CA1042898A - Thiadiazolylimidazolidinones - Google Patents

Abstract

NEW THIADIAZOLYLIMIDAZOLIDINONES
Abstract of the Disclosure The invention discloses compounds of the formula

Description

- 1~4Z898 SDecification This invention relateq to new ~ompo~itions of matter and more particularly relates to new chemical compounds of :~.
the formula . OH
N N C~ - C~

~N R - J
Il . t~) wherein Rl is cycloalkyl of from 3 to 7 carbon atoms, and R2 is alkyl.
The compounds of the present invention are unex-pectedly useful as herbicides.
In a preferred embodiment of this invention R2 ~ lower alkyl. The term lower as used herein desianates a s~raight or branched carbon chain of up to s~x carbon a~oms.
. The compounds of this invention can be readily prepared by heat~ng a compound of the formula . . .
. . -1!~42898 - N ~T
¦ OCH3 R - C C - N - C - N - C~l - C~

2 2 S R O ~ OCI13 wherein p~l and R2 are as heretofore described, in a dilute, aqueous, acidic reaction mediu~ for 2 period of about 10 to about 60 minutes. Temperatures of from about 70C to the reflux temperature of t'ne reaction mixture can be utilized.
The reaction medium can comprise a dilute aqueous inorganic acid such as hydrochloric acid at a concentration of from about 0.5 to about S percent. Upon completion of the reaction the desired product can be recovered as a precipitate by cooling the reaction mivture. This product can be used as ~uch or can be further purified by conventional means such as recrystallization and the like.
The compounds of formula II can be prepared by reacting a molar amount of an isocyanate dimer of the formula _ _ ' ' O - C = ~ - C C ~ Rl ~ ~
L S _ , ,-'., 2 ~III) wherein Rl is as heretofore described, with about two molar amounts of a dimethyl acetal of the formula OC~3 H - ~ - CH - C~ . -wherein R i~ as heretofore described. This reaction can be effected by heating a mixture of the isocyanate dimer and , the acetal in an inert organic reaction medium such as benzene j at the reflux temperature of the reaction mixture. ~eating 30! ,at reflux can be continued for a period of from about 2 to - a-: ,...
. . - .. . ., i. . - . - . .. .- - .... . .. -- - ~ . - .

- . ' . : ~:

42~398 about 30 minutes to ensure completion of the reaction.
After this time the desired product can be recovered upon evaporation of the reaction medi~m and can be used as such or can be further purified by standard techniques in the art.
The isocyanate dimer of formula III can be prepared by reactin~ a thiaaiazole of the formula ~J - M

}~ -- C~ ~C -- NH2 S (V~
wherein Rl is as heretofore described, with phosgene. ~his reaction can be effected by adding a slurry or solution of the thiadiazole, in a suitable organic solvent such as ethyl acetate, to a saturated solution of phosgene in an organic solvent such as ethyl acetate. mhe resulting mixture can be stirred at ambient temperatures for a period of from about 4 to about 24 hours. ~he reaction mixture can then be purged with nitrogen gas to remove unreacted phosgene. The desired product can then be recovered by filtration if formed as a precipitate or upon evaporation of the organic solvent used if soluble therein. This product can be used as such or can be further purified if desired.
Exemplary thiadiazoles of formula V useful for preparing the compounds of the present invention are 5-cyclopropyl-2-amino-1,3,4-thiadiazole, 5-cyclobutyl-2-amino-1,3,4-thiadiazole, 5-cyclopentyl-2-amino-1,3,4-thiadiazole, 5-cyclohexyl-2-amino~ ,4-thiadiazole and 5-cycloheptyl-2-amino-1,3,4-thiadiazole.
~he manner in which the compounds of the present invention can be prepared is more specifically illustrated in the followin~ examples.

-3-. .. ~

1~4Z~98 Example 1 Preparation of 5-Cyclopropyl-1,3,4-thiadiazol-2-yl Isoc~anate Dimer .
A saturated solution of phos~ene in ethyl acetate tlOO ml) was charged into a alass reaction vessel equipped with a mechanical stirrer. A slurrY o~ 5-cyclopropyl-2-amino-1,3,4-thiadiazole (6 grams) in ethyl acetate (100 ml~ -was added to the reaction ~essel and the resulting mixture was stirred for a period of about 16 hours, resulting in the formation of a precipitate. The reaction mi~ture was then purged with nitrogen gas to remove unreact~d phosgene. The~
purged mixture was filtered to recover the desired product S-cyclopropyl-1,3,4-thiadiazol-2-yl isocyanate dimer.

Example 2 Preparation of the Dimethvl Acetal of 2-3-Methyl-3-~5-cYcloproPyl-1,3,4-thiadiazol-~-yl~ureido~ acetaldehyde _ . .
A mixture of 5-cyclopropyl-1,3,4-thiadiazol-2-yl ~socyanate dimer (7 grams), the di~ethyl acetal of 2-methyl-aminoacetaldehyde ~5 grams) and ethyl acetate (~0 ml) were 20 charged into a glass reaction vessel equipped with a mechanical 8tirrer ~nd reflux condenser. The reaction mixture i~ heated at reflux for a period of about 2 hours. After this ti~e the mixture is stripped of solvent under reduced pressure to yield the desired product the dimethyl acetal of 2-~3-methyl-3-(5-cyclopropyl-1,3,4-thiadiazol-2-yl)ureido]
acetaldehyde as an oil.

Example 3 Preparation of 1-(5-Cyclopropyl-1,3,4-thiadiazol-2-yl)-3-ethyl-5-hydroxv-1,3-imidazolidin-2-one i, I
30The dimethyl acetal of -L3-methyl-3-(5-cyclopropyl-;1,3,4-thiadiazol-2-yl)ureido] acetaldehyde obtained from SL
, l~Z~8 Example 2, water (400 ml) and hydrochloric acid (4 ml) are char~ed into a glass reaction vessel eauippea with a mechanical stlrrer, ther~ometer and reflux condenser. The reaction mixture is heated at reflux for a period of about 15 minutes. The reaction mixture is then filtered while hot and the filtrate is cooled to for~. a precipitate. The precipi-tate is recovered by filtration, is dried and is recrystallized from ethyl acetate to yield the desired product 1~~5-cyclo-propyl-1,3,4-thi2diazol-2-yl~-3-methyl-5-hydroxy-1,3-imidazolidin-2-one having a ~elt point of 178 to 179C.

Exa~ple ~

Preparation of 5-Cyclohexyl-1,3,4-thiadiazol-~-yl Isocyanate ~imer A saturated solution of phosgene ir. ethyl acetate ~500 ml) is char~ed into a glass reaction vessel equipped with a mechanical stirrer. 5-Methc.Yy-~-am,~no-1,3,4-thiadiazole ~6 grams) is added to the reaction vessel and the resulting mixture is 5tirred and heated at reflux for a period of about

4 hours, resulting in the ~ormation of a precipitate. The reaction mixture is then purged with nitrogen gas to remove unreacted phosgene. The purged mixture is then filtered to recover the precipitate. The precipitate is then recrys-tallized from a dimethyl for~amide-water mi~ture to yield the desired product 5-cyclohexy1-1,3,4-thiadiazol-2-yl isocyanate dimer having a melting point of 237 to 239C.

Example 5 Preparation of the Dimethyl .~cetal of 2-~3-~ethyl-3-(5-cvclohexyl-1,3,~-thiadiazol-2-yl)ureiao] acetaldehyde A mi~ture of 5-cyçlohe~rl-1,3,~-_hiadiazol-~-yl lsocyanate dimer (12 gr~ms), the dimethyl acetal of 2-methyl-aminoacetaldehvd~ (6.9 gra~s) and benzene (50 ml) are charsed ;' .
.

,.~ : . . . .: , -. ~ . . . .

_ into a glass reaction vèsse~ equipped with a mechanical stirrer and reflux condenser. The reaction mixture is heated at ref~ux for a period of about 15 minutes. After this time the mixture is strlpped of benzene under reduced pressure to yield a solid product as the resiaue. The residue is then recrystallized from methar.ol to yield the desired product the dimethyl acetal of 2- ~-methyl-1-t5-cyclohexyl-1,3,4-thiadiazol-2-yl)ureido] acetaldehyde ha~ing a melt point of 133 to 134C.

Example 6 Preparation of 1-(5-Cyclohe~yl-1,3,4-thi22iazol-2-yl~-3-__ methyl-5-hydroxv-1,3-imidazolidin-2-one The dimethYl acetal of 2~ ~-methyl-3-~5-cyclohexyl-1,3,4-thiadiazol-~-yl~ur2i20 3 acet~ldehyde (lS gramsl, water 1; ~400 ml) and hydrochloric acid (4 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer, thermometer and reflux con2enser. Th~ reaction ~i:cture is heated at reflux for a period of a~out 1~ minutes. The reaction mixture is then filtered while ho. an~ the filtrate is cooled to for~ a precipitate. The precipitate is recovered ~y filtra-ti~n, is dried and is recrystallized from methanol to yield the desired product 1-(5-~yclohe~xyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxv-1,3-imiaazolidin-2-one having a melt point of 154 to 155C.

Example 7 Preparation of 5-Cyclobutyl-1,3,4-thiadiazol-2-yl Isocyanate Dimer A saturated solution of phosgene in ethyl acetate 0 ml) is charge~ into a glass reaction vessel equipped ~0 Iwith a mechanical stirrer. A slurry of 5-cyclobutyl-2-amino-1,3~4-thiadiazole ~45 qrams) in ethyl acetate (300 ml) is .. ., . .: - . ... ... .. . .. .. .. . . . . . . ..... .. . . ... . . ..

1`'~4Z~8 -- added to the reaction vessel and the resulting mixture is stirred for a period of a~ou. 16 hours, resulting in the formation of a precipitate. The reaction mixture is then purged with nitro~en gas to remove unreacted phosgene. The purged mixture is then filtered to recover the precipitate.
The precipitate is then recrystallized to yield the desired product 5-cyclobutyl-1,3,4-thiadiazol-2-yl isocyanate dimer.

Example 8 Prep~ration of the Dimethvl Acetal of 2-l3-Propyl-3-(5-cyclohutyl-1,3,4-thiadiazol-2-yl)ureido] acetaldehyde A mixture of 5-cyclobutyl-1,3,4-thiadiazol-2-yl isocy2nate di~er (0.~5 ~ole), the dim2thyl acetal of 2-propylamlnoacetaldehyde (0.1 mole) and benzene (60 ml~ are charged into a glass reaction vessel equipped with a mechanical stirrer and reflux condenser. The reaction mixture is heated at reflux for a period of about 15 minute~. After this time the mixture is stripped ~f benzene under reduced pressure to yield a solid product as the residue. The residue is then recrystallized to yield the desired product the dimethyl acetal of 2-~3-propyl-3-(5-cyclobutyl-1,3,4-thiadiazol-2-yl)-ureido~ acetaldehyde.

E~ample 9 Preparation of 1-(5-Cyclobutyl-1,3,4-thiadiazol-2-yl)-3-propyl-5-hydroxy-1,3-imidazolidin-2-one The dimethyl acetal of 2-r3-propyl-3-(5-cyclobutyl-1,3,4-thiadiazol-2-yl)ureido~ acetaldehyde (15 grams), water (400 ml) and hydrochl~ric acid (4 ml) are charged into a glass reaction vessel e~uipped with a mechanical stirrer, thermometer and reflux condenser. The reaction mixture is ` heated at reflux for a period of a~out lS minutes. The reaction mlxture is then filtered while hot and the filtrate is cooled _ 7_ .

., .. . . : . , , , : - - , .

to form a precipitate. The precipitate is recovered by filtration, is dried and is recrystallized to yield the desired product l-(5-cyclobutyl-1,3,4-thiadiazol-2-yl)-3-propyl-5-hydro.Yv-1,3-imidazolidin-2-one.

Exa~ple 10 Preparation of 5-Cyclopentyl-1,3,4-thiadia~ol-2-yl Isocvanate Dimer A s~turated solution of phosgene in ethyl ac~tate (100 ml) is charged into a glzss reaction vesse~ equipped with a mechanical stirre_. A slurry of 5-cyclopentyl-2-amino-1,3,4-thiadiazole (50 grams) in ethyl acetate ~00 ml) ~s added to the reactior vessel and the resultins mixture is stirred for a period of about 16 hours, resul.ing in the formation of a precipitate. The reaction mixture is then pur~ed with nitrogen gas to remove unreacted pbosaene. The purged mixture is then filtered to reco~er the precipitate.
~he precipitate is then recrystallized to yield tne desired product 5-cyclopentyl-1,3,4-thiadiazol-2-yl isocyanate dimer.

. .
~x~ple 11 P_eparation o~ the ~i~ethyl Acetal of 2-~3-Methyl-3-(S-cyclopentyl-1~3~4-thiadi~zol-2-yl)ureiao] acetaldehyde A mixture of 5-cyclopentyl-1,3,4-tniadiazol-2-yl isocyanate dimer (0.05 mole), the dimethyl acetat of 2-methylaminoacetaldehyde (0.1 mole) and kenzene (60 ml) are charged into a alass reaction vessel equipped with a mechanical stirrer and reflux condenser. The reaction mixture is heated at reflux 'or a period of a~cut 15 minutes. ~fter this time the mixture is stri~ed of benzene under reduced pressure to yleld a solid product as the residue. The residue is then recryst211ized to yield the desired product the dimethyl '.
~....... j . ~ . .

1~4Z~8 acetal of 2-L3-methyl-3-~5-cyclopentyl-1,3,4-thiadiazol-2-yl)-ureido ~lacetaldehy~e.

Example 12 Preparation of 1-(5-Cyclopentyl-1,3,4-thiadiazol-2-yl)-3-~ethvl-5-hydroxy-1,3-imid2zoliain-2-one .t - i The dimethyl acetal of 2-[3-me~hyl-3-(5-cyclopentyl-1,3,4-thiadiazol-2-yl)ureido~ acetalaehyde ~15 grams), water ~400 ml) and h~drochloric acid (4 ml) are charqed into a ~lass reactio~ vessel equipped with a ~echanical stirrer, thermometer and reflux concenser. ~he reaction mixture is heated at reflux for 2 period of a~out 15 minutes. The reac-tion ~-~ture is then f-ltered while hct ar.d the filtrate is cooled to form a precipitate. The precipitate is recovered ~y filtration, is dried and is recrystallized to yield the desired product 1-(5-cyclopentyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hy~roxy-1,3-imiflazolidin-2-one.

Example 13 Preparation of 5-Cysloheptyl-1,3,4-thiadiazol-2-yl Isocvanate Dimer .
A saturated solution of phosgene in ethyl acetate ~100 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer. A slur~y of 5-cycloheptyl-2-amino-1,3,4-thi~diazole tS0 grams) in ethyl acetate (300 ml) is added to the reaction vessel and the resulting mixture is ~tirred for a period of about 16 hours, resulting in the formation of a precipitate. The reaction mixturc is then purg~d with r.itro~n a3s to renove unre_cte~ ph.osger.e. The , pur~ed mixture is then filtered to recover the precipitate.
! The precipitate is then recrystallized to yield the desired 30i product 5-cycloheptyl-1,3,4-thiadinzol-2-yl isocyanate dimer.

/
.
', ~ ! , , , ' ~ , ' ' ~ , ,' ,' ' . ' ' ' .
. , .: . , . . ' . ' . .

E~8 Preparation of the Dimethyl Acetal of 2-~3-~ethvl-3-~5~
cycloheptyl-1,3,4-thiadiazol-2-yl)ureido] acetaidehyde A mixture of 5-cycloheptyl-1,3,4-thiadiazol-2-yl S isocyanate dimer (0.05 mole), the dimethyl acetal of 2-~ethyl-aminoacetalcieny~e tO.1 ~ole) a~ ~enzane (60 ~ re char~ed into a ~la~s reaction ~Jessel equippe~ with a mechar.ical st~--er ~nd rc~lux ccn~cnser. ~h2 rea_tion mixture is heated at reflux for a period of abo~t 15 ~inutes. After this time the ~i~.ture is striDped of benzene under reduced pressure to yield a solid pro~uct as the r~si~ue. The residue is then recrystallizeZ to yield the desired product th~ dil~ethyl acetal of 2-t3-~ethyl-3-(5-c-yclohQptyl-1,3,4-thiadiazol-2-yl)-ureido~ acetaldehyde.

Exa~?le 15 Preparation of 1-(5-Cycloheptyl-1,3,4-tniadiazol-2-yl)-3-methyl-5-hydroxy-1,3-inidazolidin-2-one The dimethvl ac~tal of 2-~3-methyl-3-(5-cycloheptyl-1,3,4-thiadiazol-2-~yl)~r~ido~ acetaldehy~e (15 ~rams~, water (400 ml) and hy~rochloric acid (4 ml) are ch~rgc~ into a glass r~ction ~esscl cquipped ~ith a mechar.ical s.i-ser, thermome~er and reflux con2enser. The reaction mixture is heate~ at reflux for a perio~ of about 15 minutes. The reaction mix~ure is t'-en fil~ere~ while hot and the filtrate i~ cooled to orm a precipitate. ~he preclp~tate is recovered ~y ~iltration, is drie~ and i~ recrystallized to yield the desired ~ro~uct 1-(5-cycloheDtyl-1,3,~~thiadia2ol-2-yl)-3-~ethyl-5-hy~ro~y-1,3-imi~azolidin-2-one.

A~ditional compounas within the scope of the present lnvention which can ~e pre~ared hy the procedures of the fore-goin~ examples are l-~5-cycloDropyl-1,3,4-thia2i~zol-2-yl~

., . . . / .
.. . .

.. : . . .,. ; .. . . ,. . : . ........... , - . ....... : ,: . -. .
- ~ , . . , . . . ; .. . . ........ . ... . .

lq)~Z~38 ~ 3-ethyl-~-hydro:~y-1,3-i~i~a~olidir-~-one, 1-(5-cyclopropyl-1,3,~-thia~izzol-2-yl)-3-propyl-5-hydroxy-1,3-im~idazolidin-2-one, 1-(5-cycloprop~rl-1,3,4-thiadia~ol-2-yl)-3-eth~1-5-butyl-5-hydroxv-1,3-imidazolidin-2-one, 1-~5-cyclopropyl-1,3,4-thiadiazol-2-vl)-3-pentvl-5-hydro:~y-1,3-imidazolidin-2-one, 1-t5-cvclopropyl-1,3,4-thiadiazol-2-yl)-3-hexyl-~-hydrox~-1,3-imidazolidin-2-one, 1-(5-cvclohe~l-1 J 3,4-~iaZiazol-2-yl)-3-ethyl-_-~.y~ro.~-1,3-i~i~a~olidin-2-one, 1-(5-cyclohexyl-1,3,4-thiadiazol-2-yl)-3-~ropyl-5-hydroxy-1,3-imi~azolidin-2-one, 1-(5-cvclohexyl-1,3,4-th~adiazol-2-yl)-3-butyl-5-hydrox~-1,3-imida~olidin-2-one, 1-~5-cyclohexyl-1,3,4-thiadiazol-2-yl)-3-pentyl-5-hi-droxy-1,3-i~ida~olidln-~-one, 1-~5-cyclohexyl-1,3,~-thia~iazol-2-yl)-3-he~yl-5-hydroxy-1,3-imidazolidin-2-one, 1-(5-cyclobutyl-1,3,4-~hiadiazol-2-yl)-3-ethyl-5-hydroxy-1,3-~ida~olidin-2-one, 1-~5-~yclo-pentyl-1,3,4-thiaai22ol-2-yl)-3-ethyl-i-hydroxy-1,3-imidazolidin-2-one and 1-(;-cycloheptyl-1,3,4-thiadiazol-2-yl)-3-ethyl-

5-hydroxy-1,3-i~i~azolidin-~-one.
F~r practical use as herhicides the compounds of this invention are ~enerally incorporated into herbicidal com~ositions which co~prise an inert carrier and a herbi-cidally toxic a~ount of such a compound. Such herbicidal compositions, which can also be called formulations, enable the ~ctive compound to be applied conveniently to the site of the weed infestation in any desired quantity. These compositions can ~e solids s~uch as dusts, g-anules, or wet-table powders; or tlley can be l~ui~s s~ch a_ solutions, aerosols, or e~ulsifiable concentrates.
For example, dusts can be prepare~ by grinding and blending the active compound with a soli~ inert carrier such .... . . .

~()4Z89~ ~
as the talcs, clays, silicas, pyrophyllite, and the like.
Granular formulations can be prepared by impreg~ating the compound, usually dissolved in a suitable solvent, onto and into granulated carriers such as the attapulgites or the vermicultes usually of a particle size range of from about 0.3 to 1.5 mm. Wettable powders, which can be dis-persed in water or oil to any desired concentration of the active compound, can be prepared by incorporating wetting agents into concentrated dust compositions.
In some cases the active compounds are suffidiently soluble in common organic solvents such as kerosene or xylene so that they can be used directly as solutions in these solvents. Frequently, solutions of herbicides can be dispersed under super-atmospheric pressure as aerosols.
However, preferred liquid herbicidal compositions are emulsifiable concentrates, which comprise an active com-pound according to this invention and as the inert carrier, a solvent and an emulsifier. Such emulsifiable concentrates :
can be extended with water and~or oil to any desired con-- . : :.
centration of active compound for application as sprays to the site of the weed infestation. The emulsifiers , most commonly used in these concentrates are nonionic or mixtures of nonionic with anionic surface-active agents. - :'~
With the use of some emulsifier systems an inverted emulsion (water in oil) can be prepared for direct application to weed infestations. -~
A typical herbicidal composition according to this ~
invention is ill~strated by the following example, in ~ -which the quantities are in parts by weight.
Example 16 Preparation of a Dust Product of Example 3 10 Powdered Talc go ~ I ;2--.- - - , - . , , .,, . - - , . . .

~04;2898 The above ingredients are mixed in a mechanical grinder-blender and are ground until a homogeneous, free-flowing dust of the desired particle size is obtained.
This dust is suitable for direct application to the site of the weed infestation.
The compounds of this invention can be applied as herbicides in any manner recognized by the art. One method for the control of weeds comprises contacting the locus of said weeds with a herbicidal composition com-prising in an inert carrier and as an essential active ingredient, in a quantity which is herbicidally toxic to said weeds, a compound of the present invention. The concentration of the new compounds of this invention in the herbicidal compositions will vary greatly with the ~
type of formulation and the purpose for which it is designed but generally the herbicidal compositions will comprise ;~
from about 0.05 to about 95 percent by weight of the active compounds of this invention. In a preferred embodiment of this invention, the herbicidal compositions will comprise from about 5 to about 75 percent by weight of the active compound. The compositions can also com-prise such additional substances as other pesticides, such as insecticides, nematocides, fungicides, and the like;
stabilizers, spreaders, deactivators, adhesives, stickers, fertilizers, activators, synergists, and the like.
The compounds of the present invention are also useful when combined with other herbicides and/or defol-iants, dessicants, growth inhibitors, and the like in the herbicidal compositions heretofore described. These other ` -materials can comprise from about 5% to about 95% of the active ingredients in the herbicidal compositions. Use of combinations of these ~04Z898 other herbicides and/or defoliants, dessicants, etc. with the compounds of the present invention provide herbicidal .. ~. .
com~ositions which are more effective in controlling weeds and often provide results unattainable with separate com- ' positions of the individual herbicides. The other herbi-cides, defoliants, dessicants and plant growth inhibitors, with which the compounds of this invention can be used in the herbicidal compositions to control weeds, can include -.
chlorophenoxy herbicides such as 2,4-D, 2,4,5-T MCPA, MCPB, 4(2,4-DB), 2,4-DEB, 4-CPB, 4-CPA, 4-CPP, 2,4,5-TB, 2,4,5-'I'ES, 3,4-DA, silvex and the like; carbamate herbicides such as IPC, CIPC, swep, barban, BCPC, CEPC, CPPC, an'd the like;
thiocarbamate and dithiocarbamate herbicides such as CDEC, metham sodium, EPTC, diallate, REBC, perbulate, vernolate ~.
and the like; substituted urea herbicides such as norea, .: . . .
siduron, dichloral urea, chloroxuron, cycluron, fenuron, monuron, m~onuron TCA, diuron, linuron, monolinuron, neburon, buturon, trimeturon and the like; symmetrical triazine ~ ' herbicides such as simazine, chlorazine, atraone, desme-tryne, norazine, ipazine, prometryn,atazine, trietazine, simetone, prometone, propazine, ametryne and the like; '' chloroacetamide herbicides such as alpha-chloro-N, N-dimeth- '~
ylacetamide, CDEA, CDAA, alpha-chloro-N-isopropylacetamide, -2-chloro-N-isopropylacetanilide, 4-(chloroacetyl) morpho-line! l-(chloroacetyl) piperidine, and the like; chlorinated ':;~
aliphatic acid herbicides such as TCA, dalapon, 2,3-dich- :' loropropionic acid, 2,2,3-TPA and the like; chlorinated ;
benzoic acid and phenylacetic acid herbicides such as ' :~
2,3,6-TBA, 2,3,5,6-TBA, tricamba, amiben, fenac, PBA, 2-methoxy-3,6dichlorophenyl-acetic acid, 3-methoxy-2,

6-dichlorophenylacetic acid, 2-42~8 ` methoxy-3,5,6-trichlorophenylacetic acid, 2,4-dichloro-3-nitrobenzoic acid and the like; and such compounds as amino-triazole, m21eic hydrazide, phenyl mercuric acetate, endothal, biuret, technical chlordane, dimethyl 2,3,5,6-tetrachloro-5 terephthalate, diquat, er.on, D~C, ~NBP, dichlobenil, DPA, diphenamid, dipropalin, trifluralin, solan, dicryl, ~erphos, D~'~A, DS~, MSMA, potassium azide, acrolein, benefin, bensulide, ~IS, bromacil, 2(~,4-dichlorophenyl)-4-methyl-1,2,4-oxa-diazolidine-3,5-dione, bromoxynil, cacodylic acid, C.~
CP!~, cypromid, DCB, DCPA, dichlone, diphenatril, DMTT, D~P, EBEP, EXD, RC~, ioxynil, IPX, isocil, potassium cyanate, ?`~A, MAMA, MCPES, MCPP, ~H, molinate, NPA, OC~, paraquat, PCP, picloram, DPA, PCA, pyrichlor, sesone, terbacil, terbutol, TCBA, brominil, CP-50144, H-175-1, ~-732, 'I-2901, planavin, sodium tetraborate, calcium cyanamid, DEF, ethyl xanthogen disulfide, sindone, sindone B, propanil and the like.
Such herbicides can also bé used in the ~.ethods and compositions of this invention in the form of their salts, esters, amides, and other derivatives whenever applicable to the particular parent compounds.
Weeds are undesirable plants growing where they are not wanted, having no econom~c value, and interfering with the production of cultivated crops, with the growing of ornamental plants, or with the welfare of livestock. Many t~pes of weeds are known, including annuals such as pigweed, lam~squarters, foxtail, crabgrass, wild mustard, field pennycress, ryegrass, goose-arass, chickweed, wild oats, velvet leaf, purselane, barnyard grass, smartweed, knotweed, coc~lebur, wild buckwheat, kochia, medic, corn cockle, rag-weed, sowthistle, coffee-weed, croton, cuphea, dodder, fumitory, groundsel, hemp nettle, knowel, spurge, spurry, emex, jungle _ . . -., :, . . .

1~4Z~8 --~ rice, pondwee~, dog ~ennel, carpetweed, morning glory, bedstraw, ducksalad and naiad; biennials such as wild carrot, matricaria, wild barley, campion, cha~omile, burdoc~, mullein, round-leaved mallow, bull thistle, hounds-tongue, ~.oth mullein, and purple star thistle; or perennials such as white cockle, perennial rye-grass, quackgrass, Johnson grass, Canada thistle, hedge bindweed, Bermuda grass, sheep sorrel, curly dock, nutgrass, field chickweed, dandelion, campanula, field bindweed, Russian knapweed, ~esquite, toadflax, yarrow, aster, gromwell, horsetail, ironweed, sesbania, bulrush, cattail and winter-cress.
Si~ilarly, such weeds can be classified as broad-leaf or grassy weeds. It is economically desirable to control the growth of ~uch weeds without damaging beneficial plants or li~estoc~.
The new compounds o this invention are particularly valuable for weed control because they are toxic to many species and ~roups of weeds while they are relatively non-toxic to many beneficial plants. The exact amount of compound required will depend on a variety of factors, including the hardiness o the particular weed species, weather, type of 90il, method of application, the kind of beneficial plants ~n the same area, and the li~e. Thus, while the application of up to only about one or two ounces of active compound per acre may be sufficient for good control of a ligh~ infesta-tion of weed5 growing under adverse conditions, the applica-'tion of ten pounds or more of an active compound per acre I may be required for good control of a dense infestation of ¦ I' hardy perennial weeds growing under favorable conditions.
3Q The herbicidal toxicity of the new compounds of '\this invention can be illustrated by many of the established _ /6-!;
'~
~' ''' . .. , '. ~ - , ' , , ' :' ' . : " , . ` .

l~r~4~8 -- testing technioues known to the art, such as pre- and post-emergence testing.
The herbicidal activity of the compounds of this invention was demonstrated by experiments carried out for the pre-emergence control of a variety of weeds. In these experiments small plastic greenhouse pots filled with dry soil were seeded with the various weed see~s. I~enty-four hours or less after seeding the pots were sprayefl with water until the soil was wet an2 the test co~pounds forr.ulated as aqueous e~ulsions of acetone solutions cortair.ing emulsifiers were sprayed at the indicated concen~rations on the surface of the soil.
~ fter spraying, the soil containers were placed in the greenhouse and provided with supplementary heat as required and daily or more fre~uent watering. The plants were main-tained under these conditions for a period of from lS to 21 days, at which time the condition of the plants and the de~ree of injury to the plants was rated on a scale of from 0 to 10, as follows: 0 = no injury, 1,2 = sliqht injury, 3,4 =
moderate injury, 5,6 = moderately severe injury, 7,8,9 =
severe.injury and 10 = death. The effectiveness of these corpounds is demonstratea by the following data:

_ J 7~

1~4Z~8 -~ ~A3L~ I
Injury ~atin~

Product of Product of Example 3 Example 6 Concentration Concentration (lbs./acre) llbs./acre) Weed S~ecies 4 1 0.25 ~ 1 0.25 Wild Qats 10 9 8 10 9 3 Jimsonweed 10 10 9 10 7 0 Vel~et Leaf 10 10 9 9 4 Johnsongrass 10 8 0 9 7 0 Pigweed 10 9 9 9 9 5 Mustard 10 9 9 9 9 6 Yellow Foxtail 10 9 8 9 4 0 -~arnyardgrass10 10 8 9 5 0 Crabgrass 10 7 0 10 9 0 Cheatgrass 10 10 5 9 9 3 Morning~lory 10 10 3 6 0 The herbicidal activity of the compounds of this invention was also demonstrated by experiments c~rried out for th~ post-emergence control of a variety of weeds. In these e~periments the compounds to be tested were formula~ed as aaueous emulsions and sprayed at the indicated dosaqe on the foliage of the weeds that have attained a prescribed size. After spraying the plants were placed in a greenhouse and watered daily or more frequently. Water was not applied to the foliaqe of the treated plants. The severity of the ~njury was determined 10 to 15 d~ys after treatment and was rated on the scale of from 0 to 10 heretofore described. The effectivenQss of these compounds is de~onstrated by the follow-ing data:

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. . . : :::
- - - :: :
.. - - . . . . . .

104Z898 `: -TABLE~
Injury RatL~g :
Product of Product of Example 3 Example 6 Concentration Concentration (lbs/acre) (lbs./acre) Weed Species 4 1 0.25 4 10.25 Yellow Nutsedge 9 6 O 2 O O
Wild Oats 10 10 6 10 10 7 Jimsonweed 10 10 10 10 10 8 ..
Velvet Leaf 10 10 10 10 10 10 Johnsongrass 10 10 1 10 8 Bindweed 8 10 5 4 2 Mustard 10 10 10 10 10 -'10 ~-Yellow Foxtail 10 10 7 10 9 2 Barnyardgrass 10 10 8 10 10 6 .~
Crabgrass 10 i5 O 10 8 2 ~ :
Morningglory 10 10 9 10 6 9 ;

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Claims (7)

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

1. A compound of the formula wherein R1 is cycloalkyl of from 3 to 7 carbon atoms and R2 is alkyl.

2. The compound of claim 1, 1-(5-cyclopropyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one.

3. The compound of claim 1, 1-(5-cyclobutyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one.

4. The compound of claim 1, 1-(5-cyclopentyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one.

5. The compound of claim 1, 1-(5-cyclohexyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one.

6. The compound of claim 1, 1-(5-cycloheptyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one.

7. A method of controlling weeds which comprises contacting the weeds with a herbicidal composition comprising an inert carrier and, as an essential active ingredient, in a quantity toxic to weeds, a compound of claim 1.