GB922371A - Substituted alpha-halo-or-methoxy-phenylacetic acids, their preparation and use in herbicidal compositions - Google Patents

Abstract

The invention comprises compounds of formula <FORM:0922371/IV(a)/1> wherein X is a chlorine or bromine atom or a methoxy group and each A is a hydrogen, chlorine or bromine atom or a methoxy, nitro, amino or methyl group, at least one of the A's being a halogen atom or a methoxy group and a maximum of two A's being hydrogen except that A is not amino when X is halogen and except that the 2-, 3-, and 5-positions are never occupied simultaneously by chlorine when X is chlorine or methoxy; their esters in which the esterifying group is an unsubstituted alkyl group which contains 1-10 carbon atoms, their alkali metal salts, ammonium salts, amine salts, unsubstituted alkylamine and alkanolamine salts and their amides. The compounds are used in herbicidal composition (see Group VI). The acids are prepared by reacting a benzaldehyde of formula <FORM:0922371/IV(a)/2> with cyanide to form the corresponding a -hydroxybenzylnitrile converting this to the corresponding mandelic acid by treatment with acid and (a) methylating to form the corresponding a -methoxyphenylacetic acid or (b) reacting with phosphorus penta-chloride or bromide to form the corresponding a -chloro-or -bromo-phenylacetic acid. The amino-substituted acids are prepared by reduction of the corresponding nitro compounds. The esters, salts and amides are derived from the acids by conventional procedures. In examples the preparation of the following acids is described: derivatives of a -methoxyphenylacetic acid:-2-methoxy-3,5-dimethyl-or -dichloro-, 2,3,6- or 2,4,5-trichloro-, 2-methyl-4,6-dichloro-, 3-nitro or amino-2,6- or -4,6-dichloro, 3-methoxy-2-chloro-4-or -6-nitro- or -amino-, 2-nitro-3,5-dimethyl-, 4-methoxy-3,5-dichloro-, 3-methoxy-2,4-dichloro-, 3-methoxy- 2,4,6-trichloro-, 3-methoxy-4,6-dibromo-, and 3-methoxy-2-chloro-4-bromo-; derivatives of a -chloro- or -bromo-phenylacetic acid; 2-methoxy-3,5-dimethyl-, 2-methyl-4,6-dichloro-3-nitro-2,6- or -4,6-dichloro-, 2-chloro-3-methoxy- 4-nitro-, 2-nitro-3,5-dimethyl, 3,5-dichloro-4-methoxy-, 2,4-dichloro- 3-methoxy-, 2-methoxy- 3,5-dichloro-, 3-methoxy-2,4,6-trichloro-, 2,4,5-trichloro-, 3-methoxy-4,6-dibromo- and 2-chloro-3-methoxy-4-bromo-; derivatives of a -chloro-phenylacetic acid:- 2,3,6-trichloro-and 2-chloro-3-methoxy-6-nitro-; and a -bromo- 2,3,5-trichlorophenylacetic acid. Several intermediate mandelic acids are described in examples. The following derivatives of the acids are also described in examples:-sodium, ammonium, dimethylamine, diethanolamine and morpholine salts; ethyl, n-butyl and n-decyl esters; acid chloride, amide, N-n-decylamide and N:N-diethylamide.ALSO:Herbicidal composition contain as active ingredient a compound of formula <FORM:0922371/VI/1> wherein X is a chlorine or bromine atom or a methoxy group and each A is a hydrogen, chlorine or bromine atom or a methoxy, nitro, amino or methyl group, at least one of the A's being a halogen atom or a methoxy group and a maximum of two A's being hydrogen except that A is not amino when X is halogen and except that the 2-, 3- and 5-positions are never occupied simultaneously by chlorine when X is chlorine or methoxy; its esters in which the esterifying group is an unsubstituted alkyl group containing 1-10 carbon atoms, its alkali metal salts, its ammonium salt, its amine salts, its unsubstituted alkylamine and alkanolamine salts and its amides (see Group IV (b)). The compositions may be dusts using talcs or clays as diluent, solutions in xylene, kerosene, methylnaphtha-lene or water or suspensions or emulsions in water. In examples: (1) emulsifiable concentrates are prepared by mixing (a) a ,2,3,6-tetrachlorophenylacetic acid, methanol and a non-ionic detergent or (b) n-butyl a ,2,3,6-tetrachlorophenyl-acetate, xylene, kerosene and a non-ionic emulsifier; (2) talc and sodium a ,4,6-trichloro-2-methyl-phenylacetate are mixed to form a dust composition.