CA1069329A - Herbicidal compositions and pyrazole derivatives - Google Patents

Abstract

ABSTRACT

The known compounds 1, 3-dimethyl-4 (2-chlorobenyoyl)-5-hydroxypyrazole and 1,3 - dimethyl-4-(4-nitrobenzoyl)-5-hydroxypyrazole and salts and organic acid esters of these two compounds possess herbicidal activity.

Description

l~G9329 ..

~ his invention relates to the use of pyrazole derivatives as herbicides~

f~ According to one feature of the present invention ! there is provided a herbicidal composition including 1, 3-dimethyl-4-(2-chlorobenzoyl)-5~hydroxypyrazole or 1, 3-dimethyl-4-(4-nitrobenzoyl)-5-hydrox~pyrazole or a salt thereof or an organic acid ester thereof, to~ether with an a~riculturally acceptable carrier or diluent.
. .

dccording to a ~urther feature of -this invention there is provided a me-thod for the control of unwanted plants which comprises applying to said plants or the soil 1, 3-dimethyl-4-(2-chlorobenzoyl)-5-hydroxgpyrazole or 1, 3-dimethyl-4-(4-nitrobenzoyl) - 5-hydroxypyrazo e, or a salt o.r an organic acid ester thereofO

.
~he two compounds which form the basis of the present invention are briefly disclosed without an~
indication of their properties in "~he Chemistry of ~eterocyclic Compounds" (Russian origin, 1972, No. 6, 799-804). ~heir respective structures are:

. .

~ti93Z9 Cl C~3~C~ c~

, The compounds ~ay be present in the form o~
tautomers as shown below.
X
H 4~
I . N~
C~3 ~ ~ (lV) _~X ~ I _~X
~ ~ ~ O~I
~N O c ~ ~ C~3 (TI) ~I) (I7~) wherein th~ grollp X is a 2-Ch1QrO or 4~ o substit~e~

;9;~Z9 ~he salts o~ the compounds include the salts with monovalent to trivalent metallic ions such as sodium, po-tassiu~, calcium, magnesium, aluminium, iron, manganese, zinc, nickel, cobalt or copper; the salts with complex ions such as ~Cu(H20)2~ ++, ~Mn(H20)2~ +t~
~ i(H20)4] , ~Al(OEI)~++, ~Zn(O~)~ +, ~Cu(OH) ~+, rCu(N~3)2~ r~co(~2clq2c~2~2)~ ; the salts with ammonium ion such as N+H4, N+H(C~)3, N+H2(C2H5)2, N+H a~(C~3)2' ~H3C~I2cH2oH or N H3cH2c~2oc2H5;
~0 with mineral acids such as hydrochlor-c acid, sulfuric acid, nitric acid or hydrobromic acid.

~he organic acid esters of the compounds in particular include esters which are capable ol releasing the original compounds by decomposition upon application.
Acids -~hich provide such esters include:
; (l) an aliphatic, alicyclic or aromatic carboxy].ic acid of the formv.la R3GoOH
wherein R3 is a straight or branched alkyl group having l to 17 carbon atoms such as a methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, heptyl, undecyl, .
tetradecyl or heptadecyl group;
A- an alkyl group having 1 to 4 carbon ato~s, par-ticularly l to 2 carbon atoms, and substituted with 7 to 4 halogen atoms, such as a chloromethyl, bromomethyl, iodomethyl, 2, 2, 2-trichloroethyl ~ 2, 2-dibromoe-thyl,

2, 2, 2-tribromoethyl, 2-iodoethyl, 2, 2-di iodoethyl, or l, 2, 2-tetrafluoroet~yl group;
.

a s-traight or br~nched alkenyl group having 2 -10~9;~;~9 ].7 carbon atoms, particularly 3 - 5 carbon atoms, such : as a vinyl, isopropenyl, propenyl, l-methyl-2-properlyl, ~; 2-methyl-2-propenyl, 2 butenyl, 1-methyl-2-butenyl, 2-methyl-2-butenyl, 3-butenyl, 1-methyl-3-butenyl, ~'! 5 2-methyl-3-butenyl, 2-heptenyl, 2-undecenyl, 2-tetra-J decelyl, 2-heptadecenyl, 3-heptadecenyl or 8, ll-hepta-decadienyl group;

~ a 5- to 7-membered cycloalkyl group such as a ¦ . cyclopentyl, cyclohexyl or cycloheptyl group;

i 10 a phenyl group which may have 1 to 3 substituents ii selected from a nitro group, a halogen atom and an alkyl group of 1 to 4 carbon atoms, particularly 1 carbon atom, such as a phenyl, 2-nitrophenyl, 4-nitrophenyl, 2-tolyl, ? 3-tolyl~ 4-tolyl~ 2-ChlrOPhenyl, 4-chlorophenyl, 2-bromophenyl, 4-bromophenyl,. 2, 4-dichlorophenyl, 2, 4 6-trichlorophenyl or 2-chloro-4-nitrophenyl group;
.i, . a phenylalkyl group which may have 1 - 3 sub-stituents selected from nitro groups and halogen atoms 1 in the phenyl moiety and which has 1 - 5 carbon atoms, j 20 particularly 1 or 2 carbon atoms, in the alkyl moiety, such as a benzyl, phenethyl, phenylpropyl, phenylbutyl, phenylpentyl, 4-nitrobenzy], 4-nitro-phenethyl, 2-chloro-benzyl, 4-chlorophenethyl, 2-bromobenzyl, 4-bromopheneth

3-(2, 4-dichlorophenyl)propyl or 4-(2, 4, 6-trichlorG-phenyl)butyl group;

a styryl group;

Li:_ or a phenoxyalkyl group whicll may have 1. or 2 substituents selec-ted from halogeIl atoms and meth-bTl groups in the phenyl moiety and has 1 to 3 carbon atoms in the alkyl moie-ty;

(2) a carbamic acid of the formula R
~N~O.O:~

wherein R4 and R5 individually represent a straight or branched alkyl group having 1 - 4 carbon atoms such as methyl~ ethyl, n-propyl, isopropyl, n-butyl or isobutyl group or R4 and R5 jointly represent pentamethylene group;

.(3) a sulfonic acid of the formul~.
R6 - ~2 ~ OH
wherein R6 represents a straight or branched alkyl group having 1 - 4 carbon atoms suc'n as a methyl, ethyl, n-propyl, isopropyl, n-butyl or isobutyl grollp;

an alkyl group substituted with 1 - 3 halogen atoms and having 1 - 3 carbon atoms, particulaIl.y 1 or 2 carbon atoms such as a chloromethyl, bromome~hyl~
iodomethyl, trifluoromethyl, l-chioroeth.yl~ l-bromoethyl or 17 l-dickloroethyl group;

or a phenyl group which may be slibstitu.ted by ~
straight or branched alk~l of 1 - 12 carbon ato,Tls, par-ticularly~ 1 or 2, carbon atoms, e~g., a methyl, ethyl.

;9329 n~-propyl, isopropyl, n-butyl, isobutyl or dodecyl group or by a halogen atom, e.g., chlorine;

(4) a diester of thiophosphoric acid of the formula R7~

wherein the substituents X7 may be the same or different and represen-t a straight vr branched lower alkyl group having 1 - 4 carbon atoms such as a methyl, ethyl,n~
propyl, isopropyl, n-butyl or isobutyl group;
i' ,

(5) a monoester of carbonic or thiocarbonic acid of the formula O
R8 _ y _ ~ - OE
wherein R8 represents a straigkt or branched lower alkyl group having 1 - 4 carbon atoms such as a me-thyl, ethyl, - n-propyl, isopropyl, n-butyl, isobutyl or s-butyl group;

a phenyl group;

or a phenylalkyl group which may have 1 - 3 sub-stituents selected from nitro groups and halogen atoms in the phenyl moiety and which has 1 or 2 carbon atoms in the alkyl moiety, such as a benzyl, phenethyl, 4-nitrobenzyl, 2-ch]orobenzyl, 4-chlorophenethyl, 2-bromo-benzyl, 2, 4--dichlorobenzyl or 2, 4, 5-trichlorobenzyl group;
, a pheny-l group;

3;~

or a phcnylalkyl ~rcup which ma-y have ] - , sub-stituents selected from n~tro groups ind halogan atc~
in the phenyl moiety and which has 1 or 2 carbon atoms in the alkyl moiety, such as a benzyl, phenethyl, ~-nitrobenzyl, 2-chlorobenzyl, 4~chloro-phenethyl, 2-bromobenzyl, 2, 4-dichlorcbenzyl or 2, 4~ 5-tri^hlolo-I benzyl group;

and Y represents an oxygen atom ~'' , .
~ (6)a dibasic acid of the for~ula , : ' O r' O-HO - C -- R9 - C -~ -0 ,, m wherein m is O or l;

R9 is an alkylene group having 1 to 10 carbon atoms such as a methylene 9 ethylene, trimethylene, tetra-methylene, octa-methylene or decamethylene group; a vinylene group; an o-, m, or p-phenylene group; cr a carbon-carbon bond; and .

(7) a 3-oxo-4-isoxazolin-2-~1 carboxylic acid of the formula ~10 O

.~ ~ N _ CO.OH

wherein R is hydrogen at-om or a haiogen atom.

10~i9329 ~re:EeIred acicls lor es-teri.f;cation include the carboxylic acid having th.e above formula wherein R3 is ~ a halogenoalkyl group having 1-2 carbon atoms and 1.-4 '. halogen atoms, an alkenyl group having 3-5 carbon atoms, a 5- or 6-membered cycloalkyl group, a phenyl group, optionally having 1-3 substituents selected from nitro groups, methyl groups and halogen atoms; a phenylalkyl group having 1 or 2 carbon atoms in the alkyl moiety and optionally having 1-3 substituents selected from - nitro groups and halogen atoms in the phenyl moiety; or a phenoxyal~yl gro~p having 1 or 2 carbon atoms in the alkyl moiety and optionally hav1ng 1 or 2 substituents j selected from halogen atoms and nitro groups; the sul-¦ fonic acids having the above formula wherein R6 is an ¦ 15 alkyl group of 1 - 3 carbon atoms, a halogenoalkyl group j of ]. or 2 carbon atoms and 1-3 halogen atoms or a phenyl ¦ . group optionally having Cl or C2 alk~l or halogen sub-stituents, and the dibasic acids having the above formula ~- wherein R is an alkylene group of 1 3 carbon ato~s anl m is zero or 1.

Compounds which may be employed in the present herbicidal compositions are illustratively exemplifiedi as hereunder (the Compound Nc. will be referred to again hereinbelow).

25 Compound ~o. Compound.
].......... 1, 3-dimethyl-4-(2-chlorobenzoyl)-5-hydrox~pyrazole 2. 1~ 3-dimethyl-'~-(4--nitrobenzoyl)-5-hydroxypyrazole C~_~. CoDlpound 3. 1, 3-dimethyl-4-(2 chlorobenzoyl)-5~
metho~rcarbonyl-oxypyrazole 4. 1, 3-dimethyl-4-(2~chlorobenzoyl)-5-(~, N-dimethyl-carbamorlo~y)pyrazo]e 5. 1, ~-dimethyl-4-(2-chlorobenzoyl)-7-acetoxypyrazole

6. 0, O-diethyl 0-/~, 3-dimethyl-4-(2-chlorobenzoyl)-5-pyrazo]yl7 phosphoro ~hioate

7. 1, 3-dimethyl-4-(2-chlorobenzoyl)-5-pyrazolyl methanesulfonate ~he compounds 1, 3-dimethyl-4-(2-chlorobenæoyl)-5-hydroxypyraæole or 1, 3-dimethyl-4-(4-nitrobenzoyl)--5-hydroxypyrazole, salts thereof and organic acid esters thereof can be readily prepared, for example, b~ the following processes.

PROC~SS A
1, ~-dimethyl-5-pyrazolone is reacted with the acyl halides (~), in the presence of an acid-binding agent as in the following equation~

+ llal-CO { ~ ~ {~

G~3 (V~ rIII) (VI) .
wierein the group X is a 2~chloro or 4-nitxo ~su~:stitueri-t~

10~;93Z9 ~he abo~e reac~ion may be preferably effected in the presence of a solvent. ~s tne solvent employable, any solvent may be used without particular limitation ~ if it would not participate in the reaction and there ¦ 5 may be mentioned, for instance~ ethers or mixtures thereof I such as diethyl ether, tetrahydrofuran, diethylether/
dioxan, tetrahydrofuran/dioxan; halogenated hydrocarbons such as dichloromethane, carbon tetrachloride; second-I ary or tertiary alcohols such as isopropanol, isobutanol, ¦ lO t-butanol; and the like. In particular, ethers and ! secondary alcohols are preferably employed. ~he reaction ¦ i is also preferably effected in the presence of a catalyst.

The catalyst may be an alkaline earth metal hydroxide such as calcium hydroxide. In particular, calcium hydroxide is preferabl~ used~ ~he amount of a catalyst to be employed is preferably 1 - 2 moles per mole of the starting material (VII). ~he reaction temperature is not particularly critical and the reaction may be e~fected at room temperature or a reflux temperature of the solvent employed. Particularly, the reaction may be preferably conducted at a reflux tem~erature of the solvent em-ployed. ~he reaction period Tnay vary mainly upon the reaction temperature and the sort of the reagent em-ployed, but it is usually within a range of about l to lO hours. ~he acyl halides which may be employed in the above-mentioned reac-tion may be, for example, acid chlorides or acid bromides.

After completion of the reaction, the desired co~-pol~lds may be recovered from the reaction mixture r,y a ~ O ~ 3 Z9 conventional method. ~`he startirlg material pyrazolor.e may be prepared acco.rding to the me-thod disclosed in : Chemische Berichte, 43, 2105 (1910)~

PROCESS
The compounds 1, 3-dimethyl-4-(2-chlorobenzoyl)~5-: h~droxypyrazole or 1, 3-dimethyl-4-(4-nitrobenzoyl)-5-hydroxy-pyrazo]e are obtainable by heating the corres-ponding 5-halogenopyrazole derivatives (IX) with alkal-metal hydro~ides such as sodium hydroxide or potaSsivrn hydroxide.

C~ ~ C~

. ~ Hal N
CH3 aLkali metalhydroxide : c~

(L~) . (I) whexein the grou~ ~ is a 2-chloro or 4-nitro substituen-t;~
, In the above-mentioned reacti.on~ water may be employed as a solvent or a mixtu-re of water with an organic solvent ma-~ be used and, as such organic sGlven-ts5 ma~ be menti.oned, ~or example, etners such as tetra~
hydrofuraIl or dioxan and alcohols such as methanol or etn~nol~ Tlle reaction tem~erature is not particulally c~iti.cal anl the re~ction may be effected at room tem~er~
ature or a reflux tern~era~ul~ o~ thC s~vent and 7 10~93;~

particulariy, it can be preferably effected at a teLperature around the reflux temperature of the ~solvent. The reaction period depends mainly upon :the reactîon temperature and the reagent emp]oyed, ~5 but is usually about 1 to 10 hours. ~he starting imaterial 5-halogenopyrazories are prepared accoxding to the method disclosed in Chemische Berichte, 50, 737 (1917) and United Kingdom Patent Specification ~a. 1 268 6080 ¦ 10 PROCESS C
The organic acid esters of the compounds 1, 3-dimethyl-4-(2-chlorobenzoyl)-5-hydroxypyrazole or 1, 3-dimethyl-4-(4--nitrobenzoyl)-5-hydroxypyrazole are easily prepared by reacting the compounds with an acylating agent as shown in the follo~Jing scheme.

¢ co~

acylating agent , (I) (X) wherein the group X is a 2-chloro or 4-nitro substituent ` 10~93Z9 The above-mentioned reaction may be preferably effected in the presence of a solvent. As the solvent ~ which may be employed, there is no particular limitation ¦ on a solvent if it does not participate-in the present reaction and, for example, ethers or mixtures thereof ~ such as diethyl ether, tetrahydrofuran, diethyl ether/
I dioxane, tetrahydrofuran dioxan; arromatic hydrocarbons such as benzene, toluene, xylene; halogenated hydro-carbons such as dichloromethane, chloroform, carbon tetrachloride and, in particular, the aromatic hydro-carbons and ethers are preferably employed. ~he acylat1ng agents which may be employed are acyl halides such as acid chlorides and acid bromides; carbox~lic I acids in the presence of carbodiimides such as 1, 3-¦ 15 dichlorohexylcarbodiimide; or acid anhydrides. Acid ! chlorides are preferable and the reaction is effected in the presence of an acid binding agent ~he reacticn temperature is not particularly critical and the re-action is usually conducted at room temperature and ; 20 the reagent used but is usually about 1 - 24 hours.

.
PROCESS D
~ ~he salts of 1, 3-dimethyl-4-(2-chlorobenzoyl)-5-hydroxypyrazole or lt 3-dimethyl-4-(4-nitrobenzoyl)-5-hydrOxypyrazole with a metallic, a complex ion and a a~monium ion are formed by adjusting a p~ of a solution of the compound to not less than about 3 in the pre-sence of a cation. As the solvent which may be used for the forma-tion of the above-mentioned salts, there is no particular limitation and, for instance, are 10~93;~9 prefera-oly employed water; alcolaols such as methanol or ethanol; ethers such ?~S tetrahydrofuran or dioxan;
aromatlc hydrocarbons such as benzene; halogenated hydrocarbons such as dichloromethane or chloroform or mixtures of these organic solvents with water. Depending upon changes in cation valency and solvent, various solts having diff'erent coordinate proportions of' the compound and the cation of 1~ 2, 1:3 and the like are formed.

PROC~S
The salts of 1, ~-dime-th~1-4-(2-chlorobenzoyl ? - 5-hydroxyp~razole or 1, 3-dimethyl-4--(4-nitrobenzoyl)- -'nydroxypyrazole with a minerai acid are easily prepared b~ mixirg the compound with the mineral acid in a suitable solvent. As the solvent which may be used, there is rlo particular limitation and there may 'oe preferably men-tioned, for instance, water; alcohols such as met'nanol or ethanol; ethers such as tetrahydrofuran or dioxane;
a~omatic hydrocarbons such as benzene; halogellated hydrocarbons such as dichloromethane or chloroform, or mixtures of these orga~lic solvent and water. In ge~ieral, the salts with the mineral acid are f'ormed at a p~ not more than about 30 ~he compounds 1, 3~dimethyl-4--(2-chlorobenzo~i~l)-5-hydroxypyrazole or 1, 3-dimethyl-4-(4-nitrob~nzoyl)-5-hydro~-pyrazole and salts and organic acid esters thereof have been ~ound to possess a selectjve toxicit~
to weeds.

~0 ~9 3 ~ 9 In a paddy field, pa-rticula:rl~ potent herbi.-. cid~l effects can be obtained agains-~; perelmia]. weeds such as those of the family C~peraceae, for example, "Hotarui" (Scirpus hotaru:L Ohwi),flats-`age and the li-~e 5 and those of the family Alismataceae, for example, arrowhead (Qmodaka) and arrowhead (Urikawa), which are difficult to control by conventional herbicides, by pre-and post-emergence treatment in soil without any harmful effect on newly-transplanted rice plants and growing rice plants. ~urthermore, broad-leaved weeds such as those of the family G~amineae, for example, barnyardgrass, panic grass and the like, weeds of the family Scrophulariaceae, for example, false pimpernel, "Murasakisagigoke" (Mazus miquelii ~,a~ino), "Abunome"
(~ junceum Xamilt) and the like, weeds of the family Cruciferae, for example, wavy bittercress, marsh yellow cress, "Mizutagarashi" (Cardamine lyrate ~un~) and the like~ weeds of the family Lythraeeae, for examp]e, toot'ncup, "Mizumatsuba" (Rotala m icana ChamO) and the like, and weeds of the family ~E___tae, for example, ragwort, 4merican false daisy and the like.

.
~` In a dry paddy field, pre- and post-emergence treatment in soil has shown particularly potent effect against weeds of the family Caryophyllaecae, for example, white-bird1s-eye, bog stichwort, mouse-ear chickweed, pearlwort and the like and, furthermore, weeds of the family Portulacacea, for example, common pursl.ane and the like, weeds of the family Amaran-'h~ceae, for example 7 barnyardg~ass, rough pigweed and the like, 10~9;~9 weeds of the family Chenopodi(lc~e-le, for exarnple, "Akaæa" (Cheno~odium album ~.), white goosc-foot, "Koakaza" (C. ficifolium Smith) and the like, weeds of the family Commelinaeceae, for example, Asatic dayflower and the like, weeds of the family I!abia-ta~, for example, henbit, "Kiransol' (Ajuga decumberls Thurlb.) and the like, weeds of the family Oxalidaceae7 for i example~ creeping wood sorrel, violet wood sorrel and the like, weeds of the family Leguminosae, for example, "Nekohagi" (_espedeza pilos Sieb et Zucc.), hai-ry vetch, common vetch and the like, and weeds of -the amily 3uphorbiaecaea, for example, Virginia cooper-leaf, milk purslane and the like can be effectively controlled. Narrow leaved ~eeds, in particular, t-hose of the family Cyperaceae, such as chufa and the li~e are effectively controlled and those of the family Gramineae such as wheatgrass, manna-grass~ green panicum, "AkinoenokorGgusa" (Setaria Faberi Eerrma~n), foxtail and the like are also effectively controlled.
On the other hand, crops such as rice plantsS cereals, sugar beets, pulses, cotton plants, radishes, tomatces, ca~rots, Chinese cabbages, lettuces and the like do not suffer from phytotoxicity.

Additionally, the compounds are effective as herbicides in other applications, e r g. in a fruit-garden, an ~nplanted field or a forest.

The compounds in this invention may be for~u~-lated for use to the preparations commonly emplo~ed as a herbicide, for exa~ple, powdery dusbs~ coarse dusts, 10~93Z9 fi.ne granules, gra.~ules, wetta~le powd~rs, e~u:lsifiable concentrates, aqueous liquicls, aqueous so].utions, oil suspensions and so on, with admixture cf a carrier or i diluent and, if required, other auxiliary agents. The carrier as used herein means a synthetic or natural, i inorganic or organic substance that can assi.st an active compound to reach the portion to be treated, and make i~
easy to store, transport or handle the active compound for admixing in. the herbicidal composition.

As suitable solid carriers may be mentioned iIl-organic substances such as clays (which may be repre-sented by Kaolinite, Montmorillonite or Arrapulgite), talc, mica, pyrophyllite, pumice, vermiculite, gypsum, calcium carbonate, dolomite, diatomaceous earth, magnesium carbonate, apatite, zeolite, silicic anhydride, and synthetic calcium silicate, vegetable organic sub-stances such as soy-bean meal, tobacco powderj walnut powder, wheat flour, wood meal, starch, and crystalline cellulose; synthetic or na-tural high polymer compourds such as cumarone resin, petroleum resin, alkyd resin, polyvinyl chlori.de, polyalkaylene glycol, ketone resi.n~
ester gum, copal gum, and dammar gum; waxes such as carnauba wax or beeswax; or urea.

As suitable liquid carriers may be mentioned paraffin or naphthene hydrocarbons such as kerosene, mineral oil, spin-dle oil or white oil; aromatic hyd~o-carbons such as benzelle, toluene, xylene, ethylbenzene, cumene, or methylnaphthalene; chlorinated hydrocarbons such as carbon tetrachloride, chloroform, trichloro---17- .

~0~;932~

eth-ylelle, monochlorobenzene or o-chlorotoluene;
~thers such as dioxan or tetrahydrofuran; ketones such.as acetone, methylethylketone, dilsobutylketone, cyclohexanone, acetophenone, or isophorone; esters such as ether acetate, amyl acetate, ethylene glycol : acetate, diethylene glycol acetate, dibu-tyl maleate ; or diethyl succinate; alcohols such as methanol, n-hexanol, ethylene glycol, diethylene glycol, cyclo-hexanol or benzyl alcoholi ether alcohols such as ethylene glycol ethyl ether, or diethylene ~lycol but~l ether; polar aprotic solvents such as dimethylforma-~ide or dimethyl sulfoxide; or water.

~s surface active agents, for example for emulsi-fication, dispersion, wetting, spreading, binding, con-trolled dlsintegration, stabilizing the active ingredient, improving fluidity or rust proofing one may use any non-ionic~ anionic, cationic or amphoteric surfactant, but non-ionic and/or anionic agents are preferred. As suitable non-ionic s~rface agents may ~ mentioned, for example, polymerization adducts of ethylene oxide to higher alcohols such &S lauryl alcohol, stearyl alcohol, ..
oleyl alcohol and the like, polymerization adducts of ethylene oxide to alkyl phenols such as isooctyl phenol~
nonyl phenol and the like, polymerization adducts of . 25 ethylene oxide to alkyl naphthols such as butylnaphthol, octyl naphthol and the like, polymerization ~dducts of ethylene oxide to hi~her fatty acids suck ss palmitic acid, stearic acid, oleic acid and the like, polymerization adducts of ethylene oxide to ~ono-3 ~r di-alkyl phosphoric aci.ds such as stearyl phosphoric --18- .

10f~9329 acid, dilauryl phosphoric acid a~d the li.ke, po]y-merization, adducts of ethylene oxide to amines such as dodecyl amine~ stearic acid amide and the like, polymerization adducts of ethylene oxide to 'higher fatty acid esters of polyhydric alcohols such as sor.bi-tan and said fatty acid esters, polyrnerization adducts of ethylene oxide to propylene oxide and so on~ as suitable anionic surface active agents may be men--tioned, for example, alkyl sulfate salts such as sodi~ n lauryl sulfate, oleyl sulfate amine salt and the like, alkyl sulfonate salts such as sodium dioctyl sulfG- -succinate, sodium 2-eth~lhexene sulfonate and the like, aryl sulfonate salts such as sodium isopropylnaphthalene sulfonate, sodium methylene-bisnaphthal~ne sulfona~e, sodium ligninsulfonate,. sodium dodecylbenzen.e sulfo:~ate and the like.

Moreo~er~ t'ne herbicidal compositions of this invention may be used in combination with high mo].ecular compounds or other au~iliary agents such as casein, gelatin~ albumin, glue, sodium alginate, carboxy- ' methyl cellulose, methyl cellulose, hydroxye-t'nyl cellu-lose, polyvinyl alcohol an~ the like for improved properties alld increased biological effects thereof'.

~he above-mentioned carriers and various aux:iliary agents may be used alone or in a.ny desired combination dependirg on the type of preparation, the a~plication and other factors.

In general, the herbicidal c:o~position of this ~19- -.

10~i9325~

invention may corltain the ac-tive compound in an amount of 0.1 - 9~/o by weight, based upon the com~osition.

~ Dusts may convenien-tly contain, for example, 1 I to 25,h by weight of the active compound, the remainder ' 5 being a solid carrier.

¦ Wettable powders may conveniently contain, for ¦ example, 25 - ~0% by weight of the active compound, the remainder being a solid carrier and a dispersinu and wetting ag~ent, if required, together with a protec-tive colloidal agent, a thixotroplc agent, an anti-foaming agent and the like.

Granules may conveniently contain 1 - 35% by weight of the active compo~nd, a major portion of the remainder being a solid carrier. ~he active ¢ompound is homogeneously admixed with the solid carrier or - adsorbed onto the carriér surface and the size of a granule is about 0.2 - 1.5 mm.

- .
I Emulsifiable concentrates may conveniently contain, for example, 5 - 50% by weight of the active compound and about 5 - 20% by weight of an emulsifying agent 7 the remainder being a liquid carrier, together ; with a corrosive inhibitor if requiredr ~he herbicidal compositions of this invention, which are formulated into various types of preparations as above, may be applied in a paddy or dry field at 10 -10~93Z9 2000 ~, preferably 100 - 5~0 g, of th~ active ingredient per 10 acres for pre- or post-emer~ence soil treatment to control weeds effectively. Also, in order to con-t~ol weeds unselectively in unplanted areas such as : roads, grounds, house sites, railways and the like, a~
applicatio~ rate of the active ingredient of 200 - 4000 g per 10 are can be effective.
, The nerbicidal compositions of this invention may preferably be blended with other herbicides for broa~l.er herbicidal spectra and, in some cases, a synerg~s'ic effect may be observed. As examples o~ such other her-bicides may be mentioned, lor instance, triazine type herbicides such as 2-methylthio-4, 6-bisethylamiro--1, 3~
5-triazine; 2-chloro-4, 6-bisethylamino-1, 3, 5-triazi.ne;
2-methoxy-4-ethylamino-6-isopropylamino-s- triazine;
2-methylthio-4, 6-bis-(isopropylamino)-s- triazine; and 2-methylthio--4-ethylami~o-5-isopropylamino-s- tr-a~ine 2, 4-dichlorophenox-~yacetic acid and its methy~ ethyl or buty ester; 2-^hloro-4-met~ylphanoxyaceti~ ~cid; pneno~y ~: type herbicides such as 4-chloro-2-methyl-phenoxyacetic acid or ethyl 2-methyl-4-chloropheno~ybutyrate, di.phenyi ether type herbicides such as 2, 4, 6~Ttrichloropheryl-4'-nitrophenyl ether; 2, 4-dichlorophenyl-4'nitrophenvi ether; or 3, 5-dimethylphenyl-4l-nitrophenvvTl ether, - urea type herbicides such as 3-(3, 4-dîchlorophenyl~-l-methoxy-l-methylurea; 3--(3, 4-dichlorophen~T].)- 1, 1-dimethylurea; or 3-(4-chlorophenyl)-1, l-d r~ethylurea, carbamate type herbicides svch as 3-methoxycalbc)nyl-a~inophenyl-N-(3-methylphenyl) carbamate; isopropyl ,.. ,.. ~,~,............................. . .
- ~ . ..

N-(3~chlorophe~yl) carbamate; or methyl N-(3,4-di.chlorophenyl) carbamate, uracil type herbi.cides sueh as 5-bromo-3-s-butyl--6-methyluracil; or 1-cyelohexyl-3, 5-propyleneuracil; thiolcarbamate type her.bicides sueh as S-(4-chlorobenzyl) N, ~-diethylthiolearbamate; S-ethyl N-eyelohexyl-N-ethylthiol-earbamate; S-ethyl-hexahydro-lH-azepine-l-earbothioate; or S-ethyl-N, N-di-n-propylthioearbamate;
pyridinium salt type herbieides sueh as 1, 1'-dimethyl-4, 4'-bisp-yridinium dichloride; phosphorus type herbicides - such as N-(phosphonomethyl)-glyeineto~jc~/~C-trifllloro-2, 6-dinitro-N, N-dipropyl-p-toluidine; 4-(methylsulfony].) 2 - 6-dinitro-N-N-dipropylaniline; acid anilide type herbieides sueh as 2-ehloro-2', 6'-diethyl-N-~buto~J-methyl)eeetanilide; 2-chloro-2', 5'-diethy]-N~(methox~-methyl)aeetanilide; or 3, 4-diehloroprop;.onanilide;
5-t-butyl-3-(2, 4-dichloro-5-isopropoxyphenyl)-1, 3, 4-oxadiazolin-2-one; 2-@ -isopropyl, N-(4-chloro-phenyl)-earbamoy ~ -4-ehloro-5-methyl-4-isoxazolin-3-one, 3-isopropylbenzo-2-thia-1, 3-diazinone(4) 2, 2-dioxide or 3-(2-methylphenoxy)-pyridazine, but they are not eritieal.

~he herbicidal eompositi.ons of this invention may also be applied with admixture of plan-t growth regulators such as sodium naphthyl acetate; 1, 2-dihydropyridazine-3, 6-clione; or gibberel]ins, fungi.-eicies sueh as methyl l-(butylcarbamoyl)-2-benzimid-azoleear~amate; 1, 2-bis(3--metho~ycarbonyl-2--thloureido) benzene; 3-hyd.ro.~y-5-mel;hylisoxazole; N-2, 3-dichlorophenyl-tet~achlorophib;-l].lmic acid; 5-me-thyl s-tJ.Iiazc)l~-(3~ 4-b)benz-thia~ole; 0, 0-d.iisopropyl-S-. .

10f~93Z9 benzylphosphorothioate; pentachloronjtrobenzene;
Kasuga~ycin; brasticidin S; or 4, 5, 6, 7-tetra-chlorophthalide; insecticides such as 0, 0-dieth~l 0-(2-isopropyl-4-methyl-6-pyrimidillyl)phosphorothioate;
0, 0-diethyl S-2- ~ ethylthio)ethyl7phosphorodithioa.te;
l-naphthyl N-methylcarbamate; 0, 0-dimeth,~l 0-(3-methyl--4-nitropherlyl)-thiophosphate; 0, 0-dimethyl S-(~-methylcarbamoylmethyl)-phosphorodithioa~e; S-methyl-_~~ methylcarbamoyl)oxyl-thioacetimidate;
0, 0-dimethyl S-(N-methyl-~-for~ylcarbamoyl-me,thyl)-phosphorodiothioate; 0, 0-dimethyl S--2-(ethylt'ni.7) ethyl-phosphorodithioate; 0, 0-diethyl S-2 ~ ethylthio) ethy ~ phosphorodithioate; 0, 0-diethyl S--2 r(ethylthio~
ethyl7-phosphorodithioate; or 0, 0-dimethyl-1-hydroxy-2, 2, 2-trichloræthylphosphcnate or fertilizers"

f ,. The preparation of compounds of the i.nvention and herbicidal compositions containing them will ~e more fully illustrated by way of the following examples.
' l? 3 Dimeth~l 4-(4-nitrobenzoyl)-5-hydrox~yrazole In 22 ml of d~ dioxan was dissolved 2.24 g of l, 3-dimethyl-5-pyrazolone and then 2.96 g of pot;assium hydroxide added thereto. 3.71 g of ~-nitrobenzoyl chloride was added dropwise thereto w'~ile stirring at room temperature. Aft-er completion of the dropwise addition, the mixture was lleated under .

,, : .

10t;93Z9 reflux for 1 hour. After complction of the reactiorl, ' the reaction mixture was allowed to cool and then 40 ml ~ of a 2N hydrochloric acid solution was added thereto.
I Crystalline material thus separated was recovered by t 5 filtration and washed with water to give 4.38 g of crude ~ crystals. ~'his product was re-crystallized from¦ methanol to give 3.62 g of the desired product as pale yellow prisms ha~ing a melting point of 234 - 235C.
7 Yield 69.3%.

j 10 A~alysis:
77 Calculated for CH ~ 04 : C, 55.17; H, 4.24; N, 16.09%
¦ ~ound C, 55~]7; H, 4.14; N.16.0~' Following the procedure as in the above ~xa7ple 1 1, 3-dimethyl-4-~(2-chlorobenzoyl)-5-hydroxypyrazole was prepared. It had a melting point of 154 - ]55~C.

I _A~L~ 2 1, 3-Dim~ =4=(2-chlorobenzo~l)-5-acetox~p~yrazole 1~ In a mixture of 20 ml of benzene and 0O51 g of ! 20 triethylamine was dissGlved 1.25 g of 1, 3-dimethyl-4-(2-chlorobenzoyl)-5--hydroxypyrazole and 0.4 g of acetyl chloride was added dropwise at room temperature with stirring. After cGmpletion of the reac-tion, water was added to the reaction ~ixture to dissolve the salts and an organic layer separated. 'lhe organic layer was dried over anhydrous sodium sulfate and the solvent distilled off. ~he resulting oily substance was re-10~;~3'Z9 crystallised from n-hexane to give crurle crystalline substance which was recryst-allized from methanol to give l.20 g of the desired product as colourle~s prisms melting at 78 - 79C. Yield 82. 2%.
5 Analysis:
Calcu1ated for C14Hl~C1~23 C, 57.45; H~ 4-48; lT~ 9-57i Cl, 12.11%
Found C, 57.50; H, 4.45; N5 9.~1;
Cl, 12.23%
IR spectrum (liquid paraffin) ~ 1 7~3 C=O
, ~ollowing the procedures of the above-mentionecL
Example 2? the following compounds were prepared:
1, 3-dimethyl-4-(2-chlorobenzoylj-5-(N, ~-dimethyl-&arbamoyloxy)-pyrazole m.p. 115 - 116C.
~, 3-dimetkyl-4-(4-nitrobenzoyl~-~;-acetoxypyrazole mlp. 179 - 1~0~C
EXAMP~E _3 1, 3-Dimethyl-4-(2-chlorobenzoyl)-5-pv~azol~l-me-thanesulfonate In a mixture of 0.1 g of trie-thylamine and 5 ml of dry benzene was dissolved 0~25 g of 1, 3-dimet'rrJl~
(2-chlorobenzoyl)~5-hydrox~-yrazole and then Orl g OI
methanesulfonyl chloride was added dropwise at room temperature with stirring. After completion of the dropwise addi-tion, the resulting mixture was stirred at room temperature for i2 hours~ After completion of the reaction, 10 ml of water was added to the reactl Ol?.
mixture and organic layer separated. ~he organic layer was dried over anhydrous sodium sulfa~te and thc- sol~ent iO~;93Z9 distilled off. '~he resu]ting residue was recrys-talliæed from n-hexane to give the desired product melting at 97-98C.

.

~XAMPLE 4 1~ 3-Dimethyl-4-(2-chlorobenzoyl)-5-metnoxycarbonylox-p~razole In a mixture of 20 ml of dry benzene and 0 4 28 g of triethylamine was dissolved 0.63 g of 1, 3-dimethyl-4-(2-chlorobenzoyl)-5-hydroxpyrazole and then 0.26 of methyl chlorocarbonate was added dropwise at room temperabure with stirring. After ~ompletion of the dropwise addition, the mixture was stirred at room temperature for 1 hour. After completion of the re-action, the reaction mixture was allowed to stand for 12 hours and then 30 ml of water was added thereto.
A benzene layer separated and the aqueous layer was extracted with benzene. ~he benzene layer and the benzene ex-tract were combined, and the mixture washed with water and dried over anh-ydrous sodium sulfate.
~hen, the solvent was distilled off and the resulting residue was recrystallized from a small amount of n-hexane to give the desired product as crystals melting at 69-70C.

EXAMP~; 5 0, 0-Diethyl 0- ~ , 3-dimethyl-4-(2-chlorobenzoyl)-5-~_azol ~ phos-e~ te __ A mixture of 1.0 g of 4--(2-chlorobenzoyl)-1, 3-dimethyl-5-hydrox~pyrazole, 20 ml of benzene, 0.433 g 3C f triethylamine and 0.~1 g of 0, 0-diethylthio---2~-` ~0~329 pllospho~ic chloride was he~ed unde~ reflux with ~,t;irri~l~ for ~5 hours. ~fter coin~letion of the reac~ion, the reaction mi~ure wa~ allowe~ to cool and water was added to dissolve salts. ~h~ or~,anic layer was separated, wasned with water, dri~d o~ier anhydrous sodiwn sulfate and the ~olvent was distille~
of~. The resulting oily substance was column-chroma~o-graphed over 10 g of silica gel and then recr~s~allized from n-hexane to give 0~28 g of the desired product melting at ~1 - 74 C. Yield 17.8%
Analysis:
- Calculated ~r C16H2~CI N~04PS: C,47.41~, 5.00, N-5 ~5, CrJ~ 8~8G; P~7.69~/o ~ound C, 47.~; H,4.~4; ~,5.76;
Cl, 9.o~; p~7.~5c~

EXamples of the preparations o~ herbicidal compostioD~
are given below. ~11 parts are given by weight ~erein~fter unless other~nse state~.

Ex~v~lE 6 GRIL~ ULES
70 Parts o~ a compou~d of the inve~tion were finei7 pulverized and ~0 parts of cla~ were added thereto. Tue ~5 mixttlre was blended in a ~ixer to form a premix. 10 ~art-s of the pre~ix were hmogeneously blended with 50 par~ ~f clay and 30 parts of bentoni~e in a mixer. ~o the re~ulting ble~d was added an appropriate amount of water. ~he mixture was kneaded in a l~nea~er7 ext~ded ~hrough a screen ha~in~
a diameter of 0~ ~m ~nd dried in a draft clrier at 50C~

~i93Z9 ~- ~'he so-obtained product was adjusted by a shifter to glve granules.

GRA~LES
70 Parts of a compound of the invention was finely pulverized and 30 parts of bentonite in a mixer.
~o the resulting blend was added an appropriate amount of water. The mixture was kneaded in a kneader, ex-truded through a screen having a diameter of 0.8 mmand dried in a draft drier at 50QC. The so-obtained product was adjusted by a shifter -to give granules.

EXAMP~E 8 GRANUL~S
35 Parts of a compound of the invention and 35 parts of S-(4-chlorobenzyl)N, N-diethylthiolcar-bamate were finely pulverized and 30 parts of pre-cipitated calcium carbonate were added thereto. ~ne - mixture was blended in a mixer to form a premix~
ao Parts of the premix were homogeneously blended with 50 parts Gf clay and 30 parts of bentonite in a mixer. To the resulting blend is added an appro-priate amount of water. ~he mixture was kneaded ina kneader, extruded through a screen having a diameter of 0.8 mm and dried in a draft drier at 50C. ~he so-obtained produc-t was adjusted by a shifter to give granules.

-2~-1()~93~9 ~ X1~_PrJE (~
WETr~ABL2 POl~DER
50 Parts of the compolmd designated as Compound No.~2, 29 parts of clay, 10 parts of diatomaceous earth, 5 parts of precipitated calcium carbonate, 3 parts of sodium lig-ninsulfonate, 2 parts of "~ewcoal" 1106 (~rade ~ , ~ihon Nyukazai K.K.) and 1 part of polyvinyl alcohol were homo-geneousl~ blended in a mixer and pulverized three times by means of a ~ammer, mill., EMULSI~IAB~E CO~CE~TRA~E
20 Parts of a compound of the invention, 65 parts o~
x~lene and 15 parts of "Paracoal" PS (trade ~ , ~ihon ~yukazai E.K.) were blended and homogeneously dissolved to form an emulsifiable concentrate.
E~AMPIE 11 SOLU~IONS
30 Parts of a compound of the invention, 1 part of ~ewcoal" 565 (trade ~x~Q,-~ihon l~yukazai K.K.) and 69 par s of water were blended a~d homogenously dissolved to form solutions.
Experimental results obtained us;ng herbicidal compositions thus prepared are given below. ~ke test compounds are form~lated accordi~g to the procedure in the above--me~tioned F.xamp~e 9 as wel~table powders, each ~0~19329 contailling 50% by weight of the active compound of this invention.

~ XPER-LMEN~ 1 Paddy field weed treatment tests on soil filled with water 3 Polyeth~lene pots (hereinafter abbreviated as A,~ B and C, each having a surface area of 45 cm2, were packed with pa,ddy field soil. Into Pot A were transplanted rice seedlings (two plants? variety:
Einnanpu~ at the 2.5 leaves stage and two tubers of arrowhead as a representative of perennial weed. In Pot ~, seeds of monochoria, false pimpernel and "Abunome" (Dopatrium junceum Hamilt) as represent~tives of broad-leave weed were well admixed with the soil, one grown slender spikerush was,transplanted thereint,o and two tube,rs of flatstage as perennial weed were placed into the soil. In Pot C, seeds of barnyardgrasse and "Hotarui" (~cirpus hotarui Ohwi) were well admixed with the soil and two tubers of arrowhead as pere~mial weed were placed into the soil. ~he Pot~ A, ~ and C were kept in~~a greenhouse for 3 days under paddy field condi~tions. After rooting of plants, suspensions of the test formulations were applied to the soil at 10 ml per pot under water-logged conditions. ~fter 20 da~s, the herbicidal effect on each weed and ph~totoxicit~ of the rice plant were observed and evaluated. ~he results are shown in ma~ble 1 wherein effective do~e (g/a) means the mini~um dose for a growth inhibition rate ~chlorotic area on the surface of plant) of not less tha~ 70%.

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3~

1~;93~9 E _ `E~I~I~T 2 Pre-emer~ence soil t~eatme!lt test on fi.eld weeds A field soil was placed in polyethylene pots havin~ a sux~ace area of 150 cm2 and seeds of cocksupr-grass, ~annagrass, green panicum, goose grass and chufa as representatives of narrow-leaved weeds and of shepherd's purse as a representative of broad-leaved weed~ were so~
a~d covered with the soil.

Similar polyethylene pots ha~ing a surface area of 150 cm ~ere ~illed. with a field soil and ~own with seeds of asatic dayflower as a narrow-leaved weed and of white-bird's-eye, pearlwort~ barnyardgrass, common p~slane, and whitD
goose-foot, as broad--leaved weeds.

Imm~diately after soil-covering9 some ~uspensions of 11 test compou~ds were applied to the soil svrface in eac~
pot. After 20 days from the app1ication, herb cidal elfects against ever~ weed were observed. t~he results are sho~m i~
t~able 2 wherei~ the ratings for evaluation are the same as in ~xperiment 1 and ~hown by means of effective do~e (g/a)0 3~

93~9 ~able ?

.
Herbicidal activity in field (~ffective dose ~/a . _ O rl ~ ~. O P~
. ~i h ~Q t~u~ . ~ c~ P~
~0 ~R ~u2 ~D .,:~ t~ h h ~!
0 X 0,~ ~5:1 h ~ ~ ~Q
~0 o~o ~ c) o CQ ~ L~ h ~ l . ~ ~ ,~ a) hl ~ ~ a o h 0 h : ~ ~o ~ ~ ~ ~ ~ a o 0 h h o ~ o u~ o rl o o C> ~ c) ~D ~D _ c~ ~ c~ ~ c~ c) u~

, _ _ A_. ~ ~- ~: _ . _ _ _ __ _ - . 1 5C 5 5 5C 25 2c 400 25 200 100 5 ~ 50 ___ _ _, _ _ 2 5C25 5o 2' 25100 100 400 5o200 ].OC 1.0 _ ~ ~ _. _. ~
320C 200 200 20C 25lOC 800 100 800 25 25 ~00 75C 200 100 lOC 55C 200 25 100 lOG 5 5 .

It will be apparent from the above results that ~he-- - pyrazole compounds in this invention have her~icidal activities which render them of i.ntere,st as herbici.des for paddy fields, dr~paddy fields, or fallow land.

3~

Claims (10)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A herbicidal composition including a 1,3-dimethyl-4-(2-chlorobenzoyl)-5-hydroxypyrazole or 1,3-dimethyl-4-(4-nitro-benzoyl)-5-hydroxypyrazole or a salt thereof or an organic acid ester thereof, together with an agriculturally acceptable carrier or diluent.

2. A composition according to claim 1 wherein the compound is selected from 1,3-dimethyl-4-(2) hydroxypyrazole; 1,3-dimethyl-4-(4-nitrobenzoyl)-5-hydroxypyra-zole; 1,3-dimethyl-4-(2-chlorobenzoyl)-5-methoxycarbonyl-oxy-pyrazole; 1,3-dimethyl-4-(2-chlorobenzoyl)-5-(N,N-dimethyl-carbamoyloxy) pyrazole; 1,3-dimethyl-4-(2-chlorobenzoyl)-5-ace-toxypyrazole; O, O-diethyl O-[1,3-dimethyl-4-(2-chlorobenzoyl)-5-pyrazolyl] phosphorothioate and 1,3-dimethyl-4-(2-chloroben-zoyl)-5-pyrazolyl methanesulfonate.

3. The composition according to claim 1 wherein said salt is a salt with a monovalent to trivalent metallic ion, a complex ion, ammonium ion or a mineral acid.

4. The composition according to claim 1 wherein said organic acid ester is an ester with an aliphatic, alicyclic or aromatic carboxylic acid, a carbamic acid, a sulfonic acid, a thiophosphoric acid diester, a carbonic acid, a thiocarbonic acid monoester, a dibasic acid or a 3-oxo-4-isoxazolin-2-ylcarboxylic acid.

5. The composition according to claim 1 wherein said organic acid ester is an. ester with a carboxylic acid having the formula in which R3 is an alkyl group of 1 - 7 carbon atoms, a halogenoalkyl group of 1 - 4 carbon atoms and 1 - 4 halogen atoms, an alkenyl group of 2 - 17 carbon atoms, a 5 - 7-membered cycloalkyl group, a phenyl group optionally having 1 - 3 substituents selected from a halogen atom and nitro or C1 - C4 alkyl groups, a phenylalkyl group of 1 5 carbon atoms in the alkyl moiety and optionally having 1 - 3 substituents select-ed from nitro groups and halogen atoms in the phenyl moiety, a styryl group or a phenoxyalkyl group of 1 - 3 carbon atoms in the alkyl moiety and optionally having 1 or 2 substituents selected from halogen atoms and methyl groups;
a carbonic acid having the formula in which R4 and R5 are alkyl groups of 1 - 4 carbon atoms or they jointly represent pentamethylene group;
a sulfonic acid having the formula in which R6 is an alkyl group of 1 - 4 carbon atoms, a halogenalkyl group of 1 - 3 carbon atoms and 1 - 3 halogen atoms on a phenyl group optionally having a C1 - C12 alkyl or halogen substituent;
a carbonic acid or thiocarbonic acid monoester having the formula in which R8 is an alkyl group of 1 - 4 carbon atoms, a phenyl group or a phenylalky1 group of 1 - 2 carbon atoms in the alkyl moiety and 1 - 3 substituents selected from nitro groups and halogen atoms in the phenyl moiety and Y is an oxygen atom;
a dibasic acid having the formula in which R9 is an alkylene group of 1 - 10 carbon atoms, a vinylene group or a phenylene group or a carbon-carbon bond and m is zero or 1; or an acid having the formula in which R10 is hydrogen atom or a halogen atom.

6. The composition according to claim 5 wherein said organic acid ester is an ester with said carboxylic acid wherein R3 is a halogen alkyl group of 1-2 carbon atoms and 1-4 halogen atoms, an alkenyl group of 3-5 carbon atoms, a 5- or 6-membered cycloalkyl group, a phenyl group optionally having 1-3 substituents selected from the nitro groups, halogen atoms and methyl groups, a phenylalkyl group of 1 to 2 carbon atoms in the alkyl moiety and optionally having 1-3 substituents selected from nitro groups and halogen atoms in the phenyl moiety on a phenoxyalkyl group of 1 or 2 carbon atoms in the alkyl moiety and optionallyhaving 1 or 2 substituents selected from halogen atoms and nitro groups; said sulfonic acid wherein R6 is an alkyl group of 1-3 carbon atoms, a halogenoalkyl group of 1 or 2 carbon atoms and 1-3 halogen atoms or a phenyl group optionally carrying a C1 or C2 alkyl or halogen substituent; or said dibasic acid wherein R9 is an alkyl-ene group of 1-3 carbon atoms and m is zero or 1.

7. The composition according to Claim 1, wherein said compound of formula I or a salt or ester thereof is contained in an amount of 0.1 - 99% by weight, based upon the composition.

8. A method for the control of unwanted plants which comprises applying to said plants l,3-dimethyl-4-(2-chloroben-zoyl)-5-hydroxypyrazole or 1,3-dimethyl-4-(4-nitrobenzoyl)-5-hydroxypyrazole or a salt or an organic ester thereof, in a herbicidal amount within the range 10 g to 4000 g of said compound per 10 ares.

9. The method according to Claim 8, wherein said salt is a salt with a monovalent to trivalent metallic ion, a complex ion, ammonium ion or a mineral acid.

10. The method according to Claim 8, wherein said organic acid ester is an ester with an aliphatic, alicyclic or aromatic carboxylic acid, a carbamic acid, a sulfonic acid, a thiophosphoric acid diester, a carbonic acid, a thiocarbonic acid monoester, a dibasic acid or a 3-oxo-4-isoxazolin-2-ylcarboxylic acid.