GB1588215A

GB1588215A - Plant growth regulating and weed killing agents containing anthranilic acid derivatives and certain anthranilic acid derivatives per se

Info

Publication number: GB1588215A
Application number: GB32846/76A
Authority: GB
Original assignee: Roche Products Ltd
Current assignee: Roche Products Ltd
Priority date: 1976-08-06
Filing date: 1976-08-06
Publication date: 1981-04-15
Also published as: AT352765B; ATA577677A; BE857514A; AU2751377A; ZA774613B

Description

(54) PLANT GROWTH REGULATING'AND'WEED' KILLING AGENTS CONTAINING ANTHRANILIC ACID DERIVATIVES AND CERTAIN ANTHRANILIC ACID DERIVATIVES PER SE (71) We, ROCHE PRODUCTS LIMITED, a British Company of Broadwater Road, Welwyn Garden City, Hertfordshire, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by 'which it is to be performed, to be particularly described in and by the following statement: The present invention is concerned with plant growth regulating and weed killing agents. The invention is also concerned with a process for the manufacture of said agents and with a method of regulating plant growth or for killing weeds by means of said agents or the essential active ingredient thereof. Further, the invention is concerned with certain of said active ingredients per se and with a process for the preparation thereof.

According to the present invention there is provided a plant growth regulating and weed killing agent containing an effective amount of a compound of the general formula

wherein R' represents a hydrogen atom, a straight-chain or branched-chain alkyl group containing from 1 to 6 carbon atoms, a straight-chain or branched-chain lower alkanoyl group as hereinafter defined which may be substituted by a carboxyl group or one or two halogen atoms, or a benzoyl group which may carry one or two substituents selected from halogen, nitro, amino and straight-chain or branchedchain alkyl or alkoxy containing from 1 to 3 carbon atoms, R2 represents a straightchain or branched-chain alkyl or alkoxy group containing from 1 to 3 carbon atoms and R3 represents a hydrogen atom or a straight-chain or branched-chain alkyl group containing from 1 to 6 carbon atoms, with the proviso that R2 represents a straight-chain or branched-chain alkyl group containing 2 or 3 carbon atoms or a straight-chain or branched-chain alkoxy group containing from 1 to 3 carbon atoms when R' and R3 each represent a hydrogen atom, or a salt thereof in association with a compatible carrier material.

Preferred plant growth regulating and weed killing agents provided by this invention contain a compound of formula I as hereinbefore defined in which R2 represents a straight-chain or branched-chain alkyl group containing from 1 to 3 carbon atoms, or a salt thereof. Also preferred are plant growth regulating and weed killing agents which contain a compound of formula I as hereinbefore defined in which R' represents a hydrogen atom, a straight-chain or branched-chain alkyl group containing from I to 6 carbon atoms or a straight-chain or branched-chain lower alkanoyl group which may be substituted by a carboxyl group or by one or two halogen atoms and R3 represents a hyrogen atom, or a salt thereof.

The plant growth regulating and weed killing agents defined hereinbefore are particularly useful as post-emergence and pre-emergence plant growth regulators and herbicides. However, the post-emergence plant growth regulating activity is generally predominant.

Further, there is also provided according to the present invention a method for the regulation of plant growth and for the killing of weeds, said method comprising treating the plants to be regulated or the weeds to be killed with an effective amount of a compound of formula I or a salt thereof or with a plant growth regulating agent or weed killing agent as defined earlier.

The expression "plant growth regulator" as used in this specification denotes, for example, a compound which either retards or stimulates the growth of main or side branches or shoots of plants. Such a compound is capable of influencing the flower initiation and formation, the shoot or branch formation, the parthenocarpy, the abscission of fruit and/or leaves and the ripening of fruit and/or leaves with or without the prior application of fertilizers. In addition, such compounds have an effect and an influence on the transport of substances within the plants; for example, a stimulation of the latex flow and/or the metabolism or, for example, an increase in the sugar content within the plant, which may also increase frost resistance. Such a compound may affect the extent of stomatal opening, thus increasing drought resistance and reducing or even eliminating the harmful effects of atmospheric pollutants (e.g. ozone and sulphur dioxide). The compounds of formula I and their salts are especially active in stimulating latex flow.

In shrubs, for example, this regulating activity produces a retardation of the growth in height with concomitant stimulation of the side-growth.

Plant growth regulating agents provided by the present invention are especially active in regulating the growth of the following plants (especially young plants): a) Cereals such as corn, rice, wheat, rye, barley and oats; b) Trees and shrubs such as fruit trees (e.g. apple, pear, peach, cherry and lemon) as well as cocoa, tea, coffee, banana, rubber, olive and walnut; c) Ornamental plants such as privet, hornbeam, white cedar, juniper, rose, azalea, chrysanthemum, poinsettia, cyclamen, pyrocantha, forsythia, magnolia, petunia and bromeliad; d) Field plants such as sugar cane, grapevine, cotton, soya bean, groundnut, tobacco, flax, sugar beet and pineapple; e) Vegetables such as Solanaceae (e.g. tomatoes), legumes, pumpkins and melons; f) Berries such as strawberries, bilberries, raspberries, blueberries, blackberries, and redcurrants; and g) Grasses.

According to the process provided by the present invention the plant growth regulating and weed killing agents aforesaid are manufactured by mixing an effective amount of a compound of formula I hereinbefore or a salt thereof with a compatible carrier material.

In order to achieve a homogeneous distribution of a compound of formula I or a salt thereof in the present plant growth regulating and weed killing agents, such a compound or salt is mixed with conventional liquid or solid adjuvants, modifiers, diluents or conditioning agents which are customary in plant growth regulating and weed killing agents and the resulting mixture is formulated into solutions, emulsions, emulsifiable concentrates, dispersions, dusts, granulates or wettable powders.

Plant growth regulating and weed killing agents in the form of liquid formulations suitable for direct spraying can be prepared, for example, in the form of aqueous solutions -- whenever possible -- or as solutions in solvent mixtures, for example acetone and water.

Emulsifiable concentrates containing 5-50% or more of a compound of formula I or a salt thereof depending on the solubility thereof can be prepared using suitable solvents such as N-methyl-pyrrolidine, dimethylformamide and cyclohexanone. Surface-active substances (e.g. wetting agents, dispersants, emulsifiers) are added in a sufficient amount to produce a formulation having the desired characteristics.

Typical forms in which the plant growth regulating and weed killing agents of the invention may be put up are (a) aqueous concentrates containing from 10 to 50% by weight of a compound of formula I or a salt thereof; (b) ready-to-use solutions containing from 0.0001 to 10.0% by weight of a compound of formula I or a salt thereof; (c) water-soluble powders containing from 10 to 90% by weight of a compound of formula I or a salt thereof; (d) sprayable powders containing from 35 to 65% by weight of a compound of formula I or a salt thereof; (e) dusting powders or granules containing from 2 to 10% by weight of a compound of formula I or a salt thereof; and (f) flowable liquids containing from 10 to 40% by weight of a compound of formula I or a salt thereof.

The various application forms can be better adapted to the various purposes for which a compound of formula I or a salt thereof may be used if substances which improve the dispersion, adhesion, penetration and resistance to rain are added. Such substances include fatty acids, waxes, resins, wetting agents, emulsifiers, mineral oils, vegetable oils and binding agents. In a similar manner, the biological spectrum of the present plant growth regulating and weed killing agents may be greatly broadened by the addition of substances having bactericidal, herbicidal or fungicidal properties or by the addition of fertilisers, chelate-forming agents and other plant growth regulators.

Examples of herbicides and plant growth regulators which can be present in the plant growth regulating and weed killing agents provided by the present invention are: 2,2-dichloropropionic acid, N-(4-aminobenzenesulphonyl)methylcarbamate, 2-chloro-4-ethylamino-6-isopropylamino- 1 3,5-triazine, 4-chloro-2-oxobenzothiazolin-3-yl-acetic acid, 5-bromo-6-methyl-3-( 1 -methyl-n-propyl)uracil, 3,5-dibromo-4-hydroxybenzonitrile, D,N-ethyl-2-(phenylcarbamoyloxy)propionamide, N-(4-bromo-3-chlorophenyl)-N'-methoxy-N'-methylurea, methyl 2-chloro-9-hydroxyfluorene-9-carboxylate, N'-4-(4-chlorophenoxy)-phenyl-N,N-dimethylurea, isopropyl-N-(3-chlorphenyl)-carbamate, 2,3,5,6-tetrachloroterephthalic acid dimethyl ester (DCPA), 2,4-dichlorophenoxyacetic acid, 4-isopropylamino-6-methylamino-2-methylthio- 1,3,5-triazine, n-butyl 9-hydroxyfluorene-9-carboxylate, ethylene, naphthoxyacetic acid, 3,6-dichloro-2-methoxybenzoic acid, (+)-2-(2,4-dichlorophenoxy)propionic acid, 9,1 0-dihydro-8a, 1 0a-diazoniaphenanthrene-2A, N'-(3,4-dichlorophenyl)-N,N-dimethylurea, gibberellic acid, indolylacetic acid, indolylbutyric acid, 4-hydroxy-3,5-diiodobenzonitrile, N'-(3,4-dichlorophenyl)-N-methoxy-N-methylurea, (4-chloro-2-methylphenoxy)acetic acid, 4-(4-chloro-2-methylphenoxy)butyric acid, (+)-2-(4-chloro-2-methylphenoxy)propionic acid, N-(benzothiazol-2-yl)-N,N'-dimethylurea N'-(3-chloro-4-methoxyphenyl)-N,N-dimethylurea, I ,2,3,6-tetrahydro-3,6-dioxopyridiazine, N'-(4-chlorophenyl)-N-methoxy-N-methylurea, N'-(4-chlorophenyl)-N,N-dimethylurea, naphthylacetic acid, N-l-naphthylphthalamic acid, 2,4-dichlorophenyl 4-nitrophenyl ether, 1,1 '-dimethyl-4,4'-bipyridylium-2A, 3-(m-tolylcarbamoyloxy)phenyl carbamate, 4-amino-3,5,6-trichloropicolinic acid, 4,6-bis-isopropylamino-2-methylthio- 1 ,3,5-triazine, N-(3,4-dichlorophenyl)-propionamide, i.vopropyl-N-phenylcarbamate, 5-amino-4-chloro-2-phenylpyridazin-3(2H)-one, N-dimethylaminosuccinic acid, 2-chloroethylphosphonic acid,; tribulyl-2,4-dichlorobenzyl-phosphonium chloride, 2,4,5-trichlorphenoxypropionic acid, 2,3,6-trichlorobenzoic acid, 2-chloro-4,6-bis-ethylamino-l ,3,5-triazine, sodium chloroacetate, 2,4,5-trichlorophenoxyacetic acid, 5-chloro-6-methyl-3-tert.butyluracil, 4-ethylamino-2-methylth io-6-tert.butylamino- 1 ,3,5-triazine-(tert. butyryn), 2,3,5-triiodobenzoic acid and I I ,4-trimethyl-6-isopropyl-5-propionyl-indane.

Examples of fungicides which may be present in the plant growth regulating agents provided by the present invention are: 2,4-dichloro-6-(o-chloraniline)-s-triazine, 2,4,5,6-tetrachloroisophthalic acid nitrile, p-dimethylaminophenyldiazo sodium sulphonate, I ,4-dichloro-2,5-dimethoxybenzene, manganese ethylene-bis-dithiocarbamate, zinc ethylene-bis-dithiocarbamate, coordination product from zinc and manganese ethylene-bis-dithiocarbamate, methyl I -(butylcarbamoyl)-2-benzimidazole carbamate, 2-(4-thiazole)-benzimidazole and cis-N-[trichloromethyl)-thio]-4-cyclohexene- 1,2-dicarboximide.

The amount of compound of formula I or salt thereof which can be used for the regulation of plant growth and for the killing of weeds may be based on the results set forth hereinafter. However, it will be appreciated that these results are not exhaustive and that, in addition, numerous other factors influence the amount used. For example, the amount can vary not only between different species of plants but also within a specific species (e.g. depending on factors such as the size and the age of the plant), the time of year, the type of soil and climatic conditions at the time of use such as the air temperature, light intensity, rain and wind.

Furthermore, if the plant growth regulating and weed killing agent comes into contact with the plant via irrigation of the soil, higher concentrations will be necessary since, with this type of use, the plant is indirectly treated in comparison with a direct treatment by application of the plant growth regulating and weed killing agent on to leaves and stems (e.g. by spraying).

Accordingly, the amount of the plant growth regulating or weed killing agent varies according to the plants to be controlled, the amount required for application, the method of application and the degree of regulation of plant growth which is desired. In general, the present agents contain less than 50% of a compound of formula I or a salt thereof in a ready-for use spray form (e.g. 35 to 65% in powder form and up to 10% in liquid form).

In principle, the amount of a compound of formula I or a salt thereof which is used is chosen so that an effective control of the plant growth is achieved.

Accordingly, the choice of the minimum amount of a compound of formula I or a salt thereof used is governed by the minimum amount of such compound or salt which is able to effect the lower limit of growth retardation desired. The choice of the maximum amount of a compound of formula I or a salt thereof used is correspondingly governed by that amount of such compound or salt which is able to bring about the upper limit of growth retardation desired. In the control of grasses, particularly home lawns and industrial turfs (e.g. golf courses), it has been established that a maximum growth retardation as evidenced by diminished grass height as compared to an untreated control of about 40%---60 is desirable, with about 50% growth retardation preferred. Any retardation less than 40% is ineffective in that grass control is not substantial enough to have a significant aesthetic effect and to reduce or eliminate manual care. On the other hand, retardation greater than 60% results in an undesired skimpy appearance to the lawn or turf with subsequent invasion thereof by weeds and other undesirable plants.

The amount of a compound of formula I or salt thereof corresponding to these criteria or bringing them about is determined by these aspects of the tomato plant.

In order to achieve post-emergence growth regulating and weed-killing activity, amounts of 0.5 kg to 10 kg or more of a compound of formula I or a salt thereof are used per hectare.

In a similar manner, the best post-emergence growth regulating activity is generally obtained using amounts which lie between I kg and 5 kg or more of a compound of formula I or a salt thereof per hectare. A preferred range for spray solutions lies between 1 part per million and 150,000 parts per million or more depending on the plant species to be treated. An especially preferred range lies between 100 parts per million and 10,000 parts per million.

A further advantage of plant growth regulating agents containing a compound of formula I or a salt thereof lies in the absence of both a lasting effect on the plants and a residual activity which remains in the soil. Compounds of formula I and their salts decompose slowly and there is accordingly a consequent reduction in activity.

This effect has advantages since a) a short-term effect which may be lengthened by subsequent further treatment is produced; b) the normal growth behaviour of the plant re-occurs in step with the decrease in activity; and c) no harmful residues remain either on the plant or in the soil.

The duration of the retardation effect varies according to factors such as the type of plant treated and climatic conditions.

Although the compounds of formula I and their salts possess a plant growth regulating activity, they are virtually non-toxic to animals. There are weeds which, when treated as described above, are killed. Examples of such weeds are mentioned in Examples I and 2 hereinafter. Further examples of weeds which are killed are, for example, Sorghum halepense, Imperata cylindrica, Panicum spp. and Paspalum spp.

The following Examples illustrate various formulations of the plant growth regulating and weed killing agents of the invention: A. Aqueous formulations.

The compounds of formula I form more or less water-soluble salts with bases and, in the case of compounds of formula I in which R' represents a hydrogen atom or a straight-chain or branched-chain alkyl group containing from I to 6 carbon atoms with acids.

a) With bases.

A typical formulation is: Compound of formula I 200 g.

Diethanolamine 150 g.

Deionised water ad 1000 ml.

Instead of diethanolamine there can be used other bases such as dimethylamine, triethanolamine, aminomethyl-propanol and morpholine. The concentration of the active ingredient depends on the solubility of the salt. These formulations can also contain an amount of surfactant in order to improve the wetting power, and consequently the activity, of their ready-for-use dilute systems.

The formulations will normally be diluted before use to an active ingredient concentration between 0.01 and 1.0% by weight, preferably 0.05 to 0.8% by weight.

Suitable "before dilution" formulations are as follows: (i) For a 0.8% active ingredient concentration Compound of formula I 200 g.

Surfactant 6.25 g.

Diethanolamine 150g.

Deionised water ad 1000 ml. ii) For a 0.05% active ingredient concentration Compound of formula I 200 g.

Surfactant 100g.

Diethanolamine 150g.

Deionised water ad 1000 ml.

The surfactant may be an anionic surfactant (e.g. an alkali metal salt of an alkyl sulphate such as sodium lauryl sulphate or an alkali metal salt of an alkyl arylsulphonic acid such as sodium dodecyl benzenesulphonate) or a non-ionic surfactant (e.g. condensation products of ethylene oxide with alkyl-phenols, such as the condensation product of nonyl-phenol with 8-10 moles of ethylene oxide, and with fatty alcohols, such as the condensation product of stearyl alcohol with 8-10 moles of ethylene oxide).

b) With acids.

Salts of compounds of formula I in which R' represents a hydrogen atom or a straight-chain or branched-chain alkyl group containing from 1 to 6 carbon atoms may be formed by reaction of such compounds of formula I with acids such as hydrochloric acid, sulphuric acid, phosphoric acid and acetic acid. The salts formed with hydrochloric acid are the most soluble and are preferred. Typical formulations may be prepared from the following batches of ingredients using appropriate compound of formula I: i) Compound of formula I 100 g.

Hydrochloric acid (32%) 151 g.

Deionised water ad 1000 ml.

ii) Compound of formula I 100g.

Surfactant 6.25 g.

Hydrochloric acid 151 g.

Deionised water ad 1000 ml.

(this gives, on dilution, a 0.8% active ingredient content).

iii) Compound of formula I 100 g.

Surfactant loot.

Hydrochloric acid 151 g.

Deionised water ad 1000 ml.

(this gives, on dilution, a 0.05% active ingredient content). The surfactant may be non-ionic, as described earlier, or cationic (e.g. alkylbenzylammonium compounds such as dodecyldimethylbenzylammonium chloride).

B. Powderform water-soluble formulations (by salt-formation) Two typical formulations one containing a base and the other an acid, are as foilows:- ii Compound of formula I 20.0 20.0 Soda, calcined 15.5 ii Sodium lauryl sulphate (surfactant) 1.0 Lactose 63.5 66.0 Sulphaminic acid 13.0 Ethylene oxide/propylene oxide 1.0 solid block polymerisate (80% polyethyleneglycol ether chains) (non-ionic surfactant) These formulations are prepared by mixing the ingredients and finely milling them to give a free-flowing powder which is wettable with water and dissolves to form a clear solution.

C. Solid formulations.

(i) Spray powder (wettable powder).

Compound of formula I 50.0 g.

Hydratedsilicic acid 5.0 g.

Sodium lauryl sulphate (surfactant) 1.0 g.

Sodium lignosulphonate (dispersant) 2.0 g.

Kaolin B 24 42.0 g.

The ingredients are well mixed and finely milled to give a free-flowing powder which is wettable with water and has good suspension capability.

(ii) Dusting agent.

Compound of formula I 5.0 g.

Talc 95.0g.

The components, on intimate mixing and milling, give a powder with good dusting capability.

(iii) Granulate.

Compound of formula 1 5.0 g.

Polyethyleneglycol (PEG 500) 2.0 g.

Calcium carbonate, granulated, I mm 93.0 g.

The calcium carbonate granules are uniformly sprayed with the PEG and are then mixed with the finely milled compound of formula I. The PEG acts as an adhesive and bonds the active ingredient to the carrier particles.

D. Other formulations.

(i) The following ingredients are mixed and milled in a ball mill until the particle size of the active ingredient is within the range of 1 to 5 microns.

Compound of formula 1 250 g.

Sodium salt of a sulphonated naphthalene-formaldehyde condensation product (dispersant) 25 g.

Bentonite 15 g.

Deionised water ad 1000 ml.

There is obtained a homogeneous, pourable preparation which is dispersible in water to give a ready-for-use spray dispersion.

(ii) Emulsifiable concentrate.

Compound of formula I 100 g.

Emulsifier 100g.

Cyclohexanone ad 1000 ml.

(The emulsifier is a mixture of a condensation product obtained from nonyl-phenol with 8-10 moles of ethylene oxide and the calcium salt of dodecylbenzene sulphonic acid). The active ingredient and the emulsifier are dissolved in cyclohexanone to give a clear solution which emulsifies spontaneously in water and later even solubilises.

(iii) Spray solution.

Compound of formula I 2.0 g.

Acetone 9?.9g.

Tensiofix AS (surfactant) 0.1 g.

(Tensiofix AS is a mixture of nonionic alkylphenol derivatives, polyethylene oxide alkylphenol condensation product and anionic dodecyl benzene sulphonate and also contains unspecified, but small, amounts of n-butanol and carbon tetrachloride). The formulation will normally be diluted with water and Tween 20 (Trade Mark) immediately before application to give a concentration of active ingredients of 0.1 to 0.2% by weight.

A particular advantage of the present invention is that the plant growth regulating agents possess pre-emergence and post-emergence plant growth regulating activity when used for the treatment of various plants, the range of plants being extremely wide. The growth regulating activity of the present agents will be evident from the following greenhouse test for the determination of the post-emergence activity.

in another aspect, the invention is concerned with those compounds of formula I hereinbefore which are novel and with salts thereof, namely with compounds of the general formula

wherein R' represents a hydrogen atom, a straight-chain or branched-chain alkyl group containing from 1 to 6 carbon atoms, or a straight-chain or branched-chain lower alkanoyl group as hereinafter defined which may be substituted by a carboxyl group or by one or two halogen atoms, R20 represents a straight-chain or branchedchain alkyl or alkoxy group containing from I to 3 carbon atoms and R3 represents a hydrogen atom or a straight-chain or branched-chain alkyl group containing from 1 to 6 carbon atoms, with the provisos (i) that R20 represents a straight-chain or branched-chain alkyl group containing 3 carbon atoms or a straight-chain or branched-chain alkoxy group containing 2 or 3 carbon atoms when R' and R3 each represent a hydrogen atom and (ii) that R20 represents a straight-chain or branchedchain alkyl group containing 2 or 3 carbon atoms or a straight-chain or branchedchain alkoxy group containing 2 or 3 carbon atoms when R1 represents the acetyl group and R3 represents a hydrogen atom, and salts thereof.

The straight-chain and branched-chain lower alkanoyl groups referred to earlier are those having I to 8 carbon atoms. Examples are formyl, acetyl, propionyl, butyryl, isobutyryl, valeroyl and hexanoyl. The lower alkanoyl group can be substituted by a carboxyl group as, for example, in the case of the succinyl group or by one or two halogen atoms as, for example, in the case of the chloroacetyl or dichloroacetyl group.

A preferred class of compounds of formula Ia comprises those in which, subject to the R20 provisos set out above, represents a straight-chain or branchedchain alkyl group containing from 1 to 3 carbon atoms. Also preferred are compounds of formula Ia in which, subject to the provisos set out above, R' represents a hydrogen atom, a straight-chain or branched-chain alkyl group containing from 1 to 6 carbon atoms or a straight-chain lower alkanoyl group which may be substituted by a carboxyl group or by one or two halogen atoms and R3 represents a hydrogen atom.

Examples of compounds of formula Ia hereinbefore and salts thereof are: 6-Methylamino-o-toluic acid, 6-formamido-o-toluic acid, 6-propionamido-o-toluic acid, 6-butyramido-o-toluic acid, 6-isobutyramido-o-toluic acid, 6-hexanamido-o-toluic acid, 6-(2-chloroacetamido)-o-toluic acid, 2'-carboxyl-3'-methylsuccinanilic acid ammonium salt, ammonium 6-formamido-o-toluate, N-acetyl-6-ethylanthranilic acid, 6-(n-propyl)-anthranilic acid, 6-isopropyl-anthranilic acid and 6-dimethylamino-o-to!uic acid.

In a further aspect, the invention is concerned with a process for the preparation of the novel compounds of formula Ia and their salts, which process comprises (a) for the preparation of a compound of formula Ia in which R' and R3 each represent a hydrogen atom, reducing a nitro compound of the general formula

wherein R20 has the significance given earlier, or (b) for the preparation of a compound of formula Ia in which R' represents a straight-chain or branched-chain alkyl group containing from 1 to 6 carbon atoms and R3 represents a hydrogen atom, appropriately monoalkylating a corresponding compound of formula Ia in which R' and R3 each represent a hydrogen atom, or (c) for the preparation of a compound of formula Ia in which R' and R3 each represent a straight-chain or branched-chain alkyl group containing from I to 6 carbon atoms, reductively alkylating a corresponding compound of formula Ia in which R' represents a hydrogen atom or a straight-chain or branched-chain alkyl group containing from I to 6 carbon atoms and R3 represents a hydrogen atom, or (d) for the preparation of a compound of formula Ia in which R' represents a straight-chain or branched-chain lower alkanoyl group which may be substituted by a carboxyl group or by one or two halogen atoms, appropriately acylating a corresponding compound of formula Ia in which R' represents a hydrogen atom, or (e) for the preparation of a compound of formula Ia in which R' and R3 each represent a hydrogen atom, oxidising an isatin of the general formula

wherein R20 has the significance given earlier, and, where required, converting a compound of formula Ia obtained into a salt.

The reduction of a nitro compound of formula II in accordance with embodiment (a) of the process aforesaid can be carried out by catalytic hydrogenation. Suitable catalysts which may be used are noble-metal catalysts such as platinum, palladium, rhodium and Raney-nickel catalysts. The catalyst may be supported on a conventional carrier. The catalytic hydrogenation can be carried out in the presence of any suitable inert organic solvent, particularly a lower alkanol such as methanol or ethanol. Temperature and pressure are not critical, although it is convenient to carry out the catalytic hydrogenation at about room temperature and atmospheric pressure.

In accordance with embodiment (b) of the present process, a compound of formula Ia in which R' and R3 each represent a hydrogen atom is appropriately monoalkylated to yield a compound of formula Ia in which R' represents a straightchain or branched-chain alkyl group containing from I to 6 carbon atoms and R3 represents a hydrogen atom. This monoalkylation can be carried out in a manner known per se using an appropriate alkyl halide, particularly an alkyl iodide such as methyl iodide, or an appropriate dialkyl sulphate such as dimethyl sulphate.

The reductive alkylation of a compound of formula Ia in which R' represents a hydrogen ato hydroxide) or an organic base (e.g. a tertiary organic base such as triethylamine or pyridine). The temperature at which this acylation is carried out is not critical. In general, the acylation is carried out at a temperature between about 20"C and the boiling point of the mixture.

The oxidation of an isatin of formula III in accordance with embodiment (e) of the present process can be carried out in a manner known per se. In a preferred embodiment, the oxidation is carried out by treatment with hydrogen peroxide under alkaline conditions (e.g. in an aqueous alkali metal hydroxide solution as such aqueous sodium hydroxide or aqueous potassium hydroxide, preferably aqueous sodium hydroxide). Advantageously, this embodiment is carried out at a temperature above room temperature (e.g. at about 80 C) and under normal pressure.

The nitro compounds of formula II used as starting materials in embodiment (a) of the process are either known or can be obtained in a manner known per se.

The isatins of formula III used as starting materials in embodiment (e) of the process are either known or can be obtained in a manner known per se.

The compounds of this invention form salts with bases; for example, with alkali metal hydroxides (e.g. sodium hydroxide and potassium hydroxide), with alkaline-earth metal hydroxides (e.g. calcium hydroxide) and with organic bases (e.g. ammonia, diethanolamine, triethanolamine, dimethylamine, aminomethylpropanol and morpholine). The compounds of this invention in which R' represents a hydrogen atom or a straight-chain or branched-chain alkyl group containing from I to 6 carbon atoms form salts with organic acids (e.g. acetic acid, tartaric acid, citric acid, methanesulphonic acid and p-toluenesulphonic acid and with inorganic acids (e.g. hydrochloric acid, hydrobromic acid, sulphuric acid and phosphoric acid).

The following Examples illustrate the present invention: Example 1.

In order to demonstrate growth retarding activity in per cent relative to untreated plants on grapevine, barley and blue grass, a solution containing, by weight 0.4% of 6-acetamido-o-toluic acid, 49.5% of acetone, 0.1% of Tensiofix AS and 50% of water was used. This concentration of 6-acetylamino-o-toluic acid corresponds to an amount of 4 kg/hectare. The results are given in Table 1.

TABLE 1

Percentage growth retardation relative Test Plants to untreated controls Barley (Hordeum distichon) 25 Blue grass (Poa pratensis) 50 Grapevine (Vitis vinifera) 25 Example 2.

The post-emergence retarding activity of 6-ethyl-anthranilic acid was demonstrated by spraying Digitaria sanguinalis (3 leaved stage) and Panicum miliaceum (3 leaved stage) at 5 kg a.i./ha using a spray volume of 1000 1/aha. When the plants were assessed 3 weeks later an 80% kill was observed on D. sanguinalis and Panicum miliaceum, respectively.

The compounds of formula I and their salts may be marketed in portions of varying size in packages or containers suitable for agrochemical purposes. These packages or containers may consist of paper, plastic material, glass or metal. The compounds of formula I and their salts in these packages or containers may be used for the regulation of the growth of plants or for the killing of weeds.

In a preferred embodiment, the p!ant growth regulating and weed killing agent contains an effective amount of a compound of formula I or a salt thereof in association with at least one compatible carrier material having a molecular weight of 200 or more.

Example 3.

4.53 g of 6-methylanthranilic acid were suspended in a solution of 1.64 g of anhydrous sodium carbonate in 60 ml of water. 3.78 g of dimethyl sulphate were added and the mixture was shaken at room temperature for 2.5 hours. The mixture was then cooled to OOC for l hour and the precipitate was filtered off to yield 1.75 g of a white powder. The filtrate was reduced in volume on a rotary evaporator and cooled to OOC to yield a further 2.61 g of white powder. The combined solids were crystallised from ether to yield 2.50 g of white solid. This solid was purified by chromatography on 180 g of silica gel using petroleum ether (boiling range 40"--60"C) ether/glacial acetic acid (297:99:4) for the elution. After evaporation of the eluate, there was obtained 1.48 g of a white solid which was recrystallised from ether to yield 1.41 g of 6-methylamino-o-toluic acid as a white solid of melting point 1 29.50-l300C.

Example 4.

To 4.53 g of 6-methylanthranilic acid dissolved in 100 ml of hot benzene were added 5.3 ml of chloroacetic anhydride in 10 ml of benzene. After stirring for a short time, the product precipitated out and was filtered off. After two recrystallisations from benzene, there were obtained 2.6 g of 6-(2chloroacetamido)-o-toluic acid in the form of white crystals melting at approximately 1400C.

Example 5.

The procedure described in Example 4 was repeated using 3.16 of acetic anhydride in place of the chloroacetic anhydride. After recrystallisation from ethanol, there were obtained 3.3 g of 6-acetamido-o-toluic acid of melting point 176"--180"C.

Example 6.

The procedure described in Example 4 was repeated using 4.75 g of isobutyric anhydride in place of the chloroacetic anhydride. After two recrystallisations from ethyl acetate/hexane, there were obtained 2.9 g of 6-isobutyramido-o-toluic acid of melting point 1630--165"C.

Example 7.

20.72 g of potassium 6-methyl-anthanilate were suspended in 200 ml of benzene and 10.2 g of triethylamine. To the suspension obtained were added dropwise 15.5 g of succinic acid dichloride, whereby a black precipitate formed.

The mixture was stirred at 600C for 2 hours, cooled, filtered and the sol;d washed well with water. The filtrate was acidified, the benzene layer separated and the aqueous phase extracted twice with ethyl acetate. The combined organic phases were evaporated, the oily residue was dissolved in 50 ml of ethanol and treated with aqueous ammonia. The solvent was removed by evaporation and the residue dried.

There was thus obtained 2'-carboxy-3'-methylsuccinanilic acid ammonium salt in the form of a hygroscopic solid.

Example 8.

To 30 g of 6-methylanthranilic acid dissolved in 500 ml of 88% formic acid were added at 600C 166 ml of acetic anhydride. The mixture was stirred for l hour without heating and then evaporated to dryness. The residue was recrystallised from ethyl acetate/hexane to yield 13 g of 6-formamido-o-toluic acid of melting point l440-1450C.

Example 9.

2.3 g of 6-formamido-o-toluic acid were dissolved in 20 ml of acetone and treated with 5 ml of concentrated aqueous ammonia solution. The mixture was then concentrated to dryness. The residue was washed with ether and dried. There were obtained 2 g of ammonium 6-formamido-o-toluate in the form of white crystals of melting point 1480-1520C.

Example 10.

To a solution of 1.38 g of sodium hydroxide in 35 ml of water were added 4.70 g of 6-ethylanthranilic acid and 2.94 g of acetic anhdride. The mixture was shaken vigorously for 5 minutes and then acidified with concentrated hydrochloric acid.

The product precipitated out and was filtered off and recrystallised from a hot mixture of ethanol and water. There were obtained 2.96 g of N-acetyl-6ethylanthranilic acid in the form of cream crystals melting at 1440C.

Example 11.

To a solution of 1.51 g of sodium hydroxide in 38 ml of water were added 4.67 g of 6-methylanthranilic acid and 4.07 g of propionic anhydride. The mixture was shaken vigorously for 5 minutes and then acidified with concentrated hydrochloric acid. The white precipitate was filtered off and crystallised from a hot mixture of ethanol and water to yield 5.07 g of 6-propionamido-o-toluic acid in the form of cream crystals melting at 1560--15670C.

Example 12.

To a solution of 1.29 g of sodium hydroxide in 32 ml of water were added 4.0 g of 6-methylanthranilic acid and 4.27 g of butyric anhydride. The mixture was shaken vigorously for 5 minutes and then acidified with concentrated hydrochloric acid. The precipitate was filtered off and crystallised from a hot mixture of ethanol and water to yield 4.4 g of 6-butyramido-o-toluic acid in the form of cream crystals of melting point 129"C.

Example 13.

To a solution of 1.61 g of sodium hydroxide in 40 ml of water were added 5.0 g of 6-methylanthranilic acid and 7.13 g of hexanoic anhydride. The mixture was shaken vigorously for 10 minutes and then acidified with concentrated hydrochloric acid and extracted twice with chloroform. The combined organic phases were evaporated and the oily residue was crystallised from petroleum ether (boiling range 400-600C) to yield 1.80 g of 6-hexanamido-o-toluic acid in the form of cream crystals of melting point 93.50-94.50C.

Example 14.

2.80 g of 4-(n-propyl)-isatin were dissolved in a solution of 22.2 g of sodium hydroxide in 220 ml of water and the solution was stirred at 60"C during the addition, over a period of 15 minutes, of 100 ml of 10% hydrogen peroxide. The mixture was stirred at 800C for 2.5 hours and then cooled to room temperature and acidified with concentrated hydrochloric acid to pH 3.6. The resulting light brown solid was filtered off, dried and crystallised from ether/petroleum ether (boiling range 40"--60"C) to give 0.50 g of 6-(n-propyl)-anthranilic acid in the form of white crystals of melting point 1240-l250C.

Example 15.

2.00 g of 4-isopropyl-isatin were dissolved in a solution of 19.0 g of sodium hydroxide in 190 ml of water and the solution was stirred at 600C during the addition, over a period of 15 minutes, of 50 ml of 10% hydrogen peroxide. The mixture was stirred at 800C for 30 minutes, activated charcoal was then added and the stirring was continued for a further 10 minutes. The mixture was filtered, the filtrate was cooled to room temperature and then acidified to pH 3.6 with concentrated hydrochloric acid. The resulting suspension was extracted twice with dichloromethane and the combined organic extracts were evaporated to yield a white solid which was crystallised from ether/hexane to yield 0.51 g of 6-iso propylanthranilic acid in the form of white crystals of melting point 1350-l360C.

Example 16.

4.0 g of 5% palladium-on-carbon were added to a solution of 6.0 g of 6-nitro-otoluic acid in a mixture of 400 ml of formic acid and 33 ml of 40% formalin. The mixture was shaken under 1 atmosphere of hydrogen until hydrogen uptake ceased (4 hours). The mixture was then filtered and the filtrate evaporated to give 5.22 g of a pale yellow gum which was dissolved in 400 ml of hot ethanol. The solution obtained was cooled to -200C and filtered in order to remove an insoluble byproduct. The filtrate was reduced in volume to 50 ml and cooled to -20"C to yield 1.23 g of 6-dimethylamino-o-toluic acid in the form of white crystals of melting point 107"--111"C.

Claims

WHAT WE CLAIM IS:

I. A plant growth regulating and weed killing agent containing an effective amount of a compound of the general formula

wherein R' represents a hydrogen atom, a straight-chain or branched-chain alkyl group containing from 1 to 6 carbon atoms, a straight-chain or branched-chain lower alkanoyl group as hereinbefore defined which may be substituted by a carboxyl group or by one or two halogen atoms or a benzoyl group which may carry one or two substituents selected from halogen, nitro, amino and straight-chain or branched-chain alkyl or alkoxy containing from 1 to 3 carbon atoms, R2 represents a straight-chain or branched-chain alkyl or alkoxy group containing from I to 3 carbon atoms and R3 represents a hydrogen atom or a straight-chain or branchedchain alkyl group containing from 1 to 6 carbon atoms, with the proviso that R2 represents a straight-chain or branched-chain alkyl group containing 2 or 3 carbon atoms or a straight-chain or branched-chain alkoxy group containing from 1 to 3 carbon atoms when R' and R3 each represent a hydrogen atom, or a salt thereof in association with a compatible carrier materia!.
2. An agent according to claim 1, wherein there is present a compound of formula I in which R3 represents a hydrogen atom, or a salt thereof.
3. An agent according to claim 1 or claim 2, wherein there is present a compound of formula I in which R2 represents a straight-chain or branched-chain alkyl group containing from I to 3 carbon atoms, or a salt thereof.
4. An agent according to any one of claims 1 to 3 inclusive, wherein there is present a compound of formula I in which R' represents a hydrogen atom, a straight-chain or branched-chain alkyl group containing from 1 to 6 carbon atoms or a straight-chain or branched-chain lower alkanoyl group as hereinbefore defined which may be substituted by a carboxyl group or by one or two halogen atoms, or a salt thereof.
5. An agent according to any one of claims 1 to 4 inclusive, wherein said compound of formula I is 6-formamido-o-toluic acid.
6. An agent according to any one of claims I to 5 inclusive in the form of an aqueous concentrated containing from 10 to 50% by weight of a compound of formula I or a salt thereof.
7. An agent according to any one of claims 1 to 5 inclusive in the form of a ready-to-use solution containing from 0.0001 to 10% by weight of a compound of formula I or a salt thereof.
8. An agent according to any one of claims I to 5 inclusive in the form of a water-soluble powder containing from 10 to 90% by weight of a compound of formula I or a salt thereof.
9. An agent according to any one of claims 1 to 5 inclusive in the form of a sprayable powder containing from 35 to 65% by weight of a compound of formula I or a salt thereof.
10. An agent according to any one of claims 1 to 5 inclusive in the form of a dusting agent or granules containing from 2 to 10%by weight of a compound of formula I or a salt thereof.
11. An agent according to any one of claims 1 to 5 inclusive in the form of a flowable liquid containing from 10 to 40% by weight of a compound of formula I or a salt thereof.
12. An agent according to any one of claims 1 to 5 inclusive in the form of an emulsifyable concentrate containing 5 to 50% by weight of a compound of formula I or a salt thereof.
13. An agent according to any one of claims 1 to 12 inclusive, wherein there is also present one or more other plant growth regulating agents, bactericides, herbicides and/or fungicides.
14. A plant growth regulating agent according to claim 1, substantially as hereinbefore described.
15. A process for the manufacture of a plant growth regulating agent, which process comprises mixing an effective amount of a compound of formula I given in claim 1, or a salt thereof, with a compatible carrier material.
16. A process according to claim 15, wherein a compound of formula I in which R3 represents a hydrogen atom, or a salt thereof, is used.
17. A method for the regulation of plant growth or for the killing of weeds, which method comprises treating the plants to be regulated or the weeds to be killed with an effective amount of a compound of formula I, or a salt thereof, or with an agent as claimed in claim 1.
18. A method according to claim 17, wherein there is used a compound of formula I in which R3 represents a hydrogen atom, or a salt thereof, or an agent as claimed in claim 2.
19. Compounds of the general formula

wherein R' represents a hydrogen atom, a straight-chain or branched-chain alkyl group containing from 1 to 6 carbon atoms, a straight-chain or branched-chain lower alkanoyl group as hereinbefore defined which may be substituted by a carboxyl group or by one or two halogen atoms, R20 represents a straight-chain or branched-chain alkyl or alkoxy group containing from 1 to 3 carbon atoms and R3 represents a hydrogen atom or a straight-chain or branched-chain alkyl group containing from I to 6 carbon atoms, with the provisos (i) that R20 represents a straight-chain or branched-chain alkyl group containing 3 carbon atoms or a straight-chain or branched-chain alkoxy group containing 2 or 3 carbon atoms when R' and R3 each represent a hydrogen atom and (ii) that R20 represents a straight-chain or branched-chain alkyl group containing 2 or 3 carbon atoms or a straight-chain or branched-chain alkoxy group containing 2 or 3 carbon atoms when R1 represents the acetyl group and R3 represents a hydrogen atom, and salts thereof.
20. Compounds according to claim 19, wherein R3 represents a hydrogen atom, and salts thereof.
21. Compounds according to claim 19 or claim 20, wherein R20 represents a straight-chain or branched-chain alkyl group containing 1 to 3 carbon atoms, and salts thereof.
22. Compounds according to any one of claims 19 to 21 inclusive, wherein R' represents a hydrogen atom, a straight-chain or branched-chain alkyl group containing from I to 6 carbon atoms or a straight-chain or branched-chain lower alkanoyl group as hereinbefore defined which may be substituted by a carboxyl group or by one or two halogen atoms, and salts thereof.
23. 6-Methylamino-o-toluic acid.
24. 6-Formamido-o-toluic acid.
25. 6-Propionamido-o-toluic acid.
26. 6-Butyramido-o-toluic acid.
27. 6-lsobutyramido-o-toluic acid.
28. 6-Hexanamido-o-toluic acid.
29. 6-(2-Chloroacetamido)-o-toluic acid.
30. 2'-Carboxy-3'-methylsuccinanilic acid ammonium salt.
31. Ammonium 6-formamido-o-toluate.
32. N-Acetyl-6-ethylanthranilic acid.
33. 6-(n-Propyl)-anthranilic acid.
34. 6-lsopropyl-anthranilic acid.
35. 6-Dimethylamino-o-toluic acid.
36. A process for the preparation of the compounds of formula Ia given in claim 19 and salts thereof, which process comprises (a) for the preparation of a compound of formula Ia in which R' and R3 each represent a hydrogen atom, reducing a nitro compound of the general formula

wherein R20 has the significance given in claim 19, or (b) for the preparation of a compound of formula Ia in which R' represents a straight-chain or branched-chain alkyl group containing from I to 6 carbon atoms and R3 represents a hydrogen atom, appropriately monoalkylating a corresponding compound of formula Ia in which R1 and R3 each represent a hydrogen atom, or (c) for the preparation of a compound of formula Ia in which R' and R3 each represent a straight-chain or branched-chain alkyl group containing from I to 6 carbon atoms, reductively alkylating a corresponding compound of formula Ia in which R' represents a hydrogen atom or a straight-chain or branched-chain alkyl group containing from 1 to 6 carbon atoms and R3 represents a hydrogen atom, or (d) for the preparation of a compound of formula Ia in which R1 represents a straight-chain or branched-chain lower alkanoyl group as hereinafter defined which may be substituted by a carboxyl group or by one or two halogen atoms, appropriately acylating a corresponding compound of formula Ia in which R' represents a hydrogen atom, or (e) for the preparation of a compound of formula Ia in which R' and R3 each represent a hydrogen atom, oxidising an isatin of the general formula

wherein R20 has the significance given in claim 19, and, where required, converting a compound of formula Ia obtained into a salt.
37. A process according to claim 36, wherein a compound of formula II is reduced, or a compound of formula Ia in which R1 and R3 each represent a hydrogen atom is appropriately monoalkylated, or a compound of formula la in which R1 and R3 each represent a hydrogen atom is appropriately acylated, and, where required, a compound of formula Ia obtained is converted into a salt.
38. A process according to claim 36 or claim 37, wherein there is prepared a compound of formula Ia in which R20 represents a straight-chain or branched-chain alkyl group containing from 1 to 3 carbon atoms, or a salt thereof
39. A process according to any one of claims 36 to 38 inclusive, wherein there is prepared a compound of formula Ia in which R1 represents a hydrogen atom, a straight-chain or branched-chain alkyl group containing from I to 6 carbon atoms or a straight-chain or branched-chain lower alkanoyl group which may be substituted by a carboxyl group or by one or two halogen atoms, or a salt thereof.
40. A process according to claim 37, wherein 6-methyl-amino-o-toluic acid is prepared.
41. A process according to claim 37, wherein 6-formamido-o-toluic acid is prepared.
42. A process according to claim 37, wherein 6-propionamido-o-toluic acid is prepared.
43. A process according to claim 37, wherein 6-butyramido-o-toluic acid is prepared.
44. A process according to claim 37, wherein 6-isobutyramido-o-toluic acid is prepared.
45. A process according to claim 37, wherein 6-hexanamido-o-toluic acid is prepared.
46. A process according to claim 37, wherein 6-(2-chloro-acetamido)-o-toluic acid is prepared.
47. A process according to claim 37, wherein 2'-carboxy-3'-methylsuccinanilic acid ammonium salt is prepared.
48. A process according to claim 37, wherein ammonium 6-formamido-otoluate is prepared.
49. A process according to claim 37, wherein N-acetyl-6-ethylanthranilic acid is prepared.
50. A process according to claim 36, wherein 6-(n-propyl)-anthranilic acid is prepared.
51. A process according to claim 36, wherein 6-isopropyl-anthranilic acid is prepared.
52. A process according to claim 36, wherein 6-dimethylamino-o-toluic acid is prepared.
53. A process for the preparation of the compounds of formula Ia given in claim 19 and salts thereof, substantially as hereinbefore described with reference to any one of Examples 3 to 16.
54. A compound of formula Ia given in claim 19, or a salt thereof, when prepared by the process claimed in any one of claims 36 to 53 inclusive or by an obvious chemical equivalent thereof.