Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROIIND OF TIIE INVENTION ~ ?
Field of the Invention - :
The invention relates to the herbicidal use of 5-propionyl- ~ :~
amino-3-methylisothiazole against weeds, primarily, broad leaf weeds ~ .
Description of the Prior Art
Robba and Moreau, in Annales phnrmaceutique francaises, 22,
- 1964, No. 3, pages 201-210, describe 5-propionylamino-3-methylisothiazole
as a derivative formed from 5-amino-3-methylisothiazole, (a compound
described by ~dam et al in l!.S. 2,871,243) and propionyl chloride, which
they nitrated at the 4 position of the isothiazole r:in~, to form the
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derivatlve 5-propionylamino-4-nitro-3-methylisothiazole. l'his derivative
was inactive against Trichononos va~inalis, a pathogen causing infections
of the human vagina. Stock et al, in U.S. 2,871,243, describe the starting
material, 5-amino-3-methylisothiazole, as an intermediate to the derivative
5-(p-acetamidobenzenesulphonylamino)-3-methylisothiazole, a useful bacter-
icide for Escherichia coli. Other workers, in the Journal of the Chemical
Society, 19S9, pages 3061 to 3071, describe the acetyl, dichloroacetyl and
benzoyl derivatives of the 3-amino-5-methylisothiazole but give no uses for
them. The chloroacetyl derivative, an analgesic, is listed in Volume 59 of
Chemical Abstracts, Column 2791 (1963). Stock et al, in U.S. 3,186,999,
describe semi-carbazone, and thiocarbazone derlvatives of 5-amino-3-methyl-
isothiazole, which are active against pox viruses. In Japanese patent
5641/64, S. Kamio et al (Chemical ~bstract 59, column 2791a) describe mono-
halogenocarboxylic amides of isothiazole as useful intermediates for amino-
carboxylic acid derivatives. - ;;
Others describe certain specified cyanated, halogenated, benzoated,
or urea-substituted isothia~ole derivatives as herbicides for certain weeds
or fungicides for certain fungi in U.S. Patents: 3,155,678, 3,393,992,
3,454,591, 3,541,108, 3,564,985, 3,622,593, and 3,692,795. None of the
above-mentioned references describe or suggest that a simple acylamino
derivative of 3-methylisothiazole, such as 5-propionylamino-3-methyliso-
thiazole, has herbicidal usage particularly against broad leaf weeds.
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SU~ ~ RY OF THE INVENTION
In accordance with this invention, 5-propionylamino-3-methyliso-
thiazole is employed to control weeds, notably broad leaf weeds. This -
control is achieved by use of a herbicidal amount of the compound, either
alone or formulated into a suitable agricultural composition. Preferably,
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the follage of the weed (aFter emergence of the weed) i5 contacted with
the compound, althou~h the compound can be used with good efEect in pre-
emergent treatments. Broad leaE weed specLes in particular are especially
well controlled by the compound.
l)ESCRIPTION OF TlIE PREFERREI) EMBOI)IMENTS
l~eeds, primarily broad leaf weed species, are effectively con-
trolled according to this invention by the use of 5-propionylamino-3-
methylisothiazole, usually by contacting the weeds with a herbicidal
amount of the compound. The control can be by application of the compound
to the soil or weed (e.g. the weed environment) either prior to or after
emergence of the weed, or in any combination thereof, but the preferred
method is to contact the weed after emergence of the weeds, that is when
the weeds protrude from the soil. If both crop plants and weeds are
emerging, then the compound is applied after emergence of both. A
preferred method is to contact the foliage of the weed with a lethal
dosage of the compound. This is readily achieved by applying the compound ~ -
itself or in the form of a suitable agricultural composition to the
foliage of the weed. The lethal (herbicidal) dosage will of course vary
with the plant size, weather, soil and the crop planted. A workable
lethal dosage for plant contact is from 0.25 to 500 lbs. per acre (0.27
to 550 kilogram/hectare) of the compound whether applied itself or in
the form of an agricultural composition, while from 0.25 to 50 lbs. per
acre (0.27 to 55 kilograms per hectare) is normally the range to use under
various climatic conditions, but preferably from 1 to 10 lbs. per acre
(1.1 to 11 kilogram/hectare) under optimum conditions. - `~
It has been discovered that the compound 5-propionylamino-3-
methylisothiazole is particularly effective against broad leaf weeds,
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particularly those oE the genera: Chenopo(lium, Amaranthus~ Abutilon,
l~atura, ~ , Sida, Sesbania, Xanthium, ancl Ca~ssla. The compounds
were found extremely e~fective against the broad leaf species: Chenopod;um
albu;ll (common lambsquarter), Amaranthus retroflexus (redroot pigweed),
Datura stramonium (jimsonweed), Ipomoea purpurea (tall morning glory),
Ipomoea hederocea (ivyleaf morning glory), Sida spinosa (teaweed, prickly
sida), Abutilon theophrasti (velvetleaf), Sesbania spp. (Coffeeweed),
Xanthium pennsylvanicum (common cocklebur), and Cassia obtusifolia
(sicklepod).
The following Examples illustrate the manner in which this
invention may be practiced.
EXAMPLE l
The effectiveness of 5-propionylamino-3-methylisothiazole as
a herbicide for controlling broadleaf weeds under field conditions is
illustrated in this Example.
Six 60-foot rows of Gylcine max, soybeans seeds, (variety:
Amsoy) and six 60-foot rows of Gossypium hirsutum, cotton seed, (variety:
Coker 201) were planted on a farm, in Barberton, Ohio, on August 28, 1973.
One week later a mixture of weed seeds was evenly distributed over the
crop rows in an 8 to 10 inch band, covered lightly with soil, and watered.
The mixture of weed seeds was a representative cross-section of
broad leaf weeds, and contained, in about equal weight, seeds of a specie
of each of the following genera: Chenopodium, Amaranthus, Abutilon, Datura,
Ipomeoa, Sida, Sesbania, Xanthium, and Cassia, The particular weed species
used were: Chenopodium album (common lambsquarter), Amaranthus retroflexus
(redroot pigweed), Datura stramonium (iimsonweed), Ipomoea purpurea (tall
m~rning glory), Ipomoea hederacea (ivyleaf morning glory), Sida sponosa
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(teaweed, pricl;ly sida), Abutilon theophrasti (velvetleaf), Sesbania spp.
(coEfeeweed), Xanthium penns~lvanicum (common cocklebur), and ~assia
obtusifolia (sicklepod).
Approximately Eour weeks after the weed seeds were planted,
when the soybean and cotton plants were approximately 5-6" and 4-5" tall
respectively, and the weeds were from 1" to 4" in height, the weeds were
contacted with the compound 5-propionylamino-3-methylisothiazole.
This contact was achieved by applying the compound as a directed
post-emergency spray, that is a spray directed on weeds below the crop
foliage. The band width of the spray was approximately 12 inches wide,
and the row length to which it was applied was ahout 20 feet. This row
length was followed by an untreated band of 20 feet whicll was followed by
another treated band. The volume of spray per 20 sq. ft. area (20 ft. -
long by 1 ft. wide) was 87 ml., which is equivalent to 50 gallons per acre.
The amount of the 5-propionylamine-3-methylisothia~ole per 87 ml. was - -
adjusted to give application rates of 0.5, 0.10, 2.0 lbs. per acre (0.55,
1.1, 2.2 kilograms/hectare) of the compound itself. The solvent used ~ ;
B was water which contained 0.5 vol. %/vol. of Tween 20, a surfactant.
The plots were observed at regular intervals, and two weeks after ~ -
application, a weed control rating was taken on a 0-10 scale; ~ero ("0")
no control, that is no plants were killed and ten ("10") complete control, ~ ~
all plants were killed. ~ ~ -
The average value of the con~rol rating based on two replicates
showed that at 0.5 lb./acre (0.55 kilograms/hectare) most weeds were com-
pletely killed, except maranthus retroflexus (common lambsquarter) which
had about 70% of the plants killed, Ipomoea purpurea (tall morning glory) ~; ~
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and Ipomoea hederacea (ivyleaf morning glory) which had about 90% of the
plants killed, and Xanthium pennsylvanicum (cocklebur) which had about 80%
of the plants killed.
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At an application rate of 1 lb./acre (1.1 kilograms/hectare),
about 80% of the Am~ranthus retro~lexus and Xanthium pennsylvanicum were
kLlled ~nd 100~ of the Ipomoea purpurea and the Ipomoea llederacea
were kllled while, as before~ all other weeds were completely killed.
At an application rate of 2.0 lb./acre (2.2 kilograms/hectare),
all weeds were killed.
These field test results show the compound's herbicidal
activity against weeds and, in particular, broad leaf weeds. Although
the lethal dosage shown was for 0.5 to 2.0 lbs./acre (0.55 to 2.2
kilograms/hectare), such a dosage can be varied from 0.25 to 500 lbs./acre
(0.27 to 550 kilograms/hectare), depending upon the type and the amount
of weeds and the weather, but generally 0.25 to 50 lbs./acre will suffice,
and under optimum conditions from 0.25 to 10 lbs./acre is preferred.
It is to be noted, that weed species o~ the Gossypium genera
are also effectively controlled by the compound. -
The compound 3-amino-5-methylisothiazole, itself, and the
compound 3-acetylamino-5-methylisothiazole, and 3-benzamido-5-methyliso-
thiazole when tested under comparable conditions against both broad leaf
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weeds and grassy weeds had no activity, in comparison to the higll activity
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of ~-propionylamino-~-methylisothiazole.
The compound, 5-propionylamino-3-methylisothiazole, is readily
made by reacting propionyl chloride with 5-amino-3-methylisothiazole in
the manner described by M. Robba and R. C. Moreau (Annales pharmaceutique
francaises, 22, 1964 No. 3, pages 201-210.
The compound can also be made by reacting 5-amino-3-methyl-
isothiazole with propionic anhydride, as illustrated by the following
example.
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EXA~PLE 2
A 40 gram quantity (0.265 mole) of 5-amino-3-methylisothiaæole
hydrochloride was neu~ralized wlth 270 ml. of aqueous NaO~I and the resulting
mixture extracted wlth three 100 ml. portions of ethyl ether. The extracts
were comblned, dried with anhydrous MgSO4, filtered and evaporarated under
reduced pressure to afford 32 grams of the free amine as a brown oil.
The free amine was placed into a 250 ml. three-neck flask
equipped with a stirrer, thermometer and reflux condenser. To it was added ~
a 103.4 gram quantity (0.795 mole) of propionic anhydride. Upon mixing, the ~ ;
heat given off during reaction warmed the mixture to 80C. and then it was
10 heated to 100C. and maintained at that temperature for two hours, prior
to cooling to ambient temperature. During the cooling period, product
material crystallized out of solution and a slurry formed. The crystalline
slurry was then filtered, and formed into pulp with 100 ml. of petroleum-
ether, and the pulp was air dried to form 22.8 grams of the desired product ~
15 material (22.8 gram); it had a melting point of 167-170C.
A second crystal crop was obtained by pouring the original filtrate
into 250 ml. of petroleum-ether followed by filtration of the precipitated
crystals to afford an additional 13.8 grams of an off-white product material
having the same melting point. The total weight of the product obtained ~
20 was 36.6 grams, (81% yield).
Normally, use of 5-propionylamino-3-methylisothiazole is by way
of an appropriate formulation. For example, it may be formulated as a
granule of relatively large size, as a powdery dust, as a wettable powder,
as an emulsifiable concentrate, as a solution, etc., depending upon the mode
of application desired. For pre-emergence application to control vegetation,
the compound is usually applied to the area as a spray, dust, or granule;
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for post-emergence control of an established weed, a spray or dust is
generally employed. In all these formulations, tlle active lngredient
is diluted with an lnert carrier, either a solid or liquid diluent. The
formulat:Lons may contain as little as 0.1 percent or as mucll as 99 per-
cent or more by weight of the active ingredient.
Dusts are mixtures of the active compound with finely divided
solids such as talc, altapulgite, clay, kieselguhr, and other organic
and inorganic solids which act as dispersants and carriers for the com-
pound. The finely divided solids have an average particle size of less
than about 50 microns. A typical dust formulation will contain from
1.0 to 10.0 parts by weight of 5-propionylamino-3-methylisothiazole to
99.0 to 90.0 parts by weight of talc.
Wettable powders for pre-emergent or post-emergent application
are finely divided solid particles, which disperse readily in water or
other liquids. The wettable powder is applied to the soil, seed or plant
as a dry dust or as a water or other liquid emulsion.
Typical wettable powder carriers are Fuller's earth, Kaolin
clays, silicas, and other highly absorbent, readily wet, inorganic diluents.
Wettable powders normally contain about 5 to 80 weight percent of the
active ingredient, depending on the absorbency of the carrier, and usually
contain a small amount of a wetting, dispersing, or emulsifying agent
to facilitate dispersion.
For example9 a useful wettable powder formulation comprises by
weight about 80.8 parts of 5-propionylamino~3-methylisothiazole, 17.9 parts
:
of Palmetho clay and 1.0 part of sodium lignosulfate and 0.3 parts of
sulfonated aliphatic polyester as wetting agents.
Other post-emergent formulations are emulsifiable concentrate.
These are homogeneous liquid or paste compositions which are dispersible
in water or other liquids. They may consist entirely of 5-propionylamino-3-
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methylisothiazole and a liquid or solid emulsifying agent, or they may also
contain a liquid carrier, such as xylene, heavy aromatic naphthas, or other
non-volatlle organic solvents. These emulsiEiable concentrates are dispersed
in a liquid carrier, e.g. water, and generally are applied as a spray to
the area or plant to be treated. The weight percent of 5-propionylamino-3-
methylisothiazole in these concentrates varies with the manner of applica-
tion, but generally is from 0.5 to 95 percent.
Representative wetting, dispersing and emulsifying agents for
the agricultural formulations are alkyl and alkylaryl sulfonates and sulfates,
and their alkali salts; polyethylene oxides, sulfoxided oils, fatty acid
esters of polyhydric alcohols, and other surface-active agents, e g.
Tween 20, a commercial surfactant. If used, the surfactant would vary
from 0.25 to 15 weight percent of the composition.
Other formulations for herbicidal applications include simple -~ ~
15solutions of the compound in solvents in which it is completely soluble ~ -
at the desired concentration, e.g. acetone or other organic solvents;
aerial spray formulations comprising relatively coarse particles coated -~
with 5-propionylamino-3-methylisothiazole, and pressurized spray formula-
tions such as aerosols, which use low boiling dispersant solvents such as
Freon. All of these formulations may be used to apply the active compound
to the area to be treated.
These formulations may also include other agriculturally useful
materials such as nematocides, pesticides, and herbicides which are non-
toxic to the desired vegetation, but which are effective against other
weeds, pests, and nematodes, their eggs, fungi and bacteria so that one
application will serve to rid the area of several undesirable species. For
example, 5-propionylamino-3-methylisothiazole may be used with sodium azide,
or potassium azide in formulations which contain stabilizers for both the
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azide and the isothiazole compound. Other combinations of the compound
5-propionylamino-3-methylisothiazole are those with certain ureas, thio-
carbamates, carbamates, which incr~ase the useful herbicidal spectrum
of the thiazole, reduce the number of applications required by husbandmen
and others who require use of these compounds to assist the healthful
growth of crops. It may be used in combination with fertilizers, particu-
larly those used in foliage applications, provided of course that the
composition formulation is such that 5-propionylamino-3-methylisothiazole
is not hydrolyzed, e.g., the pll conditions are maintained between 2-10,
preferably between 5 and 8. ~ ~ -
When the compound is spplied in the form of a suitable agricultural
composition, the application rate of such formulation is such that the
herbicidal dosage of the compound, itself, is between 0.25 to 500 pounds
` per acre (0.27 to 550 kilograms per hectare). Generally, the rate is from
- 15 0~25 to 50 pounds per acre (0.27 to 55 kilogram per hectare), but preferably
from 1 to 10 pounds per acre (1.1 to 11 kilograms per hectare) under optimum
conditions.
While the invention has been described with reference to specific
details of certain illustrative embodiments, it is not intended that it shall
be limited thereby except insofar as such details appear in the accompanying
claims.
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