the 1 , 2 , 3 , 5 - thiatriazolidin - 4 - one - 2 - oxide compounds of the invention may be represented by the following formula ( i ): ## str1 ## wherein r 2 , r 3 and r 5 individually are alkyl of 1 to 6 carbon atoms ; phenyl , naphthyl ; or phenyl or naphthyl substituted with 1 to 3 substituents selected from fluoro , chloro , bromo , iodo , alkoxy of 1 to 4 carbon atoms and alkyl of 1 to 4 carbon atoms or one substituent selected from trifluoromethyl , trichloromethyl , tribromomethyl , phenoxy , or phenoxy substituted with 1 to 2 fluoro , chloro , bromo or alkyl of 1 to 4 carbon atoms . preferably r 2 is alkyl of 1 to 6 carbon atoms , and more preferably alkyl of 1 to 3 carbon atoms . preferably r 3 is alkyl of 1 to 6 carbon atoms , phenyl or phenyl substituted with 1 to 2 fluoro , chloro , bromo , alkyl of 1 to 4 carbon atoms or alkoxy of 1 to 4 carbon atoms , and more preferably alkyl of 1 to 3 carbon atoms , phenyl or phenyl substuted with 1 to 2 fluoro , chloro or bromo . preferably r 5 is alkyl of 1 to 6 carbon atoms , phenyl or phenyl substituted with 1 to 2 fluoro , chloro , bromo , alkyl of 1 to 4 carbon atoms or alkoxy of 1 to 4 carbon atoms , and more preferably alkyl of 1 to 3 carbon atoms , phenyl or phenyl substituted with 1 to 2 fluoro , chloro or bromo . representative alkyl groups which r 2 , r 3 and r 5 may represent include methyl , ethyl , isopropyl , n - butyl and n - hexyl . representative aryl groups which r 3 and r 5 may represent include 1 - naphthyl , 2 - naphthyl , 2 - methyl - 1 - naphthyl , 4 - chloro - 1 - naphthyl , 2 , 4 - dichloro - 1 - naphthyl , 2 - fluorophenyl , 3 - chlorophenyl , 3 -( 4 - chlorophenoxy ) phenyl , 2 - phenoxyphenyl , 2 , 4 , 5 - trichlorophenyl , 4 - tolyl , 3 , 5 - dimethylphenyl , 4 - trichloromethylphenyl , 2 - tribromomethylphenyl , 2 - methoxyphenyl , 4 - ethoxyphenyl and 2 - methyl - 4 - chlorophenyl . in the compounds of formula ( i ), it is generally preferred that one of r 2 , r 3 or r 5 is aryl ( e . g ., phenyl , naphthyl , or substituted phenyl or naphthyl ), and two of r 2 , r 3 or r 5 are alkyl . a preferred class of compounds of formula ( i ) is that wherein r 2 is alkyl of 1 to 3 carbon atoms , r 3 is phenyl or phenyl substituted with 1 to 2 fluoro , chloro or bromo and r 5 is alkyl of 1 to 3 carbon atoms . another preferred class of compounds is that wherein r 2 is alkyl of 1 to 3 carbon atoms , r 3 is alkyl of 1 to 3 carbon atoms and r 5 is phenyl or phenyl substituted with 1 to 2 fluoro , chloro or bromo . 2 , 3 - dimethyl - 5 - tolyl - 1 , 2 , 3 , 5 - thiatriazolidin - 4 - one - 2 - oxide 2 - methyl - 1 - naphthyl - 5 - ethyl - 1 , 2 , 3 , 5 - thiatriazolidin - 4 - one - 2 - oxide 2 - phenyl - 3 , 5 - dimethyl - 1 , 2 , 3 , 5 - thiatriazolidin - 4 - one - 2 - oxide 2 , 3 - diethyl - 5 -( 3 , 5 - dichlorophenyl )- 1 , 2 , 3 , 5 - thiatriazolidin - 4 - one - 2 - oxide 2 - hexyl - 3 , 5 - diphenyl - 1 , 2 , 3 , 5 - thiatriazolidin - 4 - one - 2 - oxide 2 -( 2 - naphthyl )- 3 , 5 - dimethyl - 1 , 2 , 3 , 5 - thiatriazolidin - 4 - one - 2 - oxide 2 - methyl - 3 -( 2 - trichloromethylphenyl )- 5 - methyl - 1 , 2 , 3 , 5 - thiatriazolidin - 4 - one - 2 - oxide 2 -( 4 - phenoxyphenyl - 3 , 5 - dimethyl - 1 , 2 , 3 , 5 - thiatriazolidin - 4 - one - 2 - oxide 2 , 3 , 5 - trimethyl - 1 , 2 , 3 , 5 - thiatriazolidin - 4 - one - 2 - oxide , and 2 , 3 , 5 - triphenyl - 1 , 2 , 3 , 5 - thiatriazolidin - 4 - one - 2 - oxide the 1 , 2 , 3 , 5 - thiatriazolidin - 4 - one - 2 - oxide compounds of the invention are prepared by reacting thionyl chloride and an n - aminourea ( semicarbazide ) ( ii ) as depicted by the following reaction ( 1 ): ## str2 ## wherein r 2 , r 3 and r 5 have the same significance as previously defined . preferably reaction ( 1 ) is conducted in the presence of a base . suitable bases include inorganic bases such as alkali metal carbonates and bicarbonates , e . g ., sodium carbonate and potassium bicarbonate , and organic bases , such as trialkyl amines , e . g ., tributyl amine , and pyridine compounds , e . g ., pyridine and dimethylpyridine . the preferred bases are pyridine compounds , particularly pyridine . the precise mechanism and the reaction intermediates involved in reaction ( 1 ) are not known with certainty . however , it appears that the stoichiometry of the reaction is one mol of thionyl chloride per mol of n - aminourea . therefore , substantially equimolar amounts of n - aminourea to thionyl chloride are employed , e . g ., molar ratios of n - aminourea to thionyl chloride vary from about 1 : 1 to 1 : 1 . 5 , although molar ratios of 1 : 1 to 1 : 1 . 1 are preferred . when a base is employed in the reaction , it is generally preferred to use enough base to scavenge the hydrogen chloride produced in the reaction . therefore , molar ratios of base to thionyl chloride generally vary from about 2 : 1 to 2 . 4 : 1 , although molar ratios varying from about 2 : 1 to 2 . 2 : 1 are preferred . generally the reaction is accomplished by reacting the n - aminourea , thionyl chloride and base in an inert liquid diluent . suitable inert diluents include alkanes and haloalkanes , such as hexane , isocctane or dichloromethane , and aromatic compounds , such as benzene , toluene or chlorobenzene . generally the amount of diluent employed ranges from 1 to 50 mols per mol of n - aminourea . the reaction is suitably conducted at a temperature of from about - 10 ° c . to 100 ° c ., although temperatures of from about 0 ° c . to 75 ° c . are preferred . the reaction is conducted at or above atmospheric pressure . the reaction time will , of course , vary depending on the reaction temperature and the particular n - aminourea reactant employed . generally , however , the reaction time varies from about 1 hour to 50 hours . the 1 , 2 , 3 , 5 - thiatriazolidin - 4 - one - 2 - oxide product is isolated from the reaction mixture by conventional procedures , e . g ., extraction , chromatography , crystallization , etc . a 2 . 75 g ( 0 . 032 mol ) sample of thionyl chloride was added dropwise to a cooled ( 0 ° c .) solution of 4 . 18 g ( 0 . 023 mol ) 2 , 3 - dimethyl - 4 - phenylsemicarbazide and 3 . 62 g ( 0 . 046 mol ) pyridine in 250 ml chloroform . the resulting reaction mixture was stirred at about 25 ° c . for about 16 hours , washed twice with water , dried over magnesium sulfate and evaporated under reduced pressure to give a yellow solid . the solid was recrystallized from hexane / benzene to give the product , as a white solid , m . p . 77 - 79 ° c . the infrared spectrum of the product showed a strong carbonyl absorption band at 5 . 78 micron . the nuclear magnetic resonance ( nmr ) spectrum of the product showed two 3 - proton singlets ( methyl protons ) at 3 . 00 ppm and 3 . 26 ppm ppm and a 5 - proton singlet ( aromatic protons ) at 7 . 43 ppm ( relative to tetramethylsilane ). the product is tabulated in table i as compound no . 1 . a slurry of 10 g ( 0 . 075 mol ) 1 , 2 - dimethylhydrazine hydrochloride and 15 . 2 g ( 0 . 15 mol ) triethylamine in 300 ml dichloromethane was stirred until the hydrochloride salt dissolved . a solution of 4 - chlorophenylisocyanate in dichloromethane was then added dropwise and the resulting solution was stirred at about 25 ° c . for about 2 days . the reaction mixture was washed with water , dried over magnesium sulfate and evaporated under reduced pressure to give 2 , 3 - dimethyl - 4 -( 4 - chlorophenyl )- semicarbazide , as a white crystalline solid . a solution of 8 . 13 g ( 0 . 068 mol ) thionyl chloride in dichloromethane was slowly added to a cooled ( 0 ° c .) solution of 14 . 6 g ( 0 . 068 mol ) 2 , 3 - dimethyl - 4 -( 4 - chlorophenyl ) semicarbazide and 10 . 8 g ( 0 . 136 mol ) pyridine in 250 ml dichloromethane . the resulting reaction mixture was allowed to warm to about 25 ° c ., stirred for about 16 hours , washed with water , dried over magnesium sulfate and evaporated under reduced pressure to give a tan liquid which slowly crystallized . recrystallization of the crude product from hexane / benzene gave 14 . 7 g of the 2 , 3 - dimethyl - 5 -( 4 - chlorophenyl )- 1 , 2 , 3 , 5 - thiatriazolidin - 4 - one - 2 - oxide product , as pink crystals , m . p . 83 °- 85 ° c . the nuclear magnetic resonance spectrum of the product showed 3 - proton singlets ( methyl protons ) at 3 . 00 ppm and 3 . 26 ppm and a 4 - proton singlet ( aromatic protons ) at 7 . 46 ppm ( relative to tetramethylsilane ). the product is tabulated in table i as compound no . 2 . a 5 . 7 - g ( 0 . 1 - mol ) sample of methyl isocyanate was added dropwise to a solution of 15 . 0 g ( 0 . 1 mol ) 1 - acetyl - 2 - phenyl - hydrazine and 2 drops triethylamine in 200 ml dichloromethane . the resulting reaction mixture was stirred for 2 hours at about 25 ° c ., refluxed for about 16 hours and evaporated under reduced pressure to give 21 g of crude 1 - acetyl - 2 - phenyl - 4 - methyl semicarbazide , as a yellow solid . a mixture of 17 g ( 0 . 082 mol ) of the semicarbazide prepared above , 14 . 2 g ( 0 . 1 mol ) methyl iodide , 14 . 0 g ( 0 . 1 mol ) potassium carbonate , and 200 ml ethanol was refluxed for 2 hours , cooled , filtered and evaporated under reduced pressure . the resulting residue was diluted with dichloromethane , filtered to remove suspended solids , washed with water , dried over magnesium sulfate , and evaporated under reduced pressure to give 10 g of crude 1 - acetyl - 1 , 4 - dimethyl - 2 - phenyl - semicarbazide . the 10 - g sample of semicarbazide prepared above and 110 ml 37 % hydrochloric acid were heated at 50 ° c . for 1 hour . the reaction mixture was then poured onto ice , neutralized to ph 7 with aqueous sodium hydroxide solution and evaporated under reduced pressure to give a yellow liquid . nmr spectroscopic analysis of the yellow liquid showed the presence of the starting semicarbazide . therefore , the yellow liquid was redissolved in water , acidified with 10 % hydrochloric acid and extracted with methylene chloride to remove the starting semicarbazide . the aqueous solution was then neutralized with sodium hydroxide and evaporated under reduced pressure to give 3 . 3 g of crude 1 , 4 - dimethyl - 2 - phenylsemicarbazide . a 2 . 2 - g ( 0 . 0184 - mol ) sample of thionyl chloride was added slowly to a cooled ( 0 ° c .) solution of the 3 . 3 - g ( 0 . 0184 - mol ) sample of semicarbazide prepared above and 2 . 9 g ( 0 . 036 mol ) pyridine in 200 ml dichloromethane and then stirred at about 25 ° c . for 16 hours . the reaction mixture was washed with water , dilute hydrochloric acid , dried over magnesium sulfate and evaporated under reduced pressure to give a red oil , which was purified by filtration through silica gel to give the 2 , 5 - dimethyl - 3 - phenyl - 1 , 2 , 3 , 5 - thiatriazine - 1 , 4 - dione product as an orange oil . the nmr spectrum of the product showed two 3 - proton singlets at 2 . 96 ppm and 3 . 20 ppm and the aromatic protons as a multiplet at 7 . 13 - 7 . 90 ppm ( relative to tetramethylsilane ). the product is tabulated in table i as compound no . 4 . other compounds of the invention were prepared by procedures similar to those of examples 1 - 3 . these compounds are reported in table i . the structures of the compounds reported in table i were verified by infrared spectroscopy and / or nmr analysis . all 1 , 2 , 3 , 5 - thiatriazolidin - 4 - one - 2 - oxide compounds of the invention showed a strong carbonyl absorption band at about 5 . 86 micron . the compounds of the present invention are herbicidal in both pre - and post - emergent applications . for pre - emergent control of undesirable vegetation , the herbicidal compounds will be applied in herbicidally effective amounts to the locus or growth medium of the vegetation , e . g ., soil infested with seeds and / or seedlings of such vegetation . such application will inhibit the growth of or kill the seeds , germinating seeds and seedlings . for post - emergent applications , the herbicidal compounds will be applied directly to the foliage and other plant parts . generally , the herbicidal compounds of the invention are effective against weed grasses as well as broadleaved weeds . some may be selective with respect to the type of application and / or type of weed . the compounds of the present invention can be used alone as herbicides . however , it is generally desirable to apply the compounds in herbicidal compositions comprising one or more of the herbicidal compounds intimately admixed with a biologically inert carrier . the carrier may be a liquid diluent or a solid , e . g ., in the form of dust powder or granules . in the herbicidal composition , the active herbicidal compounds can be from about 0 . 01 to 95 % by weight of the entire composition . suitable liquid diluent carriers include water and organic solvents , e . g ., hydrocarbons such as benzene , toluene , kerosene , diesel oil , fuel oil , and petroleum naphtha . suitable solid carriers are natural clays such as kaolinite , atalpulgite and montmorillonite . in addition , talcs , pyrophillite , diatomaceous silica , synthetic fine silicas , calcium aluminosilicate and tricalcium phosphate are suitable carriers . organic materials such as walnut - shell flour , cottonseed hulls , wheat flour , wood flour or redwood - bark flour may also be used as solid carriers . the herbicidal composition will also usually contain a minor amount of a surface - active agent . such surface agents are those commonly known as wetting agents , dispersing agents and emulsifying agents , and can be anionic , cationic or nonionic in character . the herbicidal compositions may also contain other pesticides , adjuvants , stabilizers , conditioners , fillers , and the like . the amount of herbicidal compound or composition administered will vary with the particular plant part or plant growth medium which is to be contacted , the general location of application -- i . e ., sheltered areas such as greenhouses , as compared to exposed areas such as fields -- as well as the desired type of control . generally , for both pre - and post - emergent control , the herbicidal compounds of the invention are applied at rates of 0 . 2 to 60 kg / ha , and the preferred rate is in the range 0 . 5 to 40 kg / ha . pre - emergent herbicidal tests on representative compounds of the invention were made using the following method : an acetone solution of the test compound was prepared by mixing 750 mg of the compound , 220 mg of a nonionic surfactant and 25 ml of acetone . this solution was added to approximately 125 ml of water containing 156 mg of surfactant . seeds of the test vegetation were planted in a pot of soil and the test solution was sprayed uniformly onto the soil surface at a dose of 33 micrograms / cm 2 ( 3 lbs / acre ). the pot was watered and placed in a greenhouse . the pot was watered intermittently and was observed for seedling emergence , healt of emerging seedlings , etc ., for a 3 - week period . at the end of this period , the herbicidal effectiveness of the compound was rated based on the physiological observations . a 0 - to - 100 scale was used , 0 representing no phytotoxicity , 100 representing complete kill . the results of these tests appear in table ii . the test compound was formulated in the same manner as described above for the pre - emergent test . the concentration of the test compound in this formulation was 5000 ppm . this formulation was uniformly sprayed on 2 similar pots of 24 - day - old plants ( approximately 15 to 25 plants per pot ) at a dose of 33 mcg / cm 2 ( 3 lbs / acre ). after the plants had dried , they were placed in a greenhouse and then watered intermittently at their bases , as needed . the plants were observed periodically for phytotoxic effects and physiological and morphological responses to the treatment . after 3 weeks , the herbicidal effectiveness of the compound was rated based on these observations . a 0 - to - 100 scale was used , 0 representing no phytotoxicity and 100 representing complete kill . the results of these tests appear in table ii . table i : ______________________________________compounds of formula ( i ) sulfur analysis , % no . r . sup . 2 r . sup . 3 r . sup . 5 m . p ., ° c calc . found______________________________________1 ch . sub . 3 ch . sub . 3 φ 76 - 79 14 . 2 14 . 22 ch . sub . 3 ch . sub . 3 4 - cl - φ 83 - 85 12 . 4 12 . 63 ch . sub . 3 ch . sub . 3 3 - cf . sub . 3 - φ 90 - 92 10 . 9 10 . 44 ch . sub . 3 φ ch . sub . 3 oil 14 . 2 14 . 55 ch . sub . 3 ch . sub . 3 2 - f - φ 72 - 74 13 . 2 13 . 56 ch . sub . 3 ch . sub . 3 3 - ch . sub . 3 - c - φ 59 - 62 12 . 6 12 . 67 ch . sub . 3 ch . sub . 3 3 , 4 - cl . sub . 2 - φ 104 - 106 10 . 9 11 . 08 ch . sub . 3 ch . sub . 3 4 - φ - o - φ 87 - 88 10 . 1 10 . 39 ch . sub . 3 φ i - c . sub . 3 h . sub . 7 oil 12 . 6 12 . 210 ch . sub . 3 2 - f - φ ch . sub . 3 oil 13 . 2 13 . 911 ch . sub . 3 ch . sub . 3 4 - f - φ 89 - 90 13 . 2 13 . 612 ch . sub . 3 ch . sub . 3 2 , 6 - cl . sub . 2 - φ 106 - 108 10 . 9 10 . 813 ch . sub . 3 4 - ch . sub . 3 o - φ ch . sub . 3 oil 12 . 6 14 . 614 ch . sub . 3 4 - ch . sub . 3 o - φ i - c . sub . 3 h . sub . 7 oil 11 . 3 10 . 915 ch . sub . 3 3 , 4 - cl . sub . 2 - φ ch . sub . 3 147 - 149 10 . 9 10 . 916 ch . sub . 3 i - c . sub . 3 h . sub . 7 3 , 4 - cl . sub . 2 - φ 62 - 65 9 . 9 9 . 217 ch . sub . 3 ch . sub . 3 3 , 4 -( ch . sub . 3 ). sub . 2 - φ oil 12 . 6 12 . 818 ch . sub . 3 ch . sub . 3 2 , 6 -( ch . sub . 3 )- φ 73 - 75 12 . 67 13 . 019 ch . sub . 3 ch . sub . 3 4 - i - c . sub . 3 h . sub . 7 - φ 135 - 136 11 . 8 11 . 720 ch . sub . 3 ch . sub . 3 2 , 4 , 5 - cl . sub . 3 - φ 152 - 154 9 . 7 9 . 721 ch . sub . 3 ch . sub . 3 4 - n - c . sub . 4 h . sub . 9 - φ oil 11 . 4 10 . 822 ch . sub . 3 ch . sub . 3 2 - naphthyl 93 - 94 11 . 6 11 . 723 i - c . sub . 3 h . sub . 7 φ ch . sub . 3 oil 12 . 6 13 . 524 ch . sub . 3 ch . sub . 3 4 - i - φ 111 - 112 9 . 1 10 . 325 ch . sub . 3 ch . sub . 3 4 - br - φ 101 - 103 10 . 5 10 . 8______________________________________ table ii______________________________________herbicidal effectiveness at 3 lbs / acre -- pre / postno . l m p c w o______________________________________1 0 / 93 0 / 95 0 / 70 0 / 25 0 / 25 0 / 202 0 / 100 0 / 100 0 / 84 0 / 50 0 / 80 0 / 553 0 / 75 0 / 90 0 / 20 0 / 0 0 / 0 0 / 404 100 / 100 100 / 100 100 / 90 97 / 0 90 / 55 100 / 405 30 / 100 30 / 100 15 / 100 0 / 30 0 / 75 0 / 806 0 / 90 0 / 100 0 / 95 0 / 0 0 / 15 0 / 07 98 / 100 58 / 100 98 / 100 0 / 93 0 / 75 0 / 838 0 / 65 15 / 0 / 65 0 / 45 0 / 20 0 / 359 65 / 25 60 / 25 20 / 25 50 / 0 0 / 0 0 / 010 95 / 100 95 / 100 100 / 98 74 / 25 84 / 10 69 / 011 0 / 100 0 / 0 / 100 0 / 85 0 / 85 0 / 8512 0 / 0 0 / 0 / 15 0 / 10 0 / 10 0 / 2513 65 / 95 65 / 95 / 80 55 / 65 45 / 50 20 / 8514 0 / 20 0 / 0 / 20 0 / 10 0 / 10 0 / 1015 100 / 100 95 / 100 100 / 100 97 / 80 83 / 97 25 / 8016 0 / 95 0 / 100 0 / 97 0 / 60 0 / 80 0 / 7517 0 / 40 0 / 100 0 / 25 0 / 25 0 / 25 0 / 2018 25 / 0 25 / 0 25 / 0 0 / 0 15 / 0 0 / 019 0 / 100 0 / 100 0 / 100 0 / 45 0 / 85 0 / 3520 0 / 100 0 / 100 0 / 65 0 / 50 0 / 90 0 / 2521 0 / 40 0 / 80 0 / 10 0 / 60 0 / 65 0 / 5022 0 / 85 0 / 100 0 / 70 0 / 50 0 / 50 0 / 4023 10 / 75 10 / 45 10 / 25 0 / 0 0 / 0 0 / 024 0 / 80 0 / 85 0 / 75 0 / 35 0 / 40 0 / 5025 0 / 97 0 / 97 0 / 95 0 / 40 0 / 65 0 / 80______________________________________ o = wild oats ( avena fatua ) w = watergrass ( echinochloa crusgalli ) c = crabgrass ( digitaria sanguinalis ) m = mustard ( brassica arvensis ) p = pigweed ( amaranthus retroflexus ) l = lambsquarter ( chenopodium album )
novel 2 , 3 , 5 - trisubstituted - 1 , 2 , 3 , 5 - thiatriazolidin - 4 - one - 2 - oxides have been found to have herbicidal activity . these 1 , 2 , 3 , 5 - thiatriazolidin - 4 - one - 2 - oxides are prepared by reacting an n - aminourea and thionyl chloride .