This invention relates to novel thioxo-2-imidazolinyl benzoic acids, esters and salts, a process for the preparation thereof and a method for the control of undesirable monocotyledonous and dicotyledonous plant species therewith.

This invention relates to novel thioxo-2-imidazolinyl benzoic acids, esters 
and salts, a process for the preparation thereof and a method for the 
control of undesirable monocotyledonous and dicotyledonous plant species 
therewith. 
The invention relates, more particularly, to herbicidally effective formula 
I, thioxo-2-imidazolinyl benzoic acids, and their esters and salts; 
formula II, 3-thio-5H-imidazo[2,1-a]isoindole-3(2H),5-diones; formula III, 
2-thio-5H-imidazo[2,1-a]isoindole-2(3H),5-diones; and formula IV, 
1,9-b-dihydro-2-thio-5H-imidazo[2,1-a]isoindole-2(3H),5-diones, depicted 
by the following structures: 
##STR1## 
wherein R is hydrogen; C.sub.1 -C.sub.12 alkyl optionally substituted with 
one of the following groups: C.sub.1 -C.sub.4 alkoxy, halogen, hydroxyl, 
C.sub.3 -C.sub.6 cycloalkyl, benzyloxy, furyl, phenyl, halophenyl, C.sub.1 
-C.sub.4 alkylphenyl, C.sub.1 -C.sub.4 alkoxyphenyl nitrophenyl, carboxyl, 
C.sub.1 -C.sub.3 alkoxycarbonyl, cyano or tri(C.sub.1 
-C.sub.3)alkylammonium; 
C.sub.3 -C.sub.12 alkenyl optionally substituted with one of the following 
groups: C.sub.1 -C.sub.3 alkoxy, phenyl, halogen, or C.sub.1 -C.sub.3 
alkoxycarbonyl or with two C.sub.1 -C.sub.4 alkoxy groups or two halogen 
atoms; 
C.sub.3 -C.sub.6 cycloalkyl optionally substituted with one or two C.sub.1 
-C.sub.3 alkyl groups; 
C.sub.3 -C.sub.10 alkynyl; or, 
a cation, as for example, alkali metals, alkaline earth metals, maganese, 
copper, iron, zinc, cobalt, lead, silver, nickel, ammonium, organic 
ammonium, or the like; 
R.sub.1 and R.sub.2 each represent C.sub.1 -C.sub.3 alkyl or cyclopropyl, 
with the proviso that the sum of the number of carbon atoms in R.sub.1 and 
R.sub.2 is 2 to 5; and when R.sub.1 and R.sub.2 are taken together with 
the carbon to which they are attached, they may form a C.sub.3 -C.sub.6 
cycloalkyl ring optionally substituted with methyl; 
A is hydrogen, hydroxyl, C.sub.3 -C.sub.6 alkenyloxy, C.sub.3 -C.sub.6 
alkynyloxy, C.sub.1 -C.sub.6 alkylthio, NR.sub.13 R.sub.14 or C.sub.1 
-C.sub.6 alkoxy optionally substituted with phenyl, halophenyl, C.sub.1 
-C.sub.3 alkylphenyl, C.sub.1 -C.sub.3 alkoxyphenyl or di-C.sub.1 -C.sub.3 
alkylaminophenyl; 
R.sub.13 is hydrogen, C.sub.1 -C.sub.4 alkyl optionally substituted with 
phenyl, halophenyl, C.sub.1 -C.sub.3 alkylphenyl or C.sub.1 -C.sub.3 
alkoxyphenyl; 
R.sub.14 is hydrogen or C.sub.1 -C.sub.4 alkyl; 
X is hydrogen, halogen or methyl; 
Y and Z are each hydrogen, halogen, C.sub.1 -C.sub.6 alkyl, C.sub.1 
-C.sub.4 hydroxyalkyl, C.sub.1 -C.sub.6 alkoxy, C.sub.1 -C.sub.4 
alkylthio, phenoxy, C.sub.1 -C.sub.4 haloalkyl, OCF.sub.2 CHF.sub.2, 
OCF.sub.3, OCHF.sub.2, nitro, cyano, NR.sub.4 R.sub.5, C.sub.3 -C.sub.8 
straight or branched alkenyloxy optionally substituted with one to three 
halogens, C.sub.3 -C.sub.8 straight or branched alkynyloxy optionally 
substituted with one to three halogens, or phenyl optionally substituted 
with one C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy or halogen; 
R.sub.3 is hydrogen, halogen, C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 
alkylthio, C.sub.1 -C.sub.4 alkoxy, CF.sub.3, NO.sub.2, OCF.sub.3, 
OCHF.sub.2 or OCF.sub.2 CHF.sub.2 ; 
R.sub.4 is hydrogen or C.sub.1 -C.sub.4 alkyl; 
R.sub.5 is C.sub.1 -C.sub.4 alkyl; 
And, when taken together, Y and Z may form a ring in which YZ is 
represented by 
(1) the structure: -(CH.sub.2).sub.n -, where n is an integer of 2, 3 or 
4; or 
(2) by the structure: 
##STR2## 
where, L, M, R.sub.7 and R.sub.8 each represent hydrogen, halogen, 
C.sub.1 -C.sub.4 alkyl or C.sub.1 -C.sub.3 alkoxy, and X is hydrogen; 
and when R.sub.1 and R.sub.2 are not the same, the optical isomers thereof 
and except when R is a cation, the acid addition salts thereof. An 
embodiment of the invention is compounds of formula II wherein R.sub.1 is 
CH.sub.3 ; R.sub.2 is CH(CH.sub.3).sub.2 ; and X, Y, Z and R.sub.3 each 
represent hydrogen, halogen, C.sub.1 -C.sub.3 alkoxy or C.sub.1 -C.sub.3 
alkyl; or the optical isomers thereof. 
As used in the present specification and claims, the term "halogen" means 
F, Cl, Br or I, unless otherwise specified. 
In the present specification and claims, the alkali metals include: sodium, 
potassium and lithium, although sodium is generally preferred. Also, in 
the present specification and claims, unless otherwise specified, the term 
"organic ammonium" is defined as a group consisting of a positively 
charged nitrogen atom joined to from one to four aliphatic groups, each 
containing from one to 20 carbon atoms. Among the organic ammonium groups 
which are illustrative for the preparation of the aliphatic ammonium salts 
of the imidazolidinyl acids are: monoalkylammonium, dialkylammonium, 
trialklammonium, tetraalkylammonium, monoalkenylammonium, 
dialkenylammonium trialkenylammonium, monoalkynylammonium, 
dialkynylammonium, trialkynylammonium, monoalkanolammonium, 
dialkanolammonium, trialkanolammonium, C.sub.5 -C.sub.6 
cycloalkylammonium, piperidinium, morpholinium, pyrrolidinium, 
benzylammonium and equivalents thereof. 
Although some 5-oxo-2-imidazolinyl benzoic acids, esters and salts, 
dihydroimidazoisoindolediones and imidazoisoindolediones are respectively 
described as herbicidal agents in U.S. Pat. No. 4,188,487, issued Feb. 20, 
1980, U.S. Pat. No. 4,041,045, issued Aug. 9, 1977 and U.S. Pat. No. 
4,017,510, issued Apr. 12, 1977; said patents do not teach, suggest or 
disclose, the substituted or unsubstituted 5-thioxo-2-imidazolinyl benzoic 
acids, esters and salts, the 2-thio-dihydroimidazoisoimidolediones or the 
2 or 3 thio-imidazoisoindolediones of the present invention. It was 
therefore surprising to find that the compounds of the present invention, 
as shown and described above, are highly effective, selective, herbicidal 
agents, remarkably effective for the control of quackgrass, in the 
presence of graminaceous crops such as rice, barley, wheat, corn, turf, 
and the like.