GB2130214A

GB2130214A - Pyrimidin-4-one derivatives endowed with a herbicide activity

Info

Publication number: GB2130214A
Application number: GB08330735A
Authority: GB
Inventors: Roberto Colle; Franco Gozzo; Ciro Preziuso; Ernesto Signorini; Angela Zagni
Original assignee: Montedison SpA
Current assignee: Montedison SpA
Priority date: 1982-11-18
Filing date: 1983-11-17
Publication date: 1984-05-31
Also published as: GB2130214B; GB8330735D0; IT8224311A1; FR2536394A1; IT1153066B; IT8224311A0; DE3341343A1; CH658652A5; FR2536394B1; BE898258A; JPS59106472A

Abstract

Novel compounds of the general formula: <IMAGE> in which: R<1> represents an alkyl group having 1 to 4 carbon atoms, an alkylthio group having 1 to 4 carbon atoms, a hydrazine or amino group optionally substituted with one or more groups selected from alkyl having 1 to 4 carbon atoms, alkoxy having 1 to 4 carbon atoms, alkenyl having 2 to 5 carbon atoms or alkynyl having 2 to 5 carbon atoms, R<2> represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or an amino group optionally substituted by one or two alkyl groups having 1 to 4 carbon atoms, R<3> represents a phenyl group optionally substituted by from one to three substituents selected from halogen atoms, alkyl groups having 1 to 4 carbon atoms, haloalkyl groups having from 1 to 4 carbon atoms and from 1 to 3 halogen atoms, nitro, alkoxycarbonyl, CN, SO2-alkyl having from 1 to 4 carbon atoms, a 2-thienyl or a 2-,3- or 4-pyridyl group, possess herbicidal activity.

Description

SPECIFICATION Pyridin-4-one derivatives endowed with a herbicide activity This invention relates to new herbicide compounds and in particular, to pyrimidin-4-ones substituted in the 2-, 5- and optionally 3-positions, to their preparation and their use as herbicides.

Numerous compounds exerting a herbicide activity belonging to various chemical classes are known. Heretofore, there are no known herbicides belonging to the class of the pyrimidin-4-ones.

According to the present invention there is provided a compound of the formula:

in which: R' represents an alkyl group having 1 to 4 carbon atoms, an alkylthio group having 1 to 4 carbon atoms, a hydrazine or amino group optionally substituted with one or more groups selected from alkyl having 1 to 4 carbon atoms, alkoxy having 1 to 4 carbon atoms, alkenyl having 2 to 5 carbon atoms or alkynyl having 2 to 5 carbon atoms, R2 represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or an amino group optionally substituted by one or two alkyl groups each having 1 to 4 carbon atoms, R3 represents a phenyl group optionally substituted from one to three substituents selected from halogen atoms, alkyl groups having 1 to 4 carbon atoms, haloalkyl groups having from 1 to 4 carbon atoms and from 1 to 3 halogen atoms, nitro, alkoxycarbonyl, CN, SO2-alkyl having from 1 to 4 carbon atoms, a 2-thienyl or a 2-, 3- or 4-pyridyl group.

The compounds of formula (I) are endowed with a herbicide activity and are suitable for use in the protection of useful cultivations against infesting plants.

It will be appreciated that according to the l.U.P.A.C. Organic Nomenclature, Rules A and B, 1969, the compounds of formula (I) should be referred to as derivatives of (3H)-pyrimidin-4-one. However, the nomenclature of pyrimidin-4-one derivatives will be used herein to refer to compounds of formula (I) because the presence of a substituent in the 3-position (R3 substituent) makes it inappropriate to adopt the recommended nomenclature, except in the case in which R2 is a hydrogen atom.

The preparation of the compounds of formula (I) may be accomplished by adopting various methods, the choice of which is mainly dependent upon the nature of the R1 and R2 substituents.

In the following description of the synthesis processes, in the interests of clarity, the following symbols will be used to identify particular groups for the substituents R1 and R2: R represents an alkyl group of from 1 to 4 carbon atoms, SR represents an alkylthio group of from 1 to 4 carbon atoms, NHR represents monoalkyl-, monoalkenyl- or monoalkynyl-amino, NR2 represents dialkyl-, dialkenyl- or dialkynyl-amino.

A first synthesis process suitable for preparing all the compounds of formula (I) in which R2 is a hydrogen atom, regardless of the particular substituents for R1, comprises reacting a methyl or ethyl ester of a 2-formyl-arylacetic acid (II) with a salt of a nitrogen-containing base (III) according to reaction scheme (1):

in which R' represents CH3 or C2H5, X represents a mineral or organic acid and R' and R3 are as defined above.

The 2-formyl-arylacetic esters of formula (II) may be readily prepared by following the procedure described by W. Wislincenus, Berichte 20, 2931(1887), for the preparation of ethyl 2-formylphenylacetate.

The compounds of formula (III) depending on the particular substituent for R1, may be salts of S alkyl-isothiourea (R' = SR), of guanidine (R1 = NH2) of alkylguanidine (R' = NHR or NR2) or of amidine (R1 = alkyl). Such compounds are known and their preparation is fully described in the chemical literature.

Reaction (1) can be conducted in an aprotic solvent in the presence of at least an equimolar amount, in respect of compound (III), of a base and at room temperature.

Suitable catalyst-solvent systems include an alkali metal hydroxide in water or an alkali metal alcoholate in alcohol, e.g. sodium ethylate in ethanol.

A second process of the invention is suitable for preparing compounds of formula (I) in which R1 = SR, regardless of the particular substituent for R2, and is schematically represented by the following reaction schemes (2) and (3):

(I) in which R1=SR in which R, R', R2 and R3 are as defined above.

The compounds of formula (IV) which exist in two tautomeric forms:

are obtained from the 2-formyl-arylacetic esters of formula (I) by reaction with ammonia according to the method described by Decombe, Ann. Chim. 18,81 (1932), for the preparation of the compound of formula (IV) in which R' = C2H5 and R3 = phenyl.

Reaction (2) may be conducted in an aprotic polar solvent, e.g. tetrahydrofuran (THF), at room temperature and in an inert gas atmosphere.

A practical process consists in slowly adding the compound of formula (IV) to a sodium hydride suspension (in a slight excess in respect of the stoichiometric amount) in anhydrous THF, keeping the reaction medium under a nitrogen atmosphere. The mixture is maintained under stirring at room temperature until hydrogen evolution terminates. Carbon sulphide is then added, and successively the alkyl iodide in a slight excess in respect of sodium hydride. After conclusion of the reaction the compound of formula (V) is isolated according to conventional methods and is purified by crystallisation or chromatography.

Reaction (3) may be conducted in an alcoholic solvent at reflux temperature and employing a slight excess of the compound of formula (Vl) (ammonia R2 = H, amine R2 = alkyl, hydrazine R2 = NHR).

This method has proved particularly advantageous for the synthesis of the compounds of formula (I) in which R2 is an amino group.

Some of the compounds of formula (I) may be useful as intermediates for preparing other compounds of formula (I).

For example, the compounds of formula (I) in which R2 is a hydrogen atom can be alkylated in the 3-position by reaction with an alkyl halide according to reaction scheme (4): base (4) (I) + R-X

(I) + HX R2=H R2=R in which R is as defined above and X represents a halogen atom, preferably iodine.

Reaction (4) is conducted in an aprotic polar solvent such as dimethylformamide, dimethylsulphoxide or tetrahydrofuran and in the presence of a base, e.g. sodium hydride.

In a practical process, the reaction is conducted by preparing, in the anhydrous solvent, a suspension of an alkali salt of the starting compound of formula (I) by addition of alkali metal hydride, in a slight excess in respect of the stoichiometric amount, to the solution of the pyrimidin-4-one in the solvent.

The alkylating agent (alkyl iodide) is slowly added to the suspension maintained under vigorous stirring at about OOC. On conclusion of the addition, the temperature is spontaneously allowed to rise to room temperature and the mixture is maintained under stirring until completion of the reaction. The product is separated and purified according to conventional techniques.

The compounds of formula (I) in which the substituent in the 2-position (R1) is an alkylthio group (SR) may serve as starting materials for preparing the compounds of formula (I) substituted in the 2position by an optionally substituted amino group or by a hydrazine group.

The preparation is accomplished by exchanging the thioalkyl group by means of the proper amine according to reaction scheme (5): (5) (I) + NH(R')2

(I) + RSH R1=SR Rt=N(R')2 in which R is as defined above, one or both R' substituents represent hydrogen or an alkyl group of 1 to 4 carbon atoms, or one is H and the other is alkoxy or NH2.

Reaction (5) is particularly useful when the amine is a primary amine (NH2R') or dimethylamine [NH(CH3)2] Reaction (5) can be conducted according to various techniques.

According to one method the reaction is conducted in a solvent, preferably in methyl or ethyl alcohol, at reflux temperature and employing a large excess of anhydrous amine. When employing sterically hindered primary or secondary amine, the reaction should be preferably carried out under an autogenous pressure while operating at a temperature in the range of 90 to 1 500C and maintaining a high concentration of amine in solution.

According to another method, the reaction may be conducted in the absence of solvent, employing the amine in the form of an acetate and in a large excess in respect of the stoichiometric amount, e.g. from 2 to 10 times the stoichiometric amount. The reaction is conducted at a temperature of from 120 to 1600C.

The pyrimidin-4-ones of formula (I) are endowed with a herbicide activity. Their activity possesses useful characteristics which allows their use in the agricultural field in the protection of useful cultivations from infesting weeds. These characteristics may be summarised in a high and versatile herbicide action, having a wide action range and selectivity towards agricultural cultivations.

The herbicide compounds of formula (I) are active both in the pre-emergence and in the postemergence stages, which characteristic, not common among known herbicides, allows the most efficacious treatment to be selected as a function of the various factors which may occur in the agricultural practice. Furthermore, the compounds are active against both monocotyledonous and dicotyledonous infesting plants, this being a further characteristic not common among the known herbicides.

For the practical uses in agriculture, the compounds of formula (I) may be employed as such or in a formulation comprising conventional additives. In such compositions, besides the compound of formula (I) as an active ingredient, inert carriers may be present, which may be either solid or liquid, optionally together with other additives of agrarian use. According to conventional formulative practice, the compositions may be in the form of liquid concentrates, emulsifiable concentrates, suspensions, formulates in powder or in wettable powder or granulated formulates.

If desirable, in order to meet particular and specific requirements, it is possible to add to the compositions other active substances useful in agriculture, e.g. fertilizers, fungicides or other herbicides, e.g. those belonging to the class of chloroacetanilide herbicides.

The amount of the compound of formula (I) to be utilized in the defence of useful cultivations against infesting plants depends on various factors. Such factors include the degree of infestation, the type of treatment (pre-emergence or post-emergence), the relative effectiveness of the specific product of formula (I) employed also as a function of the above-mentioned factors, the type of cultivation to be weeded, the formulation utiiised and climatic and environmental factors. Generally, satisfactory results are obtained by using an amount of compound of formula (I) ranging from 0.5 to 6 kg/ha.

The invention will now be illustrated by the following Examples.

EXAMPLE 1 Preparation of 2-methylthio-5-phenyl-3H-pyrimidin-4-one (Compound No. 1) according to reaction scheme (1)

127 g (0.66 moles) of ethyl 2-formyi-phenylacetate (a) and 91.7 g (0.33 moles) of Smethylisothiourea sulphate (b) were added to a solution of 40 g of NaOH (1 mole) in 660 ml of water maintained under intense stirring at room temperature. The resulting suspension was left under stirring for 8 hours at room temperature.

The reaction mixture was then acidifed with hydrochloric acid. A solid precipitate was obtained, which was separated by filtration, washed with water and dried to yield 126 g of Compound No. 1 as a crystalline solid having a melting point of 249 to 2500C.

IR: meaningful bands at 1 642, 1 550 and 1285-1300 cm~'.

EXAMPLE 2 Preparation of 2-methylthio-3-methyl-5-phenylpyrimidin-4-one (Compound No. 2) according to reaction scheme (4)

A suspension of 95 g (0.43 moles) of Compound No. 1 prepared as described in Example 1 and of 31.3 g (0.65 moles) of sodium hydride (NaH in oil at 50%, in 150 ml of anhydrous dimethylformamide was prepared. The suspension was maintained under stirring in a nitrogen atmosphere at a temperature in the range of from 0 to 50C and 120 g (0.85 moles) of methyl iodide were added dropwise. The temperature was allowed to rise to room temperature and stirring was continued for 6 hours.

The mixture was then diluted with 500 ml of water and cooled to a temperature of O to 50C. A solid precipitated, which was separated by filtration and recrystallised from isopropyl alcohol to yield 56.2 g of Compound No. 2 as a crystalline solid having a melting point of 750C.

IR: meaningful bands at 1660, 1 510, 1420 and 1095 cm-l.

1H-NMR (CDCl3, TMS) a (ppm): 2.6 (s, 3H, S-CH3) 3.6 (s, 3H, N-CH3) 7.2-7.9 (m, 5H, aromatic protons) 8.0 (s, 1 H, CH) (s = singlet, m = multiplet).

EXAMPLE3 Preparation of 2-dimethylamino-3-methyl-5-phenylpyrimidin-4-one (Compound No. 3) according to reaction scheme (5)

254 ml (4.42 mmoles) of glacial acetic acid were added dropwise to 554 ml (8.19 moles) of anhydrous dimethylamine while maintaining a temperature between 0 and C. Dimethylamine in excess was then removed at room temperature.

The dimethylammonium acetate thus obtained was additioned with 127 g (0.544 moles) of 2methylthio-3-methyl-5-phenyl-pyrimidin-4-one (Compound No. 2 obtained as in Example 2).

The mixture was heated for 2.5 hours to 1 650C. After cooling to room temperature, 500 ml of water were added. A solid separated, which was isolated by filtration to yield 114.5 g of Compound No.

3 as a crystalline solid having a melting point of 149 to 1 500 C.

IR: meaningful bands at 1650, 1 550 and 11 50 cm-'.

1H-NMR (CDCI3, TMS) (pom): 2.91 [s, 6H, N(CH3)2] 3.55 (s, 3H, CO-N-CH3), 7.75-7.22 (m, 5H, aromatic protons) 7.82 (s, 1 H, CH) EXAMPLE 4 Preparation of intermediate ethyl 3-(bis-methylthiomethylenea mino(-2-phenyl acrylate (d) according to reaction scheme (2)

5.5 g (0.0287 moles) of ethyl 3-amino-2-phenyl acrylate (c) were added to a suspension of 4.2 g (0.0863 moles) of sodium hydride (in oil at 50%) in 60 ml of anhydrous THF and then 2 ml (0.0328 moles) of carbon disulphide were added dropwise.The mixture was stirred for 1 hour at room temperature, whereafter 3.7 ml (0.06 moles) of methyl iodide were rapidly added, limiting the exothermic heating by means of an external bath of water and ice. After stirring for 8 hours, the solvent was removed by evaporation under low pressure. The residue was collected with ethyl ether, washed with water and dried on anhydrous Na2SO4.

After removal of the solvent under low pressure, an oil was obtained, which was purified by chromatography on silica gel (eluent: n-hexane:ethyl acetate = 9:1).

2.5 g of intermediate (d) as a yellow solid having a melting point of 53 to 550C were obtained.

IR: meaningful bands at 1700, 1595, 1510, 1250 and 1050 cm-l.

1H-NMR (CDCl3, TMS) (ppm) 1.3 (t, 3H, CN3-C H2) 2.33 (s, 6H, SCH3) 4.2 (q, 2H, CH3-CH2) 7-7.5 (m, 5H, aromatic protons) 7.87 (s, 1 H, =CH) (s = singlet, t = triplet, q = quadruplet, m = multiplet).

EXAMPLE 5 Preparation of 2-methylthio-3-amino-5-phenylpyrimidin-4-one (Compound No. 4) according to reaction scheme (3).

A solution of 2 g (0.0067 moles) of ethyl 3-(bis-methylthio-methylene amino)-2-phenyl acrylate (intermediate (d) prepared as in Example 4) and 0.76 ml (0.0156 moles) of hydrated hydrazine in 30 ml of ethanol, was heated at reflux for 6 hours.

After cooling, a solid separated which was isolated by filtration to yield 0.6 g of Compound No. 4 as a crystalline solid having a melting point of 1 98 to 2000C.

IR: meaningful bands at 3300, 3260, 3200, 1680, 1500, 1485 and 1390 cm~'.

EXAMPLE 6 Preparation of 2-dimethylamino-3-amino-5-phenylpyrimidin-4-one (Compound No. 5) according to reaction scheme (5)

A solution of 0.6 g (0.00257 moles) of 2-methylthio-3-amino-5-phenyl-pyrimidin-4-one (Compound No.4 prepared as in Example 5) and 10 ml (0.15 moles) of anhydrous dimethylamine in 2C ml of absolute methanol was heated in a closed tube for 8 hours at 100 C. After cooling, a white solid separated, which was isolated by filtration to yield 0.4 g of Compound No. 5 as a crystalline solid havin a melting point of 178 to 1 790C.

IR: meaningful bands at 3280-3200, 1640, 1 540 and 1410 cm-l.

EXAMPLE 7 Compounds according to the invention which have been prepared are reported in the following Table 1.

The preparation of Compound Nos. 1 to 5 is described in detail in the preceding Examples, while the preparation of the remaining Compound Nos. 6 to 1 7 was performed in accordance with the general techniques described in the preceding Examples.

TABLE 1 Compounds of formula (1)

Compound R R R Melting point (2) 1R (cm-1) (3) No. ( C) 1 SCH3 H C6H5 249-250 1642, 1550, 1300, 1285 2 SCH3 CH3 C6H5 75 1660, 1510, 1420, 1095 3 N(CH3)2 CH3 C6H5 149-150 1650, 1550, 1150 4 SCH3 NH2 C6H5 198-200 3300, 2360, 3200, 1680, 1500, 1485 5 N(CH3)2 NH2 C6H5 178-179 3280, 3200, 1640, 1540, 1410 6 SCH3 C2H5 C6H5 oil 1665, 1500, 1440, 1390, 1300 7 SCH3 @SO-C3H7 C6H5 oil 1667, 1410, 1405, 1370, 1085 8 SCH3 n.C4H9 C6H5 oil 1670, 1500, 1395, 1305 9 NH-CH3 CH3 C6H5 260-262 3380, 1650, 1635, 1527 10 NH-C2H5 CH3 C6H5 151-154 3400, 1640, 1530, 1375 TABLE 1 (Continued)

Compound R R R Melting point (2) 1R (cm-1) (3) No. ( C) 11 NH-C4H9(n) CH3 C6H5 oil 3320, 1650, 1590, 1530 12 NH-C4H9(iso) CH3 C6H5 162-164 3310, 1650, 1550, 1525 13 NH-CH2-CH-CH2 CH3 C6H5 110-112 3270, 1635, 1580, 1520 14 N(CH3)2 C2H5 C6H5 oil 1665, 1530, 1405, 1150 15 NH2 H C6H5 250-dec. (4) 3350, 1690, 1630, 1570 16 NH-CH3 H C6H5 282-284 1650, 1615, 1580, 1370 17 N(CH3)2 H C6H5 215-217 1630, 1610, 1505, 1350 Notes to Table 1 (1) The elemental analysis of all the compounds indicated and H-NMR spectroscopy data are consistent with the assigned structures.

(2) Melting points have not been corrected.

(3) Only the most significant bands are recorded.

(4) dec. = decomposition.

EXAMPLE 8 Determination of the herbicide activity Pots having an upper diameter of 10 cm, a height of 10 cm and containing sandy soil were prepared.

Into each pot, one of the following infesting plants was sown: A - Stellaria media (dicotyledon) B - Ipomea spp (dicotyledon) C - Vigna sinensis (dicotyledon) D-Echinochloa crusgalli (monocotyledon) E -Avena fatua (monocotyledon) Water was added to each pot in an amount sufficient for a good germination of the seeds. The pots were then divided into three groups.

The first group was not treated with any herbicide and was utilized as a comparison.

The second group was treated one day after sowing with a water/acetone dispersion (20% by volume of acetone) of the compounds of the invention at a dosage rate corresponding to 6 kg/ha in the field, in order to evaluate the herbicide activity at the pre-emergence stage.

The third group was treated 15 days after sowing (i.e. when the plants, depending on the species, were already 5 to 10 cm high) with a water/acetone dispersion (20% by volume of acetone) of the compounds of the invention at a dosage rate corresponding to 6 kg/ha in the field, in order to evaluate the herbicide activity at the post-emergence stage.

During the whole test period the pots were kept in a conditioned environment at a temperature in the ranmge 15 to 24 C, at 70% relative humidity, the photoperiod being of 12 hours and the luminous intensity of 2500 lux.

Every two days the pots were uniformly watered in order to secure a humidity degree sufficient for a good development of the plants.

28 days after the treatment with compounds according to the invention, determinations of the plants' vegetative stage were carried out. The herbicide activity of the compounds of the invention was evaluated by comparing the growth and vegetative stage of the treated plants with the non-treated plants and was expressed according to a scale of values from 0 (no herbicide activity, growth like that of the control) to 4 (complete inhibition of the growth or death of the plant), the intermediate values representing intermediate situations of vegetative development The following Table 2 reports significant results.

TABLE 2

Ini I Compound No. ss (see Table 1) Treatment A B C D E 2 post-emergence 4 4 4 4 3 pre-emergence 4 4 4 4 4 3 post-emergence 4 4 4 4 4 post-emergence 4 4 4 5 pre-emergence 4 4 4 3 2 5 post-emergence 4 4 4 4 9 pre-emergence 4 4 4 4 4 9 post-emergence 4 4 4 4

Claims

1. A compound of the formula:

in which: R1 represents an alkyl group having 1 to 4 carbon atoms, an alkylthio group having 1 to 4 carbon atoms, a hydrazine or amino group optionally substituted with one or more groups selected from alkyl having 1 to 4 carbon atoms, alkoxy having 1 to 4 carbon atoms, alkenyl having 2 to 5 carbon atoms or alkynyl having 2 to 5 carbon atoms, R2 represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or an amino group optionally substituted by one or two alkyl groups having 1 to 4 carbon atoms, R3 represents a phenyl group optionally substituted by from one to three substituents selected from halogen atoms, alkyl groups having 1 to 4 carbon atoms, haloalkyl groups having from 1 to 4 carbon atoms and from 1 to 3 halogen atoms, nitro, alkoxycarbonyl, CN, SO2-alkyl having from 1 to 4 carbon atoms, a 2-thienyl or a 2-, 3- 4-pyridyl group.

2. A compound as claimed in Claim 1, in which R3 is phenyl.

3. A compound as claimed in Claim 1 or Claim 2, in which R1 is the methylthio group.

4. 2-methylthio-3-methyl-5-phenyl-pyrimidin-4-one.

5. A compound as claimed in Claim 1 or Claim 2, in which R1 is the dimethylamino group.

6. 2-dimethylamino-3-methyl-5-phenyl-pyrimidin-4-one.

7. 2-dimethylamino-3-amino-5-phenyl-pyrimidin-4-one.

8. A compound as claimed in Claim 1 or Claim 2, in which R1 is an amino group substituted by an alkyl group containing up to 4 carbon atoms.

9. 3-methylamino-3-methyl-5-phenyl-pyrimidin-4-one.

1 0. A compound as claimed in Claim 1 substantially as herein described with reference to any one of the Examples.

11. A process for preparing a compound as claimed in Claim 1, in which the substituent R1 is an alkyl thio group comprising reacting a compound of the formula:

in which R3 is as defined in Claim 1 , and R' represents a methyl or ethyl group, with carbon disulphide, an alkyl iodide in which the alkyl group contains 1 to 4 carbon atoms, and sodium hydride in an anhydrous polar solvent, in an inert gas atmosphere at room temperature, to yield a compound of the formula:

and reacting the compound of formula (V) with a compound of formula: R2-NH2 (Vl) in which R2 is as defined in Claim 1, in an alcoholic solvent and at the reflux temperature of the mixture to yield the desired product.

12. A process for preparing a compound as claimed in Claim 1, in which R2 is hydrogen, which comprises reacting a methyl or ethyl ester of 2-formyl-arylacetic acetic acid with a salt of a nitrogencontaining base according to the reaction scheme:

in which R' represents CH3 or C2H5, X represents a mineral or organic acid and R1 and R3 are as defined in Claim 1.

13. A process as claimed in Claim 11 or Claim 12 substantially as herein described with reference to any one of Examples 1 to 7.

14. A method of combatting infesting plants in agricultural cultivations which comprises distributing to the soil or onto the infesting plant an effective amount of one of more compounds as claimed in Claim 1 either as such or in a suitable composition.

1 5. A method as claimed in Claim 14 when employed in a pre-emergence herbicide treatment.

1 6. A method as claimed in Claim 14 when employed in a post-emergence herbicide treatment.

17. A method as claimed in any one of Claims 14 to 16, in which the compound(s) of formula (I) is applied at a dosage rate of 0.5 to 6 kg/ha.

18. A method as claimed in Claim 14 substantially as herein described with reference to Example 8.

1 9. A herbicide composition containing, as an active ingredient, one or more compounds as claimed in Claim 1 together with an inert carrier.