HERBICIDES CONSTITUES D'HALOPHENOXYBENZAMIDE

HALOPHENOXY BENZAMIDE HERBICIDES

Abrégé anglais

ADSTRACT OF THE DISCLOSURE
2-Nitro-5-(halophenoxy)benzoic acids and esters,
salts, amides, and acyl halides thereof comprise a class
of compounds that are highly effective pre- and post-
emergence herbicides.

Revendications

The embodiments of the invention in which an
exclusive property or privilege is claimed are defined as
follows:
1. A halophenoxy-benzamide of the formula:
<IMG>
in which X is halogen, n is an integer of from 1 to 5, and
R is an alkylamino group containing 4 to 6 carbon atoms or
a dialkylamino group in which the alkyl groups contain from
4 to 6 carbon atoms.
2. A compound according to claim 1 wherein said
compound is N-sec-butyl 2-nitro-5-(2',4'-dichloro-6'-fluoro-
phenoxy)benzamide.
3. A compound according to claim 1 wherein said
compound is N,N-di(sec-butyl)-2-nitro-5-(2',4'-dichloro-6'-
-fluorophenoxy)benzamide.
4. A compound according to claim 1 wherein said
compound is N-hexyl-2-nitro-5-(2',4'-dichloro-6'-fluoro-
phenoxy)benzamide.
5. A compound according to claim 1 wherein said
compound is N-sec-butyl-2-nitro-5-(2',4',6'-trichlorophenoxy)-
benzamide.
6. A method of controlling plant growth, which
comprises applying a herbicidally effective amount of a
compound as defined in claim 1 to the plants or to the medium
in which they are growing.
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7. A method of controlling plant growth, which
comprises applying a herbicidally effective amount of a
compound as defined in claim 2 to the plants or to the medium
in which they are growing.
8. A method of controlling plant growth, which
comprises applying a herbicidally effective amount of a
compound as defined in claim 3 to the plants or to the medium
in which they are growing.
9. A method of controlling plant growth, which
comprises applying a herbicidally effective amount of a
compound as defined in claim 4 to the plants or to the medium
in which they are growing.
10. A method of controlling plant growth, which
comprises applying a herbicidally effective amount of a
compound as defined in claim 5 to the plants or to the medium
in which they are growing.
11

Description

~433SS
Background o ~he Invention
Field of the Invention
This invention is concerned with certain phenoxy-
benzoic acid compounds and their use as herbicides.
Description of the Prior Art
It has been proposed to use as herbicides 2-methoxy-
benzoic acids (U.S. Patent 3,013,054) and 4-phenoxybenzoic
acids (French Patent 1,502,538). It is the discovery of this
invention, however, that benzoic acids having a phenoxy sub-
stituent in the 5-position are very effective herbicides.
Summary of the Invention
We have found that halophenoxy-benzamides of the
formula:
COR
2~ ~ ~ (X)n
wherein X is halogen, n is an integer of from l to 5, and R
is an alkylamino group containing 4 to 6 carbon atoms, or a
dialkylamino group in which the alkyl groups contain 4 to 6
carbon atoms, have herbicidal activity~ When n is 2 or more,
more than one halogen species may be substituted in the ben-
zene ring of the phenoxy group, that is the X's need not all
be the same and, for example, both fluoro and chloro sub-
stituents may be present in the same compound; reference to X
being halogen is to be understood in this sense.
The compounds of the above formula are novel and
constitute one aspect of the present invention.
The present invention also comprises a herbicidal

16~43;~SS
composition comprising a compound according to the invention
and a carrier therefor.
The compounds of this invention are readily prepared
by the Ullmann ether synthesis reaction between an alkali
metal (e.g., Na or K) salt of~a halophenol and a 5-halo (e.g.,
Cl or Br) -2-nitrobenzamide. The latter can readily be pre-
pared from the corresponding 5-halo-2-nitrobenzoic acid which
in turn can be readily prepared by nitrating an m-halotoluene,
followed by oxidation of the methyl group by well known
procedures. Alternatively~ and in most cases preferably, the
Ullmann ether synthesis is carried out using the corresponding
benzoic acid or benzoic acid ester, such as the methyl ester,
and in the latter case the ether formed is hydrolyzed to
obtain the benzoic acid. The product obtained in either case,
that is the halophenoxy-nitro-benzoic acid, is then converted
into the desired benzamide by any convenient procedure,
preferably by converting the benzoic acid to the corresponding
benzoyl chloride and reacting the latter with the appropriate
alkylamine or dialkylamine to obtain the desired benzamide.
Compounds according to the invention include,
for example:
N-sec-butyl-2-nitro-5-(2',4'-dichloro-6'-fluoro-
phenoxy)-benzamide,
N,N-di-sec-butyl-2-nitro-5-(2',4'-dichloro-6'-
fluorophenoxy)-benzamide,
N-hexyl-2-nitro-5-(2',4'-dichloro-6'-fluorophenoxy)-
benzamide, and
~-sec-butyl-2-nitro-5-(2',4',6'-trichlorophenoxy)-
benzamide.

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In order that the invention may be more fully
understood, the following preparative examples are given by
way of illustration only:
Example 1
Methyl-2-nitro-5-(2',4'-dichloro-6'-fluorophenoxy)-
benzoate is hydrolyzed to the acid by heating a 10 percent
solution of the methyl ester with a 5 percent solution of
sodium hydroxide at 70C for 8 to 10 hours until a clear
solution is obtained. The excess alkali is neutralized with
HCl and the free benzoic acid filtered off.
The acid is then dissolved in benzene and refluxed
for 5 to 7 hours with 20 percent excess thionyl chloride.
me solvent and thionyl chloride are stripped off after
reaction i8 complete.
The benzoyl chloride is then dissolved in benzene
and sec-butylamine added. Reaction takes place immediately
with evolution of HCl. The mixture is refluxed for 2 hours
to completion. The solvent is then stripped off to give the
product, N-sec-butyl-2-nitro-5-(2',4'-dichloro-6'-fluoro-
phenoxy)-benzamide which is then recrystallized from a mix-
ture of ether and petroleum ether.
Example 2
Example 1 is repeated, but using di-sec-butylamine
instead of sec-butylamine, to give N,N-di-sec-butyl-2-nitro-
-5-(2',4'-dichloro-6'-fluorophenoxy)-benzamide.
Example 3
Bxample 1 is repeated, but using hexylamine as the
amine, to give N-hexyl-2-nitro-5-(2',4'-dichloro-6'-fluoro-
phenoxy)-benzamide.
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~ . ,, ~ .

1043355
Example 4
Example 1 is repeated, but starting with methyl-2-
-nitro-5-(2',4',6'-trichlorophenoxy)-benzoate, to give N-sec-
-butyl-2-nitro-5-(2',4',6'-trichlorophenoxy)-benzamide.
-
.
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.;

1043355
The compounds of this invention can be applied in
various ways to achieve herbicidal action. They can be applied,
per se, as solids or in vaporized form, but are preferably applied
as the toxic components in pesticidal compositions of the
compound and a carrier. The compositions can be applied, as dusts;
as liquid sprays, or as gas-propelled sprays and can contain,
in addition to a carrier, additives such as emulsifying agents,
binding agents, gases compressed to the liquid state, odorants,
stabilizers, and the like. A wide variety of liquid and solid
carriers can be used. Non-limiting examples of solid carriers
include talc, bentonite, diatomaceous earth, pyrophyllite, fullers
earth, gypsum, flours derived from cotton seeds and nut shells,
and various natural and synthetic clays having a pH not exceed-
ing about 9.5. Non-limiting examples of liquid carriers, include
water; organic solvents, such as alcohols, ketones, amides and
esters; mineral oils, such as kerosene, light oils, and medium
oils and vegetable oils, such as cottonseed oil.
In practice, herbicidal application is measured in
terms of pounds of herbicide applied per acre. The compounds
of this invention are effective herbicides when applied in
herbicidal amounts, i.e., at rates between about 0.2 pounds
and about 10 pounds per acre.

10433S5
HERBICIDAL EFFECTIVENESS
Method of Propagating Test Species
Crabgress Digitaria Sanguinalis
Yellow Foxtail Grass Setaria glauca
Johnson grass Sorgum Halepense
Barnyard grass Echinochloa crus-galli
Amaranth pigweed Amaranthus retroflexus
Turnip Brassica sp.
Cotton Gossypium hirsutum var. DPL
oth leaf
Corn Zea Mays var. Golden Bantam
Bean Phaseolus vulgaris var.
Black Valentine
All crop and weed species are planted individually
in 3" plastic pots containing potting soil. Four seeds of each
of corn, cotton, and snapbeans are seeded to a depth equal to
the diameter of the seed. All other species are surface seeded
and sprinkled with screened soil in an amount sufficient to
cover the seeds. Immediately after planting, all pots are
watered by sub-irrigation in greenhouse trays. Pots for the
pre-emergence phase are seeded one day before treatment.
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1~43355
Planting dates for the post-emergence phase are varied
so that all the seedlings will reach the desired stage of
development simultaneously. The proper stage of seedling
development for treatment in the post-emergence phase is as
follows:
GRASSES: 2 inches in height
PIGWEED & TURNIPS: 1 or 2 true leaves visible
above cotyledons.
COTTON: first true leaf 1 inch in
length; expanded cotyledons.
CORN: 3 inches - 4 inches in height
BEANS: primary leaves expanded, grow-
ing point at primary leaf node.
Method of Treatment
Spray applications are made in a hood containing a
movable belt and fixed spray nozzle. For passage through
the spray hood, one pot of each species (pre-emergence phase)
is placed on the forward half of a wooden flat and one pot of
established plants (post-mmergence phase) is placed on the
rear half of the flat. Treatments are moved to the greenhouse
after spraying. Watering during the observation period is
applied only by sub-irrigation.
Compounds are screened initially at a rate of applica-
tion equivalent to four to eight pounds per acre. Two weeks
after treatment the pre- and post-emergence per cent injury is
vi~ually rated. Subsequent testing was carried out at 2,1
and 0.5 pounds per acre.

1~4;~SS
Herbicidal testing of the compound of Example 1
showed the results set forth in Table I. The plants are
tabulated using the following abbreviations:
Crabgrass CG
Johnson grass JG
Barnyard grass BG
Bean BN
Pigweed PW
Turnip TP
Cotton CT
Corn CN
.
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lQ4;~355
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