Note: Descriptions are shown in the official language in which they were submitted.
- 2 - ~Q~ ~2 ot7
This invention relates to novel amino-acid
derivatives, to processes for their preparation, to
herbicidal compositions containing them and to a
method of combating undesirable plant growth with these
derivatives.
Under modern methods of agricultural husbandry it
has been found possible to leave cereal crops standing
until full ripening of the ears has taken place. This
was not the case formerly when harvesting was more
dependent on weather conditions and took place over a
longer period. Unfortunately wild oat matures more
rapidly than grain crops and, when this weed is present,
a proportion of its seeds are now shed into the soil
before harvesting takes place; by this means serious
infestation of arable land by wild oat has occurred.
Moreover, it is very difficult to separate wild oat
seeds from the seeds of other grain crops and the
presence of wild oat in, for example, a sample of seed
wheat seriously affects its merchantable quality.
Attempts at chemical control of this pest have been made
but hitherto these have not been entirely successful.
It has now been discovered that a new class of amino
acid derivatives have useful selective herbicidal
properties, and in particular givé improved control of
wild oat.
The amino-acid derivatives according to the invention
are N,N-disubstituted amin~-acid derivatives of the formula:
~'
~05~ZZUl7
CS
X ~ N - CH - COR (I)
y CH3
wherein X is a halogen atom;
Y is a hydrogen atom or a halogen atom;
Z is a phenyl group optionally substituted by one or more halogen
atoms, alkyl, alkoxy, or nitro groups; and
R is hydroxy, -SR or -OR ,
wherein R is alkyl, haloalkyl, cycloalkyl, alkenyl, aryl, or a
salt-forming cation.
The terms "alkyl", "alkylene", "alkoxy", "alkenyl" are used
herein to denote groups which are both straight or branched in structure.
4 10~
For economic reasons the preferred compounds are
those in which the halogen atoms are fluorine or chlorine;
the aryl groups are phenyl groups; the alkyl, cycloalkyl
and alkenyl groups contain up to 6 carbon atoms, the
alkaryl and aralkyl groups contain up to 10 carbon atoms;
and the alkylene bridge contains up to 6 carbon atoms and
the hetero atoms which optionally interrupt the bridge
are oxygen and/or nitrogen. It will be understood that
the preferred compounds contain one or more of the
preferences expressed in this paragraph.
From the point of view of improved activity in
selectively controlling wild oats in cereal crops the
preferred compounds are those in which:
X is fluorine or chlorine;
Y is hydrogen, fluorine, or chlorine;
Z is phenyl;
R is hydroxy, -OR1 wherein R1 is alkyl of up to
6 carbon atoms, an alkali metal or alkaline earth
metal lon, or an ammonium ion optionally substi-
tuted by one or more alkyl groups of up to
6 carbon atoms.
It will be recognized that certain compounds of the
invention contain an asymmetric carbon atom and hence can
exist in two stereoisomeric forms. ~oth stereoisomeric
forms, together with mixtures thereof, fall within the
scope of this invention.
~L~5~2~7
According to a further aspect of the invention the N,N-disubsti-
tuted amino-acid derivatives according to the invention may be prepared by
reaCting a compound of formula:
CO
X ~ N - fH - COR (II)
y CH3
with a phosphorus sulphide, for example phosphorus pentasulphide, wherein X,
Y, R and Z are as defined above. This reaction proceeds smoothly at ambient
temperatures in the presence of a solvent, for example dioxane.
Compounds Of formula II are the subject of earlier patents and
patent applications by the preSent Applicant and may be prepared according
to the methods disclosed in these patents and patent applications, for
example, Canadian Patents 861,552 and 994,356 and pending Canadian Appli-
cation 216,185.
The N,N-disubstituted amino-acid derivatives of the invention
may be utilized alone, or in the form of a composition which comprises at
least one compound of the given general formula I together with a carrier
or a surface-active agent, o~ both a carrier and a surface-active agent.
6~ 951~Z~)7
The term "carrier" as used herein means a material,
which may be inorganic or organic and of synthetic or
natural origin, with which the active compound is mixed
or formulated to facilitate its application to the plant,
seed, soil or other object to be treated, or its storage,
transport or handling. The carrier may be a solid or a
fluid. Any of the material usually applied in formulating
pesticides may be used as a carrier.
Examples of suitable solid carrier are silicates,
10 clays, for example, kaolinite clay, synthetic hydrated
silicon oxides, synthetic calcium silicates, elements
such as,for example, carbon and sulphur~ natural and
synthetic resins such as 3 for example, coumarone resins,
rosin, copal, shellac,.dammar, polyvinyl chloride and
styrene polymers and c~polymers, solid polychlorophenols,
bitumen, asphaltite, waxes such as,for example, beeswax,
paraffin wax, montan wax and chlorinated mineral waxes,
and solid fertilizers, for example superphosphates.
Examples of suitable fluid carriers are water,
alcohols, such as, for example~ isopropanol, ketones such
as, for example, acetone, methyl ethyl ketone, methyl
isobutyl ketone and cyclohexanone, ethers, aromatic hydro-
carbons such as, for example, benzene and toluene,
petroleum fractions such as, for example, kerosine,
chlorinated hydrocarbons such as, for example, carbon
tetrachloride, including liquefied normally vaporous
'3L6)5i~Z~:77
- 7 -
gaseous compounds. Mixtures of different liquids are
often suitable.
The surface-active agent may be a wetting agent, an
emulsifying agent or a dispersing agent; it may be non-
ionic or onic. Any of the surface-active agents usually
applied in formulating herbicides may be used. Examples
of suitable surface-active agents are the sodium or calcium
salts of polyacrylic acids, the condensation products of
fatty acids or aliphatic amines or amides containing at
least 12 carbon atoms in the molecule with ethylene oxide
and/or propylene oxyde; partial esters of the above fatty
acids with glycerol9 sorbitan, sucrose or pentaerythritol;
condensation products of alkyl phenols, for example
p-octylphenol or p-octylcresol, with ethylene oxide and/or
propylene oxide; sulphates or sulphonates of these
condensation products; and alkali metal salts, preferably
sodium salts, of sulphuric acid esters or sulphinic acids
containing at least 10 carbon atoms in the molecule, for
example, sodium lauryl sulphate, sodium secondary alkyl
sulphates, sodium salts of sulphonated castor oil, and
sodium alkylaryl sulphonates such as sodium dodecylbenzene
sulphonate.
The compositions o~ the invention may be formulated
as wettable powders, dusts, granules, solutions, emulsifiable
concentrates, emulsions and pastes. Wettable powders are
usually compounded to contain 25, 50 or 75% of toxicant and
- 8~ 5~ 7
usually contain, in addition to solid carrier, 3-10% of
a dispersing agent and, where necessary, 0-10% of
stabilizer(s) and/or other additives such as penetrants
or stickers. Dusts are usually formulated as a dust
concentrate having a similar composition to that of a
wettable powder but without a dispersant, and are dilute
in the field with further solid carrier to give a compo-
sition usually containing ~-10~ of toxicant. Granules
are usually prepared to have a size between 10 and
100 BS mesh, and may be manufactured by agglomeration or
impregnation techniques. Generally, granules will contain
~-25% of toxicant and 0-25% of additives such as stabilizers,
slow release modifiers, binding agents, etc. Emulsifiable
concentrates usually contain, in addition to the solvent
and, when nece~sary, co-solvent, 10-50% w/v toxicant,
2-20% wfv emulsifiers and 0-20% of appropriate additives
such as stabilizers, penetrants and corrosion inhibitors.
Pastes are compounded so as to obtain a stable, flowable
product and usually contain 10-60% toxicant, 2-20% of
appropriate additives and, as carrier, water or an organic
liquid in which the toxicant is substantially insoluble.
The compositions of the invention may contain other
ingredients, for example protective colloids such as gelatin,
glue~ casein, gums and polyvinyl alcohol; sodium ~oly-
phosphates; cellulose ethers, stabilizers such as ethylenediamine tetra-acetic acid; other herbicides or pesticides;
and stickers, for example, non-volatile oils.
9 ~5B~
Aqueous dispersions and emulsions, compositions
obtained by diluting a wettable powder or an emulsifiable
concentrate according to the invention with water, also
lie within the scope of the present invention. The said
emulsions may be of the water-in-oil or of the oil-in-
water type, and may have a thick "mayonnaise"-like
consistency.
The invention also includes a method of combating
weeds which comprises applying to the weeds or their
habitat a compound according to the invention or a
composition containing it, and also a method for improving
the yields of crops at a locus which comprises applying to
the locus a compound of the invention or a composition
containing it
The compounds according to the invention, their
preparation, compositions containing them and their
herbicidal activity are further illustrated by the Examples
which follow.
EXAMPLE 1 Preparation of N-thiobenzoyl-N-(3-chloro-4-
fluorophenyl)alanine ethyl ester
A mixture of ethyl N-benzoyl-N-(3-chloro-4-fluoro-
phenyl)alanine (35 g, 0.1 M) and phosphorus pentasulphide
(66.6 g, 0.3 M) in dry 1,4 dioxan (300 ml) was stirred for
50 hours. After this time the reaction mixture was filtered
and the filtrate evaporated to low-bulk. The resulting
yellow oil was stirred vigorously with-saturated sodium
~6~S8Z~
- 10 -
bicarbonate solution (300 ml) to remove any dissolved
phosphorus, then ?xtracted with methyle..e chloride.
Evaporation of the dried extracts left a yellow oil
which was purified chromatographically using a neutral
alumina column and methylene chloride as eluant. The
first yellow band to emerge was the desired thioamide;
weight 10 g. Further elution with ethanolic methylene
chloride removed 15 g of starting amide. The structure
was confirmed by NMR, IR and mass spectra. Yield (based
on reacted starting material) 49%.
Analysis
Found : C 58.3; H 4,7; N 3.6; Cl 9.7%
C18H17ClFN02S requires: C 59.1; H 4.7, N 3.8; Cl 9.7%
EXAMPLE 2 Preparation of N-benzoyl-N-(3-chloro-4-fluoro-
phenyl)alanine isopropyl ester
A mixture of isopropyl N benzoyl-N-(3-chloro-4-fluoro-
phenyl)alanine (1~ g, 0.052 M) and phosphorus pentasulphide
(30 g, 0.13 M) in dry 1,4-dioxan (150 ml) was stirred at
room temperature for 2 days. After this time no starting
material was detected by thin layer chromatography.
The reaction mixture was filtered and the filtrate
evaporated to low-bulk leaving a yellow oil. To remove any
dissolved phosphorus compounds the residue was stirred
vigorously with saturated sodium bicarbonate solution for
1 hour and then extracted with methylene chloride.
Lo~Z6)7
Evaporation of the dried extracts left a yellow oil
which was purified chromatographically using a neutral
alumina column and methylene chloride as eluant. Obtained
14.6 g (74%). The structure was confined by infra-red
and nuclear-magnetic resonance spectrographic analysis.
Analysis
Found : C 60.3; H 4.9; N 3.4%
C1gH1gClFNO2S requires: C 60.1, H 4.9; N 3.7%.
EXAMPLES 3 to 13
Some further examples of compounds according to the
invention were prepareq by the method described in
Examples 1 and 2. Their structure was confirmed by IR and
NMR techniques. Details of these compounds are given in
lable I a~pearing below.
' . '
- 12 -
2q~'7
-- 12 --
Z t~l ~D 0 3 O Lr~ t~ ~ t~ O
=~ ~ ~ 3 1~ 1
_
CO Cl~ ~ Lr~ O O Ll~ r
3 3 L~ 3 3
~.) O~ ~1 O O ~1 3 Ll~ O
u~ ~ ~o t_ o~ t O cri ~ 3
H _ L~ L~\ Lf`\ L~ ~D L~'\ L~ L
U~ CO ~Q 0 ~q
~q ~ a) a) a
S~ ~ ~
~ .~ ~ ~ ~
¢ ~ a, ~ aJ
Z ~ S~ S~ ~ ~
cr, O O N O O
Z Z Z ~ Z;
O
C~ ~ ~ ~ ~ ~
V ~3 ~ V
L~ L~ ~ t--
~1 ~ ~1 ~ ~1 ~ ~1 ~ ~1
~ ~C ~ m ~ ~ ~ ~ ~ ~: ~
t~ ~--V ~o :~ t-- ~ t-- ~ 0~ ~ CO ~
.,o ~ o ~ o ~ o ~ o
. ~ ~ V ~ V ~ V ~ V ~
V--Z _ _
. 1
~/\ oV ~D
~_
¢ . ~ ~ ~ ~ .,~ .
E~~ , \ ~ c~ ~ O O O O
r
.X
~ ~ ~ Lr\
~ ~I: ~ V ~
'.' ~ O O Vo 0~ 0
. _
~1 ~ ~1 ~ ~
t~ ~ ~ ~ ~: ~:
a) ~ ~ a~
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P~ V V V V C~
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. ~ __ __ _,'
- 13 ~ 5~
--z ~o ~I 01 J ~1- 00 r~ o~ ~ \1
lS5~, ~ 1~ J ::~ ~ ~ r~ t- ~D ~ 1
_~ _ __
~:' O J J ~ (\J Lt~ co o~ ~ O ~J
. J J ~ Lr~ L~\ ~ 1~ J =t
O ~1 ~ ~1 ~ ~ Ll~ ~J
. . . . . . o
~ ~ ~ Ll~ ~ ~ ~ ~ ~ ~ L~ GO O~
V~ ~ ~D ~ ~ ~D L~ 1~ ^J t
_
H u~ ~q
~n cq a,
v~ a~ u~ a
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~ .~ ~ &l .~ :~
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~ ~ I::J' (L
cC ~ ~ a) s~ Z
Z; v~ F~ ~ v~ u~ u~
~ V~ ~ O O
c~ O CR ~I O ~`J ~I
Z O Z Z h Z
r I Z ~1 ~1 ~1 ~1
C) ~ C~
~D 0~ CO ~ 00
_~~ ~ ~ ~:; ~ ~ .i ~ .
X S:: ~ ~: ~ ~ ~ S: ~ ~:
a)0~ :~ cO ~Oo ~ ~D ~ 0~ ~ ~O
~ O ~ O.~ O .1 0 ~ O ~ O
v F4 v ~ C~F4 v F4 v ~ v h ~-
_
O _~ l . O
~.> V O O ~-- Q~ L~ tq
_~ . o ~I Q ~:: O ~ oo ~.
Q,-~.~1 ~J ~1 ~ ~3' 0 C) ~1
H . ~rl ~rJ ~rl I O ~rl u~ H
~ O O O o~ ~ ~ O O r~
P~ c~ ~ ~ ~ ~ 0
~1 ~ ~ n ~0 ~ J~
m ~ _ ,
u~ ,~ u~ æ
~; V~ V~ V~ o ~ o
O O O . X Q,
O
o h
' S~ ~ ~ ~1 . ~ ~ ~ O
O ?~ ?~ P~ ~ ~ :~.
S:: S: S:: S~ ~:
a~ a) a) ~ ~ ~
S ~ ~C o
. 1 Q~ Q. Q. ~ Q. ~:4
N
. . ~ . ~ 0~
. _ H j~ ~ r1 ~1 r-l r-J
X r-l h r r-J h ~ :~
_ __
~ oO O~ ~1 ~ ~ ~
X
_ ~4 _ ~ ~5
EXAMPLE 14 - Tests on herbicidal activity
To evaluate their herbicidal activity, the compounds
of the invention were tested using as a representative
range of plants: maize, Zea mays (Mz), oat, Avena
sativa (O); barnyard grass,Echinochloa crus~alli (BG),
pea, Pisum sativum (P); linseed, Linum usitatissimum (L);
mustard, ~ alba (M), sugar beet, Beta vulgaris (SB);
and tomato, Solanum lycopersicum (T).
The tests fall into two categories, pre-emergence and
post-emergence. The pre-emergence tests :involved spraying
a liquid formulation of the compound onto the soil in
which the seeds of the plant species mentioned above had
recently been sown. The post-emergence tests involved
two types of test, viz. soil drench and foliar spray tests.
In the soll drench tests the soil in which seedling plants
of the above species were growing, was drenched with a
liquid ~ormulation containing a compound of the invention,
and in the foliar spray tests the seedling plants were
sprayed with such a formulation.
The soil used in the tests was a steam-sterilized~
modified John Innes Compost mixture in which half the peat,
by loose bulk, had been replaced by vermiculite.
- The formulations used in the tests were prepared by
diluting with water solutions of the compounds in acetone
containing 0.4% by weight of an alkylphenol/ethylene oxide
condensate available under the trade name Triton X-155.
15 - ~ S8~ ~7
In the soil spray and foliar spray tests the acetone
solutions were diluted with an equal volume of water and
the resulting formulations applied at two dosage levels
corresponding to 5 and 1 kilograms of active material per
hectare respectively in a volume equivalent to 400 litres
per hectare. In the soil drench tests one volume of the
acetone solution was diluted to 155 volumes with water and
the resulting formulation applied at one dosage level
equivalent to ~0 kilograms of active material per hectare
in a volume equivalent to approximately 3,000 litres per
hectare.
The herbicidal effects of the compounds were assessed
visually seven days after spraying the foliage and
drenching the soil and eleven days after spraying the soil,
and were recorded on a 0-9 scale. A rating 0 indicates
no effect on the treated plants, a rating 2 indicates a
reduction in fresh weight of stem and leaf of the plants of
approximately 25%, a rating 5 indicates a reduction of
approximately 55%, a rating 9 indicates a reduction of 95%~
etc.
The results of the tests are set out in Table 2.
Other results from post-emergence foliar spray tests are
given in ~able 3.
,
- 1 6 ~S~ 7
1~ 1:.
:~ ¦ E 1~ O ~o o
' bO ~d .
o ~0 ~ ~ ~.~ .
. ~ ~1 _ ~
17~ 6
TABLE 3
_
Compound Dosage Post-emergence - Foliar spray
of kg/haMZ OBG P L M ~ T
e _ _ ~ ~ _I
3 5 2 7 2 O 6 5 O O
9 5 1 O 2 O 2 6 2 O
4 5 O O O 5 3 3 1 O
11 5 O 5 O O 6 1 3 2
12 5 3 7 O 5 7 4 4 O
13 5 2 7 O 6 5 6 O 2
