IL44228A

IL44228A - 5-trifluoromethyl benzimidazoles their preparation and their use as herbicides

Info

Publication number: IL44228A
Application number: IL44228A
Authority: IL
Original assignee: United States Borax Chem
Priority date: 1973-02-20
Filing date: 1974-02-18
Publication date: 1977-07-31
Also published as: ES423443A1; AU6577474A; BR7401281D0; DD109499A5; RO63036A; DE2405070A1; IT1049214B; CH605820A5; JPS5040740A; IL44228A0; NL7402240A; FR2234287A1; AR213609A1; GB1421674A; FR2234287B1

Description

Novel their preparation and their use as herbicides UNITED STATES BORAX AND CHEMICAL CORPORATION 42407 This invention relates to a novel class substituted benzimidazoles more to a class of benzimidazoles having utility as herbicides or useful as for the preparation of The novel benzimidazoles of this have the formula in which each and which may be the or are selected from lower or Y represents Og or Y is NO X is the and represents or lower y and n is when Y is X is lower or amino of the formula and n is in which R is hydrogen or lower represents a total of at least one carbon preferably about 2 to 6 carbon the herbicidal benzimidazoles have at least one amino group represented by Y at the which may be unsubstituted or which may have one or two lower The present compounds must also have a group at the of the Other possible substituents which may be at the or are those represented by X in the above Such substituents include the halogens such as iodo and lower alkoxy of 1 to about 6 carbon atoms such and an additional amino group which may be unsubstituted or which may have one or two alley1 substituents as defined by The additional ring substituents represented by may be a combination of the possiblegroups listed or there may be as many t as two of each of such ere the radical is where there is no substituent in the compounds can occur in two tautomeric 13oth forms are intended to be included in the above c represent a substituent and may contain from 1 to about 6 carbon as for and the and R2 can also represent such as cyclobutyl or The or of the benzimidazole molecule may be at least and preferably of the and have a lower alkyl Representative according to the present invention luoromethylbenzimidazolc c dimeth ro midazole benzimidazole midazole midazole da zole zole ifluoromethylbenzimidazole midazole The compounds this invention are generally as the chlorinated hydrocarbons and benzene They are readily prepared by procedures known for the preparation of benziniidazoles such as the reaction of the corresponding substituted with a carboxylic acid in the presence of a mineral acid according to the following equation i a may be employed in place of the carboxylic Such carboximidates have the formula in which is lower alkyl such as and are generally used in their hydrochloride A suitable synthesis for compounds in which Y is the group in which is hydrogen is illustrated as follows Λ suitable synthesis for the production of compounds in which Y is the group is as the benziraidazoie free of a and then add the nitro such as by reaction with nitric acid or other suitable nitrating A suitable synsthesis is illustrated as The and if desired be reduced to provide the for example with hydrogen in the presence of a catalyst such as platinum s Reference is made to Israel Patent Specification 35690 which describes preparation of British Patent The halo group can he replaced by an alkoxy or amino group by known if See also Patent which shows reduction of to produce the corresponding The following examples illustrate the preparation of representative compounds of this invention and intermediates EXAMPLE I Aqueous ethylamine was added to a stirred solution of of in 200 of dimethoxyethane The mixture was stirred for two hours while the exotherm subsided and then heated near reflux temperature The resulting mixture was evaporated to dryness reduced pressure and the residue dissolved in After washing twice with the chloroform solution was dried over sodium and the solvent removed from the filtrate by distillation Crystallization of the residue from ethanol gave of EXAMPLE II A hydrogenation bottle was charged with of platinum oxide and 300 of ethyl Shaking for hours under psi pressure resulted in the uptake of mole equivalents of The catalyst was removed by filtration and the solvent evaporated from the The resultin solid dissolved in 200 of ethanol and of ethyl methylcarboximidate hydrochloride After hours at room the solvent was removed and the residue dissolved in chloroform and Removal of the chloroform by distillation followed by of the residue from hexane gave of the product as EXAMPLE III lben dissolved in 110 of concentrated sulfuric acid was added 11 of fuming nitric acid while cooling with an ice The addition required three hours and the resulting solution was stirred for six hours at and then at room temperature for After pouring onto the product was precipitated by the addition of concentrated ammonium The crude solid was isolated and dissolved in 300 of The chloroform solution was washed with dried over and the filtrate Crystallization of the residual solid from gave of reddish whose nuclear magnetic resonance pattern confirmed it to be the desired EXAMPLE IV About 5 of was hydrogenated in 100 of methanol in the presence of of platinum The theoretical amount of hydrogen was absorbed in four hours of After filtration and removal of the the crude product was crystallized from carbon tetrachloride to give of An n r spectrum confirmed the structure as EXAMPLE V and of methanolic sodium methoxide in 25 of anhydrous methanol wassealed in a glass tube and heated at for 88 Removal of the solvent by distillation left a yellow solid residue which was triturated with hot Filtration and evaporation of chloroform from the filtrate gave a crude solid Crystallization of the residue from ethanol gave of yellow crystalline shown its nmr spectrum to be the desired EXAMPLE VI Λ solution of of in 200 of ethyl plus 100 of was hydrogenated in the presence of of platinum oxide at room The theoretical amount of hydrogen was absorbed in 19 hours of shaking at 60 The catalyst removed by filtration and the solvent evaporated at reduced The solid residue was dissolved 200 of absolute ethanol and of ethyl hydrochloride The mixture overnight at room temperature and the solvent removed at reduced Trituration of brown residue with 200 of and evaporation of solvent from the filtrate left the crude residual Crystallization from gave of shiny Recrystallization from hexane gave the pure EXAMPLE VII was added in portions three hours to a cooled mixture of 110 of concentrated sulfuric acid and 11 o white fuming nitric The resulting brown solutionwas at for six hours and then at for three Addition to ice water followed by neutralization with of concentrated aqueous ammonia gave a oily The product was extracted thrice with 100 of the extracts washed with dried over and the chloroform removed by The residue was crystallized from to give of yellow Recrystallization from hexane gave the desired Other compounds representative of the present which can be prepared according to the e zolej oil The substituted compounds of the present invention are useful as intermediates for preparing the of the invention which compounds have herbicidal The compounds as described reduced to the corresponding be zimidazole by reaction with in the presence of a catalyst such as platinum oxide according to the following The following examples illustrate the conversion o e VIII benzimidazole in 50 of ethyl acetate was hydrogenated in the presence of of platinum oxide Shaking hours at room temperature resulted in the uptake of of the amount of hydrogen needed to reduce the nitro Filtration to remove the catalyst was followed by solvent removal and trituration with hot The hot solution was filtered andthe solvent evaporated at reduced pressure leaving solid Two recrystallizations from gave the pure EXAMPLE IX Ahout 5 of was hydrogenated in 100 of methanol in the presence of of platinum The theoretical amount of hydrogen was absorbed in four hours of After filtration and removal of the the crude product was crystallized from carbon tetrachloride of brown An spectrum confirmed the structure as EXAMPLE was was sufficient for the absorption of enough hydrogen to reduce both nitro The catalyst was removed by filtration and the ethyl acetate evaporated leaving an orange viscous The latter was dissolved in of ethanol and of ethyl hydrochloride This mixture was stirred at room temperature for 16 the solvent and the residue triturated with 250 of Filtration and removal of the chloroform left a crude solid that was crystallized from to give of spectrum was consistent with the structure of e After recrystallization from the product melts at was dissovled in 15 of acetic To this bromine dissolved in 10 of acetic was added with stirring and The solution wasstirred for one hour after the addition was and then poured into The mixture was neutralized with aqueous sodium hydroxide and extracted twice with 100 of The chloroform was evaporated to dryness and the residue found to be a mixture of and thee corresponding The more soluble The crystalline isomer was obtained in EXAMPLE XI To of fluoromethylbenzimidzaole dissolved in 10 of concentrated of The resultant mixture stirred for two hours and the poured onto The resultant brown solution was made basic by addition of concentrated precipitating a light brown The mixture was extracted with chloroform and the chloroform extracts washed with water and dried over After removal of the chloroform by the residue was extracted with hexane and the hexane extract distilled to The solidYesidue was recrystallized from hexane to give of the desired EXAMPLE XIII ifluoromethylbenzimidazole was hydrogenated in the presence of platinum oxide catalyst in accordance with the procedure of Example The product was obtained as a white crystalline solid after recrystallization from a melts at EXAMPLE XIV Λ glass reaction tube was charged with of 20 of dimethoxyethane and 15 of diraethylaniine and then The sealed tube maintained at for l6 days and then The contents were evaporated to dryness and the residue extracted with hot from which crystallized of the desired product after recrystallization from EXAMPLE zimidazole V methylbe ziinidazole hydrogenated in the presence of platinum oxide catalyst according to the procedure of Example IV to give of the desired Other compounds representative of the substituted compounds of the present which can be prepared according to the 1 166 oromethylbenzim benzimidazole benzimidazole yl The substituted compounds of this invention are excellent herbicides and can as both a or a that they can be applied to soil in which the grow they can be used td kill or suppress the of weeds or to kill or prevent the emge ence of seedlings of undesirable the benzimidazoles can be used to control the growth of weeds by applying a amount of one or more of the active compounds of this invention to the locus to be that soil in which the weeds are growin or will or the foliage of the growing When used as a the compounds may be such as by mixing into the top inches of soil prior to planting the if as used herein is meant to include any plant growth which is The compounds are especially useful as emergence for selectively controlling weeds in the presence of desirable such as rice and weeds such as ates of little or no injury to the an application rate of from about to about 15 pounds of one or more of the active compounds per acre is effective in controlling plant an application rate in the range of from about to about 5 pounds per acre is At such the undesirable weeds are killed or stunted with little or no injury to desirable The followin examples illustrate the herbicidal activity of typical compounds of this EXAMPLE XVI The compounds to be tested were evaluated as both a and Greenhouse flats were planted to soybeans velvet leaf oats and millet and the flats sprayed on the same day as planting with an ethanol solution of the compound to be tested at a rate of five pounds per Another set of flacts with the same plants was treated after the plants had emerged and were about one inch in The flats were also sprayed with an ethanol solution of the compound to be tested at a rate of five pounds per The flats were kept in the greenhouse and watered when days after the flats were examined and the plants rated for herbicidal activity on a 0 to 9 scale in which 0 no substantial injury with some and 9 complete The results are shown in Table Compound SB VL 0 M 0 5 0 2 2 8 5 1 1 1 1 2 1 0 0 0 0 0 0 trifluoromethylbenzimidazole 1 1 0 1 trifluoromethylbenzimidazole 0 0 0 0 benzimidazole 0 1 1 2 0 0 0 2 0 6 5 0 0 0 0 Compound SB 0 M 6j 0 0 0 enziinidazole 9 9 9 0 1 8 6 6 9 8 6 8 methylbenzimidazole fluoromethylbenzimidazole methyl enzimidazole EXAMPLE XVII benzimidazole was evalueated as a treatment on a broad class of representative crops and The compound and its hydrochloride salt were tested according to the of Example at a rate of one pound per The hydrochloride salt was dissolved in The results are shown in Table TABLE II Plant Salt Cotton 9 Cor 0 1 Soybeans 9 1 0 Barley 1 1 Field Beans 9 Mustard 8A Foxtail 9 9 9 9 Millet 9 9 Peanuts Pigweed 9 9 Jimsonweed Teaweed 6A Watergrass 9 9 Sorghum In Table where are two the first is percent kill on a scale and the second is a percent injury to remaining plants on a 0 effect kill 1 injury 6 2 θ kill 2 7 kill 3 injury 8 kill 4 injury 9 complete kill EXAMPLE Three compounds of the present invention and a known position isomer were tested as at a rate of one pound per acre on a group of representative crops and The procedure of Example XV was The results were as shown in Table TABLE III Velvetleaf 1 Cotton 0 9 9 9 9 9 1 Jimsomweed Rice 1 2 2 0 Teaweed 2 9 Pigweed 9 9 Foxtail 0 9 ergrass 0 Crabgrass 9 0 Mustard 9 0 2 1 1 Cocklebur 9 1 Compound A methylbenz midazole Compound B Compound C Compound D The Examples in Table III show the unexpected superiority of the compounds of the present invention having and substituents when compared with the known See Frerch Patent The compounds are especially useful against the weeds and Since a relatively small amount of one or more of the active substituted benzimidazoles should be uniformly distributed over the area to be the compounds are formulated with conventional herbicide either liquid or the compounds can be impregnated on or admixed with a pulverulent solid carrier such as Calcium chloride or the compounds can be dissolved or suspended in a liquid carrier such as diesel glycols or Since many of the compounds will form salts for example with mineral they can be formulated with A surfacta t is preferably included to aid in emulsification and The surfactant can be ionic or and may be liquid or The use the terra herein is intended to include such compounds commonly referred to as wetting dispersing agents and emulsifying Typical surfactants include the the fatty alcohol sodium salt of napthalenesulfonic alkylaryl polyether long chain quaternary ammonium sodium salts of alkylsulfonic and These dispersing and wetting agents are sold under numerous trademarks may either be pure mixtures of be included in compositions containing a solid inert Concentrated compositions containing the active agent which can be subsequently for with to the desired concentration for application to plants and are also The advantages of sucliconcentrates are that they are prepared by the manufacturer in a form such that the user need only mix them with a locally available preferably thereby keeping shipping costs to a minimum while providing a product which can be used with a minimum of equipment and Such concentrates may contain from to 95 percent by weight of one or more of the active benzimidazole with a carrier or which may be a liquid or a Liquid carriers which are miscible with active agent or other liquids in which the compound may be suspended or can be A surfactant is also generally included to facilitate such dilution or dispersion in the surfactant itself comprise the carrier such The herbicidal compositions can include other beneficial adjuvants such as oils and contact other herbicides such as the chlorophenoxyacetic substituted uracils and and can be included in the insufficientOCRQuality

Claims

1. A compound of the formula in ame or different, ar l, j when Y is NO X is at the 6-position and represents hydrogen halo, or lower alkoxy and n is 1; when Y is - X is halo lower alkoxy, or amino of t and n is 0-2, in which R, is hydrogen or lower alkyl, with the proviso that R^ and R,, together represent a total of at least one carbon atom.

2. A'compound of the formula which may be the same or different are hydrogen or lower alkyl, X is halo, lower alkoxy or amino of the formula and n is 0-2, and in which ^ and Rg together represent a total of at least one carbon atom.

3. A compound of the formula in which R^ and 2 which may be the same or different are hydrogen or lower alkyl, X- epresents hydrogen, halo, or lower alko^ , and which R^ and Rg together represent a total of at least one carbon atom.

4. Λ compound as claimed in any of claims 1 to 3 in which R^ and R2 together represent a total of 2 to .6 carbon atoms. 5. . A compound as claimed in claim, 1, 2 or 4 i which said X is at the 6-pos:i.tion and n is 1. 6. A compound as claimed in any of the .preceding claims in which X is chloro. 7. A compound as claimed in any of the preceding claim's 1 to 5 n which X is hydrogen. 8. A compound as claimed in any of the preceding •claims 1 to 5 in which X is methoxy. 9. · A compound as claimed in claim 1, 2 and to 8 in which both ^'s in the 7-amino group are hydrogen. 10. A compound as claimed in any of the preceding claims in which R-L is ethyl and g is methyl. 11. 7-AiQino-l-ethyl-2-methyl-5-trifluoromethylbenzimi-dazole. 12. 7-Amino-6-chlorO"l-ethyl».2--methyl-5-trifluoromethyl-benzimidazole. 1 . Λ comp.ound as claimed in any of claims 1 to 10 in its hydrochloride salt form. 15. A compound as claimed in any of claims 1 to.9 in which and are lower alkyl. 16. A process for the production of compounds as claimed in claim 1 in whic Y is which comprises chemically reducing a compoimd as defined in claim 3. 17. A process for the production of a compound as claimed in claim 3 which comprises reacting a compound of the formula with a carboxylic or with, a carboximidate of the formula MI It R2~C0R' in which formulae R^, Rg and X have the meanings defined in claim X and R' is a lower ally1 group, 18. A herbicidal composition comprising a compound according to Claim 2 and a carrier therefor. 19. A herbicidal composition according to Claim 18 in which a surfactant is included. 20. The method for controlling unwanted plant growth which comprises applying to the locus of said plant growth, a phytotoxic amount of a compound as claimed in claim 2. 21. The method according to. Claim 20 in which said compound is applied as a post-emergence 'treatment. 22. The method according to- Claim 20 in which said compound is 7-amino-6~chloro^l-ethyl-2~raethyl~5-trifluorometlvl-benzimidazole. 23. . The method according to Claim 20 in which said compound is 7-amiiio-6-chloro-l-methyl~2~isopropyl~5-trifluoromethylbenzimidazo1e. 2¾. The method according to Claim 20 in which said compound is 7~amino-6-chloro-l-isopropyl-2-methyl-5~ trifluoromethylljenzimidazole . 25. The method according to claim 20 in which both R^'s in the 7-amino group are hydrogen. 26. The method according to' claim 20 in which about 0.2 •to 15 pounds per acre of said compound is applied.