CA1099722A - N-(2-chloro-4-pyridyl-n'-phenylurea compounds - Google Patents

Abstract

ABSTRACT

Novel N-(2-Chloro-4-pyridyl)ureas or -thioureas represented by formula (I)

Description

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The invention relates to novel N-(2-Chloro-4-pyridyl)ureas or -thioureas represented by the formula (I), agricultural composition thereof and a method of treating plants with them.
U.K. Patent specification ~o. 1 122 662 discloses that some derivatives of the urea can be used for preservation of plant materials. Further Proc. Roy. Soc. (London ~ol. B165 P2~5(1966) reports an effect for developing the plantbud, while some of them show a mild effect as iniciator of celldivision.
This invention relates to novel ~-(2-Chloro-4-pyridyl)ureas ~
10 and -thioureas cf general formula (I) and acid addition salts ~ -: :
~` thereof, a process of their preparation, agricultural compositions ., :
`~ conta~ning the same, method of using the same as agricultural composition especially as plant growth regulator, and a process for the preparing thereof.
These novel compounds of formula (I) have valuable agricul-tural properties, especially regulating effects as further eluci-dated hereinafter, which makes them useful as plant growth regu-lator.
This invention relates to novel N-(2-Chloro-4-pyridyl)ureas, or thioureas, a process of their preparation, and agricultural com-positions as plant growth regulator containing the said ureas as an effective component and method of treating plants with them.
Regulation of plant growth signifies acceleration or suppression of plant growth with a very small quantity of a chemical to regu-late and control the state of plant growth as desired. Consequent-ly, it does not signify simply the increase or decrease in the height of plants but also to have flowers of fruits when desired, or to obtain fruits without seeds, or to make the seeds dormant or inversely ta~e them out of dormancy.
; 30 Control of plant growth with plant hormones is becoming an , 9~2Z
important techni~ue in agricultural and horticultural fields. ~s cytokinin 6 (~ benzyl)adenine and kinetin have been known.
An object of this invention ls to obtain plant growth regula~
tors better than the ~nown substances~
It has been found that 4-pyridylureas and -th~ureas possess ing a chlorine atom in the 2-position of the pyridine ring posses-sed an extremely potent activity and had an action to regulate plant growth over a wide range.
The active substance obtained by this invention comprises 10 N-(2-Chloro-4-pyridyl)ureas or -thiourea indicated by the follow- -ing general formula (I) ~ ~ 2 ! Cl (where Rl represents a hydrogen atom or an alkyl group of 1 to 3 carbon atoms such as methyl, ethyl, propyl, and iso-propyl, ~2 represents an aromatic group, which may be substituted by an alkyl group of 1 to 3 carbon atoms, an alkoxyl group of 1 to 3 carbon atoms, a hydroxyl group or halogen atom, and X is an oxygen or sulfur atom) and acid addition salts thereof.
The compounds represented by formula (I), wherein X represents oxygen atom, can be prepared by conventional methods. For brevity, reference is specifically made to the compound represented by formula (I), wherein Rl is a hydrogen atom, and R2 is an unsubsti-tuted phenyl group. Following a conventional method, either (a)

2 chloro-4-aminopyridine is reacted with phenylisocyanate or (b) 2-chloro-4-pyridylisocyanate is reacted with aniline or (c) 2-chloro-isonicotinoylazide is reacted with aniline.
In effecting this reaction it is preferred to use a slight ~39~3i7Z~

excess o~ one of the reactants, although approximately equivalent amounts of reactants may also be used in the suitable solvents.
Some solventssuitable for the reaction are benzene, toluene, xylene, acetone~ methylethylketone, dimethylformamide~ dimethylace-toamide, dimethylsulfoxide, chloroform, dichlormethane, tetrachlor-methane, pyridine~ and triethylamine. Excess of aniline as reac-tant is useful as solvent. The reaction is favorably conducted in the range of -5 to 150C although it is most preferred to effect the reaction at the reflux temperature of the reaction mixture.
The reaction time between 0.5 and 5 hrs is sufficient to produce a good yield of desired product.
The compounds represented by the formula (I) wherein X repre-sents sulfur atom can be also prepared by conventional method illustrated in (a) and (b) by using the corresponding starting materials in similar reactions conditions. However, as the æti-vity of the reaction for preparing thioureas is not so good com-pared with the urea-compounds the reactions temperature should be in the range of 20 to 150C.
The above mentioned preparations (a), (b) and (c) of the inventive compounds can be represented by the following chemical formulas:

(a) ~ - NH + X = CN ~

Cl ~ NH - C - N~ ~ ~ R3 (b) ~ NC = X + ~H2 - -C N~ NH - C - NH -Cl ~ 3 /' 9972:2

3 Z ~ N ~ -Nll-c-N

Cl wherein Rl and X represent -the same meanings as in the Eorrnula (I) and R3 represents a lower alkyl, a lower alkoxyl, a hydroxyl group or a halogen atom. ; ;
Some of -the compounds of this invention are illustrated below.
N-(2-Chloro-4-pyridyl)-N'-phenylurea, N-(2-Chloro-4-pyridyl)-.~
N'~(2-chlorophenyl)urea, N-(2-Chloro-4-pyridyl)-N'-(3-chlorophellyl)-10 urea, N-(2-Chloro-4-pyridyl)-N'-(4-chlorophenyl)urea, N-(2-Chloro- ;

4-pyridyl)-N'-(2-methylphenyl)urea, ~-(2-Chloro-4-pyridyl)-N'-(3-methylphenyl)urea, N-(2-Chloro-4-pyridyl)-N'-(4-methylphenyl)urea, N-(2-Chloro-4-pyridyl)-N'-(2.5 dichlorophenyl)urea, N-(2-Chloro-4-pyridyl)-N'-(2 fluorophenyl)urea~ N-(2-Chloro-4-pyrldyl)-N'-(4-ll-propylphenyl)urea, N-(2-chloro-4-pyridyl)-N'-(2-ethoxyphenyl)urea, N-(2-Chloro-4-pyridyl)-N'-phenylthiourea.
N-(2-Chloro-4-pyridyl)ureas and -thioureas of this invention -possess accelerating action on cell mitosis9 cell enlargement, and cell differentionJ and are eEfective in acceleration of frui-ting, 20 prevention of fruit and flower from falling, growth acceleration, ;~
and growth suppresslon. By adjusting concentration of the chemi-cals, a marked suppression of growth (herbicidal) appears at a high ~;

concentration of the chemicals.
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~ction, application field, use, and plants to which these chemicals are applicable, are listed in -the following table. The .
most prominent effective use of these chemicals is found in the ! i increased number of fruits in pepos such as melon and watermelon, inhibition of flower shedding, accelerated growth oE green veget-ables, and extension of tobacco leaf area and herbicidal ef~ect.

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Action Application, use Plants to be applied 1. ~cceleration of Increased fruits pepos, tomato, eggplant, ;
fruit bearing (flowers) (fruit) apples, Japanese pears, citrus, apricot, soybean Prevention of Inhibition of grape fruit falling flower shedding 2. Acceleration of Picking fruits citrus, plum, peach, ~:fruit falling (picking excess apple, tomato, pineapple and defolliation fruits to increase fruit yield and to make fruit size ; uniform) Picking flowers apricot, Japanese pear, ~excess flowers plum, peach picked to increase fruit yield and to ~ -make fruit size unifoxm) Defoliation cotton, soybean (to remove leaves ~. :
for easier harves-ting of cotton and .
soybeans~
3. Growth Acceleration of cuttage : acceleration root growth and taking root ~ ;
Growth accelera- vegetables tion (stalk, leaves ~
roots) ~ :
Increased size of citrus, apples, apricot fruit (increase in : commercial value by larger size of fruit) .
Increased tiller- soybean, pineapple ing, accelerated bud formation Accelerated flowering plants flowering 4. Growth Supression of trees, grass, flowering ~` suppression height plants Supression of paddy rice, wheat :~
lodging :~
Suppression of potato, onion budding :
Suppression of soybean tillering (prevention of excess growth)

5. organ Formation Renewal of new rose, fruit tree branches (buds) seedlings ~v)~
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6. Others Herbicidal effect Desiccation cotton ~;

Increased sugar sugar cane, sugar beet content .
The foregoing urea derivatives of this invention show the some activity in concentrations several fraction of that o~ 6-(N~
benzyl) adenine and kinetin, which had hitherto been considered as the most potent plant growth regulating substances. Even in com-parison with 4-pyridylphenylurea of similar structure, they show lOO-fold or more activity. This increased activity is unexpectedly observed when there is a chIorine atom only on the 2-position of the pyridine ring.
To explain in more concrete terms, in the test for tobacco callus growth, while the optimal concentration to give ma~imul yield of callus is 0.01 ppm for 6-(N-benzyl) adenine and 0.1 ppm for 4-pyridylphenylurea, that of potent ~l-(2-chloro-4-pyridyl)-ureas of this invention is 0.0005 to 0.001 ppm. Generally, substi-tution on the phenylring decreases the activity in the tobacco test for the acceleration of cell differentiation, the optimal concentration of 6-benzyladenine is 10 ppm but less than 1 ppm of ~-(2-Chloro-4-pyridyl)ureas gives formation of numerous shoots.
~-(2-Chloro-4-pyridyl)ureas of this invention show the effect of increasing weight, not only in callus cells but also on pith tissue, leaf tissue, and on plants during growth.
The plant growth regulator of this invention can be applied to plants and crops in general butare especially effective in legumino-sae, solanaceae, umbelliferae, popes vitaceal and cucurbitaceae, vitaceae families The amount of a compound of this invention to be used by ; 30 spraying plant directly is genarally lOO to lOOO liters per ~Ia as ... ..~ ~
~ 6 solution of a concentration of O.O~l to lO,000 ppm, preEerably 0.01 to lO,000 ppm. When used in soil, amount 5- to lO0-fold of the above is required. It goes without saying that the amount to be applied will differ according to the object of control and the S plant to be applied. For example, 1~0-1000 liters of a solution of the following concentration should be used per ~a.

For growth acceleration and increased fruiting 0.01 - l,000 ppm For growth acceleration of callus 0.0001 - 100 ppm ~or acceleration of fruit falling and defoliation 0.1 - 10,000 ppm For growth suppression and herbicidal 10 - more than 10,000 ppm The compounds of this invention can be used a~one or mixed with other substances with effective components, such as other plant regulators, herbicides, insecticides, fungicides, and acari-cides usually in the form of solutions, emulsions, wettable powder, granules, fine granules, or powders. -~
Such preparations of this composition may be obtained by the known methods by mixing, for example, 0.1 - 50%, preferably 0.1 -10%, of the compound of this invention with a bulking agent, suchas liquid or solid diluent as a carrier and, if necessary, using an emulsifying agent or dispersion agent. As substances preferable as a liquid diluent or a carrier may be cited water, aromatic hydrocarbons like xylene, benzene, and methylnaphthalene, chlorina-ted aromatic hydrocarbons like chlorobenzene, mineral oil fractionslike paraffin, and alcohols like methanol and propanol, and polar solvents like dimethylformamide and acetone. Substances preferable as a solid diluent or carrier are, for example, talc) clay, kaolin, white carbon, wood powder and sand. As an emulsifying agent may be cited polyoxyethylene-fatty acid esters and polyoxyethyLene-fatty ~ 7 ~ 5ag~Z~

acid alcohol ethers. Dispersion agents include alkyl sul~onates, alkyl aryl sulfonates, alkali metal salts, alkali earth metal salts, and ammonium salt of lignin-sulfonic acid, and methyl-cellulose.
These compounds or preparations thereof ~ se may be added to the medium or applied directly on the plants or on the surface of leaves or stalks, in the orm of usual preparation forms or sprayed on the soil. Further, the plant growth controlling agents of this invention may be added with fertilizers, and/or extenders. ;'~
These compounds can also be used as an inorganic or organic salt such as hydrochloride, phosphate or sulfate thereof.
Some examples of preparative forms will be given below.
Preparation 1. Wettable powder N-(2-Chloro-4-pyridyl)-N'- 1%
phenylurea Sodium ~-naphthalenesulfonate-formaldehyde condensate 2%
Polyoxyethylene alkyl aryl ether 2%
Clay %
~hese ingredients are ground, mixed and dilu-ted with water.
Preparation 2. Emulsifiable concentration N-(2-Chloro-4-pyridyl)-N'-(3-chlorophenyl)urea 1%
Xylene 74%
Polyoxyethylene alkyl aryl ether 4~5%
Alkyl aryl sulfonate 0.5%
Isophorone 20~/o The above ingredients are mixed to dissolve and the resulting solution is emulsified in water.
Preparation 3. Liquid ,, ~ , . , ~ .~, ;`.',',j.i~ ' z N-(2-Chloro-4-pyridyl)-~'-(2-chlorophenyl)urea 1%
Dimethylformamide 94%
Polyoxyethylenesorbitan mono 5%
laurate Preparation 4. Granules parts by weight ~ ~-(2-Chloro-4-pyridyl)-~
; (3-methylphenyl)urea 5 parts Bentonite 15 parts Talc 47.5 parts -~
Clay 30 parts Sodium ligninsulfonate 2 parts Sodium dodecylbenzen sulfonate 0.5 parts These ingredients are mixed, ground, mixed with 25 parts o~
,. ..
water, and made into granules using an extrusion-granulation appa-ratus. Then the granuIes are dried and sieved. These granules are sprayed per se.
Preparation 5. Wettable powder N-~2-Chloro-~-pyridyl)-N'- ~`
(3-methylphenyl)urea 5%
Sodium ~-~aphthalenesulfonate-formaldehyde condensate3%
Polyoxyethylene alkyl aryl ether 3%
Clay 89% -Preparation 6. Solution ~-(2-Chloro-4-pyridyl)-N'-(3-chlorophenyl)urea100 ppm Acetone 20%
Water 80%
Synthesis 1.

~ 9 ,. . , , , . . .-9~22 Manufacture of ~-(2-chloro-4-pyridyl)-N'-phenylurea (1) To a solution of 257 mg ~2 mmol) o~ 2-chloro-4-aminopyridine dissolved in 10 ml of dry acetone, 238 mg (2 mmol) of phenyl iso-cyanate is added and the mixture is stirred at room temperature for 8 hr. The solvent is evaporated under a reduced pressure, the residue is chromatographed over alumina, and the column is develop-ed with chloroform. Eluates containing the objective substance are collected, and the solvent is evaporated under a reduced pressure. The residue is recrystallized from acetone-ether mix-ture and 364 mg of M-(2-chloro-4-pyridyl)-N'-phenylurea is ; ~;;
obtained. Yield, 73.5%., mp 173-174C. Anal. Calcd. for C12Hlo~
ClN30:, 58.19; HJ 4.07, N, 16.96%. Found: C, 58.27; H, 4.15; N, 16.93%.
(2) To a solution of 365 mg (2 mmol) of 2-chloroisonicotinoyl azide dissolved in 10 ml of dry benzene~ 186 mg (2 mmol) of aniline is added and the mixture is refluxed for 3 hrs. When cooled, the `
solvent is evaporated under a reduced pressure and the residue is chromatographed over alumina. The column is developed with chloro-form and eluates containing the objective substance are collected. ~;
The solvent is evaporated under a reduced pressure and the residue is recrystallized from acetone~ether mixture to 453 mg of N-(2-; chloro-4-pyridyl)-N'-phenylurea, mp 183-184C. Yield, 91.4%.
The following compounds were also prepared in the same manner: ~-Compound mp (C) N-(2-Chloro-4-pyridyl)-N'-(2-chlorophenyl)urea 183 N-(2-Chloro-4-pyridyl)-N'-(3-chlorophenyl)urea198-199 N-(2-Chloro-4-pyxidyl)-N'-(4-chlorophenyl)urea201-201.5 --N-(2-Chloro-4-pyridyl)-N'-(2-methylphenyl~urea184-185.5 ~(2-Chloro-4-pyridyl)-N'-(3-methylphenyl)ureag3- 95 ~`
N-(2-Chloro-4-pyridyl)-N'-(4-methylphenyl)urea188-190 ,~ 10 )9~7~2 ~-(2-Chloro-4-pyridyl)-N'-(2.5-dichlorophenyl)urea 215- 6 N-(2-Chloro-4-pyridyl)-~'-(2-fluorophenyl)~lrea 186- 7 N-(2-Chloro-4-pyridyl)-N'-(4-n-propylphenyl)urea 156-157 M-(2-Chloro-4-pyridyl)-N'-(2-ethoxyphenyl)urea 96-99 N-(2-Chloro 4-pyridyl)-~il'-(phenyl)thiourea 141-142 Example 1 ~
Test on growth effect of N-(2-chloro-4-pyridyl)-~'-phenylurea on ~ !
tobacco callus cells: -Tobacco callus was cultured in Murashige-Skoog medium contain-10 ing 0.0001-0.1 ppm of N-(2-chloro-4-pyridyl)-~'-phenylurea and 2 ppm of indoleacetic acid as auxin, for 30 days at a temperature of about 26C. Final weight of fresh callus is shown in the table. The control was a tobacco callus cultured in the Murashige-Skoog medium containing only auxin, under the same condition. For 15 the sake of comparison, values obtained ln a medium containing optimal amount 6-(N-benzyl)adenine are also given in the table.
Values are all an average of six individuals.
Table 1 Concentration(ppm) weight (mg) 20 ~-(2-chloro-4-pyridyl)-~'-phenylurea 0.0001 782 N-(2-chloro-4-pyridyl)-~'-phenylurea 0.001 4) 991 N-(2-chloro-4-pyridyl)-N'-phenylurea 0.01 17 235 1~-(2-chloro-4-pyridyl)-~'-phenylurea 0.1 519 Benzyladenine 0.015J150 25 Control 153 Example 2.
Test on growth effect of N-(2-chloro-4-pyridyl)-N'-(3-methylphenyl)-urea on tobacco callus Tobacco callus was cultured in the same way as in Example 1 30 and results shown in the following table were obtained.
~ 11 ~9qZ2 Table 2 ~f Concentration (ppm) weight (mg) ~-(2-chloro-4-pyridyl)-~'-(3-methylphenyl?urea 0.001 1,784 5" " " 0.01 6,760 " " " 0.1 4,945 " " " 1 l,508 Control 153 ~

The use of ~-(2-chloro-4-pyridyl)-N'-(3-chlorophenyl)urea `
gave a similar result.
Example 3.
Test on shoot formation efect of ~-~2-chloro-4-pyridyl)-M'-phenyl-urea from pith tissue Section(s) of tobacco pith tissue were inoculated in Murashige~
Skoog medium containing 0.01 - 10 ppm of N-(2-chloro-4-pyridyl)-~'-phenylurea, this was cultured at a temperature of about 26C for 30 days, and the number of pith sections forming shoots was counted. ~ ;
For comparison, benzyladenine was tested in a similar way. Results are shown in Tab~e 3.
Table 3. Shoot formation from pith sections ; Shoot formation*
Conc.6-(~-Benzyl)N-(2-Chloro-4-pyridyl)-N'-(ppm) adenine phenylurea 25 10 l/24 10/24 ;~ 1 12/24 13/24 0.1 2/24 10/24 ` 0.01 0/24 0/24 * No. of pith sections with shoots/no. of pith sections planted.
30 One to six shoots are formed from one pith section. -; ~ 12 ,, , ,.. , . , ,.. . ~ ., . .. . , ~ :

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Example 4.
Test on shoot -formation from callus cells by N-(2-chloro-4-pyridyl)~
N'-~2-methylphenyl)urea f Tobacco callus was inoculated in Murashige-Skoog medium con-taining 0.01 - 10 ppm of ~-(2-chloro-4-pyridyl)-N'-phenylurea, this was cultured at room temperature for 30 days, and the number of callus with shoot formation was counted. For comparison, benzyl-adenine was tested in a similar way. Results are shown in Table 4.
Table 4. Shoot formation from tobacco callus Shoot formation rate* ;

Concn. N-(2-Chloro-4-pyridyl)-(ppm)Benzyladenine ~ 2-methylphenyl)urea `~
~ -12/12a 9/12a 0.1 2/12b 1/12b 0.01 0/12 0/12 * Mumber of callus forming shoots/number of callus inoculated a Number of shoots, 50-70 ~size of individual shoots, 1-3 cm) b Number of shoots, 1-10 (size of individual shoots, 0.5-1 cm~ ~-' ~

Example 5.
Test on shoot formation from callus by N-(2-chloro-4-pyridyl)-N'-phenylurea ; Medium solutions containing 0.0001 to 1 ppm of N-(2-chloro-4-pyridyl)-N'-phenylurea were prepared and tobacco callus culture was carried out as in Example 4. The results obtained are given in ~ Table 5.

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Table 5. Shoot formation from tobacco callus Shoot formation rate*

Concn. ~-(2-Chloro-4-pyridyl)- -(ppm) Benzyladenine ~'-phenylurea 12/12a --- ~
; 1 12/12a 12/12a , .
0.1 2/12b 12/12 0.01 0/12 12/12a ; O. 001 --- 2/12b 0.0001 --- 0/12 .~ . . ;:
* Mumber of callus section forming shoots/number of callus sec-tions inoculated a ~umber of shoots, 50-70 ~size of individual shoots, 1-3 cm) b Number of shoots, 1-10 (size of individual shoots, 0.5-1 cm) ~xample 6.
. ~ .
Test~on increase in size of leaves of green vegetable by ~-(2-chloro-4-pyridyl)-N'-phenylurea : ~
Solutions containing 10, 1, and 0.1 ppm of ~-~2-chloro-4-pyridyl)-~'-phenylurea in water were prepared. To 50 ml of each solution placed in a petrie dish, 10 pieces of the leaf of Brassica repa var. ~rvidis, a round piece of 10 mm in diameter ;
cut out with a corkborer, were place in the solution, one group with back of the leaf in contact with the solution and the other 'r .~`-~.:
25 group with surface of the leaf in contact with the solution. The -dishes were allowed to stand at room temperature for 8 days, and ~ diametex and weight of each leaf pieces. The control leaves were -~ left in water. These results are shown in Table 6~
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Table 6 With back of the leaf With surface of the leaf in contact with water in contact with water Concn. Diameter Weight Concn. Diameter Weight 5 (ppm~ (mm) (mg) (ppm) ~mm) (mg) 13.7 30.5 10 13.2 26.8 ~ `
1 13.5 32.1 1 14.2 31.1 0.1 14.2 33.3 0.1 13.9 28.1 Control 12.1 21.7 Control 11.9 21.0 ~xample 7. Test on acceleration o~ fruit bearing in pepos.
Watermelon (variety 'Yamato') raised outdoors was used as test plant. Artifical pollination was made at the peak of flower-; ing, and solutions of the chemical in desired concentration were painting or sprayed on the gynophore. Fruit-bearing rate was examined 2 weeks after the treatment.
; Table 7.
Treatment Chemical Concentra- Fruit-bearing tion (ppm) rate (/O) Painting N-(2-Chloro-4-pyridyl)- 1,000 100 M'-phenylurea BA (liquid) 1,000 65 " 10,000 100 . :
, No treatment Spraying N-(2-Chloro-4-pyridyl)- 1,000 90 , N'-phenylurea " 500 87 ` " 100 82 BA (liquid) 10,000 83 No treatment 15 . .
:, . . , ~ . . . .

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BA (Benzyladenine) is a liquid agent containing 3% 6-(~-benzyl)-aminopurine.
Example 8. Test on suppression o height and extension of lea~
area, in tobacco plant Seedlings of tobacco ~variety, Bright Yellow) were transplan-ted in anglazed pots of Ca 13cm in diameter and the pots were left in a green house. Solutions of the chemical of desired concentra-tion were sprayed with a sprayer, 15 ml for each pot, homogeneously on leaves and stalk at the time when 6-8 leaves were out. One sec-tion of the pots was sprayed once and the other section three times -at 13-day intervals. ~xamination of the result was mode when middle leaves started to become yellow (35 days after the initial ~;~
spraying of the chemical), and height of the plant, fresh weight of stalk and leaves, and average area of 5 lower leaves were mea-15 sured, and ratio of these values to those of the non-treated plants ;
was calculated. Experimental section was 3 pots per area and their average was taken. Results are lisied in the following ;;
table.
Compound Concn. ~o. of Percent to non-treated area tested ~ppm) spray-ing ~eight Fresh weight Leaf area N-(2-chloro500 1 74 171 158 -4-pyridyl) '-phenyl- 3 42 169 145 urea 5 % Wp-3 72 206 1~35 BA 3% 500 1 99 151 118 li~uid ., 72;~

Compound Concn. No. of Percent to non~treated area tested (ppm) spray-ing Height Fresh weight Leaf area Non-treated 100 100 100 (74.6 cm) (126.6 g/stock) (278 cm /
leaf) ~xample 9. Inhibition of flower shedding and acceleration of fruit bearing in grape.
&rapevine (Variety Delaware) raised in plastic house covering was used for the examination, and the effect of N-(2-Chloro-4-pyridyl)-N'-phenylurea or BA (200 or 100 ppm) was added to 100 ppm of gibberellin solution, and racemose flowers were dipped in each solution (April 14). Ten days after full bloom (May 4), all the fruit clusters were again soaked and treated with 100 ppm solution of gibberellin. The grapevine were then left to usual cultivation conditions until harvest. Grapes were harvested on June 29, and weight of each cluster, length of cluster, density of berries, number of berries on each cluster, and berry diameter were measured.
These values were compared with those found with grapes with gibber-elling treatment alone. Experimental area contained 2 new branches, 3 repitation, and average value of 15 fruit clusters was calculated.
Results are shown in the following table.

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Example 10. Test on herbicidal effect.
Soil containing the subterranean stems of narrowleaf water-plantain (Alisma canaliculatum) and bulrush (Scirpus luncoides) homogeneously was filled in ceramic pots of 30 cm in diameter.
Seqds of barnyard grass (Echinochloa crus-qall.i), u~hrella plant (Cyperus diformis), and monochoria ~Monochoria vaqinalis) were each sown in pots, 50 seeds to each pot. Then paddy rice seedlings (Variety Kinmaze) at the two-leaf stage was planted, 5 seedlings per pot, and the pots were filled with water so as to have water layer of 3 cm above the soil. When the barnyard grass reached the one-leaf stage, the desired ~uantity of the solutions of test .
chemical(s), prepared according to Preparation 1, was sprayed uni- : :

formly over the surface of water. Herbicidal effect was examined 14 days after the chemica]. treatment. Result of this test was expressed by the following index:

5: complete control of weeds 4: over 80% " "

3: over 600/o 2: over 40% "

1: over 20% " "

0: No effect Compound AmountControl of Weeds Effect ( g/ )Barnyard Umbrella Mono- Bul- Narrow-grass plant choria rush leaf rice water plantain N-(2- 1 5 5 5 4 5 0 :~:
j chloro-. 4-pyridyl) .
-N-phenyl~
urea 0.5 4 4 4.5 3 4.5 0 Example 11.

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Test on increase of leaf and new branches in Datura Sunguinea Datura Sunguinea sp. (average height of 8 cm) were transplan-ted outdoors. Solution of the compound at desired concentration was sprayed with a sprayer, 15 ml each plant, on the leaves and stalk of the plant at the time when the average height of the ; plant was 20 cm. 3 weeks after plants were harvested and height of the plant, total weight of fresh leaves and stalks on the new branches were measured. Average values oE 5 plants are listed in Table.
10 Compound Concent. Height I'otal Weight New branches ~` (ppm) (cm) (g) (g) N~(2-chloro-4- 20 80 450 80 pyridyl)-N'-phenylurea ;
" 100 75 500 100 Control 103 348 40 Example 12. ;~
~ Test on increase of leaf and new branches in Datura Sunguina ; Datura Sunguina sp. (average height of 8 cm) were transplan ted outdoors and tests using N-(2-chloro-4-pyridyl)-N'-(3-brom~
phenyl) urea have been conducted as in Example 11 and results shown in the following table were obtained.
Compound Concent Height Total weight New branches (ppm) (cm) (g) (g) N-(2-chloro-4- 60 81 450 78 pyridyl)-N'-(3-bromphenyl)urea " 300 74 490 98 Control 102 352 41 Various modifications and equivalents will be apparent to one ~'~t ' O~ ~ ' .

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skilled in the art and may be made in the compounds, compositions and methods of the present invention without departing from the spirit or scope thereof, and it is therefor to be understood that the invention is not to be limited to the specific e~amples and embodiments disclosed herein.

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Claims (10)

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

1. An N-(2-chloro-4-pyridyl)urea represented by the formula:

wherein R1 represents a hydrogen atom or a lower alkyl group, R2 represents a phenyl group which may be substituted with an alkyl group containing 1 to 3 carbon atoms, an alkoxy group containing 1 to 3 carbon atoms or a halogen atom and X is an oxygen atom or sulfur atom, and an acid addition salt thereof.

2. A compound according to claim 1, wherein X is an oxygen atom.

3. A compound according to claim 1, wherein X is a sulfur atom.

4. A compound of claim 1, wherein R1 is a hydrogen atom.

5. A compound of claim 1, wherein X is an oxygen atom and R1 is a hydrogen atom.

6. N-(2-chloro-4-pyridyl-N'- phenylurea.

7. N-(2-chloro-4-pyridyl)-N'-(3-chlorophenyl)urea.

8. N-(2-chloro-4-pyridyl)-N'-(3-methylphenyl)urea.

9. A method for controlling plant growth which comprises treating plant with an N-(2-chloro-4-pyridyl)urea represented by the formula:

wherein R1 represents a hydrogen atom or a lower alkyl group, R2 represents a phenyl group which may be substituted with an alkyl group containing 1 to 3 carbon atoms, an alkoxy group containing 1 to 3 carbon atoms or a halogen atom, and X is an oxygen atom or a sulfur atom; and an acid addition salt thereof.

10. A process for preparation of a N-(2-chloro-4-pyridyl)urea represented by the formula:

wherein R1 represents a hydrogen atom or a lower alkyl group, R2 represents a phenyl group which may be substituted with an alkyl group containing 1 to 3 carbon atoms, an alkoxy group containing 1 to 3 carbon atoms, or a halogen atom, and X is an oxygen atom or a sulfur atom which comprises reacting:
a) a corresponding 2-Chloro-4-aminopyridine with a corresponding phenylisocyanate, or b) a corresponding 2-Chloro-2-pyridylisocyanate with a corres-ding aniline or a derivate thereof, or c) a corresponding 2-Chloroisonicotinoylazide with aniline or a derivative thereof.