GB2045754A

GB2045754A - Tetrahydrobenzothiazolyl- imidazolidinones processes for their preparation, and their use as herbicides

Info

Publication number: GB2045754A
Application number: GB8006873A
Authority: GB
Original assignee: Velsicol Chemical LLC
Current assignee: Velsicol Chemical LLC
Priority date: 1979-03-02
Filing date: 1980-02-29
Publication date: 1980-11-05
Also published as: FR2450257B1; JPS55133381A; IT1127362B; AT365409B; GB2045754B; IL59334A0; ATA113780A; DE3007556A1; NL8001243A; NZ192923A; AR222375A1; IT8048013A0; DK88880A; AU5537680A; BE882010A; CH645109A5; SE8001556L; IL59334A; CA1126734A; BR8001161A

Abstract

Novel compounds of the general formula <IMAGE> wherein X is an alkyl, alkoxy, alkylthio, halogen, dialkylamino or cyano group; n is 0 or an integer of from 1 to 4; and R is an alkyl, alkenyl or haloalkyl group are used as herbicides.

Description

SPECIFICATION Tetrahydrobenzothiazolylimidazolidinones process for their preparation, and their use as herbicides This invention relates to new compositions of matter. More specifically, this invention relates to new chemical compounds of the formula

wherein Xis selected from the group consisting of alkyl, alkoxy, alkylthio, halogen, dialkylamino and cyano; n is an integer from 0 to 4; and R is selected from the group consisting of alkyl, alkenyl, haloalkyl and alkynyl The compounds of the present invention are unexpectedly useful as herbicides and are particularly effective in the post-emergence control of weeds.

In a preferred embodiment of this invention Xis selected from the group consisting of lower alkyl, lower alkoxy, lower alkylthio, chlorine, bromine, di(lower alkyl)amino and cyano; and R is selected from the group consisting of lower alkyl, lower alkenyl, lower chloroalkyl and propargyl.

The compounds of the present invention can be readily prepared by heating a compound of the formula

wherein X, n and R are as heretofore described, in a dilute, aqueous, acidic reaction medium for a period of about 10 to about 90 minutes. Temperatures of from about 60"C to the reflux temperature of the 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 5 percent. Acidic water-ethanol mixtures can also be used. Upon completion of the reaction, the desired product can be recovered as a precipitate or residue upon cooling or evaporation of the reaction mixture. This product can be used as such or can be further purified by conventional means such as recrystallization and the like.

The compounds Formula II can be prepared by reacting a carbamate of the formula

wherein Z is methyl or ethyl, and X and n are as heretofore described, with an acetal of the formula

wherein R is as heretofore described. This reaction can be effected by dissolving the compound of Formula Ill in an equimolar or slight molar excess of the acetal of Formula IV and heating the resulting mixture at a temperatu re of from about 90"C to about 130"C for a period of from 12 to 48 hours in a reaction vessel blanketed with inert gas. The reaction product can then be recovered upon distillation to remove unreacted starting material and can be used as such or can be further purified if desired by standard techniques.

The compounds of Formula Ill are known in the literature but when not readily available can be prepared from a compound of the formula

wherein Z and n are as heretofore described, by reaction with methyl or ethyl chloroformate. This reaction can be effected by slowly adding the chloroformate to a solution of the compound of Formula Ill in an organic solvent in the presence of an acid acceptor. The acid acceptor itself may serve as the solvent such as for example pyridine. After the addition is completed, stirring of the reaction mixture can be continued to ensure completion of the reaction. After such time the desired product can be recovered and can be purified by conventional techniques such washing to remove acid acceptor hydrochloride, recrystallization and the like.

The compounds of Formula V when not readily available can be prepared by the techniques referred to in U.S. Patent 3,682,945.

The compounds of Formula II can also be prepared by reacting a molar amount of an isocyanate dimer of the formula

wherein X and n are as heretofore described, with about two molar amounts of a dimethyl acetal of the formula

wherein R2 is 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 toluene at the reflux temperature of the reaction mixture. Heating at reflux can be continued for a period of from about 2 to about 30 minutes to ensure completion of the reaction. After this time the desired product can be recovered upon evaporation of the reaction medium and can be used as such or can be further purified by standard techniques in the art.

The isocyanate dimer of Formula VI can be prepared by reacting the tetrahydrobenzothiazole of Formula V with phosgene. This reaction can be effected by adding a slurry or solution of the benzothiazole, in a suitable organic solvent such as ethyl acetate, to a saturated solution of phosgene in an organic solvent such as ethyl acetate. The resulting mixture can be stirred at ambient temperatures for a period of from about 4 to about 24 hours. The 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 as desired.

Exemplary tetrahydrobenzothiazole compounds of Formula V suitable for preparing the compounds of the present invention are: 2-amino-4,5,6,7-tetrahydrobenzothiazole 2-amino-4-ch loro-4,5,6,7-tetrahydrobenzothiazole 2-amino-5-methyl-4,5,6,7-tetrahydrobenzothiazole 2-amino-7-ethyl-4,5,6,7-tetrahydrobenzothiazole 2-amino-5-hexyl-4,5,6,7-tetrahydrobenzothiazole 2-amino-5-methoxy-4,5,6,7-tetrahydrobenzothiazole 2-amino-5-cyano-4,5,6,7-tetrahydrobenzothiazole 2-amino-5-methylthio-4,5,6,7-tetrahydrobenzothiazole 2-amino-5,5-diethyl-4,5,6,7-tetrahydrobenzothiazole 2-amino-5-methyl-7-propoxy-4,5,6,7-tetrahydrobenzothiazole 2-amino-5-propylthio-4,5,6,7-tetrahydrobenzothiazole Exemplary suitable acetals of Formula IV for preparing the compounds of this invention are the dimethyl acetal of 2-methylamino-acetaidehyde, the dimethyl acetal of 2-ethylaminoacetaldehyde, the dimethyl acetal of 2-propylaminoacetaldehyde, the dimethyl acetal of 2-butylaminoacetaldehyde, the dimethyl acetal of 2-pentylaminoacetaldehyde and the dimethyl acetal of 2-hexylaminoacetaldehyde.

The manner in which the compounds of the present invention can be prepared is more specifically illustrated in the following examples.

EXAMPLE 1 Preparation of2-Amino-5,5, 5,7,7-tetrameth yl-4, 5,6,7-tetrah ydrobenzo thiazole 3,3,5,5-Tetramethylcyclohexanone (9.9 grams), cyanamid (2.1 grams), sulfur (1.6 grams) and ethanol (8 ml) were charged into a glass reaction vessel equipped with a mechanical stirrer and addition funnel.

Diethylamine (5 ml) was then added dropwise to the reaction mixture with cooling to maintain the reaction mixture below about 45"C. After the addition was completed, the reaction mixture was heated at 40 to 45"C for a period of 2 hours. After this time the reaction mixture was poured into water (100 ml) and was acidified with hydrochloric acid to a pH of 4. The mixture was then washed with ether and the aqueous phase withdrawn and adjusted to a pH of 9 with aqueous sodium hydroxide. The resulting mixture was extracted with ether. The ether extract was then dried over anhydrous magnesium sulfate and evaporated to yield the desired product 2-amino-5,5,7,7-tetramethyl-4,5,6,7-tetrahydrobenzothiazole as a solid melting at 120 to 122".

EXAMPLE 2 Preparation of Ethyl N-(5,5, 7, 7-Tetramethyl-4,5,6, 7-tetrahydrobenzothiazol-2-yl)carbamate 2-Amino-5,5,7,7-tetramethyl-4,5,6,74etrahydrobenzothiazole(1 6 grams; 0.075 mol) dissolved in pyridine (100 ml) was charged into a glass reaction vessel equipped with a mechanical stirrer and addition funnel.

Ethyl chloroformate (11 grams; 0.1 mol) was then added dropwise with stirring and cooling of the reaction mixture. After the addition was completed the reaction mixture was allowed to warm to room temperature and stirring was continued for a period of about 1 hour. After this time the reaction mixture was poured into ice water resulting in a white precipitate. The precipitate was recovered by filtration, was dried and recrystallized from methanol to yield the desired product ethyl N-(5,5,7,7-tetramethyl-4,5,6,7tetrahydrobenzothiazol-2-yl) carbamate having a melt point of 1240 to 125"C.

EXAMPLE 3 Preparation of the DimethylAcetal of2-Jl-Methyl-3-(5,5, 7, 7-tetrarnethyl-4,5, 6, 7-tetrahydrobenzothiazol-2- yl)ureido]acetaldebyde Ethyl N-(5,5,7,7-tetramethyl-4,5,6,7-tetrahydrobenzothiazol-2-yl )carbamate (2 grams) and the dimethyl acetal of 2-methyl-aminoacetaldehyde (20 ml) were charged into a glass reaction flask equipped with a magnetic stirrer, reflux condenser and gas addition tube. The reaction mixture was blanketed with nitrogen gas and was heated at 120"C for a period of about 50 hours. After this time the reaction mixture was distilled under reduced pressure to remove excess unreacted starting material leaving a brown oily residue.This residue was purified by elution chromotography using ethyl acetate as the eluant. The chromatgraphed solution was then stripped of solvent to yield the desired product dimethyl acetal of 2-[1 -methyl-3-(5,5,7,7 tetramethyl-4,5,6,7-tetrahydrobenzothiazol-2-yi)ureido]acetaldehyde as a colorless solid having a melting point of 10800.

EXAMPLE 4 Preparation of l-(5,5, 7,7- Tetrameth yl-4,5, 6, 7-tetrahycrobenzothiazok2-yl)-3-rnethyAs-hy & xy- 1,3imidazolidin-2-one The dimethyl acetal of 2-[1 -methyl-3-(5,5,7,7-tetramethyl-4,5,6,7-tetrahydrobenzothiazol-2- yl)ureido]acetaldehyde (2.5 grams) was dissolved in dilute hydrochloric acid (25 ml; 3.7% conc.). The solution was heated at a temperature of 85"C for a period of about 10 minutes resulting in the formation of a precipitate. Additional hydrochloric acid (15 ml) was added and stirring was continued for about 90 minutes.

After this time the precipitate was recovered by filtration, was washed with water and dried to yield the desired product 1 -(5,5,7,7-tetramethyl-4,5,6,7-tetrahydrobenzothiazol-2-yl)-3-methyl-5-hydroxy-1 3- imidazolidin-2-one having a melt point of 135 to 13800.

EXAMPLE 5 Preparation of 5,5,7-Trimethyl-4,5,6,7-tetrahydrobenzothiazol-2-yl lsocyanate Dimer Asaturated solution of phosgene in ethyl acetate (200 ml) and 2-amino-5,5,7-trimethyl-4,5,6,7tetrahydrobenzothiazole (6.0 grams) were charged into a glass reaction vessel equipped with a mechanical stirrer and reflux condenser. The reaction mixture was heated at reflux for a period of about 5 hours. After this time the reaction was stripped of solvent and unreacted starting materials to yield the desired product 5,5,7-trimethyl-4,5,6,7-tetrahydrobenzothiazol-2-yl-isocyanate dimer as a brown crystalline solid.

EXAMPLE 6 Preparation of the Dimethyl Acetal of 2-[1-Methyl-3-(5,5, 7-trimethyl-q5,6, 7-tetrahydrobenzothiazol-2-y/l- ureido jacetaldehyde 5,5,7-Trimethyl-4,5,6,7-tetrahydrobenzothiazol-2-yl isocyanate dimer (7.5 grams), the dimethyl acetal of 2-methyl-aminoacetaldehyde (5 grams) and toluene (15 ml) were charged into a glass reaction vessel equipped with a mechanical stirrer and reflux condenser. The reaction mixture was then heated, with stirring for a period of about 1 hour. After this time the mixture was cooled and filtered. The filtrate was washed with water, dried and evaporated, leaving the desired product dimethyl acetal of 2-[1-methyl-3-(5,5,7-trimethyl 4,5,6,7-tetrahydrobenzothiazol-2-yl)ureido]acetaldehyde as a brown oil.

EXAMPLE 7 Preparation of 1- (5,5,7- Trirneth yl-4, 5,6,7-tetrah ydrobenzo thiazol-2-yl)-3-rn ethyl-S-h ydroxy- 1,3-imidazolidin- 2-one The dimethyl acetal of 2-[1 -methyl-3-(5,5,7-trimethyl-4,5,6,7-tetrahydrobenzothiazol-2- yl)ureido]acetaldehyde (8.5 grams), water (25 ml), ethanol (25 ml) and concentrated hydrochloric acid (8.5 ml) were charged into a glass reaction vessel equipped with a mechanical stirrer, thermometer and reflux condenser. The reaction mixture was then heated at reflux for a period of about 10 minutes. After this time the reaction mixture was stripped of solvents to yield the desired product 1-(5,5,7-trimethyl-4,5,6,7- tetrahydrobenzothiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one as a brown solid.

EXAMPLE 8 Preparation of Ethyl N-(5,7-Dimethoxy-4,5,6,7-tetrahydrobenzothiazol-2-yl)carbamate 2-Amino-5,7-dimethoxy-4,5,6,7-tetrahydrobenzothiazole (0.10 mol) dissolved in pyridine (125 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer, thermometer and addition funnel.

Ethyl chloroformate (0.12 mol) is then added dropwise to the reaction mixture with stirring and cooling. After the addition is completed the reaction mixture is allowed to warm to room temprature and stirring is continued for a period of about 1 hour. After this time the reaction mixture is poured into ice water to form a precipitate. The precipitate is recovered by filtration, is dried and recrystallized to yield the desired product ethyl N-(5,7-dimethoxy-4,5,6,7-tetrahydrobenzothiazo l-2-yl )carbamate.

EXAMPLE 9 Preparation of the Dimethyl Acetal of2-[l-Ethyl-3-(5, 7-dimethoxy-4,5, 6, 7-tetrahydrobenzothiazol-2- yl)ureidol-acetaldehyde.

Ethyl N-(5,7-dimethoxy-4,5,6,7-tetrahydrobenzothiazol-2-yl)-carbamate (0.08 mol) and the dimethyl acetal of 2-ethylaminoacetaldehyde (30 mi) are charged into a glass reaction vessel equipped with a stirrer, reflux condenser and gas addition tube. The reaction mixture is blanketed with nitrogen gas and is heated at 125"C for a period of about 8 hours. After this time the reaction mixture is distilled to remove excess starting material. The residue is purified by elution chromatography using ethyl acetate as the eluant. The chromatographed solution is then stripped of solvent to yield the desired product dimethyl acetal of 2-[1 -ethyl-3-(5,7-dimethoxy-4,5,6,7-tetrahydrobenzothiazol-2-yl )ureido]acetaldehyde.

EXAMPLE 10 Preparation of 1-(5,7-Dimethoxy-4,5,6,7-tetrahydrobenzothiazol-2-yl)-3-ethyl-5-hydroxy-1,3-imidazolidin-2- one The dimethyl acetal of 2-[1-ethyl-3-(5,7-dimethoxy-4,5,6,7-tetrahydrnbenzothiazol-2-yl)ureido]- acetaldehyde (0.05 mol) and dilute hydrochloric acid (25 ml; 3% conc.) are charged into a glass reaction vessel equipped with a mechanical stirrer and thermometer. The reaction mixture is heated at a temperature of about 85 C for a period of about 45 minutes resulting in the formation of a precipitate. After this time the precipitate is recovered by filtration and dried to yield the desired product 1-(5,7-dimethyoxy-4,5,6,7tetrahydrobenzothiazol-2-yl)-3-ethyl-5-hydroxy-1 ,3-imidazol idin-2-one.

EXAMPLE 11 Preparation of Ethyl N-(5-Ethyl-7-chloro-4,5,6,7-tetrahydrobenzothiazol-2-yl)carbamate 2-Amino-5-ethyl-7-chloro-4,5,6,7-tetrahydrobenzothiazole (0.10 mol) dissolved in pyridine (125 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer, thermometer and addition funnel.

Ethyl chloroformate (0.12 mol) is then added dropwise to the reaction mixture with stirring and cooling. After the addition is completed the reaction mixture is allowed to warm to room temperature and stirring is continued for a period of about 1 hour. After this time the reaction mixture is poured into ice water to form a precipitate. The precipitate is recovered by filtration, is dried and recrystallized to yield the desired product ethyl N-(5-ethyl-7-chloro-4,5,6,7-tetrahydrobenzothiazol-2-yl )carbamate.

EXAMPLE 12 Preparation of the Dimethyl cetal of 2-[1-Allyl-3-(5-ethyl-7-chloro-4,5,6,7-tetrahydrobenzothiazol-2-yl)- ureido]acetaldehyde.

Ethyl N-(5-ethyl-7-chloro-4,5,6,7-tetrahydrobenzothiazol-2-yl)-carbamate (0.08 mol) and the dimethyl acetal of 2-allylaminoacetaldehyde (30 ml) are charged into a glass reaction vessel equipped with a stirrer, reflux condenser and gas addition tube. The reaction mixture is blanketed with nitrogen gas and is heated at 1 25CC for a period of about 8 hours. After this time the reaction mixture is distilled to remove excess starting material. The residue is purified by elution chromatography using ethyl acetae as the eluant. The chromatographed solution is then stripped of solvent to yield the desired product di-methyl acetal of 2-[1 -alIyl-3-(5-ethyl-7-chloro-4,5,6,74etrahydrobenzothiazol-2-yl)u reido]acetaldehyde.

EXAMPLE 13 Preparation of 1-(5-Ethyl-7-chloro-4,5,6,7-tetrahydrobenzothiazol-2-yl)-3-allyl-5-hydroxy- 1,3-imidazolidin-2- one The dimethyl acetal of 2-[1-allyl-3-(5,5-diethyl-4,5,6,7-tetrahydrobenzothiazol-2-yl)ureido]acetaldehyde (0.05 mol) and dilute hydrochloric acid (25 ml; 3% conc.) are charged into a glass reaction vessel equipped with a mechanical stirrer and thermometer. The reaction mixture is heated at a temperature of about 85 C for a period of about 45 minutes resulting in the formation of a precipitate. After this time the precipitate is recovered by filtration and dried to yield the desired product 1 -(5-ethyl-7-chloro-4,5,6,7tetrahydrobenzothiazol-2-yl )-3-a llyl-5-hydroxy-1 ,3-imidazolidin-2-one.

EXAMPLE 14 Preparation of Ethyl N- (7-Me th ylthio-4, 5,6, 74etrahydrobenzothiazol-2-yl)carbamate 2-Amino-7-methylthio-4,5,6,7-tetrahydrobenzothiazole (0.10 mol) dissolved in pyridine (125 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer, thermometer and addition funnel. Ethyl chloroformate (0.12 mol) is then added dropwise to the reaction mixture with stirring and cooling. After the addition is completed the reaction mixture is allowed to warm to room temperature and stirring is continued for a period of about 1 hour. After this time the reaction mixture is poured into ice water to form a precipitate.

The precipitate is recovered by filtration, is dried and recrystallized to yield the desired product ethyl N-(7-methylthio-4,5,6,7-tetra hydrobenzothiazol-2-yl) carbamate.

EXAMPLE 15 Preparation of the Dimethyl Acetal of 2-1'1- Chloroethyl-3-(7-methylthio-4,5, i-tetrah 7-tetrahydrobenzothiazol-2-yl) ureidolacetaldehyde Ethyl N-(7-methylthio-4,5,6,7-tetrahydrobenzothiazol-2-yl )-carbamate (0.08 mol) and the dimethyl aceta I of 2-Q-chloroethyl-aminoacetaldehyde (30 ml) are charged into a glass reaction vessel equipped with a stirrer, reflux condenser and gas addition tube. The reaction mixture is blanketed with nitrogen gas and is heated at 1 25"C for a period of about 8 hours. After this time the reaction mixture is distilled to remove excess starting material. The residue is purified by elution chromatography using ethyl acetate as the eluant.The chromatographed solution is then stripped of solvent to yield the desired product dimethyl acetal of 2-[1 -ss-chlorethyl-3-(7-methylthio-4,5,6,7-tetrahydrobenzothiazol-2-yi)u reidojaceta Idehyde.

EXAMPLE 16 Preparation of 1-r7-Methylthio,4,5, 6, ydrob enzo thiazol-2-yl)-3- frchlornethyl-5-h ydroxy- 1,3-imidazoli- din-2-one The di methyl acetal of 2-[1 --chlornethyl-3-(7-methylthio-4,5,6,7-tetrahydrobenzothiazol-2- yl)ureido]acetaldehyde (0.05 mol) and dilute hydrochloric acid (25 ml; 3% conc.) are charged into a glass reaction vessel equipped with a mechanical stirrer and thermometer. The reaction mixture is heated at a temperature of about 85"C for a period of about 45 minutes resulting in the formation of a precipitate. After this time the precipitate is recovered by filtration and dried to yield the desired product 1-(7-methylthio 4,5,6,7-tetrahydrobenzothiazol-2-yl)-3--chlornefhyl-5-hydroxy-1 ,3-imidazolidin-2-one.

EXAMPLE 17 Preparation of Ethyl-N-{5-Propyl-7-cyano-4,5,6,7-tetrahydrobenzothiazol-2-yl)carbamate 2-Amino-5-propyl-7-cyano-4,5,6,7-tetrahydrobenzothiazole (0.10 mol) dissolved in pyridine (125 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer, thermometer and addition funnel.

Ethyl chloroformate (0.12 mol) is then added dropwise to the reaction mixture with stirring and cooling. After the addition is completed the reaction mixture is allowed to warm to room temperature and stirring is continued for a period of about 1 hour. After this time the reaction mixture is poured into ice water to form a precipitate. The precipitate is recovered by filtration, is dried and recrystallized to yield the desired product ethyl-N-(5-propyl-7-cyano-4,5,6,7-tetrahydrobenzothiazol-2-yl )carbamate.

EXAMPLE 18 Preparation of the Dimethyl Acetal of 2-I-But-3-en yl-3- (5-prop yl- 7-c yan o-4,5,6, 7-tetrahydrnhenzothlazoA2- yl)-ureido]acetaldehyde Ethyl N-(5-propyl-7-cyano-4,5,6,7-tetrahydrobenzothiazol-2-yl)carbamate (0.08 mol) and the dimethyl acetal of 2-but-3-enylamino-acetaldehyde (30 ml) as charged into a glass reaction vessel equipped with a stirrer, reflux condenser and gas addition tube. The reaction mixture is blanketed with nitrogen gas and is heated at 125"C for a period of about 8 hours. After this time the reaction mixture is distilled to remove excess starting material. The residue is purified by elution chomatography using ethyl acetate as the eluant.

The chromatographed solution is then stripped of solvent to yield the desired product dimethyl acetal of 2-[1 -but-3-enyl-3-(5-propyl-7-cyano-4,5,6,7-tetrahydrobenzothiazol-2-yl)ureido]acetaldehyde.

EXAMPLE 19 Preparation of l-(5-Prop yl- 7-cyano-4, 5,6, 7-tetrah ydrobenzo thiazol-2-yl)-3-b ut-3-en yl-5-h ydroxy- 1,3- imidazolidin-2-one The dimethyl acetal of 2-[1 -but 3-enyl-3-(5-propyl-7-cyano-4,5,6,7tetrahydrobenzothiazol-2- yl)ureido]acetaldehyde (0.05 mol) and dilute hydrochloric acid (25 ml; 3% conc.) are charged into a glass reaction vessel equipped with a mechanical stirrer and thermometer. The reaction mixture is heated at a temperature of about 85"C for a period of about 45 minutes resulting in the formation of a precipitate. After this time the precipitate is recovered by filtration and dried to yield the desired product 1-(5-propyl-7-cyano4,5,6,7-tetrahydrobenzothiazol-2-yl )-3-but-3-enyl-5-hydroxy-l ,3-i midazolidin-2-one.

EXAMPLE 20 Preparation of Ethyl N- (5-Hex yl- 7-propoxy-4, 5,6, 7-tetrahydrobenzothiazol-2-yl)carbamate.

2-Amino-5-hexyl-7-propoxy-4,5,6,7-tetrahydrobenzothiazole (0.10 mol) dissolved in pyridine (125 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer, thermometer and addition funnel.

Ethyl chloroformate (0.12 mol) is then added dropwise to the reaction mixture with stirring and cooling. After the addition is completed the reaction mixture is allowed to warm to room temperature and stirring is continued for a period of about 1 hour. After this time the reaction mixture is poured into ice water to form a precipitate. The precipitate is recovered by filtration, is dried and recrystallized to yield the desired product ethyl N-(5-hexyl-7-propoxy-4,5,6,7-tetrahydrobenzothiazol-2-yl)carbamate.

EXAMPLE 21 Preparation of the Dimeth yl A cetal of2-Jl-Prop yl-3-/5-hexyl-7-propoxy-4,5, 6, 7-tetrahydrobenzothiazol-2- yl)ureido]-acetaldehyde Ethyl N-(5-hexyl-7-propoxy-4,5,6,7-tetrahydrobenzothiazol-2-yl)carbamate (0.08 mol) and the dimethyl acetal of 2-propylaminoacetaldehyde (30 ml) are charged into a glass reaction vessel equipped with a stirrer, reflux condenser and gas addition tube. The reaction mixture is blanketed with nitrogen gas and is heated at 125"C for a period of about 8 hours. After this time the reaction mixture is distilled to remove excess starting material. The residue is purified by elution chromatography using ethyl acetate as the eluant.The chromatographed solution is then stripped of solvent to yield the desired product di-methyl acetal of 2-[1 -Propyl-3-(5-hexyl-7-propoxv-4,5,6,7-tetrahydrobenzothiazol-2-yl)u reido]acetaldehyde.

EXAMPLE 22 Preparation of 1-(5-Hexyl-7-propoxy-4, 5,6, 7-tetrah ydrobenzothiazol-2-yl)-3-prop yl-5-h ydroxy- 1,3- imidazolidin-2-one The dimethyl acetal of 2-[1 -propyl-3-(5-hexyl-7-propoxy-4,5,6,7-tetrahydrobenzothiazol-2- yl)ureido]acetaldehyde (0.05 mol) and dilute hydrochloric acid (25 ml; 3% conc.) are charged into a glass reaction vessel equipped with a mechanical stirrer and thermometer. The reaction mixture is located at a temperature of about 85"C for a period of about 45 minutes resulting in the formation of a precipitate. After this time the precipitate is recovered by filtration and dried to yield the desired product 1 -(5-hexyl-7-propoxy 4,5,6,7-tetrahydrobenzothiazol-2-yl)-3-propyl-5-hydroxy-1,3-imidazo lidin-2-one.

EXAMPLE 23 Preparation of Ethyl N-{5-Ethylthio-4,5,6,7-tetrahydrobenzothiazol-2-yl)carbamate 2-Amino-5-ethylthio-4,5,6,7-tetrahydrobenzothiazole (0.10 mol) dissolved in pyridine (125 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer, thermometer and addition funnel. Ethyl chloroformate (0.12 mol) is then added dropwise to the reaction mixture with stirring and cooling. After the addition is completed the reaction mixture is allowed to warm to room temperature and stirring is continued for a period of about 1 hour. After this time the reaction mixture is poured into ice water to form a precipitate.

The precipitate is recovered by filtration, is dried and recrystallized to yield the desired product ethyl N-(5-ethylthio-4,5,6,7-tetrahydrobenzothiazol-2-yl)carbamate.

EXAMPLE 24 Preparation of the DimethylAcetal of 2-f 1-Bromomethyl-3-65-ethylthio-4,5,6, 6, 7-tetrahydrobenzothiazol-2- yl)ureidol-acetaldehyde Ethyl N-(ethylthio-4,5,6,7-tetrahydrobenzothiazol-2-yl)-carbamate (0.08 mol) and the dimethyl acetal of 2-bromomethylamino-acetaldehyde (30 ml) are charged into a glass reaction vessel equipped with a stirrer, reflux condenser and gas addition tube. The reaction mixture is blanketed with nitrogen gas and is heated at 12500 for a period of about 8 hours. After this time the reaction mixture is distilled to remove excess starting material. The residue is purified by elution chromatography using ethyl acetate as the eluant.The chromatographed solution is then stripped of solvent to yield the desired product dimethyl acetal of 2-[1 -bromomethyl-3-(5-ethylthio-4,5,6,74etrahydrobenzothiazol-2-yI)ureidoiaceta Idehyde.

EXAMPLE 25 Preparation of l-(5-Eth ylthio-4, 5,6, 7-tetrah ydrobenzothiazol-2-yl)-3-bromometh yl-5-h ydroxy- 1,3- imidazolidin-2-one The dimethyl acetal of 2-[1 -bromomethyl-3-(5-ethylthio-4,5,6,7-tetrahydrobenzothiazol-2- yl)ureido]acetaldehyde (0.05 mol) and dilute hydrochloric acid (25 ml; 3% conc.) are charged into a glass reaction vessel equipped with a mechanical stirrer and thermometer. The reaction mixture is heated at a temperature of about 85"C for a period of about 45 minutes resulting in the formation of a precipitate. After this time the precipitate is recovered by filtration and dried to yield the desired product 1 -(5-ethylthio-4,5,6,7 tetrahydrobenzothiazol-2-yl)-3-bromomethyl-5-hydroxy-1 ,3-imidazolidin-2-one.

EXAMPLE 26 Preparation of Ethyl N-(4,5, 6,7-tetrah ydrobenzo thiazol-2-yl)carbamate 2-Amino-4,5,6,7-tetrahydrobenzothiazole (0.10 mol) dissolved in pyridine (125 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer, thermometer and addition funnel. Ethyl chloroformate (0.12 mol) is then added dropwise to the reaction mixture with stirring and cooling. After the addition is completed the reaction mixture is allowed to warm to room temperature and stirring is continued for a period of about 1 hour. After this time the reaction mixture is poured into ice water to form a precipitate. The precipitate is recovered by filtration, is dried and recrystallized to yield the desired product ethyl N-(4,5,6,7-tetrahydrobenzothiazol-2-yl)carbamate.

EXAMPLE 27 Preparation of the DimethylAcetal of2-[l-Methyl-3-(4,5,6, 7-tetrahydrobenzothiazol-2-yl)ureido] acetaldeh yde Ethyl N-(4,5,6,7-tetrahydrobenzothiazol-2-yl)carbamate (0.08 mol) and the dimethyl acetal of 2methylaminoacetaldehyde (30 ml) are charged into a glass reaction vessel equipped with a stirrer, reflux condenser and gas addition tube. The reaction mixture is blanketed with nitrogen gas and is heated at 125"C for a period of about 8 hours. After this time the reaction mixture is distilled to remove excess starting material. The residue is purified by elution chromatography using ethyl acetate as the eluant.The chromatographed solution is then stripped of solvent to yield the desired product dimethyl acetal of 2-[1 -methyl-3-(4,5,6,7-tetrahydrobenzothiazol-2-yl)u reido]acetaldehyde.

EXAMPLE 28 Preparation of 1-(4,5, 6, 7-tetrahydrobenzothiazol-2-yl)-3-meth yl-5-h ydroxy- 1, 3-imidazolidin-2-one The dim ethyl acetal of 2-[1 -methyl-3-(4,5,6,7-tetrahydrobenzothiazol-2-yl)ureidojacetaldehyde (0.05 mol) and dilute hydrochloric acid (25 ml; 3% conc.) are charged into a glass reaction vessel equipped with a mechanical stirrer and thermometer. The reaction mixture is heated at a temperature of about 85"C for a period of about 45 minutes resulting in the formation of a precipitate. After this time the precipitate is recovered by filtration and dried to yield the desired product 1-(4,5,6,7-tetrahydrobenzothiazol-2-yl)-3- methyl-5-hydroxy-1 ,3-imidazolidin-2-one.

Additional compounds within the scope of the present invention which can be prepared by the methods detailed in the foregoing examples are: 1 -(5-propylthio-4,5,6,7-tetrahydrothiazol-2-yl)-3--iodobuwl-5-hydroxy-1 ,3-imidazolidin-2-one, 1 -(5- butylthio-4,5,6,7-tetrahydrothiazol-2-yl)-3-methyl-5-hydroxy-1 ,3-imidazolidin-2-one, 1 -(7-pentylthio-4,5,6,7- tetrahydrothiazol-2-yl)-3-butyl-5-hydroxy-1 ,3-imidazolidin-2-one, 1 -(7-hexylthio-4,5,6,7-tetrahydrothiazol-2 yI)-3-pentyl-5-hydroxy-1 ,3-imidazolidin-2-one, 1 -(5,7-diethoxy-4,5,6,7-tetrahydrothiazol-2-yl)-3-hexyl-5- hydroxy-1 ,3-imidazolidine-2-one, 1 -(5-butoxy-4,5,6,7-tetrahydrothiazol-2-yl)-3-pent-4-enyl-5-hydrnxy-1 ,3- imidazolidin-2-one, 1 -(7-hexyloxy-4,5,6,7-tetrahydrothiazoi-2-yl )-3-hex-3-enyl-5-hydroxy-1 ,3-i midazolidi n-2one, 1 -(5,7-dibutyl-4,5,6,7-tetrahydrothiazol-2-yl )-3-p-fluoroethyl-5-hydroxy-1 ,3-imidazolidin-2-one, 1 -(5,5,7- triethyl-4,5,6,7-tetrahydrothiazol-2-yl)-3-6-chloroheXyl-5-hydroxy-1,3-imidazolidin-2-one,1-(5,5,7-trimethyl- 7-cyano-4,5,6,7-tetrahydrothiazol-2-yl )-3-methyl-5-hydroxy-1 ,3-i m idazo I id i n-2-one,1 -(5-cyano-5, 7-dimethyl4,5,6,7-tetrahydrothiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one,1 -(5-di methylamino-4,5,6,7- tetrahydrothiazol-2-yl)-3-methyl-5-hydroxy- 1 ,3-imidazolidin-2-one, 1 -(5-diethylamino-4,5,6,7- tetrahydrothiazol-2-yl )-3-methyl-5-hydroxy- ,3-i midazolidine-2-one, 1 -(7-dibutylamino-4,5,6,7- tetrahydrothiazol-2-yl)-3-propargyl-5-hydroxy-1 ,3-imidazolidin-2-one, 1 -(5,5,7-tri methyl-4,5,6,7- tetrahydrothiazol-2-yl)-3-propargyl-5-hydroxy-1 ,3-i midazolidi n-2-one, 1 -(5-bromo-4,5,6,7-tetrahydrnthiazI- 2-yl)-3-propargyl-5-hydroxy-1 ,3-imidazolidin-2-one.

For practical use-as herbicides the compounds of this invention are generally incorporated into herbicidal compositions which comprise an inert carrier and a herbicidally toxic amount of such a compound. Such herbicidal compositions, which can also be called formulations, enable the active compound to be applied conveniently to the site of the weed infestation in any desired quantity. These compositions can be solids such as dusts, granules, or wettable powders; or they can be liquids such as solutions, aerosols or emulsifiable concentrates.

For example, dusts can be prepared by grinding and blending the active compound with a solid inert carrier such as the talcs, clays, silicas, pyrophyllite, and the like. Granular formulations can be prepared by impregnating the compound, usually dissolved in a suitable solvent, onto and into granulated carriers such as the attapulgites or the vermiculites, usually of a particle size range of from about 0.3 to 1.5 mm. Wettable powders, which can be dispersed 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 sufficiently 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 suhper-atmospheric pressure as aerosols. However, preferred liquid hericidal compositons are emulsifiable concentrates, which comprise an active compound 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 concentration 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 illustrated by the following example, in which the quantities are in parts by weight.

EXAMPLE 29 Preparation ofa Dust Product of Example 10 Powdered Talc 90 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 comprising 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 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 comprise 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 defoliants, 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 other herbicides and/or defoliants, dessicants, etc. with the compounds of the present invention provide herbicidal compositions which are more effective in controlling weeds and often provide results unattainable with separate compositions of the individual herbicides.The other herbicides, 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-TES, 3,4-DA, silvex and the like; carbamate herbicides such as IPC, CIPC, swep, barban, BCPC, CEPC, CPPC, and the like; thiocarbamate and dithiocarbamate herbicides such as CDEC, metham sodium, EPTC, diallate, PEBC, perbulate, vernolate and the like; substituted urea herbicides such as norea, siduron, dichloral urea, chloroxuron, cycluron, fenuron, monuron, monuron TCA, diuron, linuron, monolinuron, neburon, buturon, trimeturon and the like; symmetrical triazine herbicides such as simazine, chlorazine, atraone, desmetryne, norazine, ipazine, prometryn, atrazine, trietazine, simetone, prometone, propazine, ametryne, and the like; chloroacetamide herbicides such as alpha-chloro-N, N-dimethylacetamide, CDEA, CDAA, alpha-chloro-Nisopropylacetamide, 2-chloro-N-isopropylacetanilide, 4-(chloroacetyl)morpholine, 1-(chloracetyl)piperidine, and the like; chlorinated aliphatic acid herbicides such as TCA, dalapon, 2,3,-dichloropropionic 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, dicamba, tricamba, ami ben, fenac, PBA, 2-methoxy-3,6-dichlorophenylacetic acid, 3-methoxy- 2,6-dichlorophenylacetic acid, 2-methoxy-3,5,6-trichlorophenylacetic acid, 2,4-dichlorn-3-nitrnbenzoic acid and the like; and such compounds as amino-triazole, maleic hydrazide, phenyl mercuric acetate, endothal, biuret, technical chlordane, dimethyl 2,3,5,6-tetrachloroterephthalate, diquat, erbon, DNC, DNBP, dichlobenil, DPA, diphenamid, dipropalin, trifluraline, solan, dicryl, merphos, DMPA, DSMA, MSMA, potassium azide, acrolein, benefin, bensulide, AMS, bromacil, 2-(3,4-dichlorophenyl)-4-methyl-1,2,4-oxadiazolidine-3,5- dione, bromoxynil, cacodylic acid, CMA, CPMF, cypro-mid, DCB, DCPA, dichlone, diphenatril, DMTT, DNAP, EBEP, EXD, HCA, ioxynil, IPX, isocil, potassium cyanate, MAA, MAMA, MCPES, MCPP, MH, molinate, NPA, OCH, paraquat, PCP, picloram, DPA, PCA, pyrichlor, sesone, terbacil, terbutol, TCBA, brominil, CP-50144, H-176-1, H-732, M-2901, planavin, sodium tetraborate, calcium cyanamid, DEF, ethyl xanthogen disulfide, sindone, sindone B, propanil and the like.

Such herbicides can also be used in the methods and composition 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 economic value, and interfering with the production of cultivated crops, with the growing of ornamental plants, or with the weifare of livestock. Many types of weeds are known, including annuals such as pigweed, lambsquarters, foxtail, crabgress, wild mustard, field pennycress, ryegrass, goose-grass, chickweed, wild oats, velvet leaf, purselane, barnyard grass, smartweed, knotweed, cocklebur, wild buckwheat, kochia, medic, corn cockle, ragweed, sowthistle, coffee-weed, croton, cuphea, dodder, fumitory, groundsel, hemp nettle, knowel, spurge, spurry, emex, jungle rice, pondweed, dog fennel, carpetweed, morning glory, bedstraw, ducksalad and naiad; biennials such as wild carrot, matricaria, wild barley, campion, chamomile, burdock, mullein, roundleaved mallow, bull thistle, hounds-tongue, moth mullien, 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, mesquite, toadflax yarrow, aster, gromwell, horsetail, ironweed, sesbania, bulrush, cattail and winter-cress.

Similarly, such weeds can be classified as broadleaf or grassy weeds. It is economically desirable to control the growth of such weeds without damaging beneficial plants or livestock.

The new compounds of this invention are particularly valuable for weed control because they are toxic to many species and groups of weeds while they are relatively nontoxic to many beneficial plants. The exact amount of compound required will depend on a variety of factors, including the hardiness of the particular weed species, weather, type of soil, method of application, the kind of beneficial plants in the same area, and the like. 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 light infestation of weeds growing under adverse conditions, the application often pounds or more of active compound per acre may be required for good control of a dense infestation of hardy perennial weeds growing under favorable conditions.

The herbicidal toxicity of the new compounds of this invention can be illustrated by many of the established testing techniques known to the art, such as pre- and post- emergence testing.

EXAMPLE 30 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 seeds. Twenty-four hours or less after seeding, the pots were sprayed with water until the soil was wet and the test compounds formulated as aqueous emulsions of acetone solutions containing emulsifiers were sprayed at the indicated concentrations on the surface of the soil.

After spraying, the soil containers were placed in the greenhouse and provided with supplementary heat as required and daily or more frequent watering. The plants were maintained under these conditions for a period of from 15 to 21 days, at which time the condition of the plants and the degree of injury to the plants was rated on a scale of from 0 to 10, as follows: 0 = no injury, 1,2 = slight injury, 3,4 = moderate injury, 5,6 = moderately severe injury, 7,8,9 = severe injury and 10 = death. The effectiveness of these compounds is demonstrated by the following data set out in Tables I and II. Numbers with decimal piaces are the result of averaging two or more ratings obtained from replicate experiments.

The herbicidal activity of the compounds of this invention was also demonstrated by experiments carried out for the post-emergence control of a variety of weeds. In these experiments the compounds to be tested were formulated as aqueous emulsions and sprayed at the indicated dosage on the foliage of the various weed species 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 foliage of the treated plants. The severity of the injury was determined 10 to 15 days after treatment and was rated on the scale of from 0 to 10 heretofore described.The effectiveness of these compounds is demonstrated by the following data set forth in Tables lli and IV. Vaiues with decimal places again are the result of averaging of replicate experiments.

TABLE I - PRODUCT OF EXAMPLE 4 Pre-emergence: Injury Rating Concentration - Ibs/acre Weed Species 8.0 2.0 1.0 0.5 0.25 0.125 Yellow Nutsedge 5 0 0.0 - - Wild Oats 10 10 6.7 5.0 2.5 1.0 Jimsonweed 10 10 10.0 - 4.0 5.0 Velvetleaf 10 10 9.0 8.5 10.0 8.5 Johnsongrass 9 10 7.7 6.5 2.5 2.0 Pigweed 9 9 7.0 3.5 1.5 1.0 Wild Mustard 10 10 10.0 10.0 10.0 4.0 Yellow Foxtail 10 8 7.0 5.5 2.0 1.5 Barnyardgrass 10 10 9.3 10.0 7.0 0.0 Crabgrass 9 8 8.0 7.0 3.0 1.5 Cheatgrass 10 9 7.0 5.0 3.5 0.5 Morningglory 8 10 8.3 7.0 4.0 4.5 Birdweed - - 10.0 5.0 3.0 1.5 Quackgrass - - 5.5 4.5 4.0 2.5 Sprangletop - - 10.0 9.0 4.5 3.5 Pintobeau - - 9.5 6.5 3.0 2.5 Sugarbeet - - 9.0 8.5 8.0 9.5 Wheat - - 9.5 8.0 7.5 2.5 Rice - - 4.0 3.5 3.0 2.0 Soybean - - 6.5 4.0 1.0 1.0 Cotton - - 10.0 5.0 2.5 0.5 Sorghum - - 10.0 10.0 5.0 4.5 Corn - - 7.0 5.5 3.0 0.5 Alfalfa - - 10.0 3.5 2.0 1.0 Oat - - 6.5 2.5 2.0 1.0 TABLE II - PRODUCT OF EXAMPLE 7 Pre-emergence: Injury Rating Concentration - Ibs/acre Weed Species 2.0 1.0 0.5 0.25 0.125 Yellow Nutsedge 3.0 0.0 0.0 Wild Oats 10.0 9.3 2.7 0.0 0.0 Jimsonweed 10.0 4.0 2.5 4.0 1.0 Velvetleaf 10.0 10.0 8.5 5.5 1.0 Johnsongrass 10.0 6.5 3.2 0.0 0.0 Pigweed 10.0 6.0 3.5 0.0 0.0 Wild Mustard 10.0 9.0 10.0 1.0 0.5 Yellow Foxtail 9.0 6.7 2.2 0.5 0.5 Barnyardgrass 10.0 5.7 5.2 2.0 1.0 Crabgrass 6.0 4.5 1.7 1.5 2.0 Cheatgrass 10.0 6.7 1.7 0.5 0.0 Morningglory 10.0 7.6 8.4 5.0 1.5 Birdweed - 10.0 5.5 3.0 0.0 Cocklebur 7.0 2.0 1.0 0.0 Quackgrass - 10.0 6.0 2.5 0.0 Sprangletop - 5.0 2.5 0.0 0.0 Pintobeau - 6.0 3.0 0.0 0.0 Sugarbeet - 10.0 10.0 8.0 6.0 Wheat - 9.5 5.5 1.5 1.0 Rice - 4.0 2.5 3.5 0.0 Soybean 6.0 3.7 0.7 0.3 1.0 Cotton 2.0 1.7 0.0 0.0 0.0 Sorghum - 10.0 4.0 2.0 1.0 Corn 3.0 0.5 0.0 0.0 Alfalfa - 5.0 0.0 0.0 0.0 Oat 4.0 0.0 0.0 0.0 TABLE III - PRODUCT OF EXAMPLE 4 Post-emergence: Ihjury Rating Concentration - Ibs/acre Weed Species 2.0 1.0 0.5 0.25 0.125 Wild Mustard 10.0 10.0 10.0 10.0 10.0 Wild Oat 10.0 3.5 4.0 2.0 1.0 Bindweed 10.0 10.0 10.0 10.0 3.0 Barnyardgrass 10.0 10.0 10.0 10.0 5.0 Crabgrass 9.0 9.5 9.5 10.0 10.0 Yellow Foxtail 9.0 10.0 10.0 6.0 4.0 Johnsongrass 10.0 9.5 8.0 3.0 2.0 Morningglory 10.0 10.0 10.0 10.0 10.0 Jimsonweed 10.0 10.0 10.0 10.0 5.0 Yellow Nutsedge 5.0 2.0 2.0 - Pigweed 10.0 10.0 10.0 10.0 10.0 Velvetleaf - 10.0 10.0 10.0 10.0 Quackgrass - 10.0 6.0 4.0 2.0 Sprangletop - 10.0 10.0 4.0 3.0 Cheatgrass - 10.0 10.0 2.0 2.0 Pintobeau - 10.0 10.0 10.0 10.0 Sorghum - 10.0 10.0 10.0 10.0 Wheat - 10.0 5.0 10.0 1.0 Rice - 5.0 4.0 4.0 2.0 Cotton - 10.0 10.0 10.0 10.0 Corn - 7.0 10.0 4.0 3.0 Alfalfa - 10.0 10.0 10.0 10.0 Oat - 2.0 2.0 0.0 0.0 Soybean - 10.0 10.0 10.0 10.0 Sugarbeet - 10.0 10.0 10.0 10.0 TABLE IV- PRODUCT OF EXAMPLE 7 Post-emergence: Ihjury Rating Concentration - Ibs/acre Weed Species 2.0 1.0 0.5 0.25 0.125 0.062 Wild Mustard 10.0 10.0 10.0 10.0 6.5 2.0 Wild Oat 10.0 5.0 2.0 0.0 0.0 0.0 Bindweed 10.0 10.0 9.0 5.5 1.0 0.0 Barnyardgrass 10.0 10.0 7.2 6.0 3.5 2.0 Crabgrass 10.0 8.7 6.2 4.5 2.0 0.0 Yellow Foxtail 10.0 5.7 5.7 2.5 1.0 0.0 Johnsongrass 10.0 8.0 6.0 5.5 3.5 5.0 Morningglory 10.0 10.0 10.0 6.5 10.0 5.0 Jimsonweed 10.0 9.3 9.2 8.5 8.5 10.0 Yellow Nutsedge 2.0 0.5 0.0 - - Pigweed 10.0 8.3 7.5 6.0 4.0 3.0 Velvetleaf - 10.0 10.0 10.0 8.5 7.0 Quackgrass - 10.0 10.0 7.0 2.0 2.0 Sprangletop - 10.0 6.0 5.5 1.0 0.0 Cheatgrass - 10.0 5.0 5.0 0.0 0.0 Pintobeau - 5.0 10.0 7.0 7.0 3.0 Sorghum - 10.0 5.0 1.0 1.0 0.0 Wheat - 2.0 1.5 1.0 0.0 0.0 Rice - 7.0 5.5 10.0 0.5 0.0 Cotton - 10.0 10.0 8.5 7.5 10.0 Corn - 4.0 3.0 0.5 0.5 0.0 Alfalfa - 10.0 10.0 9.5 9.5 4.0 Oat - 2.0 0.5 1.0 0.5 0.0 Soybean 10.0 10.0 7.0 4.5 3.5 3.0 Sugarbeet - 10.0 10.0 8.5 6.5 2.0

Claims

1. A compound of the general formula

wherein Xis an alkyl, alkoxy, alkylthio, halogen, dialkylamino or cyano group; n iso or an integer of from 1 to 4; and R is an alkyl, alkenyl or haloalkyl group.

2. 1 -(5,5,7-trimethyl-4,5,6,7-tetrahydrobenzothiazol-2-yl)-3-methyl-5-hydroxy-1 ,3-imidazolidin-2-one.

3. 1-5,5,7,7-tetramethyl-4,5,6,7-tetrahydrobenzothiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one.

4. 1 -(5,7-dimethoxy-4,5,6,7-tetrahydrobenzothiazol-2-yl )-3-ethyl-5-hydroxy-1 ,3-imidazolidin-2-one.

5. 1 -(5,5,7-trimethyl-7-cyano-4,5,6,7-tetrahydrobenzothiazol-2-yl)-3-methyl-5-hydroxy-1 ,3-i m idazolidin-2- one.

6. 1 -(5-cyano-5,7-dimethyl-4,5,6,7-tetrahydrobenzothiazol-2-yl )-3-methyl-5-hydroxy-1,3-imidazol idin-2- one.

7. 1-(5-propyl-7-cyano-4,5,6,7-tetrahydrobenzothiazol-2-yl)-3-but-3-enyl-5-hydroxy-1,3-imidazolidin-2- one.

8. 1 -(5-hexyl-7-propoxy-4,5,6,7-tetrahydrobenzoth iazol-2-yl)-3-propyl-5-hydroxy-1,3-imidazolidin-2-one.

9. A compound as claimed in claim 1 substantially as hereinbefore described in any one of the Examples 1 to 28.

10. A herbicidal composition comprising an inert carrier and, as essential active ingredient, in a quantity toxic to weed, a compound as claimed in any one of claims 1 to 9.

11. A herbicidal composition as claimed in claim 10, substantially as hereinbefore described in Example 29.

12. A method of controlling weeds which comprises contacting said weed with a herbicidal composition comprising an inert carrier and, as an essential active ingredient, in a quantity toxic to weeds, a compound as claimed in any one of claims 1 to 9.

13. A method of controlling weeds which comprises contacting said weed with a compound as claimed in any one of claims 1 to 9, in a quantity toxic to weeds.

14. A method of controlling weeds substantially as herein before described in Example 30.

15. A process for the preparation of a compound of the general formula 1 as defined in claim 1, which comprises heating a compound of the general formula

wherein X, n and R have the meanings given in claim 1, in a dilute, aqueous, acidic reaction medium for a period of about 10 to about 90 minutes.

16. A process for the preparation of a compound of the general formula I as defined in claim 1, substantially as herein before described in any one of Examples 1 to 28.