CA1275098A - 1-aryl-1,4-dihydro-4-oxo-5-carboxypyridazine derivatives and their use as plant growth regulators and hybridizing agents - Google Patents

Abstract

ABSTRACT

This invention relates to 1-aryl-1,4,-dihydro-4-oxo-5-carboxypyridazin derivatives of the formula wherein R1 is a (C1-C4) alkyl group, a phenyl group, a naphthyl group or a phenyl or napththyl group substituted with up to three substituents selected from the group consisting of halogen, nitro, trihalomethyl, (C1-C4)alkoxy, (C1-C4)alkyl and cyano; R5 is a carboxy (COOH) group or an alkali metal salt thereof, a carbalkoxy (COOR) group or a carboxamide (CONRR) group wherein R is a (C1-C4)alkyl group and the agronomically acceptable acid addition salts thereof;
and R6 is a (C1-C4)alkyl group, a phenyl group, a naphthyl group or a phenyl or naphthyl group substituted with up to three substituents selected from the group consisting of halogen, nitro, trihalomethyl, (C1-C4)alkoxy, (C1-C4)alkyl and cyano.
These derivatives are not only useful as plant growth regulators and hybridizing agents for cereal crops but possess the additional utility of having an improved margin of safety as concerns plant injury and seed quality.

Description

AGENTS

In the field of chemical hybridizing agents l-aryl-1,4-dihydro-~4-oxo-6-alkylpyridazine-3-carboxylic acids are highly active pyridazine type gametocides.
Although t-hese compounds are highl.y effective as chemical hybridizi~g agents they do possess the disadvantage of producing plant injury-and poor seed quality when overdo~ed sli~h~ly above their e~fective dosage rate.
The 5~carboxypyridazines of the present invention are unexpectedly sa~er ohemical hybridizing agents since ~hey do not have any adverse effects as :regards the quality of seed or amount of plan~ injury at d~sage rates far above wha~ is required to produ~e maximum male sterility which allows for higher percent yields of hybrid :seed produced.
S~MMARY OF T~E IN~ENTION
This invention relates to 1-aryl-1,4 dihydro-4-o~o~
5-carboxypyridazines of the formula ,1 ~` :iL27~V~8 wherein Rl is an aryl or alkyl group;
R5 is a carboxy (COOH) group or the alkaline metal salt thereof~ a carbalkoxy (COOR) group or a carboxamide (CONRR) group wherein R ls an alkyl group and the agronomically acceptable acld addition salts thereof, and R6 is an alkyl or aryl group.
The pyrldazines of this type offer the advantage of causing less in~ury to treated plants while inducing male sterility thereby making them excellent plant growth regulators for use as cereal hybridizing agents.
As utilized in the present specification and claims, the term l'aryl" is meant to include phenyl or naphthyl groups or phenyl or naphthyl groups substituted with up to three sub-stituents selected from the group consisting of halogen, nitro, trihalomethyl, (Cl-C4)alkoxy, (Cl-C~)alkyl, and cyano. The term alkyl as utilized in the present specification and claims is meant to include alkyl groups of up to 4 carbon atoms which may be straight or branched chain alkyl groups.
A preferred embodiment of this invention relates to compounds of ~ormula (I) wherein Rl is an aryl group substituted with up to three sub-stltuents selected from the group consistlng of halogen~ nitro, trihalomethyl, (Cl-C4)alkoxy, (Cl-C4)alkyl, and cyano; and R6 is a (Cl-C4)alkyl group.
A more preferred embodiment of this invention relates to compounds of ~ormula I wherein R5 is a carboxy (COOH) group or an alkali metal salt thereof, or a carbalkoxy (COOR) group wherein the group R is an alkyl group o~ up to 4 carbon atoms and the agronomically acceptable acid additlon salts thereof.
A most preferred embodiment of this invention relates to compounds according to Formula I wherein Rl is a phenyl group substituted with up to two substituents selected from the group consisting of halogen, nitro, trifluoromethyl, methoxy, methyl, and cyano, and R6 is a methyl group or ethyl group.

- ~7s(3~a Typical compounds whi~h are encompassed by this invention include:
l-phenyl-1,4-dihydro~4-oxo-6-methylpyriclazine-5--carboxylic acid 1-phenyl-1,4-dihydro~4-oxo~6 ethylpyridazine-S-carboxylic acid l-phenyl-1,4-dihydro-4-oxo-6-propylpyriclazine ~-carboxylic acid 1-phenyl-1,4-dihvdro-4-ox~-6-butylpyridazine-5-carboxylic -acid l-phenyl-1,4-dihydro-4-oxo-6-benzylpyridazine-5-carboxylic acid 1 phenyl-1,4-dihydro 4-oxo-6-phenylpyridazine-5-carboxylic acid 1-(4-chlorophenyl)-1,4-dihydro-4-oxo-6-methylpyridazine-5-carboxylic acid 1-(4-bromophe~yl)-1,4-dihydr~-4-oxo-6-ethylpyridazine-5-carboxylic acid 1-t3,4-dichlorophenyl)-1,4-dihydro-4-oxo-6-propylpyridazi~e ~5-carboxylic acid 1-(4-iodophenyl)-1 ~4r dihydro-4-oxo-6-butylpyrida%ine-5-carboxylic acid 1-(4-fluorophenyl)-1,4-dihydro-4-oxo-6-benzylpyridazine-~-carboxylic acid 1-(4-chlorophenyl)-1l4-dihydro 4-oxo-6-phenylpyridazine-5-car~oxylic aci~
1-(3-chlorophenyl)-1,4-dihydro-4-oxo~6-methylpyridazi~e-5-~arboxylic acid 1-(2-chlorophenyl)-1,4-dihydro~4-oxo-6-ethylpyridazine-5-carboxylic acid 1-(3-bromophenyl)-1,4-dihydro 4-oxo-6-propylpyridazine-5-carboxylic acid 1-(2-bromophenyl)-1,4-dihydro-4-o~o-6-butylpyridazine-5-car~oxylic acid " ~ ~7~098 1-(2,4,6-trichlorophenyl)-1,4-dihydro-4-oxo-6-benzyl-pyridazine-5-carboxylic acid 1 (4-metbylphenyl)-1,4-dihydro-4-oxo-6-phenylpyridazine-5-carboxylic acid 1-(4-trifluoro~ethylphenyl)-1,4-dihydro-4 ox~-6-methyl-pyridazinew5-carboxylic aci~
1-(3 ethoxyphenyl)-1,4-dihydro-4-oxo-6-ethylpyridazine-5-carboxylic acid 1-(4 methylthiophenyl)-1,4-dihydrG-4-oxo-6-propyl-~yridazine-5-carboxylic acid 1-(3-cyanophenyl)-1,4-dihydro-4-oxo-6-butylpyridazine-5-carboxylic acid 1-(2-chloro-4-methylphenyl)-1,4~dihydro-4-oxo-6-benzyl-pyridazine-5-carboxylic acid 1-(2-tr;fluoromethyl-4-chlorophenyl)-1,4-dihydro-4-oxo--6-methylpyridazine-5-carboxylic acid 1-(2-trifluoromethyl-4-bromophenyl)-1,4 dihydro-4-oxo-6-ethylpyridazine-5 carboxylic acid 1-(2-chloro-5-trifluoromethylphenyl) 1,4-dihydro-4-ox~-6-ethylpyridazine-5-carboxyli~ acid 1-(2-naphthyl)-1,4-dihydro-4-oxo-~ butylpyridazine-5-carboxylic acid and the agronomically acceptable alkali metal and acid addition salts thereof.
The ollowing is a sequence utilized to prepare the compounds of the present invention.

.

7S~9~3 t)2~3 ----~ C~2C~, __~
CO2C~ ,COCl C2C~I~ xyle:~e C~g `t~
.. ,,.. _, III

~D~ ~ ~ >

TV CB,OE
.~
' so4 a~
~ > C~,~
--CD2 ~5 . .
Vl:
;

The synthetic sequence outlined ab~ve is unique in its ability to produce (V) and (VI). No directed syntheses of either of these classes of c~mpounds has been reported in the literature.

... . .

The compounds of Formula (V) are the subJect Or a copending Canadian Patent Applicati.on 386~273 filed September 21, 1981 by Dennis R. Patterson, which is assigned to a common assignee.
In the above reaction sequence a 3-oxoglutarate is :first reacted with sodlum hydride thereby replaclng a hydrogen atom ~rom the active mekhylene group followed by reactlon with acetyl chlorlde to .~orm the intermediate of Formula II which then rearranges under acld conditions to form the pyrone of Formula III. The pyrone ls then reacted wlth a d:Lazonlum salt to form a hydrazone o~ Formula IV. The hydrazone is then rearranged ln the presence o~ a base to form the dicarboxypyridazine of Formula V which i.s then decarboxylated under acidic conditions to form the 5-carboxypyrldazine of Formula VI.
A more preferred synthetlc route to the compounds of the present lnvention is outlined below.

o ~

3C~, ~3 CO,c~ 2CX3 ~ 80Z

C~l Cl CH,COCl C~,o ~ c~,o ~ o,a > C~ W~ N~08 ~ ~
1~ o~,~,o Cl C~, Cl -VIII 42~ IX lOOZ

v~
i,,~

~27~

In this approach the 3-oxoglutarate i5 first reacted with a diazonium salt to form the hydrazone of Formula VII which is then reacted with isopropyl magnesium chloride followed by reaction with acetyl chloride to form the dicarboxypyridazine ester of Formula VIII which is then hydrolyzed to the corresponding acid of Formula IX. Decarboxylation under strongly acidic conditions as above will again form the monocarboxy pyridazine of Formula VI.
The following examples are provided to illustrate the processes for preparing the compounds of the present invention.
These examples are not to be considered in any way as being limitations on the breadth and scope of the present invention.

Process A-Synthesis of 6-methyl-5-carbomethoxy-4-hydroxy-2-pyrone Via dimethyl-2-acet~1-3-oxoglutarate A 3-liter, three necked, round bottomed flask was equipped with addition funnel, paddle stirrer and thermometer. The Elask was charged with 300 ml dry toluene and sodium hydride (50% as a dispersion in mineral oil, 82.8 g, 1.72 moles). The addition funnel was charged with dimethyl~3~oxoglutarate (dimethyl ester of acetone-1,3-dicarboxylic acid, 300 g, 1.72 moles). The flask was cooled to 5 in an ice-water bath. The diester was added dropwise to the sodium hydride slurry, not allowing the reaction temperature to exceed 10. Complete addition required 3 hrs.
The resulting mixture was stirred 30 min. at 5. Acetyl chloriae (135 g, 1.72 moles) was then added dropwise through the addit;on funnel, being careful to maintain the pot temperature at 5-10.
After complete addition, the resulting slurry was stirred a further 30 min., then poured slowly into 500 ml water saturated with ammonium chloride. The resulting mixture showed a pH of 6.
The layers were separated.

." 1 ~
.. ~.. i ~" ~

\ ~`~

The aqueous phase was extracted with m~thylene chloride (3 x 100 ml). The combined organic layers were taken to dryness in vscuo to leave a yellow oil. ~acuum distillation of this oil (at O . 5 mm ~g) gave fractions boiling ~rom 50-1~0. ~ major fraction, bp 85-110 (97g) contained the desired ~c~tylated diester, along with some s~arting material, as inferred by NM~.
The impure acetylated diester (97 g) obtained above, was dissol~ed in 300 ml dry ~ylene, along with p-toluene-sulfonic acid (100 mg). This mixture was refluxed into a Dean-Stark trap for 12 hr. ~he resulting dark solution was cooled in an ice-water ~ath. The desired pyrone crystalli~es out as fine needles (28.1 9, 10% yield based on dimethyl 3-oxoglutarate). An analytical sample was crystallized ~rom ethyl acetate. ~R (CDC13): 5.6 ppm (S, 1~); 4.1 (S, 3H1; 2.7 (S, 3~). IR (C 2C12):
~75h, 5.95, 6.90, 9.10. mp 104-106.
Elemental AnalYsis Expe~ted: C: 52.:18; ~: 4..38 Pound: C: 52.30; ~: 4.44 Syntùesis of l-(p-chlorophenyl)-l~4-~ih~r~-4-ox~-3 carboxy-5-carbomethoxy ~6-methylpyridazlne A 250 ml, three necked, round bottomed flask was e~uipped with addition ~unnel, paddle stirrer, and thermometer. The .flask was charged with ~0 ml ~ethanol, sodium acetate (16.0 9, 0.198 mole), and pyrone (8.0 g, 0.043 mole). p-Chlorobenzenediazonium chloride ~as prepared on the side by th~ dropwise addition of ssdium nitrite (3.3 g, 0.047 m~le) in 10 ml water to a cooled (5) slurry containing p-chloroaniline (5.6 g, 0.043 mole) in aqueous hydrochloric acid (16.5 ml 12N ~C1 ~0.198 mole] plus 10 ml water). The diaz~nium chloride solution was added dropwi~e to the solution containing the pyr~ne. This addition wa~ carried out during 10 min.

~7~

with no noticeable exotherm. After complete addition, the resulting orange slurry was stirred for 40 min. at room temperature. Suction filtration gave an orange filter cake which was washed repeatedly with water, then sucked dry during 2 hr.
The filter cake thus obtained was placed back into the three necked flask used aboveO Methanol (200 ml) was added to glve a slurry. Morpholine ~10.0 g., 00115 mole~ was added in one portion, A mildly exothermic reaction occurred, and a dark, homogeneous solution was obtained. After stirring 10 min~, the solution was poured into 300 ml water. This was extracted with methylene chloride (3 x 100 ml). The combined organic extracts were extracted repeatedly with dilute aqueous sodium hydroxide (pH 8). The combined aqueous basic layers were acidified with 6N
hydrochloric acid. With cooling and scratching, a solid crystallized from solution. Suction filtration gave the product a light brown powder (8.2 g, 60~ yield based on the pyrone NMR
(CDC13): 7.5 ppm (multiplet, 4H); 4.0 (S, 3~) 2.3 (S, 3H). IR
(CH2C12): 5.75 , 6.22, 6.90. mp 203-204 (dec.). An analytical sample was crystallized from methanol.
Elemental Analysis Expected: C: 52.10; H: 3.44; N: 8.63 Found: C: 52.06; H: 3.43; N: 8089 Synthesis of l-(p-Chlorophenyl)-1,4-dihydro-4-oxo-5-carboxy-6-5 methylpyridazinel-(p-chlorophenyl)-1,4-dihydro-4-oxo-3-carboxy-5-carbomethoxy-6-methylpyridazine (2.0 g, 6.2 mmoles) was dissolved in 10 ml, concentrated sulfuric acid, in an atmosphere of dry nitrogenO This was warmed rapidly to 200 and maintained there for 40 min. The resulting dark solution was cooled, then poured into cold water (50 ml). A brown precipitate formed immediately.
Suction filtration and thorough washing with water gave the desired acid tl.0 g 63% yield), pure by NMR.

, .

.. - ~;f~75~

.

--1.0--NRM (CDC13): 8..5 ppm (S, 1~); 7.~ tAB quarte~, 4~); 2.8 ppm (S, 3~). IR (Nujol): ~.81~ . mp 207-208 (dec.).
~ n analytical sample was obtained by ~rystallization from-methanol.
E:~ l~s Expected: C: 54.45; ~: 3.43; ~: 10.59 Found: C: 54.45; ~: 3OS2; N: 10.16 Pr~cess B:

_Ae r~ ~ b-dr~z~7e A 10-liter widemouthed polyethylene container -was fitted with a s~irrer paddle and addition funnel. This container was charged with dimethyl-3-oxoglutarate (1 kg, 5.75 ~oles), methanol (1.5R.), and sodium acetate (1 kg, 12.. 19 moles). p-Chlorobenzenedi~zonium chloride (5.75 moles) was generated on ~he side in seven equal portions, by combining p-chloroaniline (7 x 104 g, 5.75 moles), hydrochloric acid (7 x 314 ml ~2Nr ~6 moles), .water (7 200 ml) and sodium nitrate (7 x 65..6 g in .100 ml ~2~
6.66 moles). The diazonium salt was added dropwi~e, rapid-y to the reaction kettle. The p~ was monitored periodically and maintained at 5 during the course o~ the rea~tion by adding sodium acetate vla spatula. At the end of the procedure, another 800 g of sodium acetate bad been added. The resulting mixture was allowed t~ stand ov~rnight, then suction filtered and the filter cake w~shed thoroughly with water.. ~he brick-red filter cake was air dried to give 1.4 kg of the desired p-oduct (I) (80~ yield). NMR tCDC13): 7.5 ppm (S, 4~); 3.9 ppm (S, 6~); 3.7 ppm (S, 2~. This compound is known to the literature. See: Bulow and ~opfner, Berichte, 34, 71 (1901); ibid, 44, 2835 (1911).
~2~b~ .
~ dry l-liter, four-necked roun~ bottomed flask wa~

~L27~ 8 fitted with stirrer, thermometer, nitrogen inlet, and rubber septum. The flask was charged with dimethyl-2,3-dioxyglutarate, 2~p-chlorophenyl hydraæone (50 g, 0.16 mole) in dry tetrahydrofuran (170 ml). This solution was maintained under an atmosphere of dry nitrogen while cooling to ~ C.
Isopropyl magnesium chloride (72 ml, 2.25 N in ethyl ether, 0.16 mole) was added dropwise vla syringe, maintaining the pot temperature at 5-10C. After complete addition, the mixture was stirred for lS min. in the cold, then acetyl ohloride (12 ml, 13.0 9, 0.16 mole) was added dropwise, rapidly, keeping the temperature of the reaction mixture below 1~ C. The resulting dark ~olu~ion was allowed to warm to room temperature during

2 hrs. Water (200 ml) was added. This mixture was stirred for 30- min., then extracted with ethyl ace~ate. The extracts wexe dried over MgSO4, then filtered and reduced in volume ln vacuo. The resulting dark oil was dissolved in -et~yl ether, and cooled in an ice bath. The desired diester ~rystallized out to give 22.1 g yellow powder (42%
yield), ~p 153-54~C. NMR (CDC13): 7.6 ppm (multiplet, 4H); 4.0 ppm (S, 6~); 2.3 ppm (S, 3 I~ (C~2C12): 5.75~ , 6.12 , 9.15 Table I below sives the structure, melting poin~ and elemental analysis for some of the more representative compounds encompassed by the present invention which were prepared by the processes discussed above.

TABLE I
~0~

R6 N ,N

~X

9.~750913 ' C ~ u u~ ~ ~ e c~ u7 ~ 1~ ~ r~ m ~ _~
_~Oj ~ ~ ~ 0 ~

~ ~ r- ~ ~ u ~ ,n c~ r~ ~ u~ u7 0 ~r ~r ~ ~ r~ ~ e~ rl ~ ~ ~ ~r ~r ~r ~ r~
E ~ _1 c~ ~ ~.D t`l ~ o ~ ~ ~ ~ O u er 1`
I`C~ er~ C~ C~ 00~ ~1~ ~DO ~ 0~0 u7u U~U~ 0~ ~D~ Ul~ C~ ~D~O 1`1` ~-

3 _ ~ r ~ _ ~, ~

J" ;_ ~

~ ¦ Z ~ Z l Z ~ Z ~ Z ~ ~ Z I ' a xlu ~~U ~U~ I= ~U ~5~ U jl-ZXj~ ~ r~ ~r In ~O r~ cl c~ j 3L275V~38 u~ c~ r ~ ~ ~ ~ ~o ~ ~o r~ ~D c~ ~ ~ r~
o o ~ t- o ~ ~ ~; ~ ~ u~ r ~ ~ o ~r 0 o o ~ ~r ~ ~ o o a~ a~ ~ a~ r r o o r~
~u~ ~ ~_ _~_1 c ~: c:~ ~.o a~ ~'J ~ ~ t~ ~ ~ Q ~ t~ c~ t~
_I Z t~ o ~ o~ ~ ~r In cn r-~ ~ ~ o a~ c~
.n ~r ~ CD CD ~ ~ r u~~ r~l ~ a~ u~ c~
E _ o r- ~ l u~ ~-- :r ~ t` ~D ~--I ~) ~ O a~
_1 ~ a~ r- u~ ~O ~r ~rco c) I` r- ~ ~ ~ .0 ~u~ ~ ~P~ u~u~ u~u~ u~ ~ u7u~

O O
C ~.~ . _ O cl O O O` $ O O _~ O 0~0 O u~
o ~ o r~ a~ a~ ' u~
~:r _l O O ~ _l c~ r~
wl ~ ~ c~ ~ ~ ., ~

el ~ ~ . ;
Z Z 117 .:J Qc~ jZ __ XIU (J C j~ Y ~ l U~ o~

~ i JJ
-Zl ~ o Xlo ~ ~` ~ 1~' ~ ~c ~

~;~7509~3 - 13a -The compounds of the invention are particularly useful as chemical hybridization agents in cereal crops, such as wheat, barley, corn, rice sorghum, millets, oats, rye, triticale, forage crops and the like. When used as chemical hybridization agents, the compounds effectively induce a high degree of selective male sterility, without also inducing significant female sterility, in the treated plants and without causing significant growth inhibition of the treated plants. ~s used herein, the term male sterility includes both actual male sterility, as evidenced by a lack of ma]e flower parts or by sterile pollen, and functional male sterility, in which the male flower parts are unable -to cause pollination. The compounds of the invention also cause other plant growth regulatory responses, such as, for example, control of flowering, control of fruiting and inhibition of seed formation in non-cereal species and other related growth regulatory responses.

750~8 When used as plant growth regulators, the compounds of the invention are applied in any amount which will be sufficient to effect the desired plant response without causing any undesirable or phytotoxic response. For example, when the compounds oP the invention are used as chemical hybridization agents, they are generally applied to the crops to be treated at a rate of about 1/32 to about 20 pounds per acre and preferably about 1/8 to about 10 pounds per acre. The rate of application will vary depending on the crop being treated, the compound being used Eor treatment, and related factors.
To obtain hybrid seed, the following procedure is generally employed. The two parents to be crossed are planted in alternate strips. The female parent is treated with a compound of the invention. The male-sterile female parent thus produced will be pollinated by pollen Erom the other, male-fertile, male parent, and the seed produced by the female parent will be hybrid seed which can then be harvested by conventional means.
A preferred method of applying a compound of the invention as a chemical hybridization agent is by foliar application. When this method is employed, selective male sterility is most effectively induced when the compound is applied bet-~een flower-initation and meiosis. The compounds of the inventions may also be applied as a seed treatment by soaking the seed in a liquid formulation containing the active compound or by coating the seed with the compound. In seed treatment applications, the compounds of the invention will generally he applied at a rate oE about 1/4 to about 10 pounds per hundred weight of seed. The compounds of the invention are also effective when applied to the soil or to the water surEace in rice crops.

I i' ~2~

The compounds of the invention can be used as plant growth regulators either individually or in mixtures. For example, they can be used in combination with other plant ~rowth regulators;
such as auxins~ gibberellins, ethylene-releasing agents such as ethephon, pyridones, cytokinins, maleic hydrazide, succinic acid 2,2-dimethylhydrazide, choline and its saltE;, (2-chloromethyl) trimethyl-ammonium chloride, triiodobenzoic acid, tributyl-2,4 dichlorobenzylphosphonium chloride, polymeric ~-vinyl-2-oxazolidinones, tri(dimethylaminoethyl) phosphate and its salts,and N-dimethylamino-1,2,3,6-tetrahydrophthalamic acid and its salts, and the like, and under some conditions may be used advantageously with other agricultural chemicals such as herbicides, fungicides, insecticides, and plant bactericides.
A compound of the invention can be applied to the growth medium or to plants to be treated either by itself or, as is generally done, as a component in a growth regulant composition or formulation which also comprises an agronomically acceptable carrier. By "agronomically acceptable carrier" is meant any substance which can be used to dissolve, disperse, or dif~use a compound in the composition without impairing the effectiveness of the compound and which by itself has no significant detrimental effect on the soil~ equipment, crops, or agronomic environment Mixtures of the compounds of the invention may also be used in any of these formulations. The compositions of the invention can be either solid or liquid formulations or solutions. For example, the compounds can be formulated as wettable powders, emulsifiable concentrates, dusts, granular formulations, aerosols, or flowable emulsion concentrates. In such formulations, the compounds are extended with a liquid or solid carrier and, when desired suitable surfactants are incorporated.

, !

~275~98 It is usually desirable,-particularly in fGliar applications, to include adjuvants, such 2S wetting agents, spreading agents, dispersing agents, stickers, adhesives, and the like, in accordance with agricultural prac~ices.
~xamples of adju~ants which are ~mmonly used in the art can be found in the John W. ~cCutcheon, Inc. publication ~Detergents and Emulsifiers Annual.~ -The compounds of the invention can be dissolved in any appropriate solvent. ~xamples o~ .solvents which are useful in the practioe of this invention include water, al~ohols, ketones, aromatic hydrocarbons, halogenated hydrocar~ons, dimethyl~ormamide, dioxane, dimethyl sulfoxide, an~ the like.. Mixtures of these .solvents can also be used. The concentration of the solution can vary from about 2% to .15 about 98% by weight with a prefer.red range being about .20%
to about 75%.
~or the preparation o~ emulsifiable concentrates, the compound can be dissolved :in organic sol~en~s,.such as benzene, toluene, ~ylene, methyla~ed naphthalene, corn oil, .20 pine oil, o-dichlorvbenzene, i~ophoronel cyclohexanone, methyl oleate, and the like, or in mixtures of these-solvents~ together with .an emulsifying agent or surfa~tant which -p~rmits dispersion in water. Suitable emulsifiers in~lude, for exEmple, the ethylene oxide derivatives of alkylphenols or lc)ng-chain alcohDls, mercaptans, carboxylio a~ids, and reactive amines and partially esterified polyhydri~ alcohols. .Solvent-soluble sulfates or sulfonates, such as the alkaline earth-salts or amine sal~s of alkylbenzenesulfonates and ~he ~atty alcohol ~odium sulfates, having surf aoe-~ctive properties can be used as emulsifiers either alone or in conjunction with an ethylene oxi~e reaction produ~t. Flowable emulsion concentr~tes are formulated similarly to the emulsifiable concentrates and in~lude, in addition to the above components, water and a stabilizing agent such as a water-soluble cellulose .. . .. . . . . .. . .

~ ~7509~

der ivative or a water-soluble salt of a polyacrylic acid.
The concentration of the active ingredient in emulsifiable concentrates of usually about 10% to 60!~ by we ight and in flowable emulsion concentrates, this can be as higb as about 75%.
Wettable powders suitable for spraying, can be prepared by admixing the compound -with i~ finely divided solid, such ~s clays, inorganic silicates and carbonates, and silicas and incorporating wetting agents, sticking agents, a~d/or dispersing agents in such mixtures. The conoentration of active ingr~dients in.such formulations is usually in ~he range of abou~ 20% to 98~ by weight, preferably about 40% to 75~. A dispersing a~ent may generally constitute about 0.5% to about 3% by weigh. of ~he composition, and a wetting agent may generally constitute from about 0.1% to about 5% by weight of the composition.
Dusts can be prepared by mixing the compounds of the invention with finely divided iner* solids which may be organic or inorganic in nature. Materials used for this purpose include,.for-example, botanical flours, silicas, silic~tes, carbonates and clays. One convenient method of preparing a dust is to dilut a wettable powder with a finely divided carrier. Dust concentrates ~on~aining abou~
20~ to 80~ o~ the acti~e ingredient are commonly made and are subsequently diluted ~o about 1~ to 10~ by weight use ooncentrations.
Granular formulations can be prepared by impregnating a solid such as granular ~uller's ear~h, vermiculite, yround corn cobs r seed~ ls,-~ncl-ùaing br~n or oth~r grain hulls, or similar ma~erial. A ~soluti:on of one or more of the compounds in a volatile oxganic solv~n~ can be sprayed or mixed with the granular -solid and the solvent then removed by evaporation. ~he granular material can have any suitable size, with a preferably size range of 16 to 60 ~75~

mesh. The active compound will usually comprise about 2 to 15%
by weight of the granular formulation.
Salts of the compounds of the invention can be formulated and applied as aqueous solutions. The salt will typically comprise about 0.05 to about 50% by weight, preferably about 0.1 to about 10%, of the solutionO These compositions can also be further diluted with water if desired prior to actual application, In some applications, the activity of these compositions can be enhanced by incorporating into the composition an adjuvant such as glycerin, methylethylcellulose, hydroxyethylcellulose, polyoxyethylenesorbitan monooleate, polypropylene glycol, polyacrylic acid, polyethylene sodium malate, polyethylene oxide, or the like~ The adjuvant will generally comprise about 0.1 to about 5% by weight, preferably about 0.5 to about 2%, of the composition. Such compositions can also optionally include an agronomically-acceptable surfactant.
The compounds of the invention can be applied as sprays by methods commonly employed, such as conventional hydraulic sprays, aerial sprays, and dustso For low-volume applications a solution of the compound is usually used. The dilution and volume of application will usually depend upon such factors as the type of equipment employed, the method of application, the area to be treated and the type and stage of development of the crop being treated.
The following examples will further illustrate the growth regulatory activity of the compounds of the invention but are not intended to limit the invention in any way.

Chemical Hybridization Activity The following procedures are used to evaluate the activity of the compounds of the invention for inducing male sterility in cereals.
An awned variety (Fielder) and an awnless variety - -7S09~3 .
~19-(May-64) o~ spring wheat are planted at the rate of 6 to 8 seed~ per 6 incb pot containiDg a sterile-medium of 3 parts soil and 1 part humus. The plants are grown under ~hort-day (9 hour) conditions for the first 4 weeks to obtain good vegatative growth before flower initiation.
The plants are then mo~ed to long-day (16 hour) conditions which are provided by high intensity lights in the green hou~e. The plants are fertilized at 2, 4, and 8 weeks zfter planting with a water soluble fertilizer (16-25-16) at the rate of 1 tsp/gal of water, and are frequently sprayed with isot~x for aphid cont~ol and dusted with sulfur for powdery mildew contr~l.
Test ~ompounds are foliarly applied to the awned female plan~ when ~hese plants reach the flag leaf emergence stage (stage 8 on Feekes' scale). All compounds are applied in a carri-er volume of SQ ~al~A cDntaining a surfactant, uch as Triton~ X-100 surfactant at the rate o. 2 oz~50 gal.
After spike emergence but before anthesis, 4 to 6 spikes per pot are bagged to prevent ou~crossing. At the firs~ signs of flower opening, two spikes per ~ot are cross pollinated, using the approach method, with the awnless male parent. As soon as the seeds become plainly visible, spike length is measured and seeds per spikelet counted in both bagged and crossed spikes. Male sterility can then be calculated as percent inhibition of seed set in bagged spikes of treated plants, and female fertility in cros~ed spikes can be calculated as percent of control seed set.
After maturity the seed on crossed spikes are planted for determination of percent hybridization.
Percent sterility, percent fertility, and percent height inhibition are calculated from the following formulas:
a. % Sterility = (Sc ~ St/Sc~ x 100 S~ - seeds/spikelet in bagged spikes o~ control plants.

~7S(~8 -2.0-;
S~ = seeds/spikelet in bagged spikes of treated plan~s, b. % Fertility = (Ft/FC) x 100 ~t = seeds/spikelet in approach ~rossed spikes of treated plants Fc = seeds~spikelet in unbagged spikes of control plants c. % ~eight inhibition = (}~c ~ ~t/E
Ec = ~eight of control plants Et = ~eight of treated plants Table II summarizes typical results obtained in the eval~ation of compounds of the invention. ~ da~h indicates that no determina~ion of value was made.

TABL~ II

Yo~

R ~ ~ ~

~X

)9~

Ex. Rate (~Acre) ~ ~,~, 91.0 o 2 g9.1 2 1/8 29 . 4 O

:~ 100 o 2 ~57 9 0 8 "100 0 8 5~.3 0 1~ 77 0 0 2 100 . 0 0 8 100 . O ~
6 1~8 82.0 0 a loo . o O

7 1~8 28.-0 0 2 100 . 0 0 8 100 . 0 0

4 5.0 0 R 3.0 0 4 100. 0 0 8 100 . 0 0 TABL13 II ( continued ) Rate (il!Acre)SterilitY 5; ~ (o-9) 1 10 . O o 2 3.0 0 4 8.0 o 8 8.0 o 11 1/~ 2.0 o 4 16.0 o 12 1/2 1. 0 o 4 57.0 0 13 1 99.0 o 2 100 . 0 o 4 100 . 0 o 8 100 O 0 o 14 1/4 0 . 8 o .1/2 0 o 2 6.0 o 1~ 1/410 ~ 8 o 1/239 . 4 o ~0.8 o 2100 . 0 16 1/419 . 9 o 1/241 . 2 o 90.5 0 2 93.2 o 17 1/8 4~.2 o 1/2 7.0 o 2 27.1 8 14.0 o The 5-carbc xypyr i daz i nones of the present invention exhibit an improved margin of safety while maintaining high levels of activ~ty .as cDmpared to the 3-carboxypyridazones.
Greenhouse data on the l-aryl 1,4-dihydro-4-oxo-6-alkylpyridazine--5-carboxylic acids of the present invention as compared to l(p-chlorophenyl)-1,4 dihydro-4-oxo-6-methyl pyridazone-3-carboxylic acid, a kn~wn compound, are presented in Table III.

TABLE III

. Na~

;750 TABLE III ~continu~d) X R Dosage (t~/acre)Sterility Injury H CH3CH2- 1/8 3.1~ 0 1/2 26 . 6% 0 2 46.9~ 0 8 55.3~ 0 3,4-diClCH3CH2- 1/8 5~7~ 0 1/2 57O9~ 0 2 99 . 1% 0 8 100 . 0% 0 4-ClCH3CH2- 1/8 77 . 0~ ~ 0 1/2 98.0% 0 2 100 . 0% 0 8 100 . 0% 0 4-BrCH3CH2- 1/8 20 . 0% 0 1/2 82 . 0% 0 2 99 . 0% 0 8 100.0% 0 1/2 28 . 0% 0 2 100.0% 0 8 100 . 0~ 0 COa,Na 1/4 7~ . 0~ 0 ~B3 ~ 1/2 96.0%
r O l 1 100.0~ 1 2 100 . 0% 5 ~1 75~

The improved safety margin of the 5-carboxypyridazinones relative to the known l-(p-chlorophenyl)-1,4~dihydro-4-oxo-6-methylpyrldazine-3-carboxyllc acid also makes them effective cereal breedlng tools when applied directly to the seed of the ~emale parent before planting.
lt ls to be understood that changes and variations of the subject matter of this invention may be made without department from the spirit of the invention as defined by the appended claims.

..~j,~. .,

Claims (81)

I CLAIM:

1. A compound of the formula wherein R1 is a (C1-C4)alkyl group, a phenyl group, a naphthyl group or a phenyl or naphthyl group substituted with up to three substituents selected from the group consisting of halogen, nitro, trihalomethyl, (C1-C4)-alkoxy, (C1-C4)alkyl and cyano, R5 is a carboxy (COOH) group or an alkali metal salt thereof, a carbalkoxy (COOR) group or a carboxamide (CONRR) group wherein R is a (C1-C4)alkyl group and the agronomically acceptable acid addition salts thereof; and R6 is a (C1-C4)alkyl group, a phenyl group, a naphthyl group or a phenyl or naphthyl group substituted with up to three substituents selected from the group consisting of halogen, nitro, trihalomethyl, (C1-C4)-alkoxy, (C1-C4)alkyl and cyano.

2. A compound according to claim 1 wherein R1 is a phenyl or naphthyl group substituted with up to three substituents selected from the group consisting of halogen, nitro, trihalomethyl, (C1-C4)alkoxy, (C1-C4)alkyl and cyano; and R6 is a (C1-C4)alkyl group.

3. A compound according to claim 2 wherein R5 is a carboxy (COOH) group or an alkali metal salt thereof or a carbalkoxy (COOR) group wherein R is an alkyl group of up to 4 carbon atoms and the agronomically acceptable acid addltion salts thereof.

4. A compound according to claim 3 wherein R6 is a methyl group or an ethyl group.

5. A compound according to claim 1 wherein is phenyl.

6. A compound according to claim 5 wherein R1 is a phenyl group substituted with up to two substituents selected from the group consisting of halogen, nitro, trifluoromethyl, methoxy, methyl, and cyano.

7. A compound according to claim 6 wherein is a phenyl group substituted with up to 2 halogen atoms.

8. A compound according to claim 3 wherein R5 is a carboxy (COOH) group or an alkali metal salt thereof.

9. A compound according to claim 8 wherein is a phenyl group substituted with up to two substituents selected from the group consisting of halogen, nitro, trifluoromethyl, methoxy, methyl and cyano and R6 is a methyl or ethyl group.

10. A compound according to claim 9 wherein R1 is a phenyl group substituted with up to two halogen atoms.

11. A compound according to claim 1 wherein R6 is lower alkyl.

12. A compound according to claim 1 wherein R1 is phenyl, R5 is a carboxy (COOH) group or an alkali metal salt thereof or a carbalkoxy (COOR) group wherein R is an alkyl group of up to 4 carbon atoms and the agronomically acceptable acid addition salts thereof, and R6 is lower alkyl.

13. A compound selected from the group consisting of 1-phenyl-1,4-dihydro-4-oxo-6-methylpyridazine-5 carboxylic acid 1-phenyl-1,4-dihydro-4-oxo-6-ethylpyridazine-5-carboxylic acid 1-phenyl-1,4-dihydro-4-oxo-6-propylpyridazine-5-carboxylic acid 1-phenyl-1,4-dihydro-4-oxo-6-butylpyridazine-5-carboxylic acid 1-phenyl-1,4-dihydro-4-oxo-6 benzylpyridazine-5-carboxylic acid 1-phenyl-1,4-dihydro-4-oxo-6-phenylpyridazine-5-carboxylic acid 1-(4-chlorophenyl)-1,4-dihydro-4-oxo-6-methylpyridazine-5-carboxylic acid 1-(4-bromophenyl)-1,4-dihydrD-4-oxo-6-ethylpyridazine-5-carboxylic acid 1-(3,4-dichlorophenyl)-1,4-dihydro-4-oxo-6-propylpyridazine -5-carboxylic acid 1-(4-iodophenyl)-1,4-dihydro-4-oxo-6-butylpyridazine-5-carboxlic acid 1-(4-fluorophenyl)-1,4-dihydro-4-oxo-6-benzylpyridazine-5-carboxylic acid 1-(4-chlorophenyl)-1,4-dihydro-4-oxo-6-phenylpyridazine-5-carboxylic acid 1-(3-chlorophenyl)-1,4-dihydro-4-oxo-6-methylpyridazine-5-carboxylic acid 1-(2-chlorophenyl)-1,4-dihydro-4-oxo-6-ethylpyridazine-5-carboxylic acid 1-(3-bromophenyl)-1,4-dihydro-4-oxo-6-propylpyridazine-5-carboxylic acid 1-(2-bromophenyl)-1,4-dihydro-4-oxo-6-butylpyridazine-5-carboxylic acid 1-(2,4,6-trichlorphenyl)-1,4-dihydro-4-oxo-6-benzyl-pyridazine-5-carboxylic acid 1-(4-methylphenyl)-1,4-dihydro-4-oxo-6-phenylpyridazine-5-carboxylic acid 1-(4-trifluoromethylphenyl)-1,4-dihydro-4-oxo-6-methyl-pyridazine-5-carboxylic acid 1-(3-ethoxyphenyl)-1,4-dihydro-4-oxo-6-ethylpyridazine-5-carboxylic acid 1-(4-methylthiophenyl)-1,4-dihydro-4-oxo-6-propyl-pyridazine-5-carboxylic acid 1-(3-cyanophenyl)-1,4-dihydro-4-oxo-6-butylpyridazine-5-carboxylic acid 1-(2-chloro-4-methylphenyl)-1,4-dihydro-4-oxo-6-benzyl-pyridazine-5-carboxylic acid 1-(2-trifluoromethyl-4-chlorophenyl)-1,4-dihydro-4-oxo-6-methylpyridazine-5-carboxylic acid 1-(2-trifluoromethyl-4-bromophenyl)-1,4-dihydro-4-oxo-6-ethylpyridazine-5-carboxylic acid 1-(2-chloro-5-trifluoromethylphenyl)-1,4-dihydro-4-oxo-6-ethylpyridazine-5-carboxylic acid 1-(2-naphthyl)-1,4-dihydro-4-oxo-6-butylpyridazine-5-carboxylic acid and the agronomically acceptable alkali metal and acid addition salts thereof.

14. A compound of the formula wherein X is mono or di-halogen, Y is methyl or ethyl or an agronomically acceptable acid addition salt thereof, and R6 is a C1-C4 alkyl group.

15. A compound according to claim 14 wherein X
is in at least one of the 2, 3 or 4-positions.

16. A compound according to claim 15 wherein X
is selected from the group consisting of chlorine, bromine or iodine.

17. A compound according to claim 14, wherein X
is 4-chloro, R6 is n-propyl and Y is methyl, ethyl or an alkali metal salt.

18. A compound according to claim 14, wherein X
is 4-chloro, R6 is ethyl and Y is methyl, ethyl or an alkali metal salt.

19. A compound according to claim 17 wherein the alkali metal salt is the sodium or potassium salt.

20. A compound according to claim 18 wherein the alkali metal salt is the sodium or potassium salt.

21. A composition for inducing male sterility in cereal grain plants comprising an effective amount of a compound according to claim 1, 2 or 3 and an agronomically acceptable carrier.

22. A composition for inducing male sterility in cereal grain plants comprising an effective amount of a compound according to claim 4, 5 or 6 and an agronomically acceptable carrier.

23. A composition for inducing male sterility in cereal grain plants comprising an effective amount of a compound according to claim 7, 8 or 9 and an agronomically acceptable carrier.

24. A composition for inducing male sterility in cereal grain plants comprising an effective amount of a compound according to claim 10, 11 or 12 and an agronomically acceptable carrier.

25. A composition for inducing male sterility in cereal grain plants comprising an effective amount of a compound according to claim 13, 14 or 15 and an agronomically acceptable carrier.

26. A composition for inducing male sterility in cereal grain plants comprising an effective amount of a compound according to claim 16, 17 or 18 and an agronomically acceptable carrier.

27. A composition for inducing male sterility in cereal grain plants comprising an effective amount of a compound according to claim 19 or 20 and an agronomically acceptable carrier.

28. Method of inducing male sterility in cereal grain plants comprising applying to said plants, an effective amount of a compound of claim 1.

29. A method according to claim 28 wherein said effective amount is from about 1/32 to about 20 pounds per acre.

30. A method according to claim 29 wherein said effective amount is from about 1/8 to about 10 pounds per acre.

31. A method according to claim 28 wherein said compound is applied to said plants prior to meiosis.

32. A method according to claim 28 wherein said compound is applied to the foliage of said plants.

33. A method according to claim 28 wherein said compound is applied to the soil.

34. A method according to claim 28 wherein said plants are rice, and said compound is applied to the water surface of rice crops.

35. A method according to claim 28 wherein said compound is applied between flower-initiation and meiosis.

36. A method according to claim 28 including the further step of collecting seed from said plants after pollination.

37. A method of treating cereal grain seed to induce male sterility in cereal grain plants comprising applying to said seed an effective amount of a compound of claim 1.

38. A method according to claim 37 wherein said compound is applied to said seed by soaking the seed in a liquid formulation containing said compound.

39. A method according to claim 37 wherein said compound is applied at a rate of about 1/4 to about 10 pounds per hundred weight of seed.

40. Seed obtained according to the method defined in claims 37, 38 or 39.

41. In a method of producing hybrid cereal grain seed wherein female to be and male to be parent plants are planted in alternate strips, the improvement comprising treating said female to be plants with a compound according to claim 1, 2 or 3 and harvesting said seed after pollination.

42. In a method of producing hybrid cereal grain seed wherein female to be and male to be parent plants are planted in alternate strips, the improvement comprising treating said female to be plants with a compound according to claim 4, 5 or 6 and harvesting said seed after pollination.

43. In a method of producing hybrid cereal grain seed wherein female to be and male to be parent plants are planted in alternate strips, the improvement comprising treating said female to be plants with a compound according to claim 7, 8 or 9 and harvesting said seed after pollination.

44. In a method of producing hybrid cereal grain seed wherein female to be and male to be parent plants are planted in alternate strips, the improvement comprising treating said female to be plants with a compound according to claim 10, 11 or 12 and harvesting said seed after pollination.

45. In a method of producing hybrid cereal grain seed wherein female to be and male to be parent plants are planted in alternate strips, the improvement comprising treating said female to be plants with a compound according to claim 13, 14 or 15 and harvesting said seed after pollination.

46. In a method of producing hybrid cereal grain seed wherein female to be and male to be parent plants are planted in alternate strips, the improvement comprising treating said female to be plants with a compound according to claim 16, 17 or 18 and harvesting said seed after pollination.

47. In a method of producing hybrid cereal grain seed wherein female to be and male to be parent plants are planted in alternate strips, the improvement comprising treating said female to be plants with a compound according to claim 19 or 20 and harvesting said seed after pollination.

48. A method of inducing male sterility in cereal grain plants comprising applying to said plants, an effective amount of a compound of claim 13.

49. A method according to claim 48 wherein said effective amount is from about 1/32 to about 20 pounds per acre.

50. A method according to claim 49 wherein said effective amount is from about 1/8 to about 10 pounds per acre.

51. A method according to claim 48 wherein said compound is applied to said plants prior to meiosis.

52. A method according to claim 48 wherein said compound is applied to the foliage of said plants.

53. A method according to claim 48 wherein said compound is applied to the soil.

54. A method according to claim 48 wherein said plants are rice, and said compound is applied to the water surface of rice crops.

55. A method according to claim 48 wherein said compound is applied between flower-initiation and meiosis.

56. A method according to claim 48 including the further step of collecting seed from said plants after pollination.

57. A method of treating cereal grain seed to induce male sterility in cereal grain plants comprising applying to said seed an effective amount of a compound of claim 13.

58. A method according to claim 57 wherein said compound is applied to said seed by soaking the seed in a liquid formulation containing said compound.

59. A method according to claim 57 wherein said compound is applied at a rate of about 1/4 to about 10 pounds per hundred weight of seed.

60. A method of inducing male sterility in cereal grain plants comprising applying to said plants, an effective amount of a compound of claim 14.

61. A method according to claim 60 wherein said effective amount is from about 1/32 to about 20 pounds per acre.

62. A method according to claim 61 wherein said effective amount is from about 1/8 to about 10 pounds per acre.

63. A method according to claim 60 wherein said compound is applied to said plants prior to meiosis.

64. A method according to claim 60 wherein said compound is applied to the foliage of said plants.

65. A method according to claim 60 wherein said compound is applied to the soil.

66. A method according to claim 60 wherein said plants are rice, and said compound is applied to the water surface of rice crops.

67. A method according to claim 60 wherein said compound is applied between flower-initiation and meiosis.

68. A method according to claim 60 including the further step of collecting seed from said plants after pollination.

69. A method of treating cereal grain seed to induce male sterility in cereal grain plants comprising applying to said seed an effective amount of a compound of claim 14.

70. A method according to claim 69 wherein said compound is applied to said seed by soaking the seed in a liquid formulation containing said compound.

71. A method according to claim 69 wherein said compound is applied at a rate of about 1/4 to about 10 pounds per hundred weight of seed.

72. A process for the preparation of a compound of claim 1 which comprises converting dimethyl-3-oxoglutarate to a 3-carboxy-5-carbomethoxypyridazinone by a) reacting a molar amount of dimethyl-3-oxoglutarate with about a molar amount of sodium hydride in an inert solvent at temperatures from about 0° to about 10°C, reacting the mixture with an acid chloride, subjecting the mixture to acid conditions, reacting the resulting pyrone with about a molar amount of a diazonium salt at a temperature from about 0° to about 50°C and subjecting the reaction mixture to basic conditions, or b) reacting the dimethyl-3-oxoglutarate with about a molar equivalent of an aryldiazonium chloride in an inert solvent to produce a hydrazone, reacting the hydrazone with isopropyl magnesium chloride and an acid chloride in an inert solvent and hydrolyzing the resulting 3,5-dicarbomethoxypyridazinone to produce the 3-carboxy-5-carbomethoxypyridazinone;
and reacting the 3-carboxy-5-carbomethoxypyridazinone with an excess amount of aqueous concentrated sulfuric acid in an inert atmosphere at temperatures from about room temperature to about 250°C and isolating the compound of claim 1.

73. A process for the preparation of a compound according to claim 1 which comprises reacting a molar amount of dimethyl-3-oxoglutarate with about a molar amount of sodium hydride in an inert solvent at temperatures from about 0° to about 10°C; reacting the mixture with an acid chloride; subjecting the mixture to acid conditions; reacting the resulting pyrone with about a molar amount of a diazonium salt at temperatures from about 0°C to about 50°C; subjecting the reaction mixture to basic conditions to form a 3-carboxy-5-carbomethoxypyridazinone; reacting the 3-carboxy-5-carbomethoxypyridazinone with an excess amount of an aqueous sulfuric acid in an inert atmosphere at temperatures from about room temperature to about 250°C and isolating the compound of claim 1.

74. A process for the preparation of a compound according to claim 1 which comprises reacting dimethyl-3-oxoglutarate with a molar equivalent of an aryldiazonium chloride in an inert solvent to produce a hydrozone; reacting the hydrazone with isopropyl magnesium chloride and an acid chloride in an inert solvent; hydrolyzing the resulting 3,5-dicarbomethoxypyridazinone to produce a 3-carboxy-5-carbomethoxypyridazinone; reaction the 3-carboxy-5-carbomethoxypyridazinone with an excess of concentrated sulfuric acid at temperatures from about room temperature to about 250°C and isolating the compound of claim 1.

75. Use of the compound of claim 1, 2 or 3 as a plant growth regulator.

76. Use of the compound of claim 4, 5 or 6 as a plant growth regulator.

77. Use of the compound of claim 7, 8 or 9 as a plant growth regulator.

78. Use of the compound of claim 10, 11 or 12 as a plant growth regulator.

79. Use of the compound of claim 13, 14 or 15 as a plant growth regulator.

80. Use of the compound of claim 17 or 18 as a plant growth regulator.

81. Use of the compound of claim 19 or 20 as a plant growth regulator.