NO138882B - NEW N-BENZOYL-N- (3-CHLORO-4-FLUOROPHENYL) -2-AMINO PROPIONATES WITH HERBICIDING EFFECT - Google Patents

Description

The invention relates to new selective herbicides for control

of field oats in cereal crops.

Our British Patent No. 1,289,283 describes and

protects a class of selective herbicidal compounds of the formula:

where X means a hydrogen or chlorine atom and Y means a carboxyl

group or the salts or alkyl esters thereof. In particular, ethyl-

the esters of such carboxylic acids exemplified, and proved superior in certain respects to the related compound ethyl-N-benzoyl-N-(3,4-dichlorophenyl)-2-aminopropionate known from our British Patent No. 1,164. 160.

Although these known compounds of British Patent Nos. 1,164,160 and 1,289,283 have shown good selective herbicidal properties when used to control midge in wheat crops, they have proved less reliable when used in barley because of their tendency to produce phytotoxic symptoms in the crop as well as in the field oats.

It has now surprisingly been found that two closely related compounds to those already known are significantly more effective as selective herbicides for the control of ragweed in cereal crops.

The invention is thus the new compounds with the following general formula:

where R is methyl or isopropyl.

The compounds can be prepared by a method which includes reaction of methyl or isopropyl-N-(3-chloro-4-fluorophenyl)-2-aminopropionate with a benzoyl halide, suitably benzbyl chloride. The preparation of the compounds is illustrated in more detail in the examples below.

The compounds can be used in ways that are known for herbicides and can be used in herbicidal preparations comprising a carrier or a surface-active agent, or both a carrier and a surface-active agent together with, as active substance, a compound according to the invention. The compounds can be used to combat the growth of field oats in cereal crops in an area, by applying to the area a selective herbicidal amount of a compound according to the invention.

The term "selective herbicidal amount" as used herein denotes an amount of the compound sufficient to cause a substantial reduction in growth of field oat while at the same time exerting a negligible phytotoxic effect on the crop. The selective herbicidal action is illustrated in the examples below.

The term "carrier" as used herein means a solid or liquid material, which may be inorganic or organic and of synthetic or natural origin, with which the active compound is mixed or compounded to facilitate its application to the plant, seed, soil or other place to be processed, or its storage, transport or handling.

The surfactant can be an emulsifier or a dispersant or a wetting agent. It can be ionic or non-ionic.

All the carriers or surfactants that are usually used in the composition of pesticides can be used together with the new compounds, and suitable examples of these can be found, for example, in the applicants' British patents no. 1,289,283 or 1,164,160.

The preparations can be produced in the form of

wettable powders, dusts, granules, solutions, emulsifiable concentrates, emulsions, suspension concentrates and aerosols. Wettable powders are usually formulated to contain 25, 50 or 75% by weight of toxicant and usually contain, in addition to solid carrier, 3-10% by weight of a dispersing agent and, if necessary, 0-10% by weight of stabilizer(s) and/ or additives, such as penetrants or adhesives. Dust is usually prepared as a dust concentrate with a similar composition to a wettable powder, but without a dispersant, and diluted in the field with additional solid carrier to give a preparation that usually contains 1/2-10% by weight of toxicant. Granules are usually produced to have a size between 10 and 100 BS mesh (1.676-0.152 mm), and can be produced by agglomeration or impregnation techniques. Generally, granules contain 1/2-25% by weight of toxicant and 0.10% by weight of additives, such as e.g. stabilizers, slow-release modifiers and binders. Emulsifiable concentrates usually contain, in addition to solvent and, if necessary, co-solvent, 10-50% w/v toxicant, 2-20% w/v* emulsifiers and 0.20% w/v of suitable additives, such as .ex. stabilizers, penetrants and corrosion inhibitors.

Suspension concentrates are put together in such a way that it is achieved

a stable, non-sedimenting, flowing product which usually contains 10-75% by weight of toxicant, 0.5-15% by weight of dispersing agents, 0.1-10% by weight of suspending agents, such as protective colloids

and thixotropic agents, 0-10% by weight of suitable additives, such as e.g. antifoam agents, corrosion inhibitors, stabilizers, penetrants and adhesives, and which carry water or an organic liquid in which the toxicant is substantially insoluble. certain organic solids or inorganic salts may be dissolved in the carrier to help prevent sedimentation or as anti-freeze - funds for water.

Aqueous dispersions and emulsions can e.g. is produced

by diluting a wettable powder or a concentrate containing the new compounds.

The aforementioned emulsions can be of the water-in-oil or oil-in-water type, and can have a thick "mayonnaise"-like structure.

The preparations may also have others

ingredients, such as other compounds that have pesticides,

especially insecticidal, acaricidal, herbicidal and fungicidal properties.

Example 1

Preparation of isopropyl-N-benzoyl-N-(3-chloro-4-fluorophenyl)-2-aminopropionate

a) Preparation of N-(3-chloro-4-fluorophenyl)-2-aminopropionic acid 3-chloro-4-fluoroaniline (600 g) was dissolved in isopropyl

alcohol (2.3 L) and water (122 L), 2-chloropropionic acid (445 g) and sodium bicarbonate (692 g) were added to the solution which was heated under reflux with stirring for 24 hours. The mixture was cooled to 60°C and additional 2-chloropropionic acid (445 g) and sodium bicarbonate (692 g) were added. The mixture was then heated at reflux for a further 72 hours. The cooled mixture was diluted with water (25 L) and extracted with methylene chloride (7 L).

The aqueous solution was acidified with concentrated hydrochloric acid to pH 4. The crude acid which precipitated was filtered off, washed with water and dried.

b) Preparation of isopropyl-N-(3-chloro-4-fluoroferryl)-2-aminopropionate

N-(3-chloro-4-fluorophenyl)-2-aminopropionic acid (725 g,

prepared as in a)) was dissolved in dry isopropyl alcohol (2.5 1). The solution was saturated with hydrogen chloride gas and heated at reflux for 4 hours. The volatile components were then distilled off and the residue was washed with ice cold aqueous sodium bicarbonate solution to give the desired ester. c) Benzovation of isopropyl-N-(3-chloro-4-fluorophenyl)-2-aminopropionate Isopropyl-N-(3-chloro-4-fluorophenyl)-2-aminopropibnate (840 g, prepared as in b)) in dry toluene (2 1) was treated with benzoyl chloride (562 g) and the mixture was heated under reflux for 5 hours. The solvent and excess benzoyl chloride were de-

distilled and the residue recrystallized from benzene to give isopropyl-N-benzoyl-N-(3-chloro-4-fluorophenyl)-2-aminopropionate,

sm.p. 63-65 C.

Analysis:

Calculated for C19H19<N>03C1F: C 62.7, H5.2, N 3.9%

Found: C 62.6, H 5.4, N 3.6%.

Example 2

Preparation of methyl-N-benzoyl-N-(3-chloro-4-fluorophenyl)-2-aminopropionate

a) Preparation of methyl-N-(3-chloro-4-fluorophenyl)-2-aminopropionate

N-(3-chloro-4-fluorophenyl)-2-aminopropionic acid (5.0 g) was

dissolved in dry methanol (50 mL). The solution was saturated with hydrogen chloride gas and heated at reflux for 4 hours. The volatile components were then distilled off and the residue washed with ice cold aqueous sodium bicarbonate solution to give the desired ester.

b) Benzoylation of methyl-N-(3-chloro-4-fluorophenyl) 2-aminopropionate

Methyl -N-(3-chloro-4-fluorophenyl)-2-aminopropionate (2.32 g,

prepared as in a)) in dry toluene (50 ml) was treated with benzoyl chloride (14.5 g) and the mixture was heated under reflux for 5 hours. The solvent and excess benzoyl chloride were de-

distilled and the residue recrystallized from benzene to give methyl-N-benzoyl-N-(3-chloro-4-fluorophenyl)-2-aminopropionate, m.p. 77-79°C. Analysis:

Calculated for C17H15N03C1F: C 60.8, H4.5, N4.2%

Found: C 61.2, H 4.6, N 4.1%.

Example 3

Selective herbicidal properties of isopropyl-N-benzoyl-N-(3-chloro-4-fluorophenyl)-2-aminopropionate (compound 1, against ryegrass in barley).

25 grains of barley (var. Imber) or 30 oat seeds

(Avena fatua) are sown in John Innes Compost No. 1 in 7 cm pots.

When the plants had reached the 1 1/2 - 2 1/2 leaf stage, the pots were sprayed with a solution of the test compound in a 1:1 acetone/water mixture containing added wetting agent/adhesive. Barley plants were treated with doses from 10 to 0.6 kg/ha and field oats with doses from 2.0 to 0.15 kg/ha. Each dosage was repeated four times. The pots were stored in a greenhouse at approx. 21°C with 16 hours

daylight.

Examinations were carried out 10-14 days after spraying. Barley was cut off at soil level and the plant weight expressed as a percentage of untreated barley weight. Percentage reduction in the weight of the rolled oats was assessed visually. These numbers were then used to calculate the growth inhibition dosages, and the dosage that gives a 109% reduction of barley (GID^Q) was compared with the dosage that gave a 90% reduction of field oats (GIDgQ). The selectivity factor for the compound is then obtained from the expression:

The results of this test are shown in the following table, where the results obtained with the closely related compounds: ethyl-N-benzoyl-N-(3,4-dichlorophenyl)-2-aminopropionate (compound P),

ethyl N-benzoyl-N-(4-fluorophenyl)-2-aminopropionate (compound Q),

ethyl-N-benzoyl-N-(3-chloro-4-fluorophenyl)-2-aminopropionate (compound R) and

n-propyl-N-benzoyl-N-(3-chloro-4-fluorophenyl)-aminopropionate

(compound S),

is listed as a comparison.

From these results it is clear that the compound

according to the invention is a significantly more selective herbicide for field oats than its most closely related compounds. The results marked with an 'A' were all obtained from tests carried out simultaneously and are thus strictly comparable to each other. The results marked 'B' were obtained from a different test series so any comparison made with the 'A' results should be treated accordingly.

Example 4

Selective herbicidal properties of methyl-N-benzoyl-N-(3-chloro-4-fluorophenyl)-2-amino-propionate (compound 2)

25 grains of barley or wheat and 30 grains of spelled oats (Avena spp)

were sown in John Innes compost No. 1 in 7 cm pots. When the plants had reached the 1 1/2 - 2 1/2 leaf stage, the pot was sprayed with a solution of the test compound in a 1:1 acetone/water mixture containing added wetting adhesive. The crop plants were treated with doses of from 10 to 0.6 kg/ha and the field oats with from 2.0 to 0.15 kg/ha. Each dosage was repeated four times. The pots were kept in a greenhouse at approx. 21°C with 16 hours of daylight.

Investigations of the growth were carried out 10-14 days after the spraying. The cultivation plants were cut off at soil level and the plant weight was expressed as a percentage of the weight of untreated such plants. Percentage reduction in growth of field oats was assessed visually. These numbers were then used to calculate the growth inhibition dosages, and the dosage that gives a 10% reduction of the cultivation plants

(GID1Q) was compared with that which gives a 90% reduction in the growth of field oats (GIDgQ). The selective factor for the compound is then obtained from the expression:

The results of this test appear in the following table where the results obtained with the closely related compounds: ethyl-N-benzoyl-N-(3-chloro-4-fluorophenyl)-2-aminopropionate (compound R) and

ethyl N-benzoyl-N-(3,4-dichlorophenyl)-2-aminopropionate

(compound P)

also stated as a comparison.

From these results it appears that the methyl ester according to the invention exhibits a slightly higher activity and a greater selectivity than the corresponding ethylene analogues.

Claims (1)

N-benzoyl-N-(3-chloro-4-fluorophenyl)-2-aminopropionates with herbicidal action, characterized in that they have the general formula: wherein R is methyl or isopropyl.