Patent GB-968661-A (GB)
Title: Herbicidal compositions containing 3-substituted uracils
IPC: C07D239/70
Filed: 1960-08-15
Abstract: 3-Substituted uracils of the isomeric formulae: <FORM:0968661/C1/1> or <FORM:0968661/C1/2> where R1 is a covalent organic radical of molecular weight 15-250 which is C1- 10 alkyl, substituted C1- 3 alkyl, phenyl which may be substituted, C7-8 aralkyl, C7- 12 substituted aralkyl, C3-6 alkenyl, propynyl, butynyl, C5-8 cycloalkyl or cycloalkenyl, or cyano; R2 is hydrogen, halogen, C1-4 alkyl, C1-3 alkoxy NO2, C2-4 alkoxymethyl, hydroxymethyl, hydroxyethyl, allyl, thiocyanato, cyano, halogenomethyl or methylthiomethyl; R3 is hydrogen, chlorine, C1-5 alkyl, methoxy or ethoxy; or R2 and R3 together make up a bridge of formula (CH2)n where n is 3, 4 or 5; and X is oxygen or sulphur; with the proviso that if R2 is hydrogen, then either R3 is C1-5 alkyl and R1 is C3-6 alkyl, allyl, propynyl or C5-8 cycloalkyl or cycloalkenyl; or R3 is hydrogen and R1 is C5-8 cycloalkyl or cycloalkenyl; are prepared by heating a urea R1NH.CX.NH2 with an ester R1OCOCHR2.COR3 (where R1 is C1-6 alkyl) in the presence of an acidic compound and under substantially anhydrous conditions to produce a compound R1NHCXNHCR3=CR2COOR1, and heating this under substantially anhydrous conditions in the presence of a strong base to effect ring closure to give a metal salt (the metal being that of the base) of the compound of the above formula; and acidifying to obtain the free uracil.  Novel compounds.  The following groups of compounds of the above general formula are claimed as novel: (i) those in which R1 is C5-8 cycloalkyl or cycloalkenyl, or a group -CR5R6R7, where R5 is hydrogen or methyl, R6 is methyl or ethyl, and R7 is C1-5 alkyl; R2 is chlorine or bromine and R3 is methyl; (ii) those in which R1 is C5-8 cycloalkyl or cycloalkenyl, R2 is hydrogen and R3 is C1-5 alkyl; (iii) those in which R1 is as defined in (i) above, and R2 and R3 together make up (CH2)n, where n is 3, 4 or 5; and (iv) those in which R1 is phenyl or substituted phenyl or C5-8 cycloalkyl or cycloalkenyl, R2 is halogen or methyl or nitro, and R3 is hydrogen; and metal salts thereof. Other preparative methods, used in examples are the halogenation of compounds with R2=H to give R2 as chlorine or bromine; nitration of compounds with R2=H to give R2 as NO2; reactions of compounds with R2=H with lead thiocyanate and bromine to give R2 as thiocyanato; reaction of R1NH.CX.NH2 with diethyl oxalacetate or a -substituted oxalacetate followed by acidification (giving e.g. 3-cyclo-hexyluracil-6-carboxylic acid and 3-cyclohexyl-5-methyluracil-6-carboxylic acid) and decarboxylation, giving compounds with R1 in the 3-position, H or the a -substituent in the 5-position (R2) and R3 as hydrogen; reaction of a urea or thiourea substituted by R1 with an alkyl 2-cycloalkanone-1-carboxylate, (giving e.g. 2-(3-methylureido)-1-cyclopentene carboxylic acid ethyl ester) followed by reaction with a base and acidification, giving R2 and R3 as tri-, tetra- or pentamethylene; reaction of compounds with R2=H with formaldehyde to give 5-hydroxymethyl compounds or with chloromethyl methyl ether to give 5-chloromethyl compounds, or converting 5-hydroxymethyl to 5-chloromethyl with thionyl chloride; reaction of 5-chloromethyl compounds with alkoxides or methyl-mercaptides to give R2 as alkoxymethyl or methylthiomethyl; reaction of R1NCO with R3C(NH2)=CHCOOC2H5 followed by ring closure with a base and then acidification; formation of alkali metal salts by reacting a uracil compound with an alkali metal methoxide in alcohol; and formation of other metal salts by metathesis.  Many examples are given.  The uracils of the formula given are herbicides (see Division A5).  Specifications 492,742, 677,342, 968,662, 968,663, 968,664 and 968,665 are referred to.ALSO:Herbicidal compositions comprise at least one compound of the isomeric formul <FORM:0968661/A5-A6/1> or <FORM:0968661/A5-A6/2> where R1 is a covalent organic radical of molecular weight 15-250 which is C1-10 alkyl, substituted C1-3 alkyl, phenyl which may be substituted C7-8 aralkyl, C7-12 substituted aralkyl, C3-6 alkenyl, propynyl, butynyl, cyano or C5-8 cycloalkyl or cycloalkenyl; R2 is hydrogen, halogen, C1-4 alkyl, C1-3 alkoxy, NO2, C2-4 alkoxymethyl, hydroxymethyl, hydroxyethyl, allyl, thiocyanato, cyano, halogenomethyl or methylthiomethyl; R3 is hydrogen, chlorine, C1-5 alkyl, methoxy or ethoxy; or R2 and R3 together make up a bridge of formula (CH2)n, where n is 3, 4 or 5; and X is oxygen or sulphur; with the proviso that if R2 is hydrogen, then either R3 is C1-5 alkyl and R1 is C3-16 alkyl, allyl, propynyl or C5-8 cycloalkyl or cycloalkenyl; or R3 is hydrogen and R1 is C5-8 cycloalkyl or cycloalkenyl; or a metal salt of such a compound (see Division C2), associated with (i) a diluent which is at least in part an oil (see below); (ii) a diluent which is at least in part a solid; (iii) a diluent which is a liquid other than an oil (such as water) and a surface active agent; or (iv) a surface active agent. The invention also comprises a method of controlling the growth of weeds at a locus which comprises applying to the locus a herbicidally effective quantity of a compound of the above formula or a metal salt thereof, if desired in the form of a composition as defined.  The subject-matter of Specifications 968,663, 968,664, 968,665 and 968662 is disclaimed.  An oil is defined as a liquid immiscible with water and soluble in ether, and which boils at not below 125 DEG  C.  Suitable oils are aliphatic and aromatic hydrocarbons, e.g. hydrocarbons of petroleum origin. Suitable solid diluents are talc, natural clay, pyrophillite, diatomaceous earth, synthetic fine silica, calcium silicate, magnesium and calcium carbonates, calcium phosphates, sulphur, lime, and flours such as those of walnut shell, wheat, redwood, soya-beam and cottonseeds.  Binders used for granular or pellet compositions include goulac, dextrin, swollen starch, glue and polyvinyl alcohol. Conventional additives such as gelatin, blood, albumin, rosin and alkyd resins may also be added. Compositions may also contain other herbicides, such as 2,3,6-trichlorobenzoic acid and salts, 2,3,5,6-tetrachlorobenzoic acid and salts, 2-chloro-N,N-diallylacetamide, N,N-dipropylthiolcarbamic acid ethyl ester, 2,2-dichloropropionic acid and salts, methylarsonic acid and salts, borates, chlorates, ammonium sulphamate, 2,4-dichlorophenoxyacetic acid, 2,4,5-trichlorophenoxyacetic acid, N-phenyl carbamic acid isopropyl ester, N-(m-chlorophenyl) carbamic acid isopropyl ester, trichloroacetic acid, maleic hydrazide, 1,1-dimethyl - 3 - (3,4 - dichlorophenyl)urea, 1,1-dimethyl - 3 - (p - chlorophenyl)urea, 1,1-dimethyl - 3 - phenylurea, 1 - n - butyl - 1 - methyl - 3 - (3,4 - dichlorophenyl)urea, 1-methoxy - 1 - methyl - 3 - (3,4 - dichlorophenyl) urea, 1 - methoxy - 1 - methyl - 3 - (p - chlorophenyl)urea, 1,1,3 - trimethyl - 3 - (3,4 - dichlorophenyl)urea, 2 - chloro - 4,6 - bis-(ethylamino) - s - triazine, 2 - chloro - 4 - ethylamino - 6 - isopropylamino - s - triazine, 2-chloro - 4,6 - bis - (methoxypropylamino) - s-triazine, 2 - methoxy - 4,6 - bis - (isopropylamino) - s - triazine, 2,4 - bis - (isopropylamino) - 6 - methoxy - s - triazine, dinitro - secbutylphenol, 2,3,6 - trichlorophenylacetic acid, 5,6 - dihydro - (4A, 6A) - dipyrido-(1,2-A, 21,1-C)-pyrazinium dibromide and 2,6-dichlorobenzonitrile.  Other materials employed in specific examples include methyl isobutyl ketone, dibutyl ketone, Na2SO4, Na2HPO4 and sodium pentachlorophenate.  Specifications 492,742 and 677,342 also are referred to.