CS201538B2 - Herbicide means and method for making the active compon ent ingredient - Google Patents

Abstract

The compounds corresponding to the formula: <IMAGE> in which the symbols have the meaning given in Claim 1, are prepared by oxidation of the corresponding N-oxides of 2-thiopyridine, in an inert solvent, at between 0 DEG C and the boiling temperature of the solvent. These compounds have a selective herbicidal action and can be used for destroying weeds in various crops, especially flax, lucerne, cotton, soya, ground nut, tomato and tobacco.

Description

(54) Herbicidal composition and method for producing the active ingredient

The invention relates to a novel herbicidal composition and to a process for the preparation of its herbicidally active components.

W. Ealter et al., Liebíg's Ann. 695, 77 (1966), described 2- (phenylmethylsulfinyl) pyridine-N-oxide (also called 2-Ь (β 2 -pyridine N-oxide) and 2- (phenylmethylsulfo) -nyl) pyridine N-oxide (also called 2-benzylsulfonylpyridine N-oxide), but found no use for these substances.

In U.S. Patent No. 3,107,994, Rawlings et al. some herbicidal 2- (alkenylthio) pyridine-N-oxides, and in U.S. Pat. No. 3,155,671, D'Amico discloses some herbicidal 2-thiopyridine-N-oxides.

Further work, illustrating the state in the art are for example: ^l E. Shaw et al., JACS 72, 4362 (1950) and U.S. Pat. No. 3,772,307 (Kaminsky et al.).

The novel 2-sulfinyl and 2-sulfonylpyridine-N-oxide derivatives, in particular as herbicides, have considerably better activity than the various compounds of the earlier works.

Weeds compete with the demands of cultivated crops for light, moisture, nutrients and space. Weeds reduce the production of foliage of fruit or seeds of agricultural plants. Thus, the presence of weeds can reduce crop quality and yield. Weed control is essential for maximum production of a number of agricultural and garden plants, such as soybeans (Glycine max L.), peanuts (Arachis hypogaea L.), flax (Linum usitatissium L.) and cotton (Gossypium sp.).

According to the invention, unwanted weeds are removed by a herbicidal composition which contains the compound 2-sulfinyl- or 2-sulfonylpyridine-N-oxide of the formula I as active substance,

where n is 1 or 2,

R1 is hydrogen, C1-C3-alkyl or phenyl,

R 2 has one of the following meanings: when R 1 is hydrogen, then R 2 is cyclohexyl, 2,2-dichlorocyclopropyl, 2,2-dichloro-1-methylcyclopropyl, propenyl, benzyl, styryl, cyano, naphthyl, methylnaphthyl, pyridyl, benzothiazolyl, phenyl, phenyl substituted with 1 to 5 substituents, which may be the same or different and are selected from the group consisting of C 1 -C 3 -alkyl, halogen, nitro, cyano, C 1 -C 6 -alkoxy, methylenedioxy, 2,2-dichlorocyclopropyl, or trifluoromethyl, and when R 1 is C 1 -C 3 -alkyl or phenyl, then R 2 is C 1 -C 1 -alkyl, naphthyl, thienyl, phenyl, phenyl substituted with 1 to 3 substituents, which may be the same or different and are selected from the group consisting of C 1 —C2 — alkyl, halogen, nitro and m-ethylsulfonyl, or

R 1 and R 2 may be joined together as a chain of methylene groups to form a cyclic aliphatic ring containing 5 to 7 carbon atoms.

The herbicidal composition according to the invention may advantageously comprise the following herbicidally active compounds: a compound of formula (I) wherein R 1 is hydrogen or methyl and R 2 and n are as defined above; the compound of formula (I) wherein R 2 is phenyl, phenyl substituted with 1 to 3 methyl groups, phenyl substituted with 1 to 3 halogens or 2-naphthyl and R 1 and n are as defined above; the compound of formula (I) wherein R 1 is hydrogen and R 2 is phenyl substituted with 1 to 3 methyl groups or phenyl substituted with 2 to 3 chlorine atoms and n is as defined above; a compound of formula I wherein R 1 is methyl and R 2 is phenyl, phenyl substituted with 1 or 2 methyl groups, monohalophenyl or 2-naphthyl and n is as defined above; optionally, it may contain one of the following compounds as a compound of Formula I:

2- (2,5-Dimethylphenylmethylsulfonyl) pyridine N-oxide;

2 '- (2' _, 4,6-trimethylphenylmethylsulfonyl) pyridine-N-oxide,

2- (2,6-dic Horleny N-isopropyl) pyridine-N-oxide,

2r (2,4-dichlorophenylmethylsulfinyl) pyridine N-oxide,

2- (2,6-Dichlorophenylmethylsulfinyl) pyridine N-oxide;

2- [1- (4-Methylphenyl) ethylsulfonyl] pyridine N-oxide,

2- (2 ', 4'-thi-4'H (1''''''''''''l''''''''''''''lizo''''''''''''lizo-N-oxide),

2- (2-Methylphenyl) pyridine-N-oxide;

2- [1- (4-fluorophenyl) ethylsulfonyl] pyridine N-oxide,

2- [1- (2,5-Dimethylphenyl) ethylsulfonyl] pyridine-N-oxide,

2- (1-phenylethylsulfonyl) pyridine-N-oxide,

2- (1- (2-naphthyl) ethylsulfonyl) pyridine N-oxide,

2- (1- (4-chlorophenyl) ethylsulfonyl) pyridine N-oxide,

2- (1- (4-bromophenyl) ethylsulfonyl) pyridine N-oxide,

2- (2,3,6-trimethylphenylmethylsulfonyl) pyridine N-oxide;

2- (2,3,6-Dimethylphenylsulfonyl) pyridine-N-oxide; or

2- (2,5-Dimethylphenylmethylsulfonyl) pyridine N-oxide.

The process for the preparation of the active ingredients of the formula I according to the invention as described above is carried out by reacting a 2-thiopyridine N-oxide derivative of the formula

in which

R1 and R2 are as defined above, reacted with an oxidizing agent in the presence of a solvent or catalyst, such as a tungsten, vanadium, zirconium or molybdenum salt, at a temperature of from 0 ° C to the reflux temperature of the reaction mixture.

Hydrogen peroxide, peracetic acid or aromatic peracids are preferably used as oxidizing agents.

As solvents, glacial acetic acid or water can be used and operated at a temperature of from 50 ° C to the reflux temperature of the reaction mixture.

Aromatic peracids or peracetic acid may also be used as the oxidizing agent, and non-polar solvents may be used as solvents and work may be performed. at 0 to 60 ° C.

The herbicidally active pyridine N-oxide derivatives described herein are useful for both preemergence and postemergence. weed control and. moreover, they are remarkable for their ability to selectively control weeds without damaging the harvest of desired plants. Very effective control. weeds, such as creeping grass [Agropyron repens (L.) Beauv.J, seed, millet (Panicum texanumj. Buckl., shear (Setaria faberi Herrm.j), gray shrew [Setaria lutescens (Weigel) Hubb.J, shear. green [Setaria viridis · (L.) Beauv], hedgehog · corn [Echinochloa crus — galli (L.) Beauv] and deaf oats (Avena fatua L.) can be obtained with substances such as 2- (2,5) -dimethylphenylmethylsulfonyl] pyridine N-oxide without damaging plants such as flax (Linum usitatissimum L.), alfalfa (Medicago sativa L.), cotton (Gossypium sp.), soybeans [Glycine max (L. Merr], peanuts (Arachis hypogaea L.), tomatoes (Lycopersicon esculentum Milí.) And tobacco (Nicotiana tabacum L.).

Described here. Surprisingly and unexpectedly, 2-sulfufinyl and 2-sulfonylpyridine-N-oxide herbicides are more effective than their corresponding sulfide precursors.

The procedure for using these 2-sulfinyl and 2-sulfonylpyridine-N-oxides derivatives may be the same as in conventional agricultural practice. The substances are usually applied as adjuncts containing a carrier and / or a surfactant. If desired, the formulation may contain more than one of the disclosed pyridine-N-oxide derivatives; as well as other active herbicides may be included in the formulation.

The substances may be impregnated with finely ground or granulated inorganic or organic carriers such as clay, sand, vermiculite, corn cones, activated carbon or other known granular carriers. The impregnated granules are then spread on the soil. Further, the substances can be prepared as wettable powders by grinding them to a fine powder and mixing with an inactive powdered carrier to which a surfactant dispersant has been added. Typical solid powdered carriers are various mineral silicates such as mica, talc, pyrophyllites and clays. The wettable powders can then be dispersed in water and sprayed onto the soil surface or weeds. Similarly, an emulsifiable concentrate can be prepared by dissolving the substance in solvents such as benzene, toluene or other aliphatic or aromatic hydrocarbons to which a surfactant has been added. The emulsifiable concentrates may then be dispersed in water and applied by spraying. Suitable surfactants are known to those skilled in the art and examples of suitable surfactants can be found in McCutcheons Detergents and Emulsifiers, 1970, Allured Publishing Corp., Ridgewood, New Jersey; or Hoffman et al. U.S. Patent 2,614,916, paragraphs 2 to 4, and 2,547,724, paragraphs 3 and 4. Concentrations. The active ingredients in the formulations may vary over a wide range, e.g. from 1 to 95%. Concentration of active substance in soil dispersions or. leaves is almost invariant from 0.002%. up to 75 ·%. Substances are often applied at doses of 0.112 to 28 kg / ha. When used as pre-emergence herbicides, the substances are applied to soil containing weed seeds and crop plants (either on the surface of the soil, or incorporated into the top layer of soil with a depth of 25 to 75 mm).

The most appropriate application rate in each individual case will depend on such factors as soil type, soil pH, soil organic matter content, amount and intensity of water precipitation before and after treatment, air and soil temperature, light intensity and daylight exposure time. All these factors can affect the effectiveness of the substances when used as herbicides.

The herbicidal effect may include selective weed control in cultures such as soybean cotton flax and peanuts.

The 2-siulinyl and 2-suufonyl pyridine-N-oxide derivatives useful as herbicides of the present invention can be prepared from known compounds [see A. R. Katritsky, J. Chem. Soc. 191 (1957), U.S. Pat. Nos. 3,107,994 and 3,155,671, mentioned above, and articles by E. Shaw et al. and W. Walter et al. mentioned above). The starting 2-thiopyridine-N-oxides are prepared by one of two methods:

(1) Reaction of 2-chloropyridine-N-oxide with a suitable mercaptan in the presence of a substance capable of binding an acid, such as caustic earth hydroxide;

(2) reacting the sodium salt of 2-mercaptopyridine N-oxide with a suitable halide, preferably of the benzyl type,. however, another type of substance may be used.

The results of both procedures are comparable.

An alternative method of synthesis involves oxidizing 2-thiopyridine prepared by a method described in the literature. Oxidation is the conversion of both sulfur and nitrogen to a higher oxidation stage in a simple preparation step. In this case, the reaction products are sulfones as a result of the oxidation process: sulfide-> sulfoxide-> sulfone sulfone-N-oxide. The most common oxidizing agent is 30 to 50% hydrogen peroxide in glacial acetic acid, but other agents may also be used. An excess of three equivalents of peroxide is required.

Conversion of 2-thiopyridine N-oxide to analogous sulfine or sulfonyl compounds is accomplished using one or two equivalents of an oxidizing agent such as hydrogen peroxide, peroxoacetic acid and aromatic peracids, but other reagents may also be used. The amount of peroxide relative to the substrate depends on the desired product. The general reaction scheme and the number of equivalents can be illustrated as follows:

The choice of the solvent used depends on the oxidizing agent as described in the literature (Katritsky and Lagowski, Chemistry of the Heterocyclic N-Oxides, Academic Press, 1971). When hydrogen peroxide is used, glacial acetic acid and water are most suitable, and non-polar solvents such as chloroform for aromatic peracids. When water is chosen as the solvent, a tungsten, vanadium, zirconium or molybdenum salt type is usually used as the catalyst (U.S. Patents 3,005,852, Freyermuth et al., Oct. 24, 1961, 3,006,962 to Schultz et al. October 1961, 3,006,963, Buc et al, October 31, 1961, and British Patent 1,335,626, Eastman Kodak Co., October 31, 1973). The reaction temperature and time depend on the sulphide taken into the reaction and varies from 50 ° C to reflux temperature for water and acetic acid and from 0 ° C to 60 ° C for chloroform.

The compounds of the invention can be used to selectively control various grasses and broadleaf weeds including Amaranthus retroflexus L. and cabbage (Portulaca oleracea) L.] in a variety of cultures such as flax (Linum usitatissimum L.), alfalfa (Medicago sativa) L.), cotton (Gossypium sp.), Soybeans [Glycine max. (L). Merr], peanuts (Arachis hypogaea L.), tomatoes (Lycopersicon esculentum Milí.) And tobacco (Nlcotiana tabacum L.). The active substances can be in the form of aqueous solutions or suspensions which can be sprayed onto the soil surface before weeds and crop plants have emerged and before or after sowing the seeds of the crop plants. The soil may shallowly ferment after application, but this is not necessary as in the case of the application of a pre-emergence herbicide. The compounds of the invention can also be applied by spreading granular formulations before weed and crop plants emerging.

A variety of weeds, such as the woodweed [Digitarium ischaemum (Schreb.) Muhl.], Can be controlled by post-emergence application of the compounds of this invention. .

The compounds of the invention can be added to solutions of other herbicides so that the number of different weed species killed by simple application is increased. The formulations of the compounds of the invention may also contain other herbicides, so that the spectrum of different weed species destroyed by spraying or granule application can be expanded.

The following examples serve to illustrate the practice of the invention in more detail. The examples summarized in Table I illustrate the preparation of the substances used in the invention and the following examples illustrate the weed control of these substances. Melting points are not corrected in the examples. In Table I, the IR symbol in the -analysis column indicates that infrared data is given in Table II for the compound. Infrared data was measured on a Perkin-Elmer Infracord (Trade Mark). In the examples illustrating the use of substances, each substance is identified by the case number to the relevant substance in Table I.

Compounds prepared in Examples 1 to 19, 21, 24, 31, 32, 34, 36, 41, 42, 44, 46, 56 to 59, 66, 68 to 71, 77, 79, 80, 82, 83, 86 to 88, 92 to 99, 102, 103, 107 to 109, 111 and 112 are novel compounds of the invention.

She said dl

2- (2,5-Diaminophenylmethylsulfonyl) pyridine N-oxide

To a stirred solution of 792 g (2.2 mol) (40% aqueous solution) of 2-mercaptopyridine N-oxide, as the sodium salt, in 1400 mL of ethanol is added 344 g (2.2 mol) of 2,5-dimethylbenzyl chloride during the 15 minute period. The mixture is heated for 15 min. under reflux, filtered hot and mixed with 5 liters of cold water. The resulting product is filtered off and dried. Yield: 533 g of 2- [2,5-dimethylphenylmethylthiopyridine-N-oxide, corresponding to 97% of theory. Melting point: 140-142 ° C.

A. To a very vigorously stirred solution of 74 g (0.3 mol) of the thio compound in 250 ml of glacial acetic acid at 45-50 ° C is added 75 ml of 30% hydrogen peroxide over a 15-minute period. The temperature is raised to 70 degrees Celsius and after 30 minutes raised again to 80-90 ° C. This temperature is maintained for 3 hours. The temperature of the reaction mixture is then allowed to drop to ambient temperature, and cold water is added to the reaction mixture with vigorous shaking in an amount 2 to 3 times the volume of the reaction mixture. The light yellow solid formed is filtered off. Recrystallization from ethanol yielded 74.5 g of fine crystals, m.p. 156-158 ° C (10 N-0 1275 cm ^-1 , SO 2 1140, 1315 cm -1). Yield: 89%.

Analysis:

Calculation for C14H15NO3S

C, 60.63; H, 5.45; N, 5.05; S, 11.54.

Found:

C, 60.66; H, 5.56; N, 5.18; S, 11.81.

B. To a hot (80-90 ° C) vigorously stirred slurry of 30 g (0.12 mol) of the thio compound in 150 mL of water containing 10 g of acetic acid and 0.2 g of sodium tungstate with two waters is slowly added 26 mL % hydrogen peroxide. The addition induces an exothermic reaction and the temperature must be maintained at 80-90 ° C during the addition of the first 14 ml. For the remaining 12 ml, the temperature is raised to 95-105 ° C.

The initial slurry passes from the sulfoxide stage to the sulfone stage where separation occurs. The total reaction time is around. 1 hour. The reaction mixture is filtered, washed with water and air dried. Melting point: 156-158 ° C. The melting point after mixing with the eutectic sample does not show a decrease. Yield 32.8 g (quantitative).

Example 2

2- (2,4,6-Trimethylphenylmethylsulfonyl) pyridine N-oxide

A mixture of 17 g (0.05 mol) of 2-mercaptopyridine N-oxide as the sodium salt (40% aqueous solution) and 8.5 g (0.05 mol) of α-chloroisodurene in refluxing solution is heated under reflux for 15 minutes. 50 ml ethanol. The volatiles are removed and the residue extracted with boiling chloroform (150 mL), filtered and dried over sodium sulfate. Evaporation and trituration of the residue with a few drops of acetone induced crystallization. Yield is obtained

11.5 g of 2- (2,4,6-trimethylphenyimethylthio) pyridine-N-oxide. Melting point: 137-138 ° C. The structure was confirmed by IC and NMR.

To a well cooled (0-10 ° C) solution of 15 g (0.06 mol) of the thio compound in 200 ml of chloroform is slowly added 25 g (0.12 mol) of inetachloroperoxybenzoic acid (MCPBA) (85 ¹ %) in 400 ml with vigorous shaking. ml of chloroform. After the addition is complete, the temperature is allowed to rise to ambient temperature and stirring is extended to 24 hours. The reaction mixture is washed thoroughly with 300 ml of saturated sodium bicarbonate solution and dried over Na 2 SO 4. magnesium sulfate. Evaporation of chloroform and crystallization of the solid residue from methanol yielded 15 g (86% of theory) of the product. Melting point 173-175 ° C (N-0 IR 1275 cm @ ^-1, SO2 1310, 1140 cm-1).

Analysis:

Calcd. For C 15 H 17 NO 3 S

C 61.90; H, 5.84; N, 4.81.

Found:

C, 61.97; H, 6.06; N, 4.79.

Example 3

2- (2,6-Dichlorophenylamino) pyridine N-oxide

A mixture of 37 g (0.1 mol) of 2-mercaptopyridine N-oxide sodium salt (40% aqueous solution) and

19.5 g (0.1 mol) of 2,6-dichlorobenzyl chloride in 200 ml of ethanol is heated at 65-70 ° C for 30 min, then cooled and filtered. The filter cake is washed thoroughly with water and finally 40 ml of acetone. The dry cake (25.3 g) represents 92% yield of 2- (2,6-dichlorophenylmethylthio) pyridine-N-oxide. Melting point: 240-241 ° C. The structure was confirmed by IR and NMR.

A solution of 5.8 g (0.02 mol) of the thio compound in 100 ml of chloroform is cooled to 0-10 ° C. The solution is well mixed and 4 g (0.02 mol) of MCOBA (85%) is added. After 24 hours at ambient temperature, the reaction mixture is thoroughly washed with sodium bicarbonate solution, dried and evaporated. Crystallization from hot ethyl acetate yielded 4.3 g (71% of theory) of the product. Melting point 135-137 ° C. (ID N-0 1260 cm -1, SO 1050 апЧ)

Analysis:

Calcd. For C 12 H 9 Cl 2 NO 2 S

C, 47.65; H, 2.98; N, 4.64.

Found:

C, 47.25; H, 2.95; N, 4.29.

Example 4

2- [1-enyl) ethylsulfonyl] pyridine N-oxide

Intermediate 2- (1- (4-chlorophenyl) ethylthio] pyridine N-oxide is prepared from 1- (4-chlorophenyl) ethyl chloride and 2-mercaptopyridine N-oxide (sodium salt) as described in Example 2. The melting point is 106-108 ° C. The structure was confirmed by IR and NMR.

The thio compound (0.02 mole) is oxidized with MCPBA (0.04 mole) and isolated as previously described in Example 2. The yield is 78% of theory, mp 188-191 ° C (IR N-0 1300 cm -1 ^). , SO 2 1340, 1160 cm -1].

Analysis:

Calcd for C15H12ClNO3S

C, 52.44; H, 4.06; N, 4.71.

Found:

C, 52.09; H, 4.11; N, 4.61.

Example 5

2- (1- (4-Methylphenyl) ethylsulfonyl) pyridine-N-oxyl

Intermediate 2- [1-4-Methylphenyl) ethylthio] pyridine N-oxide is prepared from 1- (4-methylphenyl) ethyl chloride and 2-iodopenthoojyridine N-oxide (sodium salt) as described in Example 2. Melting point 83- 85 ° C. The structure was confirmed by IR and NMR.

Thio compound (0.02 mole) is oxidized with MCPBA (0.04 mole) and isolated as described in Example 2 (N-0 IR 1275 cm-1, SO 2 1315, 1140 ^cm-1).

Analysis:

Calcd. For C 14 H 15 NO 3 S

C 60.35; H, 5.45; N, 5.02.

Found:

C 61.18; H, 5.70; N, 5.22.

Example

2- (1- (2,5-Dimethylphenyl) ethylsulfonyl) pyridine N-oxide

The intermediate 2- (1- (2,5-dimethylphenyl) ethylthio) pyridine N-oxide is prepared from 1- (2,5-dimethylphenyl) ethyl chloride and sodium 2-mercaptopyridine N-oxide as described in Example 2. Melting point 188-120 ° C.

The structure was confirmed by IR and NMR.

The thio compound is oxidized (0.05 mol) with MCPBA (0.1) mol and isolated as described in Example 2. The yield is 83% of theory. Melting point: 160-163 ° C.

(IC-0 N 1275 cm ^1, SO 1315, 1145 cm ^"1).

Example 7

2- [1- (2-Naphthyl) ethylsulfonyl] pyridine N-oxide

The intermediate 2- (1- (2-naphthyl) ethylthio) pyridine N-oxide is prepared from 1- (2-naphthyl) ethyl chloride and sodium 2-mercaptopyridine N-oxide as described in Example 2. Melting point 112- 115 DEG C. The structure was confirmed by IR and NMR.

The thio compound (0.02 mol) is oxidized with MCPBA (0.04 mol) and isolated as described in Example 2. Crystallization from ethanol yielded 73% of the product. M.p. 144-146 ° C.

(N-0 IR 1275 cm ^1, SO ₂ 1310, 1140 cm ^"1).

Example 8

2- (2,3,6-Trimethylphenylmethylsulfinyl) pyridine-N-oxide

Intermediate 2- (2,3,6-trimethylphenylmethylthio) pyridine N-oxide was prepared from ^2- bromo-prehenitene with 2-mercaptopyridine-N-oxide sodium salt as described in Example 2. The yield was 50% of theory. Melting point 108-110 ° C. The structure was confirmed by IR and NMR.

The thio compound (0.03 mol) is oxidized with MCPBA (0.03 mol) and isolated as described in Example 2. The yield is 50% of theory. Melting point 72-75 ° C.

(N-0 IR 1250 ^cm-1, 1050 cm ¹ SO).

Example 9

2- (1-Phenylethylsulfonyl) pyridine N-oxide

To a well stirred cold (0-10 ° C) solution of 46.3 g (0.2 mole) of 2- (1-phenylmethylthio) pyridine N-oxide in 400 mL of chloroform is slowly added a solution of 80 g (0.4 mole) MCPBA in one liter of chloroform. After three hours at 0-10 ° C, the temperature is allowed to rise to ambient temperature and the reaction mixture is allowed to stand for 24 hours. After washing with saturated sodium bicarbonate solution to remove acid residues, the chloroform solution is dried and evaporated. Yield: 47 g (90% of theory). Melting point 141-143 ° C.

(N-0 IR 1260 cm ^1, SO 2 1300, 1140 ^cm-1).

Analysis:

Calcd for C13H13NO3S

C 59.40; H, 4.95; N, 5.32.

Found:

C 59.03; H, 4.90; N, 5.35.

Example 10

2- (2,4-Dichlorophenylmethylsulfinyl) pyridine N-oxide

A well stirred solution of 5.8 g (0.02 mol) of 2- (2,4-dichlorophenylmethylthio) pyridine N-oxide in 50 ml of chloroform is treated at 0-10 ° C with 4 g (0.02 mol) of MCPBA (85). %) in 50 ml of chloroform. The mixture is then allowed to warm to ambient temperature and held at this temperature for 16 hours. The reaction mixture is washed with saturated sodium bicarbonate solution, dried and evaporated. 5.5 g (89% of theory) of the product are obtained. Melting point: 138-141 ° C. The structure was confirmed by IC and NMR.

(IC-0 N 1240 cm ^-1, 1050 cm ^-1 SO).

They did

2- (2-Methylphenylmethylsulfonyl) pyridine N-oxide

The intermediate 2- (2-methylphenylmethylthio) pyridine N-oxide is prepared as described in Example 2 from α-chloro-o-xylene and sodium 2-mercaptopyridine N-oxide. Melting point 134-136 ° C. Yield: 85%. The structure was confirmed by IC and NMR.

The slurry consisting of 14 g (0.06 mol) of the thio compound, 100 ml of water, 0.5 g of sodium tungstate (with two waters) and 4 ml of glacial acetic acid is heated to 75 ° C. 12 ml of hydrogen peroxide (30%) (0.12 mol) is added in portions with a slightly exothermic reaction during the addition of the first 6 ml. The remaining 6 ml is added at the temperature of the steam bath in three 2in portions. At the same time, the course of the reaction is checked by KJ-starch indicator papers to guarantee the consumption of added peroxide. The final temperature after one hour was 97 ° C. The reaction mixture is cooled, filtered and the cake washed with water and a small amount of cold ethanol. After drying, 15.4 g (99% of theory) of the product is obtained. Melting point: 159-160.5 degrees C. The structure was confirmed by IR.

Analysis:

Calcd for C13H31NO3S

C 59.31; H, 4.98; N, 5.32.

Found:

C 59.30; H, 5.21; N, 5.31.

Example 12

2- (2,2-Dichloro-1-methylcyclopropylmethylsulfonyl) pyridine N-oxide

To a well stirred solution of 62.5 g (0.25 mol) of 2- (2,2-dichloro-1-methylcyclopropylmethylthio) pyridine in 250 ml of glacial acetic acid at ambient temperature is slowly added 90 g (0.8 mol) of 30% hydrogen peroxide.

During 2. hours the temperature is raised. at 80 ° C and held for 20 hours. Then an additional 10 ml of peroxide a is added. heating extended for another 4 hours.

The volume of the reaction mixture was reduced to approximately one third on a rotary evaporator and this residue was poured into a vigorously stirred quadruple volume of cold water. The separated product is filtered off and dried to 31.5 g in vacuo. Yield 42%. Melting point 93-94 ° C.

(IC N-0 1280 cm -1, SO 2 1315, 1140 cm ^4. )

Analysis:

Calcd for C10H11Cl2NO5S

C 40.50; H, 3.72; Cl, 23.95; N, 4.72. .

Found:

C, 40.36; H, 3.77; Cl, 24.15; N, 4.63.

Example 13

2- (2,3,6-Trichlorophenylmethylsulfinyl) pyridine-N-oxide

The intermediate 2- (2,3,6-chloro-phenylmenylthir) -pyridine-N-oxide is prepared from 2,3,6-trichloro-benzyl chloride and sodium 2-mercaptropyridine-N-oxide as described in Example 3. Melting point 232-234 Noc: 2 ° C. The yield is quantitative. The structure was confirmed by IC and NMR.

The thin slurry consisting of 6.4 g (0.02 mol) of the thio compound in 50 ml of chloroform is cooled to 5-10 ° C and a solution of 4 g (0.02 mol) of MCPBA in 100 ml of chloroform is slowly added. The reaction mixture is allowed to warm to room temperature, stirred for 16 hours, washed with saturated sodium bicarbonate solution and dried over sodium sulfate. The dry solution is evaporated to dryness and the crude product is refluxed in ethanol, cooled and filtered. Yield: 65%. Melting point 168-170 ° C.

(IC N-0 1350 cm -1, SO 1050 cm -1).

Analysis:

Calculation for C 18 H 18 ClN 2 O 2 S

C, 42.82; H, 2.39; N, 4.16; S, 9.54.

Found:

C, 42.01; H, 2.32; N, 4.18; S, 9.74.

Example 14

2- (2,6-Dichloro-Imethyteulfonyl) pyridine-N-oxide

A mixture of 37 g (0.1 mol) of a 40% strength solution of sodium 2-mercaptopyridine-N-oxide and 19.5 g (0.1 mol) of 2,6-licenzylchloride (200 ml of ethanol) is heated for 30 min. 65 ° C, cooled and filtered The filter cake is washed thoroughly with water and finally with 40 ml of acetone, and vacuum drying of the cake yields 25.3 g (92% of theory) of the product, 2- (2.6). 240 DEG-21 DEG C. The structure was confirmed by IC.

A thin slurry consisting of 29 g (0.1 mol) of the thio compound in 300 ml of chloroform at 10 ° C is slowly reacted with 40 g (0.2 mol) of MCPBA (85%) in 450 ml of chloroform. The mixture is allowed to warm to ambient temperature and the result is a clear solution which is left for 16 hours. Then the solution is washed with saturated sodium bicarbonate solution, dried over magnesium sulphate and evaporated to dryness. The residue is slurried in boiling methanol (400 mL), cooled and filtered. Yield: 28 g (89% of theory). Melting point: 214-215.5 ° C.

Analysis:

Calculation for. C12 H9C12NO3S

C, 45.32; H, 2.83; N, 4.40.

Found:

C, 45.67; H, 2.89; N, 4.55.

Example 1 5

2- (2,3,6-Trfchlorennylmethylsulphonyl) pyridine-N-oxide

The compound 2- (2,3,6-chlorophenylmethylthio) pyridine N-oxide is prepared from 2,3,6-trichlorobenzyl chloride and sodium. salts. 2-mercaptropyridine-N-oxide as described in Example 1. Melting point 232-234 ° C. The yield is quantitative. The structure was confirmed by IC and NMR.

To the slurry consisting of 6.4 g (0.02 mol). The solution is then added slowly to 50-10 ° C and cooled to 5-10 ° C. 8 g (0.04 mol) of MCPBA in 100 ml of chloroform. The temperature of the reaction mixture is allowed to rise to ambient temperature, the mixture is stirred for 16 hours, washed with saturated sodium bicarbonate solution and dried over sodium sulfate. The dry solution is evaporated to dryness and the crude product is heated to reflux in methanol. Then the solution is cooled and filtered. Yield: 6.7 g (95%). Melting point 194-196 ° C. The structure was confirmed by IC and NMR.

Example 16

2- (1- (4-fluorophenyl) ethylsulfonyl) pyridine N-oxide

The compound is prepared. from the sodium salt of 2-mercaptopyridine-N-OXide. and 1- (4-fluorophenyl) nitride as described in Example 4. The yield of 2- [1- (4-fluorophenyl) methylthiropyridine-N-oxide was 40%. Temperature. mp 95-97 ° C. The structure was confirmed by IC and NMR.

The oxidation of the thio compound (0.04 mol) with (0.08 mol) MCPBA and the isolation process are the same as in Example 7. The yield is 83%, melting point 142-144 ° C.

Analysis:

Calculation for C13H12FNO3S

C 55.50; H, 4.30; N, 4.98.

Found:

C 55.47; H, 4.61; N, 5.07.

Example 17

2- (1- (4-Bromophenyl) ethylsulfonyl] pyridyl-N-oxide)

The compound 2- (1- (4-bromophenyl) ethylthio) pyridine N-oxide is prepared from 1- (bromophenyl) ethyl chloride and sodium 2-mercaptopyridine N-oxide as described in Example 16, m.p. 113-111. The structure was confirmed by IR and NMR.

The thio compound (0.05 mol) is oxidized with MCPBA (0.1 mol) and isolated in the same manner as described in Example 9. The yield is 85%. The structure was confirmed by IR and NMR.

Analysis:

Calculation for C 13 H 15 BrNO 3 S

C, 45.63; H, 3.45; N, 4.09.

Found:

C, 45.04; H, 3.32; N, 4.15.

The compounds listed in the following Table 1 can be prepared in the same manner. Table 2 shows the infrared spectra values. The numbers assigned to the formulations in Table 1 are used to identify the compounds in the following examples.

Compound 44 in Table 1 also contains minor amounts of the 4-ethylphenyl isomer.

Herbicidal compounds

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Main belts (cm ¹ )

Example so " n N-oxide 12 1315, 1140 2 1280, 844 28 1320, 1145 2 1280, 845 24 1320, 1155 2 1280, 845 20 May 1320, 1150 2 1280, 840 21 1310, 1140 2 1270,840 22nd 1320, 1140 2 1275,840 23 1320, 1145 2 1280, 840 1 1310, 1130 2 1270, 835 26 1320, 1150 2 1280, 845 11 1310, 1130 2 1270,840 14 1320, 1120 2 1240,840 2 1310, 1140 2 1275,840 33 1320,1155 2 1280, 840 34 1310, 1140 2 1280, 840 9 1300, 1140 2 1260,840 35 1310, 1150 2 1250, 840 31 1320, 1160 2 1275, 835 37 1320, 1140 2 1280, 845 36 1320, 1140 2 1275, 835 42 1310, 1120 2 1270,840 41 1320, 1140 2 1280, 840 44 1320, 1150 2 1270,840 55 1320, 1120 2 1280, 845 48 1320, 1150 2 1280, 850 62 1330, 1130 2 1290, 845 64 1340, 1160 2 1290, 855 4 1340, 1160 2 1300, 850 38 1320, 1120 2 1275,840 39 1210, 1125 2 1270,840 43 1310, 1140 2 1280, 845 45 1310, 1130 2 1250, 840 49 1310, 1150 2 1240, 850 47 1300, 1140 2 1270,840 3 1050 1 1260,840 46 1055 1 1260, 830 54 1040 1 1250, 835 10 1050 1 1240,840 52 1040 1 1250, 835 53 1050 1 1240, 835 51 1060 1 1250, 840 56 1050 1 1255,840 57 1050 1 1260, 845 58 1055 1 1260,840 59 1060 1 1260, 845 60 1055 1 1260,840 61 1050 1 1260,840 63 1060 1 1260, 845 65 1050 1 1260,840 29 1040 1 1240,830 32 1050 1 1240, 845 66 1065 1 1270, 850 67 1065 1 1270, 845 27 Mar: 1300, 1130 2 1285,840 68 1310, 1140 2 1260,840 69 1320, 1140 2 1260, 845 70 1330, 1130 2 1280, 850 15 Dec 1325, 1125 2 1240, 850 72 1310, 1140 2 1280, 850 30 1330, 1155 2 1280, 840 7 1310, 1140 2 1275, 855 74 1320, 1140 2 1275, 845

Example Sat Major strips (cm ^-1 ) n N-oxide 76 1320, 1145 2 1280, 850 5 1315, 1140 2 1275, 845 78 1220, 1155 2 1280, 850 16 1310, 1140 2 1280, 840 6 1315, 1145 2 1275, 845 17 1310, 1140 2 1275, 845 81 1320, 1150 2 1280, 850 82 1335, 1150 2 1280, 850 25 1050 1 1245, 840 71 1050 1 1260,840 13 1040 1 1260,825 73 1045 1 1240,840 79 1025 1 1245, 840 75 1040 1 1250, 840 77 1030 1 1240,840 19 Dec 1050 1 1260,840 50 1050 1 1250, 845 80 1055 1 1250, 840 83 1045 1 1250, 840 84 1320, 1130 2 1275,840 86 1320, 1140 2 1280, 845 88 1310, 1120 2 1250, 845 91 1310, 1140 2 1270, 845 18 1315, 1150 2 1275, 845 85 1045 1 1250, 849 87 1049 1 1260, 820 89 1050 1 1240, 835 90 1045 1 1235, 840 93 1330, 1140 2 1280, 845 92 1310, 1140 2 1270, 845 95 1320, 1130 2 1260,840 97 1320, 1130 2 1230,840 99 1320, 1140 2 1270, 845 100 ALIGN! 1320, 1120 2 1275, 845 104 1320, 1145 2 1280, 850 102 1310, 1140 2 1280, 845 94 1050 1 1250, 840 8 1045 1 1240,840 96 1040 1 1240, 835 98 1040 1 1250, 835 101 1050 1 1350, 840 103 1050 1 1240,840 105 1140, 1310 2 1270, 845 106 1140, 1300 2 1240,890 (SO 1050) 1 107 1040 1 1250, 840 108 1140, 1320 2 1260,840 109 1145, 1320 2 1280, 845 110 1140, 1300 2 1240,840 111 1130, 1315 2 1230, 845 112 1040 1 1230,840 113 1050 1 1245, 835 114 1130, 1315 2 1250, 840

L

Example 115.

To illustrate the efficacy of the described 2-sulfinylpyridine-N-oxides and 2-sulfonylpyridine-N-oxides as pre-emergence herbicides, 600 mg of the substance was dissolved in 100 ml of an organic solvent (e.g. acetone) and 30 mg of conventional emulsifier [isooctylpolyethoxyethanol] was added. Dilute the solution to 100 ml with distilled water. Dilute 20 ml of this 6000 ppm solution to 250 ppm with distilled water. The substance is applied at a rate of 11.21 kg / h by spraying 46 ml of a 250 ppm solution onto the soil surface in a plastic pot of 0.114 meter diameter, sown with seeds of the following weeds: Amaranthus retroflexus L., Portulaca oleracea L.) or Durman's cucumber (Datura stramonium L.), Ipomea purpurea (L.) Roth, Rosebud [Digitaria ischaemum (Schreb.) Muhl.J, Echinochloa crusgalli (L.) Beauv.ja bér (Setaria faberi Herrm.). The efficacy against weeds in percentage compared to untreated plants as a control was determined two weeks after treatment. Table III shows the test results of the pre-emergence herbicides of the invention prepared according to the above examples.

Table III

Herbicidal activity of 2-sulfinyl and 2-sulfonylpyridine-N-oixide

Percent weed Cabbage purse *) Durman virgin cucumber Povijnice purple Hedgehog corns the leg Rosička lysá Ber Example Amaranth bent 19 Dec 50 0 *) 15 Dec 100 ALIGN! 100 ALIGN! 100 ALIGN! 12 15 Dec 90 *) 0 95 100 ALIGN! 100 ALIGN! 20 May 25 100 *) 0 98 98 100 ALIGN! 21 100 ALIGN! 100 ALIGN! 90 100 ALIGN! 100 ALIGN! 100 ALIGN! 22nd 100 ALIGN! 90 0 100 ALIGN! 100 ALIGN! 100 ALIGN! 23 100 ALIGN! 75. 0 98 100 ALIGN! 100 ALIGN! 24 100 ALIGN! 100 ALIGN! 5 98 100 ALIGN! 100 ALIGN! 25 100 ALIGN! 98 25 98 100 ALIGN! 100 ALIGN! 1 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 26 20 May 0 0 90 100 ALIGN! 95 27 Mar: 50 0 0 98 100 ALIGN! 100 ALIGN! 28 98 0 0 98 100 ALIGN! . 98 29 0 0 0 98 100 ALIGN! : 100 30 95 0 0 60 90 90 31 100 ALIGN! 0 0 100 ALIGN! 100 ALIGN! . 100 ALIGN! 11 : 85 80 25 98 100 ALIGN! 100 ALIGN! 32 95 95 20 May 90 95 95 2 100 ALIGN! 0 20 May 95 100 ALIGN! 100 ALIGN! 19 Dec 100 ALIGN! 80 80 95 100 ALIGN! 100 ALIGN! 33 100 ALIGN! 50 25 90 100 ALIGN! 100 ALIGN! 34 100 ALIGN! 20 May 0 95 100 ALIGN! 100 ALIGN! 9 ^; . 100 ALIGN! 100 ALIGN! 95 95 100 ALIGN! '100 35 100 ALIGN! 0 0 95 100 ALIGN! 100 ALIGN! 36 98 0 0 98 98 95 37 0 0 0 90 90 75 38 . 100 ALIGN! 0 0 100 ALIGN! 100 ALIGN! 100 ALIGN! 39 0 25 0 85 85 85 8 100 ALIGN! 0 94 100 ALIGN! 100 ALIGN! 100 ALIGN! 40 0 0 0 75 98 100 ALIGN! 41 100 ALIGN! 0 0 95 100 ALIGN! 100 ALIGN! 42 100 ALIGN! 70 0 90 100 ALIGN! 100 ALIGN! 43 75 0 0 95 98 98 44 100 ALIGN! 0 0 98 100 ALIGN! 100 ALIGN! 45 80 0 0 90 90 90 46 100 ALIGN! 0 20 May 98 100 ALIGN! 100 ALIGN! 47 95 0 0 98 98 98 48 100 ALIGN! 65 0 98 98 98 49 100 ALIGN! 50 0 98 98 98

Example Amaranth Durman Povijnice Hedgehog Rosy hairless Ber bent virgin cucumber purple corns foot

10 98 40 70 100 ALIGN! 100 ALIGN! 100 ALIGN! 50 98 0 0 95 98 98 51 98 0 30 98 100 ALIGN! 100 ALIGN! 52 95 0 10 98 98 98 53 85 0 65 98 98 98 54 40 0 15 Dec 98 98 98 55 100 ALIGN! 0 0 100 ALIGN! 100 ALIGN! 100 ALIGN! 56 100 ALIGN! 0 50 98 98 100 ALIGN! 57 100 ALIGN! 25 40 98 98 98 58 100 ALIGN! 20 May 0 95 98 98 59 100 ALIGN! 0 85 98 98 100 ALIGN! 60 100 ALIGN! 0 85 98 98 Í100 61 95 10 25 95 98 98 62 100 ALIGN! 0 35 95 98 98 63 100 ALIGN! 0 0 90 98 98 64 100 ALIGN! 0 0 85 85 90 65 100 ALIGN! 0 35 98 100 ALIGN! 100 ALIGN! 66 100 ALIGN! 0 50 95 98 100 ALIGN! 67 100 ALIGN! 0 0 98 98 98 4 100 ALIGN! 25 0 100 ALIGN! 100 ALIGN! 100 ALIGN! 68 100 ALIGN! 0 0 100 ALIGN! 100 ALIGN! 100 ALIGN! 69 100 ALIGN! 0 0 100 ALIGN! 100 ALIGN! 100 ALIGN! 70 95 - - 60 50 30 71 100 ALIGN! 0 0 100 ALIGN! 100 ALIGN! 100 ALIGN! 15 Dec 100 ALIGN! 100 ALIGN! 15 Dec 100 ALIGN! 100 ALIGN! 100 ALIGN! 13 100 ALIGN! 75 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 72 95 0 0 95 98 98 73 100 ALIGN! 0 0 98 98 98 74 0 50 0 98 98 100 ALIGN! 75 0 0 0 98 98 98 76 0 0 90 98 98 98 5 95 0 50 98 98 98 77 - - - 100 ALIGN! 100 ALIGN! 100 ALIGN! 78 0 0 0 98 98 98 16 100 ALIGN! 85 98 100 ALIGN! 100 ALIGN! 100 ALIGN! 6 95 80 95 100 ALIGN! ... 100 100 ALIGN! 79 - 25 - 100 ALIGN! 100 ALIGN! 100 ALIGN! 7 - 35 0 100 ALIGN! 100 ALIGN! 100 ALIGN! 80 0 0 0 98 100 ALIGN! 100 ALIGN! 17 0 0 0 98 100 ALIGN! 100 ALIGN! 81 0 0 0 98 100 ALIGN! 100 ALIGN! 82 0 0 0 50 75 100 ALIGN! 83 100 ALIGN! 0 0 100 ALIGN! 100 ALIGN! 100 ALIGN! 84 100 ALIGN! 0 0 100 ALIGN! 100 ALIGN! 100 ALIGN! 85 100 ALIGN! 0 0 98 100 ALIGN! 100 ALIGN! 86 100 ALIGN! 100 ALIGN! 0 100 ALIGN! 100 ALIGN! 100 ALIGN! 87 100 ALIGN! 0 0 98 100 ALIGN! 100 ALIGN! 88 100 ALIGN! 0 0 100 ALIGN! 100 ALIGN! 100 ALIGN! 89 - - - 100 ALIGN! 100 ALIGN! 100 ALIGN! 90 0 0 0 80 80 80 91 50 0 0 90 85 85 18 100 ALIGN! 30 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 92 100 ALIGN! 95 75 98 98 98 93 100 ALIGN! 95 65 98 98 98 94 100 ALIGN! 60 85 100 ALIGN! 100 ALIGN! 100 ALIGN! 8 100 ALIGN! 0 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 95 100 ALIGN! 0 0 95 100 ALIGN! 100 ALIGN! 96 100 ALIGN! 0 0 100 ALIGN! 100 ALIGN! 100 ALIGN!

Example

18 201S38 20 May LaskaVec ohnutý Durman virgin cucumber Povijnice purple Hedgehog corns the leg Rosička lysá Ber

97 100 ALIGN! 0 0 100 ALIGN! 100 ALIGN! 100 ALIGN! 98 100 ALIGN! 0 50 100 ALIGN! 100 ALIGN! 100 ALIGN! 99 100 ALIGN! 0 0 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 0 0 95 100 ALIGN! 100 ALIGN! 101 100 ALIGN! 0 80 100 ALIGN! 100 ALIGN! 100 ALIGN! 102 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 103 30 30 0 30 20 May 20 May 104 0 0 0 30 10 10 105 30 30 0 85 100 ALIGN! 100 ALIGN! 106 0 0 0 70 100 ALIGN! 100 ALIGN! 107 100 ALIGN! - 0 95 100 ALIGN! 95 108 100 ALIGN! - 0 95 98 98 109 0 - 95 50 95 95 110 0 0 5 98 95 95 111 90 0 62 95 95 95 112 20 May 0 0 80 80 80 113 0 0 25 95 95 95 114 100 ALIGN! 0 25 98 98 98

Example 116

The selective effect of herbicides is desirable if it allows control of weeds grown among the desired crop plants. To determine the usefulness of the compounds of the invention as selective pre-emergence herbicides, 0.8 g of the substance is dissolved in 50 ml of an organic solvent such as acetone containing 25 mg of a conventional emulsifying agent, e.g. in 113.5 l of water per 0.4047 hectare per soil surface over an area of 0.38 mxx 0.51 m. Weed and crop plants were sown into the soil before treatment. The percentage of weed control and percentage of damaged crop plants was determined three weeks after treatment. . Table IV shows the use of these compounds as selective pre-emergence herbicides.

Table IV

Test of selective efficacy of pre-emergence herbicides

Damage of crop plants in%

Example Just Lucerne Cotton Soybeans Peanuts 1 0 10 0 0 0 14 0 0 0 0 0 9 50 10 0 75 0

Exterminated weeds in. %

Example Amaranth bent Cabbage purse Deaf oats Millet Ber Hedgehog corns the leg 1 98 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 14 70. 100 ALIGN! 100 ALIGN! 100 · 100 ALIGN! 100 ALIGN! 9 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN!

Example 117

To determine efficacy at a dose of 2.24 kg / ha, 46 ml of a 50 ppm solution (Example 115) was applied by spraying onto the soil surface in a 0.114 m diameter pot. The seeds of several weed species were again in the soil in each pot before chemical treatment. The percentage of weed control as a percentage of untreated control plants was determined two weeks after sowing. Table V shows the efficacy test results at a dose of 2.24 kg / ha.

Table V

Herbicidal activity at 2.24 kg / ha

Exterminated weeds in%:

Example Degree of oxidation Hedgehog corns the leg Bér sivý Rosička lysá Green harness • Dried oats Millet 58 sulfoxide 90 90 80 50 0 100 ALIGN! 21 sulfone 100 ALIGN! 100 ALIGN! 90 75 100 ALIGN! 100 ALIGN! 61 sulfoxide 90 70 85 70 0 95 22nd sulfone 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 90 100 ALIGN! 25 sulfoxide 100 ALIGN! 90 100 ALIGN! 90 90 100 ALIGN! 23 sulfone 95 100 ALIGN! 100 ALIGN! 100 ALIGN! 90 100 ALIGN! 46 sulfoxide 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 90 100 ALIGN! 1 sulfone 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 59 sulfoxide 95 95 95 95 0 100 ALIGN! 11 sulfone 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 95 100 ALIGN! 56 sulfoxide 100 ALIGN! 100 ALIGN! 100 ALIGN! 95 50 100 ALIGN! 2 sulfone 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 85 100 ALIGN! 51 sulfoxide 95 95 90 90 20 May 100 ALIGN! 33 sulfone 90 95 95 60 40 100 ALIGN! 55 sulfone 85 70 100 ALIGN! 70 20 May 100 ALIGN!

Table VI

Herbicidal activity at 0.56 kg / ha

Weed control in ° / o:

Example Degree of oxidation Hedgehog corns the leg Bér sivý Rosička lysá Green harness O.ves deaf Millet 57 Sulfoxide 90 80 85 40 0 100 ALIGN! 31 sulfone 90 95 100 ALIGN! 50 30 100 ALIGN! 3 ^^ lfoxid 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 90 100 ALIGN! 14 sulfone 100 · 100 ALIGN! 100 ALIGN! 95 60 100 ALIGN! 10 sulfoxide 95 100 ALIGN! 100 ALIGN! 85 20 May 100 ALIGN! 34 sulfone 95 100 ALIGN! 85 80 50 100 ALIGN! Example 118 C) Phenol (90% aqueous solution) 178.5 g

The following are examples of formulations that can be used in accordance with the present invention. However, these examples do not limit the scope of the invention.

1. 9.6% of active substance in emulsifiable concentrate (0.453 kg / 3.78 L)

(a) 2- (2,5-dimethylphenylmethylsulphonyl) pyridine-N-oxide 0.6 g

b) A mixture of oil-soluble sulfonates with polyoxyethylene ether Emcol N139-BU (Trade Mark) of Witco Chemical Corp .; eg nonylphenolpolyoxytthyltn and calcium dodecylbenzene sulfonate 0.55 g

c) Chloroform 2,1 g

d) Benzaldehyde 2.7g

2. 11,3% of active substance in soluble concentrate (0,453 kg / 3,78 l)

a) 2- (phenylmethylsulfonyl) pyridine-N-

-oxide24 g

b) A mixture of oil-soluble sulfonates with a polyoxyethylene ether Emcol N5003 (trade mark) of Witco Chemical Corp .; eg, sodium lignin sulphonate and polycondensate ethylene oxide, propylene oxide and propylene glycol 12.0 g

3. 50% of active ingredient in wettable powder

a) 2- (2,5-Dimethylphenylmethylsulfonyl) pyridine-N-oxide 300 g

(b) Alkaryl polyththalcohol OPE (octylphenoxypolyethoxyethanol) [Triton X-120 (Trade Mark), Rohm & Hass] 6 g

c) Sodium N-methyl-N-palmitoyl taurate [Igepon TN-74 (Trade Mark) GAF Corp.] 6 g

d) Polymerized sodium alkylnaphthalenesulfonic acid sodium [Daxed 11 (Trade Mark) Dewey & Almy Chemical Company] 22 g

(e) Kaolinite clay [Dixie - Clay (trade mark)] 84 g

(f) Hydrated amorphous silica [Hi Sil 233 (trade mark)] 192 g

4. 5% active substance - granules

a) 2- '(2,5-dimethoxyphenylmethylsulfonyl) pyridine-N-oxide -1.0 g

b) methylene chloride 9.0 g

(c) The above solution is sprayed with 25/50 mesh hydrated magnesium aluminum silicate [Attaclay (Trade Mark)] 19.0 g

The use of the compositions containing the novel weed control agents represents a particularly advantageous method according to the invention, since these herbicidal compositions can be used. to achieve unusually effective results.

Example 119

The effects of S734 (see Example 1) and R750 (see Example 6) were compared. with various known herbicides.

A. · The chemical identity of the following herbicides compared to Compound S734 for the sediment tests is as follows:

LASSO (alachlor) 2-chloro-2 ', 6'-diethyl-N- (methoxymethyl) acetanilide

VERNAM (Vernolat) S-propyl 1-dipropylthiocarbamate

DESTUN (perfluidone) 1,1'-trifloor N-2-methyl-4- [phenylsulfonyl] phenyl] methanesulfonamide

ROUNDUP (glyphosate) N- (phosphoromethyl) glycine

BASAGRAN (bentazone) 3-isopropyl-1H-2,1,3-benzothladlazine-4- (3H) -one 2,2-dioxide

MSMA (mea) methanarsonic acid DUAL (metolachlor) 2-chloro-N- (2-ethyl-6-methylphenyl) -N- (2 - [(4-methyl-phenyl) -N- (2-methyl) -ethyl] acetamide)

B. Greenhouse tests with compounds S 734 (Example 6) and R750 (Example 1) were performed as follows:

The soil of three different types was placed in 11.4 cm diameter plastic pots. Three tubers of cyperus rotundus L., round or Cyperus esculentus L., were placed 1.27 cm below the soil surface in each pot. A solution of 250 ppm S734 or R750 was prepared by dissolving 25 mg of the chemical compound in 5 mL. acetone containing 15 mg of a conventional emulsifier. reagents - for example iso-octylpolyethoixyethanol, trademark "Triton X100"] and adding distilled water to bring the volume up to 100 ml. The 250 ppm solution was then diluted with distilled water to prepare 12.5, 6.25 and 3.12 ppm solutions. The respective solutions were cast over the soil surface at a dose of 46 ml per pot. The doses of the active ingredients were 0.56 kg / ha, 0.28 kg / ha and 0.14 kg / ha, after being treated with 12.5, 6.25 solutions. and 3.12 ppm. Commercial products were diluted with distilled water to the appropriate concentrations for the indicated doses of application of the active ingredients and poured onto the soil surface as indicated above. Percent control was determined visually by comparison with untreated control pots 6 weeks after treatment.

Field tests were performed using conventional field trial techniques. Soil areas normally · heavily contaminated with grass or baywood, were loosened and settled typically by plowing and cultivation. The plots were measured and labeled with the treatment used. Typical plot size. was 1.83 m x 7.62 m for · S734 (example

6) and ·. R750 (Example 1), which had previously been formulated as a 50% wettable powder (Example 118-3), were mixed with water at doses of 0.11 kg to 1.36 kg per 75.68 liters. The spray mixtures were applied to the prepared soil at a rate of 187 liters per hectare by a hand sprayer pressurized with 2.11 kg / cm ² using carbon dioxide.

Pre-culture applications (PPI) were prepared prior to sowing cereals such as soybeans -Glyclne max. (L) Mett] and were followed immediately by a 5.08 cm deep light cultivation. sowing grain, but before weed or grain emerges.

Pre-emergence applications were not followed by light cultivation. Commercial herbicides were mixed with water and applied as above for PRE. and PPI treatment. Commercial herbicides after aplication (hereafter POST) were applied at a time when the china was 15.24 cm tall. The percentage of weed control was determined by visual comparison with untreated controls 16 to 75 days after treatment.

Comment:

Explanation of the abbreviations used in the following tables and in the above example:

Introduced before cultivation (PPI), pre-emergence (PRE) and post-emergence (POST).

In Table II, 'percentage of soil coverage' refers to the relative amount of weeds present in untreated soil. In this example, 56.7% (average of all controls) of untreated soil were covered. weeds. The percentage of control of treated plots was. then compared to the plots with 56.7% of the land covered.

S734 is clearly more effective than R750, for example (Table II) 2.24 kg / h and S734 kills 98% of the controlled round eel, while 2.24 kg / h and the R750 kills only 40% of the checked bite in 2.5 months.

The types of soil for greenhouse tests were as follows:

„Sanford”

Sand containing 1,4% organic matter-O. M.

„Decatur”

Clay containing 12.7% organic matter — o. m.

„Ahaskie”

Sandy clay containing 3.1% organic matter.

Abbreviations have the following meanings:

2 '015 3 8

2% Μ. - The soil contained 2% organic matter. Organic matter is important because it can bind and inactivate some pesticides applied to the soil.

Dual pre-Herbicide DUAL (metolachlor) was applied before emergence.

Gooseberry refers to the "broadleaf" weeds of gooseberry and bent-grass.

White goosefoot (Chenopodium album L.) Amaranthus retroflexus L.

R750 - S734

Bay Check Test (Sanford, Florida) Subtraction under 2.5 months

Treated Dose Percent inspection of round rum: S734 PPI 2.24 sq 98 R750 PPI 2.24 kg / hh 40 VERNAM PPI 2.24 kg / lrn 60 DESTUN PRE 2,24 m2 / ha 75 ROUNDUP POST 1.12 kg / ha 40 BASAGRAN POST 1.12 kg / ha 20 May MSMA POST 2.24 к ^ Ри 0

...... R750. - S734 .............

Check test (Odenburg, La.)

Treated Dose Subtraction after 2 months Percent control of edible rum Notes _ R750 PPI 1.12 kg / ha 0 He was somewhat. growth inhibited R750 PPI 2.24 kg / ha 68 but they formed. with nuts R750 PPI 3.36 kg / ha 86 S734 PPI 1.12 kg / ha 39 Inhibition of root growth and formation S734 PPI 2.24 kg / ha 71 of nuts S734 PPI 3.36 kg / ha 89 LASSO. PPI 2.24 kg / ha 15 Dec LASSO PPI 4.48 kg / ha 26 Control  - 0

Sandy clay - 2% organic material O. M. No damage to soybeans observed.

R750 - S734

Test of edible rum (Cerro Gords, Illinois)

Reading after 6 weeks

Dose Treated Percent control of edible rum R750 PPI 3.36 kg / ha S734 PPI 3.36 kg / ha LASSO PPI 3.36 kg / ha VERNAM PPI 3.73 kg / ha Control - in% soil coverage 90.0 96.0 80.0 93.3 (56.7)

Treated 27 Mar: Dose 28 R750 - S734 Weed control test (Ohio) Broad-leaved weed percentage (goosefoot, amaranth) grasses (green grass, Texas millet) R750 PRE 1.12 kg / ha 35 45 R750 PRE 2.24 kg / ha 40 65 S734 PRE 1.12 kg / ha 45 60 S734 PRE 2.24 kg / ha 65 85 LASSO PRE 3.36 kg / ha 75 80 DUAL FOR 3.36 kg / ha 80 95 Soil - Crosby Silty Clay 2 1/2% 0 M. Check the bay could not be done due to poor condition.

S734

Tail Check (Sanford, Florida) Fall

The treated Dose Percentage of check-in Subtraction in 16 days Readings in 2.5 months S734 PPI 0.28 kg / ha 71 55 S734 PPI 0.56 kg / ha 88 75 S734 PPI 1.12 kg / ha 93 88 S734 PPI 2.24 kg / ha 97 90 Vernam PPI 2.24 kg / ha 94 80 R750 PPI 2.24 kg / ha S734 (40) Spring Checklist test of rock (Sanford, Autumn Florida) The treated Dose Percentage Controls 16 Day Subtraction Control šáchoru okrouhého Readings in 2.5 months S734 PPI 0.28 kg / ha 71 55 S734 PPI 0.56 kg / ha 88 75 S734 PPI 1.12 kg / ha 93 88 S734 PPI 2.24 kg / ha 97 90 Vernam PPI 2.24 kg / ha 94 80 R750 PPI 2.24 kg / ha - (40) Spring

Claims (11)

OBJECT OF THE INVENTION A herbicidal composition comprising a compound as an active ingredient A 2-sulfinyl- or 2-sulfonylpyridine-N-oxide of formula I wherein n is 1 or 2, R1 is hydrogen, C1-C6-alkyl or phenyl, R2 has one of the following meanings: when R1 is hydrogen then R2 is cyclohexyl, 2,2-dichlorocyclopropyl, 2,2-dichloro-1-methylcyclopropyl, propenyl, benzyl, styryl, cyano, naphthyl, methylnaphthyl, pyridyl, benzothiazolyl, phenyl, phenyl substituted with 1 to 5 substituents, which may be the same or different and are selected from the group consisting of C 1 -C 2 -alkyl, halogen, nitro, cyano, C 1 -C 2 -alkoxy, methylenedioxy, 2,2-dichlorocyclopropyl or trifluoromethyl and when R 1 is C 1 -C 6 -alkyl or phenyl, then R 2 is C 1 -C 1 -alkyl, naphthyl, thienyl, phenyl, phenyl substituted with 1 to 3 substituents, which may be the same or different and are selected from the group consisting of C 1 -C 6 -alkyl; C2-alkyl, halogen, nitro and methylsulfonyl, or 2 » R 1 and R 2 may be joined together as a chain of methylene groups to form a cyclic aliphatic ring containing 5 to 7 carbon atoms. 2. A herbicidal composition as claimed in claim 1 comprising a compound of formula (I) wherein R1 is hydrogen or methyl and R2 and n are as defined in claim 1. 3. A herbicidal composition as claimed in claim 1 comprising a compound of formula (I) wherein R2 is phenyl, phenyl substituted with 1 to 3 methyl groups, phenyl substituted with 1 to 3 halogens or 2-naphthyl and R1 and n are as defined in 1. . 4. A herbicidal composition according to claim 1 comprising a compound of formula I wherein R1 is hydrogen and R2 is phenyl substituted with 1 to 3 methyl groups or phenyl substituted with 2 to 3 chlorine atoms and n is as defined in 1. 5. A herbicidal composition according to claim 1 comprising a compound of formula (I) wherein R1 is methyl and R2 is phenyl, phenyl substituted with 1 or 2 methyl groups, monohalophenyl or 2-naphthyl and n is as defined in 1. 6. The herbicidal composition of claim 1, wherein the compound of formula (I) is one of the following: 2- (2,5-Dimethylphenylmethylsulfonyl) pyridine N-oxide 2- (2,4,6-trimethylphenylmethylsulfonyl) pyridine-N-oxide, 2- (2,6-dichlorophenylmethylsulfonyl) pyridine-N-oxide, 2- (2,4-dichlorophenylmethylsulfinyl) pyridine N-oxide, 2- (2,6-dichlorophenylmethylsulfinyl) pyridine-N-oxide, 2- (1- (4-methylphenyl) ethylsulfonyl] pyridine N-oxide, 2- (2,3,6-trichlorophenylmethylsulfonyl) pyridine N-oxide, 2- (2-methylphenylmethylsulfonyl) pyridine-N-oxide, 2- (1- (4-fluorophenyl) ethylsulfonyl) pyridine N-oxide, 2- (1- (2,5-Dimethylphenyl) ethylsulfonyl] pyridine-N-oxide, 2- (2,3,6-trichlorophenylmethylsulphinyl) pyridine N-oxide, 2- (1-phenylethylsulfonyl) pyridine N-oxide, 2- (1- (2-naphthyl) ethylsulfonyl) pyridine N-oxide, 2- (1- (4-chlorophenyl) ethylsulfonyl] pyridine N-oxide, 2- (1- (4-bromophenyl) ethylsulfonyl) pyridine N-oxide, 2- (2,3,6-trimethylphenylmethylsulfonyl) pyridine N-oxide a 2- (2,3,6-trimethylphenylmethylsulfinyl) pyridine N-oxide. 7. A composition according to claim 1, wherein the compound of formula I is 2- (2,5-dimethylphenylmethylsulfonyl) pyridine N-oxide. 8. A process according to claim 1, wherein the 2-thiopyridine N-oxide derivative of formula (II): R1 and R2 as defined in 1 are reacted with an oxidizing agent in the presence of a solvent or catalyst, such as a tungsten, vanadium, zirconium or molybdenum salt, at a temperature of from 0 ° C to the reflux temperature of the reaction mixture. cooler. 9. A process according to claim 8, wherein the oxidizing agent is hydrogen peroxide, peracetic acid or an aromatic peracid. 10. The process of claim 8 wherein the oxidizing agent is hydrogen peroxide and glacial acetic acid or water solvents at a temperature of from 50 ° C to the reflux temperature of the reaction mixture. 11. A process according to claim 8, wherein the oxidizing agent is an aromatic peracid or peracetic acid, the solvent being a non-polar solvent and a temperature of from 0 to 60 [deg.] C.