorinating agent.
For example, it can be obtained by reacting with antimony trifluoride or liquid hydrogen fluoride. By adjusting the amount of fluorinating agent used in the reaction, it is possible to obtain a compound having an alkyl group containing both fluorine and chlorine atoms. For example, 2-chloro-5-trichloromethylpyridine is reacted with a small amount of antimony trifluoride to yield 2-chloro-5-chlorodifluoromethylpyridine. In these halogen exchange reactions, a portion of the halogen substituent at the 2-position of pyridine is also exchanged, and therefore a portion of the 2-fluoro compound is also obtained. This is actually no disadvantage. This is because the 2-position halogen is substituted when the subsequent halogenopyridine is converted into the compound of the present invention. It is believed that some of the chlorinated compounds required as starting materials here are novel compounds. Examples are 2-chloro-5-trichloromethylpyridine and 2,3
-dichloro-5-trichloromethylpyridine. They have some biological activity as insecticides and are useful as intermediates for making the compounds of this invention. When 3-methylpyridine is reacted with chlorine in the liquid phase under the influence of ultraviolet light, 2-chloro-5-trichloromethylpyridine is produced. In this case, 3
- The reaction of methylpyridine (as free chlorine or in salt form) with chlorine is usually carried out in an inert organic solvent. Convenient solvents are halogenated hydrocarbons,
For example, carbon tetrachloride, but other solvents such as hydrocarbons and ethers may also be used, provided they do not react under the conditions of use and produce undesirable by-products in unacceptable amounts. The reaction is slow below room temperature and is conveniently accelerated by heat. Convenient reaction temperatures are, for example, from 50 to 130°C. The solution can be heated under reflux. Preferably, dry reactants and solvents are used. Ultraviolet light may be supplied to the reaction from a suitable electric lamp, or may be dipped into the reaction mixture for best effect. The reaction usually provides a reaction mixture and the desired 2-chloro-5-trichloromethylpyridine can be isolated by conventional methods, such as distillation. In another method for producing 2-halogeno-3- or -5-trifluoromethylpyridine, 2-
Halogeno-3- or -5-carboxypyridine can be reacted with sulfur tetrafluoride in the presence of hydrogen fluoride as shown below for 2-chloro-5-trifluoromethylpyridine. The present invention will be explained below with reference to production examples, reference examples, and test examples. In the production examples and reference examples, unless otherwise specified, all parts are by weight and all temperatures are in degrees Celsius. Production Example 1 This Production Example shows the production of Compound No. 1 according to the present invention. (a) Preparation of 2-chloro-5-trichloromethylpyridine 2-bromo-5- in dry carbon tetrachloride (600 ml)
The hydrochloride salt was obtained by filtration of methylpyridine (55g) and subsequent treatment with dry hydrogen chloride. The precipitated solid was crushed and the mixture was heated to reflux. Dry chlorine was passed through the boiling mixture for 61/2 hours while simultaneously being irradiated by an ultraviolet lamp placed inside the reaction flask. The mixture was then cooled, filtered and evaporated to give a light yellow liquid which solidified on cooling. This was identified as the desired chloro compound by its nuclear magnetic resonance spectrum. (b) Production of 2-chloro-5-trifluoromethylpyridine and 2-chloro-5-difluorochloromethylpyridine 2-chloro-5-trichloromethylpyridine (18g) and antimony trifluoride (50g) were mixed at 140~
Heated at 145°C for 1 hour. The mixture was cooled, mixed with ice and concentrated hydrochloric acid, and extracted with ether. The extracts were washed with water, dried over magnesium sulphate and evaporated. The products from several such preparations were combined and distilled by passing at atmospheric pressure through a short column packed with Fenske rings.
The product boiling between 124-154°C was collected and identified as 2-chloro-5-trifluoromethylpyridine.
The fraction with a higher boiling point was redistilled at a pressure of 20 mmHg to obtain 2-chloro-5-difluorochloromethylpyridine with a boiling point of 82-90°C. (c) Production of 2-p-methoxyphenoxy-5-trifluoromethylpyridine Sodium hydride (50% oil dispersion washed with petroleum, 4.2 g) was dissolved in dry dimethyl sulfoxide (100% oil dispersion, 4.2 g).
ml), stirred in dimethyl sulfoxide (100 ml)
A solution of p-methoxyphenol (10.4 g) dissolved in was added over several minutes. The mixture was stirred for 30 minutes to obtain the sodium salt. A solution of 2-chloro-5-trifluoromethylpyridine (15.0 g) in dimethyl sulfoxide (80 ml) was added to the solution over a period of several minutes. Then heat the mixture to 70-75℃
The mixture was heated for 3 hours and left to cool overnight. Thin layer chromatography revealed that only one compound was present. The mixture was diluted to 1.5 with water and then extracted with ether (3x600ml). The ether extract was washed several times with water, then with 1M sodium hydroxide solution and finally with water (2 x 200ml). The ether extract was dried and evaporated to give the required pyridine compound as a brown oil. (d) Production of 2-p-hydroxyphenoxy-5-trifluoromethylpyridine 2-p-methoxyphenoxy-5-trifluoromethylpyridine (10.5 g) was mixed with glacial acetic acid (50 ml) and 48% bromide. Stir and heat under reflux in hydrogen acid (50ml) for 71/2 hours. The solution was then evaporated and the remaining oil was treated with sodium bicarbonate solution and shaken with ether (2x300ml). The ether extract was shaken with 2M sodium hydroxide solution (200ml) then water (150ml). The aqueous layer was collected, acidified with 2M hydrochloric acid and extracted with ether (2 x 300ml). By drying and evaporating the ether extract, 2
A brown oil was obtained identified as -p-hydroxyphenoxy-5-trifluoromethylpyridine. (e) Production of ethyl α-(5-trifluoromethyl-2-pyridyloxy)phenoxypropionate 2-p-hydroxyphenoxy-5-trifluoromethylpyridine (0.22g), α-bromopropionic acid Ethyl (0.24g) and potassium carbonate (0.18g) in methyl ethyl ketone (5ml)
Stir and heat under reflux for an hour. The mixture was allowed to cool overnight, then filtered and the residue was washed with methyl ethyl ketone. The filtrate and washings were evaporated and the remaining oil was subjected to high vacuum to remove traces of solvent. The nuclear magnetic resonance spectrum of the oil was consistent with the assigned structure and the compound was identified as ethyl α-(5-trifluoromethyl-2-pyridyloxy)phenoxypropionate. (f) Production of α-(5-trifluoromethyl-2-pyridyloxy)phenoxypropionic acid The product of (e) (0.14 g) was mixed with isopropanol (2
ml) with an aqueous solution of sodium hydroxide (1.6 ml of a solution containing 1 g of NaOH per 100 ml of water).
Stirred at room temperature for an hour. Evaporate the mixture in vacuo,
The residue was taken up in water, acidified and extracted with ether (2x50ml). An oily substance identified as the desired carboxylic acid was obtained from the ether extract. (g) Preparation of 2-[4-(5-trifluoromethylpyridyl-2-oxy)phenoxy]propionyl chloride The carboxylic acid (1.2 g) prepared as described in section (f) above was mixed with thionyl chloride (20 ml). The mixture was heated under reflux for 1 hour, and excess thionyl chloride was removed under reduced pressure. Traces of thionyl chloride were removed by mixing the residue with toluene and evaporating the toluene under reduced pressure. The propionyl chloride derivative was obtained as an oil. (h) Production of Compound No. 1 Acid chloride (0.78
g) in excess ethylamine aqueous solution (20ml, 100ml
solution containing 70 g of ethylamine). Excess ethylamine solution was removed under reduced pressure. The residue was diluted with water and extracted with ether. The ether solution was washed with 2M hydrochloric acid and water, dried and evaporated. The residue was recrystallized from petroleum (boiling point 60-80°C) to obtain an ethylamide compound with a melting point of 96-98°C. According to this method, p-chlorophenylhydrazine (formula

Compound No. 1 was produced using the formula. Reference Example 1 This reference example describes the preparation of 2-chloro-5-trichloromethylpyridine by chlorination of 3-methylpyridine under the influence of ultraviolet light. 3-Methylpyridine (10ml) was dissolved in dry carbon tetrachloride (300ml). Heat the solution to reflux (approximately 80
°C), dry chlorine gas was passed through the boiling mixture for 3 hours,
At the same time, it was irradiated from inside with a 100 watt ultraviolet lamp that emits light with a wavelength of 185 nm. When preparative thin layer chromatography (silica, chloroform/cyclohexane) was performed on a sample of the evaporated solution obtained in this way, three main products were obtained with an overall yield of 10-15%. Most of them were identified by nuclear magnetic resonance as the desired 2-chloro-5-trichloromethylpyridine. This was confirmed by mass spectrometry analysis of the resulting solution. The other two main components are 2-chloro-3-trichloromethylpyridine and (trichloromethyl)pyridine.
Each was present in an amount of 1/2 and 1/3 of the main product. Reference Example 2 The present invention describes the production of 2-chloro-5-trichloromethylpyridine from the salt of 3-methylpyridine. The hydrochloride salt was obtained by treating 3-methylpyridine (15g) with dry HC gas in dry carbon tetrachloride (200ml). The oil thus obtained was stirred and heated to reflux. Dry chlorine gas was bubbled through the refluxing mixture for 4 hours, during which time it was internally illuminated with the ultraviolet lamp used in Preparation Example 1. The reaction mixture was then cooled and separated into a solution and an oily solid by decanting. The latter was purified and found to contain unreacted 3-methylpyridine. Evaporation of the former gave an oily semi-solid which was found by thin layer chromatography to have the characteristics of 2-chloro-5-trichloromethylpyridine. Reference Example 3 This reference example describes the production of 2-chloro-5-trifluoromethylpyridine by an alternative method to Production Example 1(b). 6-Chlornicotinic acid (23.6 g), sulfur tetrafluoride (37.4 g) and anhydrous hydrogen fluoride (18.7 g) were heated at 120° C. for 8 hours while stirring in an autoclave. The mixture was cooled, poured onto ice and neutralized with concentrated sodium hydroxide solution at 0°C. The mixture was extracted with ether and the extracts were washed with water, dried and evaporated. The residue was distilled and the fractions at 140-150°C were collected. Analysis showed that it consisted of 2-chloro-5-trifluoromethylpyridine and some 2-fluoro-5-trifluoromethylpyridine. Reference Example 4 This Reference Example describes the production of 2-chloro-5-trifluoromethylpyridine by an alternative method to the methods of Production Examples 1(b) and Reference Example 3. 2-chloro-5-trichloromethylpyridine (30.8 g) and anhydrous hydrogen fluoride (80 g) were heated at 200° C. for 10 hours while stirring in an autoclave.
The mixture was cooled, poured onto ice and neutralized at 0°C. The mixture was filtered and the residue and filtrate were extracted with ether. The ether extract was washed with water, dried and evaporated to give an oily substance. Distill this and
The fraction boiling at 140-154°C was collected. Analysis showed this to be 2-chloro-5-trifluoromethylpyridine and some 2-fluoro-5-trifluoromethylpyridine. Reference Example 5 This Reference Example shows the production of ethyl 2-[4-(3-chloro-5-trifluoromethylpyridyl-2-oxy)phenoxy]propionate by Route A. (a) Preparation of 2-amino-3-bromo-5-methylpyridine 2-Amino-5-methylpyridine (108 g) was heated to 90-100°C in glacial acetic acid (300 ml) while dipping into acetic acid (55 ml). Dissolved bromine (160 g) was slowly added under stirring. After the addition is complete, add more of the mixture.
Stir and heat for 30 minutes, then cool overnight. The precipitated solid was collected by filtration and mixed with ice, and the mixture was neutralized with concentrated aqueous ammonia while maintaining the temperature at 0-5°C. The solid was collected, washed with water, and dried to obtain a bromine compound. (b) Preparation of 3-bromo-2-chloro-5-methylpyridine The product from (a) (145g) was dissolved in concentrated hydrochloric acid (750ml) and water (450ml) and the solution was cooled to -10°C. Sodium sulfite (54g) dissolved in cold water (450ml)
was added dropwise over a period of 90 minutes with stirring, during which time the mixture was maintained at -5°C. The solution was stirred for a further 2 hours and then basified with concentrated aqueous ammonia, keeping the temperature below 20°C. The precipitated solid was washed with water, dried and dissolved in ether (1500ml).
Washed with cold sodium hydroxide solution (1M, 1). Wash the ether solution twice with water (one each time),
Drying and evaporation gave the desired 3-bromo-2-chloro-5-methylpyridine. (c) Production of 2,3-dichloro-5-trichloromethylpyridine
Treated with dry hydrogen chloride in a vacuum. The precipitate was crushed, the suspension was heated to reflux, dry chlorine was bubbled into the mixture and it was illuminated with an ultraviolet lamp. After 41/2 hours, the mixture was cooled, filtered, and the filtrate was evaporated to yield the required 2,3-dichloro-5-trichloromethylpyridine. The mass spectrum was consistent with the structure assigned to this mixture. (d) Preparation of 2,3-dichloro-5-trifluoromethylpyridine The product of (c) (1.0 g) and antimony trifluoride (3.0 g) were heated at 170-180°C for 30 minutes. The mixture was then cooled, mixed with ice and water, and extracted with ether. The ether extract is 2,3-dichloro-
A brown oil was obtained containing a mixture of 5-trifluoromethylpyridine and 3-chloro-2-fluoro-5-trifluoromethylpyridine and a small amount of 2,3-dichloro-3-chlorodifluoromethylpyridine. (e) 3-chloro-2-p-methoxyphenoxy-
Production of 5-trifluoromethylpyridine p-methoxyphenol (1.5 g) was mixed with sodium hydride (a 50% oil dispersion washed with petroleum,
0.6g) was added to the solution in dry dimethyl sulfoxide (30ml) and the mixture was stirred for 15 minutes. The product (1.5 g) obtained from several preparations carried out as described in section (d) was collected and a solution dissolved in dimethyl sulfoxide (20 ml) was added to the reaction mixture and heated at 60°C for 4 hours. . Additional sodium hydride (0.3% oily dispersion, washed with petroleum)
g) and potassium carbonate (1.38g) were added. Heating was continued for an additional 4 hours. The mixture was poured onto ice and water and extracted with ether (400ml). Wash the ether extract with water, dilute sodium hydroxide and water;
The product was obtained by drying and evaporating. (f) Production of 3-chloro-2-p-hydroxyphenoxy-5-trifluoromethylpyridine The product of (e) (2 g) was mixed with pyridine hydrochloride (20 g).
and heated at 170-180°C for 6 hours. The mixture was cooled, diluted with dilute hydrochloric acid, and extracted with ether. An oily solid was obtained from the ether extract and purified by preparative thin layer chromatography using silica as an adsorbent and 6% ethanol-chloroform as a solvent. 2,3-dichloro-5-methylpyridine was also produced by an alternative method as follows. (h) Production of 2-amino-3-chloro-5-methylpyridine 2-amino-5-methylpyridine (10.8
g) was maintained at 10-15°C with concentrated hydrochloric acid (100ml) while hydrogen peroxide (30%, 21ml) was added dropwise under stirring. After the addition is complete, the mixture is heated to 11/ without cooling.
The mixture was stirred for 4 hours and poured onto ice (approximately 200 g). The mixture was adjusted to pH 8~ by dropping concentrated aqueous ammonia.
I made it 9. During this time, the temperature was maintained at approximately 0°C by adding ice. Add the solution to chloroform (2 x 300ml)
Extracted with. The required chloro compound was obtained as a yellow solid from the chloroform extract. (i) Preparation of 2-bromo-3-chloro-5-methylpyridine The product of section (h) (5.7 g) was mixed with hydrobromic acid (48%,
50 ml) was cooled at -15°C to -10°C, and bromine (2.6 ml) was added.
was added dropwise under stirring. Next, a solution of sodium nitrite (5.53 g) dissolved in water (12 ml) was added dropwise over 45 minutes while maintaining the temperature at -5 to 0°C.
Once the addition was complete, the mixture was stirred for an additional 30 minutes at 0°C and poured onto ice. The mixture was made slightly alkaline by dropwise addition of concentrated aqueous ammonia, while the temperature was maintained at 0° C. by addition of ice. The mixture was extracted with ether (150ml). The ether extracts were washed with water, sodium bisulfite solution and water, then dried and evaporated. The residue was filtered and evaporated from petroleum solution (boiling point 40-60°C). The residue was identified as 2-bromo-3-chloro-5-methylpyridine. (j) Production of 2,3-dichloro-5-trichloromethylpyridine
This was converted to the hydrochloride salt by treatment with dry hydrogen chloride in ml). Chlorine was passed into the suspension, which was kept at 80°C and illuminated by a UV lamp in the reaction flask. After 3 hours, remove the solvent and 2.
A residue of 3-dichloro-5-trichloromethylpyridine was obtained. Reference Example 6 In this reference example, 2,3-dichloro-5-trichloromethylpyridine was fluorinated using a fluorinating agent instead of the fluorinating agent in Reference Example 5.
The production of 5-trifluoromethylpyridine is explained. 2,3-dichloro-5-trichloromethylpyridine (35 g) was heated with anhydrous hydrogen fluoride (100 g) in an autoclave at 200° C. for 10 hours with stirring. The cooled reaction mixture was poured onto ice and neutralized with sodium hydroxide at 0°C. The mixture was extracted with methylene chloride (750ml). The extracts were washed with water (500ml), sodium carbonate solution (500ml) and water (500ml), dried and evaporated. The remaining oil was evaporated and collected as a fraction boiling 77-83°/25 Torr. This was identified as the desired pyridine derivative. Reference Example 7 This Reference Example further shows the production of 2,3-dichloro-5-trifluoromethylpyridine. Water was removed by melting antimony trifluoride (61 g) under vacuum. The cooled material was crushed and heated to 65-70°C while antimony pentachloride (6.6g) was added dropwise under stirring. Then 2,3
-dichloro-5-trichloromethylpyridine (40
g) was added dropwise to the reaction mixture and the whole was heated to 160° C. for 45 minutes. The mixture was cooled and steam distilled.
The distilled oil was extracted with ether (2x
100ml). The ether extract was washed with tartaric acid solution, then water, sodium bicarbonate and water and dried. The residual oil was distilled off. 71~80°／18Torr
The fraction boiling at is identified as the desired pyridine derivative. Reference Example 8 This reference example describes the production of 3-chloro-5-trifluoromethyl-2-p-hydroxyphenoxypyridine according to route B. Dry dimethylformamide (30ml) was degassed by heating at reflux for 30 minutes under a stream of argon.
Hydroquinone (49.5 g) and anhydrous potassium carbonate (6.84 g) were added and heated under reflux for 90 minutes. A solution of 2,3-dichloro-5-trifluoromethylpyridine (6.48 g) in dry, degassed dimethylformamide (30 ml) was added to the above mixture for 4 hours.
It took some time to add. The mixture was cooled overnight and diluted with water (500ml). The mixture was acidified with dilute hydrochloric acid and extracted with ether (2x400ml). The ether extract was washed with water (2 x 500ml) and extracted with dilute sodium hydroxide (300ml). The ether extracts were washed with water and the aqueous fractions were collected and reacidified with hydrochloric acid. The acidified aqueous solution was extracted with chloroform (2 x 400ml). A light brown oil was obtained from the chloroform extract and triturated with petroleum (boiling point 30-40°C) to give a colorless solid identified as the desired 3-chloro-5-trifluoromethyl-2-p-hydroxyphenoxypyridine. I got it. Reference Example 9 This Reference Example shows the production of n-propyl 2-[4-(3-chloro-5-trifluoromethylpyridyl-2-oxy)phenoxy]propionate. The product of Reference Example 8 (1.0 g) was stirred under reflux for 4 hours with potassium carbonate (0.5 g) and n-propyl 2-bromopropionate (1.8 g) in methyl ethyl ketone (25 ml). Cool the mixture;
An oily substance was obtained by filtration and evaporation of the filtrate, which was mixed with 20 parts by volume of ether as eluent on two 2 mm thick plates, each measuring 20 cm x 20 cm.
Purification was achieved by thin layer chromatography using a mixture of 100 parts by volume of hexane. The product was extracted with ethanol. Evaporation of the ethanol gave a colorless oil identified as the title compound by nuclear magnetic resonance spectroscopy. Reference Example 10 This reference example describes the production of 2-[4-(3-chloro-5-trifluoromethylpyridyl-2-oxy)phenoxy]propionic acid. 2-[4-(3-chloro-5) produced in Reference Example 9
-trifluoromethylpyridyl-2-oxy)phenoxy]n-propylpropionate (2.19g)
was treated in isopropanol (20 ml) by dropwise addition of 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 diluted to 300ml with water. The solution was extracted with methylene chloride (2 x 50ml) and acidified with 2M hydrochloric acid. The acidified solution was extracted with methylene chloride (2 x 150ml) and the extract was dried and evaporated to give an oil. This solidified on standing and was dried under vacuum at 85°C to obtain the title compound having a melting point of 104-107°C. Production Example 2 This production example describes the production of compounds No. 2 and No. 4 in Table 1. (a) Production of 2-[4-(3-chloro-5-trifluoromethylpyridyl-2-oxy)phenoxy]propionyl chloride The carboxylic acid (16.5 g) produced by the method of Reference Example 10 was mixed with excess thionyl chloride ( 200ml) and heated under reflux for 2 hours. The acid chloride was obtained as a yellow oil by removing excess thionyl chloride under reduced pressure. Dry this with ether (220ml)
This solution was added to Compound No. 2 and
It was used to manufacture No.4. Since the methods are conventional ones, we will keep the explanations simple and summarize them in the table below.

[Table]
Production Example 3 This production example shows the production of compound No. 3 in Table 1. The solution (20 ml) prepared in section (a) of Production Example 2 was mixed with phenylhydrazine (0.95 g) and dry ether (20 ml).
ml) at room temperature, and the mixture was diluted with 1
It was stirred overnight. The mixture was then diluted with water and acidified with 2M hydrochloric acid. Separate the ether layer, wash with water,
Dry. Evaporation of the ether gave phenyl hydrazide as a fixed melting point of 109-110°C. Production Example 4 Compounds Nos. 5 and 6 were treated with 2-[4-(5-chloro-3-trifluoromethylpyridyl-2-oxy)phenoxy]propionyl chloride by the method described in Section (h) of Production Example 1. Each was produced by reacting with morpholine or aniline. The propionyl chloride necessary for these preparations was prepared by reacting the corresponding acid with thionyl chloride according to the method described in section (g) of Preparation Example 1. The required carboxylic acid was obtained by hydrolyzing the propyl ester with sodium hydroxide according to the method described in Preparation Example 1, section (f). Next, the herbicidal efficacy of the compounds of the present invention will be illustrated by test examples. Test Example A This Test Example A shows the herbicidal properties of the compound of general formula () of the present invention. Each compound has this
Span 80 with 21.8g per unit and 8.2 per unit
Tween 20 in methylcyclohexanone was mixed with 5 ml of an emulsion prepared by diluting to 500 ml with water. Span 80 is a trademark for a surfactant consisting of sorbitan monolaurate. Tween 20 is a trademark for a surfactant consisting of a condensate of 20 molar proportions of ethylene oxide and sorbitan monooleate. The mixture of compound and emulsion was shaken with glass beads and diluted to 12 ml with water. The spray composition thus obtained was applied to young pot plants of the types named in Table 2 below (post-emergence test).
sprayed at a rate equal to 1000/ha. Damage to plants was evaluated on a scale of 0 to 3 by comparison with untreated plants 14 days after spraying. Here, 0 indicates no effect, and 3 indicates a 75-100% weed killing rate. In the pre-emergence herbicidal activity test, seeds of the test species were placed on the surface of a fiber tray in the soil and the composition
It was sprayed at a rate of /ha. The seeds were then covered with more soil. Three weeks after spraying, the seedlings in the sprayed fiber trays were compared to the unsprayed control trays and damage was rated on the same scale of 0-3. The (-) mark in the results table indicates that the test was not conducted. The results are shown in Table 2 below.

[Table] The abbreviations of test plants shown in Table 2 have the following meanings. Lt Lettuce To Tomato Ot/Av Cultivated oats and wild oats ( Avena fatua ) Wild oats were used for post-emergence tests, and cultivated oats were used for pre-emergence tests. Ll Lolium perenne (perennial rye grass) Cu Cyperus rotundus St Setaria viridis The results in Table 2 clearly demonstrate the selectivity of the herbicidal activity of the compounds of the present invention, and the weed species used in the test were not significantly damaged or damaged. , was suppressed, whereas dicots remained essentially undamaged. Test Example B This test example demonstrates the herbicidal properties of yet another compound of the invention. These compounds were tested in the same manner as Test Example A. The results were evaluated and expressed in the same manner. The results are shown in the table below. Please refer to this table as a continuation of Table 2.

【table】

Claims (1)

[Claims] 1. The following general formula () {In the formula, Z and Y each represent a chlorine or hydrogen atom, or a trifluoromethyl group, provided that at least one of Z and Y is a trifluoromethyl group, and R ² is (1) Carboxamide group [Formula] [However, R ³ is hydrogen, R ⁴ is a phenyl group or chlorophenyl group,
or the group -NR ⁵ R ⁶ (R ⁵ is hydrogen and R ⁶ is a phenyl group or chlorophenyl group), or the group -NR ³ R ⁴ in the carboxamide group as R ² is a morpholino group. or R ² represents (2) group [Formula] (R ⁷ is a phenyl group), or R ² represents (3) a haloalkoxycarbonyl group or (4) a phenoxycarbonyl group (However, this phenoxycarbonyl group may have a halogen or methyl substituent.) However, when Z is a trifluoromethyl group, R ² is represented by the formula [Formula] (However, R ³ is hydrogen and R ⁴ is a phenyl group or a chlorophenyl group), a group of the formula [formula] or a phenoxycarboxyl group (however, this phenoxycarbonyl group has a halogen or methyl substituent) ), and also
When R ² is a haloalkoxycarbonyl group, only a mono-chloro-(C ₁ -C ₄ )alkoxycarbonyl group is shown.} A pyridine derivative represented by the following formula. 2. Apply the following general formula () to undesirable herbaceous plants or where they grow. {In the formula, Z and Y each represent a chlorine or hydrogen atom, or a trifluoromethyl group, provided that at least one of Z and Y is a trifluoromethyl group, and R ² is (1) Carboxamide group [Formula] [However, R ³ is hydrogen, R ⁴ is a phenyl group or chlorophenyl group,
or the group -NR ⁵ R ⁶ (R ⁵ is hydrogen and R ⁶ is a phenyl group or chlorophenyl group), or the group -NR ³ R ⁴ in the carboxamide group as R ² is a morpholino group. or R ² represents (2) group [Formula] (R ⁷ is a phenyl group), or R ² represents (3) a haloalkoxycarbonyl group or (4) a phenoxycarbonyl group (However, this phenoxycarbonyl group may have a halogen or methyl substituent.) However, when Z is a trifluoromethyl group, R ² is represented by the formula [Formula] (However, R ³ is hydrogen and R ⁴ is a phenyl group or a chlorophenyl group), a group of the formula [formula] or a phenoxycarbonyl group (however, this phenoxycarbonyl group has a halogen or methyl substituent) ), and also
When R ² is a haloalkoxycarbonyl group, only a mono-chloro-(C ₁ -C ₄ )alkoxycarbonyl group is used. A method of suppressing plant growth.