Note: Descriptions are shown in the official language in which they were submitted.
~ ~5 3~ ~ ~
The present invention provides novel herbicidally active,
nuclear-substituted phenoxy-phenoxy-alkanecarboxylic acid
derivatives, processes for their manufacture, herbicidal
compositions which contain these novel compounds as active
ingredients, and methods of selectively controlling grass-
like weeds in crops of cul~ivated plants which comprises the
use of the novel active substances or of compositions which
contain them.
The novel active compounds have the formula I
O-C-CO-R5 ~I)
CN R2
wherein
Rl represents hydrogen, halogen, the trifluoromethyl or
cyano group,
R2 represents hydrogen or halogen,
each of
R3 and R4 independently represents hydrogen or lower alkyl,
and
R5 represents a OH, -O-cation, -O-alkyl, -O-alkoxyalkyl,
-S-alkyl, -S-alkenyl, -S-CH2-COO-alkyl, -O-alkenyl,
-O-alkynyl, -O-cycloalkyl, -O alkyl-N(dialkyl) group,
an unsubstituted or substituted benzyloxy, phenoxy
or phenylthio radical, and NH2, NH-alkyl, -N(dialkyl),
alkyl
or -N~
O-alkyl.
- 2 -
~ ~5 ~
Lower alkyl radicals represented by R3 and R4 are to be
understood as meaning herein s~raigh~-chain or branched
radicals containing 1 to 4 carbon a~oms. The alkyl-containing
groups represented by R5 can contain a higher number of
carbon atorns and have longer alkyl chains (up to 10 carbon
atoms), preferably also in this case 1 to 6 or 1 to 4 carbon
atoms. Corresponding alkenyloxy, alkenylthio and alkynyloxy
groups contain up to 4 carbon atoms. Cycloalkoxy groups
contain 3 to 12, preferably 5 or 6, carbon atoms.
Particularly preerred active compounds are those in
which R4 is hydrogen and R3 represents hydrogen, ethyl and,
in particular, methyl.
Possible substituents of phenoxy, phenylthio and
benzyloxy groups R5 are one or more selected from the group
consisting of halogen, alkyl and nitro.
By cations of the -O-cation group (represented by R5)
are meant mono- and polyvalent cations of inorganic or organic
bases, including quaternary ammonio bases, in particular the
cations of alkali metal and alkaline earth metal hydroxides.
The preferred halogen atom represented by Rl and R2 is
chlorine.
Herbicidal compositions containing 4-phenoxy-phenoxy-
alkanecarboxylic acid derivatives of similar structure and
having a special action on grass for the selective control
of grass-like weeds in mono~ and dicotyledonous cultivated
plants are known from D~-OS 2,223,894. Derivatives of these
-- 3 --
~ ~ 3~ ~ ~
alkanecarboxylic acids which are trifluoromethylated in the
para-position of ~he ~erminal phenyloxy radical have also
been described (Belgian patents 831,218 and 831,~69).
The surprising discovery has now been made that, on
account of the presence of ~he cyano substituent, the novel
active compounds of the formula I of the present invention
are clearly superior in their action on grass to the above
mentioned active substances as a consequence ei~her of their
better action against grass~like weeds and/or their better
selectivity, for e~ample in soya and cotton.
Accordingly the active compounds of the invention are
suitable for the preemergent and especially postemergent
selective control of grass-like weeds (for example panic-
grasses) of the genera Digitaria, Setaria, Echinochloa,
Rottboellia, and also Alopecurus, Apera, Lolium etc. and
especially also Avena fatua (wild oats), not only in crops
of dicotyledonous cultivated plants (such as cotton, soya,
sugar beet etc)., but in particular in crops of monocotylede-
nous plants as well, such as cereals (wheat, barley, rye,
oats), rice etc. In this respect, and especially for solving
the problem of controlling wild oats in wheat, the novel
active compounds and the compositions which contain them
constitute a notable enrichment o the stock of technical
knowledge.
Some of the active compounds of the invention also
.. . . . . . . .
~ ~S 3~
possess advantageous growth-regulating effects (growth
inhibition) .
Particularly preferred active compounds of the formula I
are those wherein R2 represents hydrogen and which contain a
further substituent Rl in addition to the cyano group, such
as in particular chlorine or the CF3 group. Moreover, it has
been established that compounds in which the cyano group and
Rl (if present) are in the ortho- or para-position have a
particularly good action and selec~ivity. If Rl is chlorine,
then compounds with ortho-cyano - para-chloro and ortho-chloro-
para-cyano configuration have the best action. If Rl is
hydrogen, the cyano group is preferably in the para-position.
Further important compounds are those in which R4 repre-
sents hydrogen and R3 is different from hydrogen, for example
lower alkyl, in particular methyl. The simplest ester form
(R5 = OCH3) has outstandingly good activity.
The novel compounds of the formula I are obtained by
the methods which are known per se for the synthesis of
phenoxy-phenoxy-alkanecarboxylic acids and derivatives
thereof.
In a first such process, according to the invention a
substituted halogenonitrobenzene of the formula II
Rl ~ llal (II)
CN
-- 5 --
, . . . . .... ., ... ~
~ ~ 3~ ~ ~
is reacted with a p-hydroxy-phenoxy-alkanoic acid derivative
of the formula III
R~
HO ~ O-C-CO-R5 ~III)
- ~2 R3
in the presence of a base.
In a second process, according to the invention a
substituted p-hydroxy-diphenyl ether of the formula IV
OH (IV)
CN R2
is reacted with an a-halogenoalkanoic acld derivative of
the formula V
4 (V)
Hal - C - CO - R5
R3
in the presence of a base.
In a third process, the cyano group is introduced in
the final process step. Accordingly, in this process a
4-(halogenophenoxy)-a-phenoxy-alkanecarboxylic acid derivative
.~ ~ 6 -
~ ~ 3
of the formula VI
1 ~ ~ O C-COR5 (VI)
R3
Hal R2
wherein Hal represents a halogen atom, such as a chlorine,
bromine or iodine atom, is reacted with potassium or sodium
cyanide in a polar solvent in the presence of a catalyst
which activates the halogen atom, such as tetrakis (tri-
phenylphosphine)-nickel (Ni~P(C6H5)3]4), preferably in a
protective gas atmosphere (nitrogen, argon etc.) at tempera-
turesbetw~n 20 and 120C, preferably between 50 and 70C,
i.e. in analogy to the reactions described in Adv. Chem. Ser.
132, 252 (1974) and Journ. Organomet. Chem. 54, C 57 (1973).
If Rl represents halogen in the starting material of the
formula VI, it is also possible to replace th;s further
halogen atom by a cyano group.
If a carboxylic acid (R5 = OH) is used in these processes
as starting material of the formulae III, V or VI, then this
group can subsequently be converted into another derivative
of the formula I as defined herein, for example by esterificat~
ion etc. Conversely, when using an ester of the formula III,
V or VI, the ester group can subsequently be con~erted into
the ~ree carboxylic acid or a salt thereof by saponification
-- 7 --
~53~8
or into another ester by -~ransesterification.
In the formulae II to VI of the starting materials, the
symbols Rl to R5 are as defined in formula I and Hal represents
a halogen atom, s~lch as a chlorine or bromine atom.
The above reacti.ons can be carried nut in ~he presence
or absence of solvents or diluents which are inert to the
reactants. Polar organic solvents,such as methyl ethyl ketone,
dimethyl formamide, dimethyl sulphoxide, alcohols, ketones etc.,
are preferred. The reaction temperatures are between 0 and
200C, and the reaction time is from 1 hour to several days,
depending on the starting material, choice of reaction
temperature, and solvent. The process is usually carried out
at normal pressure. Suitable bases (condensation agents) for
the reaction are those normally employed, for example KOH,
NaOCH3, NaHC03, K2C03, potassium tert. butylate etc., and
also organic bases, such as triethylamine etc.
The starting materials of the formulae II to VI are
partly known. Starting materials of these formulae which have
not yet been described can be easily prepared by conventional
processes and techniques. Phenoxyphenols o the formula IV can
be prepared from hydroquinonemonoalkyl ethers and monochloro-
or dichlorobenzonitriles for example in accordance with the
methods described in Journ. ~m. Chem. Soc. 61, 2702 (1939)
or in Chem. Abstracts 5~, 92~h (1960).
., , , , ., . , ,,., .. , ., . ... . ., . , ~ .. ..... .. .. .
~ ~5 ~ O ~
The following Examples illustrate the process o the
present invention. Further active compo~mds which are prepared
in corresponding manner are listed in ~he su~sequent table.
9 _
- ~ .
~ ~ 3
Example 1
a) Preparation of the starting material:
A three-necked flask is charged at room temperature with 7 ~
of pulverised potassium hydroxide and 12.4 g of hydroquinone-
monome~hyl ether in 300 ml of dimethyl sulphoxide. ~ith
stirring and at a temperature between 15 and 20C, 17.2 g of
dichlorobenzonitrile are added in small amounts and stirring
is continued initially for one hour at room temperature. The
reaction ~lixture is then heated for 12 hours at 70C. ~'or
working up, the reaction mixture is poured into an ice-water
mixture and the precipitated substance becomes solid after a
time. The solid is collected with suction and recrystallised
from methanol, affording 20 g of 2-cyano-~-chloro-(4'-methoxy-
phenoxy)-benzene with a melting point of 101-102C.
A tllree-necked 1ask is charged, while introducing a flow of
nitrogen, with 60 ml of glacial acetic acid and 25 ml of
acetic anhydride. Thereafter 24 ml of 67% hydriodic acid are
added dropwise while cooling with ice. The ambient temperature
rises to 30C. The mixture is then heated to a bath temperature
of 90C and 26 g of 2-cyano-4-chloro-(4'-metho~yphenoxy)-
benzene are added in small amounts at this temperature. The
bath temperature is raised to 120C and the reaction mixture
is further stirred for 3 hours. ~fter cooling, the reaction
mixture is poured into ice-water with vigorous stirring. The
precipitate is collected with suction, washed with water and
- 10 -
~ ~ 3~ ~ ~
dried. Recrystallisation from benzene/pe~roleum ether yields
20 g of 2-cyano-4-chloro-(4'-oxy phenoxy)-benzene of the
formula
Cl ~ - ~ OH
~N
with a melting point of 105-107C.
b) A mixture of 20 g of this 2-cyano-4-chloro-(4'-oxy-phenoxy)-
benzene, 18 g of methyl 2-bromo-propionate, 12 g of anhydrous
potassium carbonate and 250 ml of methyl ethyl ketone is
heated, with stirring, for 12 nours to reflux temperature.
After cooling, the reaction mixture is filtered and washed
with methyl ethyl ketone. The filtrate is then concentrated
in vacuo. The residual viscous oil is subjected to high vacuum
distillation, affording 16 g of methyl 4-(2'-cyano-4'-chloro-
phenoxy)-a-phenoxy propionate with a boiling point of 199-
203C/O.Ol Torr.
Example 2
A two-necked flask is charged, in an atmosphere of argon,
with 1.7 g of tetrakis-(triphenylphosphine)-nickel(O~ and a
degassed solution of 8.5 g of methyl 4-(4'-chlorophenoxy)-~-
phenoxy-propionate in 25 ml of absolute ethanol is added. The
mixture is heated with stirring to 60C for 30 minutes. Then
1 g of sodium cyanide is added and stirring i9 continued for
- 11 -
... ... . . .. . .. . . , .. . .. ; .. . .. ..... . ...... . . .. ... .. . . ..
.
~ ~ ~ 3~ ~ ~
2 hours at 70C. Then a further 0.25 g of sodium cyanide is
added and stirring is continued for a furt,her 2 hours at 70C,
in the process of which a t ansesterification also takes place.
After the reaction mix~ure has cooled, it is filtered through
"Hyflo" and the solvent is removed by rotary evaporation. The
residual viscous oil is chromatographed over 200 g of silica
gel with benzene/methylene chloride, yielding 2.5 g of ethyl
4-(4'-cyanophenoxy)-a-phenoxy-propionate as the very last
raction; b.p. 171-174C/0.01.
The compounds of the above Examples as well as further active
compounds of the formula I which are prepared in corresponding
manner according to the invention are listed in the following
table.
The listed compounds are those in which R2 and X4 represent
hydrogen and which therefore have the narrower formula
Rl ~ 0-CU C0-R5
CN
- 12 -
.
:~L53~
TABLE
_ .
Compound Position o~ Rl R3 R5 PhyOical constan-ts
the CN group . . m.p C/b.p C/torr
with posltlon
_ ~
1 2-CN 4-Cl CH3 -ûC~13 b p 199-203 /0 01
2 4-CN H CH3 -OC2H5 b.p. 171-171 /0 01
3 2-CN -Cl H -OCH3 m.p. 119-120
4-CN 2-Cl CH3 -OCH3 b.P. 210 /0 002
4-CN H CH3 -OCH3 m.p. 64-65
6 2-CN 4-Cl CH3 -OH m.p. 154-155
7 2-CN 4-Br C~13 -OCH3
8 2-CN 4-GN CH3 -OCH3
9 2-CN 4-Cl CH3 -OC2H5 b.p. 194 /0.05
2-CN H CH3 -OCH3 oil
11 2-CN 4-Cl H -OC2H5 m.p. 102-104
12 2-CN 4-Cl H -OC4Hg(n) oil
13 2-CN 4-Cl C2H5 2 5 oil
14 2-CN 4-Cl C~13 -NH2 m.p. 197
2-CN 4-Cl CH3 ( 2 5)2 oil
16 2-CN 4-Cl CH3 O-benzY' m.p. 113-115
17 2-CN 4-Cl C~13 -O-CH -CH=CH2 i '
18 2-CN 4-Cl CH3 -O CH2CYCH oil
19 2-CN 4-Cl CH3 -0-C~I-CwCH2 i '
Cl
2-CN 4-Cl CH3 -O-Cil -C=CH2 i
Cl~3
CH3
21 2-CN 4-Cl CH3 -N/ oi l
Cl!H9( n )
22 2-CN 4-Cl CH3 -oC3H7(rl) oi l
23 2-CN 4-Cl CH3 3 7( ) oil
24 2-CN 4-Cl CH3 -OC4Hg(n) b.p. 2n3 /0.08 torr
2-CN 4-Cl CH3 -0C4Hg(iSo) b.p. 190 /0.02 torr
- 13 ~
:~.....
~53~
Compound Position of Rl 3 5 Physical constants
the CN group . m.p. /b.p. C/torr
~Ith poslt on
_ _ _
26 2-CN 4-Cl CH3 -OC~ H9( s ec) oi l
27 2-CN 4-Cl CH3 -O-cycl ohexyl oi l
28 2-CN 4-Cl CH3 -O-phenyl m.p. 15529 2-CN 4-Cl CH3 -0-(CH2)2-0-CH3 oi l
2-CN 4-Cl CH3 -OC4Hg(tert) oi l
31 2-CN 4-Cl CH3 -0-CH2-CH-C-CH3 oi l
32 2-CN 4-Cl CH3 -0-CH2-CH=CH-CH3 oi l
33 2-CN -Cl CH3 -S-phenyl oi l
34 4-CN H CH3 -OC3H7(n) b.p. 190/0.01 torr
4-CN H CH3 -OC4Hg(n) b.p. 177-183 /0.015 torr
36 4-CN H CH3 -OC4Hg(iso) b.p. 203 /0.05 torr
37 4-CN 2-Cl CH3 -OC2H5 oi l
38 4-CN 2-Cl CH3 -OC4Hg(n) oil
39 2-CN 4-Cl CH3 -0-CH2~ Cl oil
2-CN 3-Cl CH3 -OCH3 m.p. 84-85
41 4-CN H CH3 (CH2)2 C 3 b.p. 188/0.04
42 2-CN 4-Cl CH3 -N(C113)2 i l
43 2-CN 4-Cl CH3 -S-C~I -COOC2H5 oi l
44 2-CN 4 -Cl CH 3 -NHCH3 m. p . 1 bO
C~13
2-CN 4-Cl CH3 -0-C11243 res i nous
46 2-CN 4-Cl CH3 -0-CH2-~ resi nous
47 2-CN 4-Cl CH3 O (CH2)4 3 viscous oil
/C~13
48 2-CN 4-Cl CH3 -0-CH2-CII-C2H5 i
49 2-CN 4-Cl CH3 O (CH2)2 H( 3)2 i~
2-CN 4-Cl CH3 -0-C~12-C(CH3)3 i~
~i3~
Compound Position of R R R5 Physical constants
the CN group 1 3 m.p. C/b.p. C/torr
_ ___ _
51 4-CN H CH3 CH3 oi l
52 2-CN 4-Cl CH3 CH3 oi l
53 4-CN H CH3 CH3 oi l
54 2-CN 4-Cl CH3 -0-CH2-CH(C2H5)2 oil
4-CN H CH3 -0-CH2-CH(C2H5)2 oi l
56 2-CN 4-Cl CH3 -SC113
57 4-CN H CH3 -SCH3
58 2-CN '-CF3 CH3 -OCH3 m.p. 105-106
59 2-CN 4-CF CH -OH m.p. 158-162
2-CN 4-CF33 CH33 -C2'15 ~ 180 /0.65
61 2-CN 4-CF3 CH3 -OCH -CH=C112 b p 178 /0.018
62 2-CN 4-CF3 C~13 ( 2)2 3 b.p. 195/0.02
63 2-CN 4-CF3 CH3 -S-CH2-C~-CH2 b . p . 200/0 . 07
64 2-CN 4-CF3 CH3 -OCH2-C-CH oi l
2-CN 4-CF3 CH3 -OCH2-CII(CH3)2 m.p. 69-70
66 2-CN 4-CF3 CH3 OC3H7( ) oi l
67 2-CN 4-CF3 CH3 -OCH -C=CH2 oil
CH3
68 2-CN 4-CF3 c,~3 -N(C2H5)2 m.p. 115-119
69 2-CN 4-CF3 C~13 O-phenyl m.p. 97-99
2-CN 4-CF3 CH3 -OC4Hg( n) oil
71 2-CN b-CF3 CH3 -SC~3 b.p. 200-210 /0.4
72 4-CN 2-CF3 c,,3 -OCH3
73 4-CN H CH3 -OC3H7(iso) oil
74 4-CN H C113 -OC4Hg(sec. ) oi l
4-CN H C113 -SCH3 oi l
. 76 4-CN 2-Cl CH3 -0-C3H7(n) oil
77 4-CN 2-Cl CH3 -OC3'17( i so) oi l
- 15 -
~s~
Co~pound PositiDil of Rl R R Physical constants
the CN ~roup __ 3 5 m,p. C/b.p. C/torr
78 4-CH 2-Cl C~13 -OC~Hg( iso) oi l
79 4-CN . 2-Cl C1~3 -OC4H9(sec. ) oil
4-CN 2^Cl CH3 2 <C 11 oil
31 ~ CH 2-CI C113 __~ L
The compound methyl 4-(2'-cyano-4'-chlorophenoxy) -a- 3-chloro-
phenoxy-propionate of the formula
CH3
Cl ~ O ~ O-CH-COOCH3
CN Cl
is prepared as an example of active compounds in which R2
represents halogen, and is obtained in the form of an oil.
The novel active substances (compounds) of the formula I
are stable compounds which are soluble in conventional organic
solvents, such as alcohols, ethers, ketones, dimethyl formamide,
dimethyl sulphoxide etc.
The compositions of the present invention are obtained
in known manner by homogeneously mixing and grinding active
substances of the general formula I with suitable carriers
and/or additives, with or without the addition of antifoam
agents, wetting agents, dispersants and/or solvents which are
inert to the active substances. The active substances can be
formulated as follows:
- 16 -
~ ~ 3
solid formulations:
dusts, tracking agents, granules (coated granules,
impregnated granules and homogeneous granules);
active substance concentrates which are dispersible in water:
wettable powders, pastes, emulsions, emulsifiable concen~
trates;
liquid formulations: solut-.ions.
The concentration of ac~ive substance in the compositions
of this invention is between 1 and 80 percent by weight. ~s
circumstances may require, the active substances can also be
applied in low concentrations of about 0.05 to 1 percent by
weight.
The compositions of the present invention can be mixed
with other biocidal active substances or compositions. Thus
in addition to containing the cited compounds of the formula I,
the compositions of the present invention can also contain,
for example, insecticides, fungicides, bactericides, fungi-
static agents, bacteriostatic agents, nematocides or further
pesticides, in order to broaden the activity spectr~lm.
Granules
The following substances are used to prepare 5% granules:
parts of one of the active substances of the
formula I,
0.25 parts of epichlorohydrin,
0.25 parts of cetyl polyglycol ether,
- 17 -
~s~
3.50 parts of polyethylene glycol,
91 parts of kao]in (particle size 0.3 - 0.8 mm).
The active su~stance is mixed with epichlorohydrin and
dissolved with 6 paxts of acetone, and the polyethylene
glycol and cetyl polyglycol ether are then added. The resultant
solution is sprayed on kaolin and subsequently evaporated in
vacuo.
Wettable Powder
The following constituents are used to prepare
a) a 70% and b) a 10% wettable powder:
a~ 70 parts of methyl 4-(2',-cyano-4'-chlorophenoxy)-
a-phenoxypropionate,
5 parts of sodium dibutylnaphthalene sulphate,
3 parts of naphthalenesulphonic acid/phenolsul-
phonic acid/formaldehyde condensate (3:2:1),
10 parts of kaolin,
12 parts of Champagne chalk;
b) 10 parts of methyl 4-(2'-cyano-4'-trifluoromethyl-
phenoxy)-a-phenoxypropionate,
3 parts of a mixture of the sodium salts of
saturated fatty alcohol sulphates,
5 parts of naphthalenesulphonic acid/formaldehyde
condensate.
82 parts of kaolin.
The respective active substance is applied to the
- 18 -
~ ~ 3~ ~ ~
corresponding carriers (kaolin and cllalk) and therl these are
mixed and ground, to yield we~table powders of excellent
wettability and suspension power. By diluting these wet~able
powders with water it is possible to obtain suspensions
containing 0.1 to 8% of active s~stance. These suspensions
are suitable for controlling weeds in cultivat;ons of plants.
Paste
The following substances are used to prepare a 45% paste:
45 parts o ethyl 4~ cyano-phenoxy)-a-phenoxy-
propionate or one of the other cited active compounds
of the formula I,
5 pa~ts of sodium aluminium silicate,
14 parts of cetyl polyglycol ether with 8 moles of
ethylene oxide,
l part of oleyl polyglycol ether with 5 moles o
ethylene oxide,
2 parts of spindle oil,
10 parts o polyethylene glycole,
23 parts of water.
The active substance is intimately mixed with the
additives in appropriate devices and ground~ A paste is ob-
tained from which, by dilution with water, it is possible to
manufacture suspensions of the desired concentration of active
substance.
Emulsiiable ~oncentrate
The ollowing ingredients are mixed to prepare a 25%
emulsiiable concentrate:
- 19 -
25 parts of isohutyl 4-(2'~cyano-4'-chlorophenoxy)-
a-phenoxy-propionate or one of the other cited active
compounds of the formula I,
5 par~s of a mixture o nonylphenolpolyoxyethylene and
calcium dodecylbenzenesulphonate,
35 parts of 3,5,5 trimethyl-2-cyclohexen-1-one,
35 parts o~ dimethyl formamide.
This concentrate can be diluted with water to give
emulsions in suitable concentra~ions o e.g. 0.1 to 10%. Such
emulsions are suitable for controlling weeds in ~ultivations
of plants.
The novel 4-phenoxy-a-phenoxyalkanecarboxylic acids which
contain at least one cyano group in one phenyl nucleus and
their derivatives of the formula I, and the compositions which
contain them, have an excellent selective herbicidal action
against grass-like weeds in a wide variety of cxops of culti-
vated plants.
Since the novel active compounds destroy virtually only
grass-like weeds and attack broad-lea~ed (dicotyledonous)
plants only to an insigni~icant extent, they are accordingly
suitable for controlling grass-like weeds in crops o~ all
dicotyledonous cultivated plants, such as cot~on, soya, sugar
~eet, leguminosae, celery, clover, lucexnes, melons, cucumbers,
tobacco etc. In addition, they exl~ibit a markedly better
selectivity, for example in soya, cotton and sugar beet, than
do the closely related chlorinated and trifluorom2thylated
- 20 -
active substances of D~ OS 2,223,~9~ and of Belgian pa~ents
831,218 and ~31,469 wl~ich do not con~ain a cyano group. A
control of maize in soya cul~ures is also possible.
However, i~ is particularly surprising that the novel
active compounds of the formula I also possess an outstanding
selectivity in the control of grass-like weeds, especially o
Panicum-like weeds, in cultures of monocotyledonous plants,
such as cereals (~heat, barley etc.) and rice.
Accordingl~, panic-grasses of the genera S~taria,
Echinochloa, Digitaria, Rottboellia and the like can also be
controlled exceptionally well selectively in cultures of
monocotyledonous plants, such as wheat and barley etc., aside
from in soya.
The novel compounds also have an excellent action against
other grass-like weeds, such as Alopecurus, Lolium, Apera,
Agrostis etc.
An especially preferred field of use is the selective
control of the problem weed Avena fatua (wild oats) and its
related species in wheat, barley and sugar beet.
Although the novel active compounds of the formula I are
effective in pre- and post emergent application, the post-
emergent appllcation in the form of contact herbicides is
preferred. But the pre-emergence use is also of interest.
The novel active compounds are preerably formulated
for example as 25% wettable powders or for example 20%
emulsifiable concentrates and diluted with water, and applied
- 21 -
~ ~S 3~ ~ ~to the plant cultures in the post-ernergence stage.
Herbicidal act_ n on a~yin~ e active cornpounds after
emergence of the plants (post-emer~ent applicati~
Different cultivated plants and grass-like weeds are
reared from seeds in pots in a greenhouse until they have
reached the 4- to 6-leaf stage. Then the plants are sprayed
with aqueous active substance emulsions (obtained from a 20%
emulsifiable concentrate) in different rates o~ application
corresponding to 8, 4, 2, 1 and O.S kg/hectare. The treated
plants are then kept at optimum light, watering, temperature
(22-~5C) and humidity (50~70% rela~ive humidity) conditions.
~valuation of the test was made 15 days after treatment using
the following rating:
9 = plants undamaged (as untreated control plants)
1 = plants completely withered
8-2 - intermediate stages of damage.
Cultivated plants:
Hordeum (barley)
Triticum (wheat)
Oryza (rice)
Glycine (soya)
Gossypium (cotton)
Beta (sugar beet)
Grass-like weeds and undesi_ ble plants:
Avena fatua
Loli~un perenne
- 22 -
3~
Alopecurus myos.
Zea (maize)
Rottboellia exaltata
Digitaria sang.
Setaria italica
Echinochloa grus galli.
The result of the test showed that the tested active
compounds of the invention of the formula I containing a cyano
substituent exhibit a marlcedly better selectivity towards
wheat, soya, cotton, sugar beet and rice in that they damage
these cultivated plants very much less that the constitutionally
closest kno~m compounds which do not contain a cyano group.
- 23 -
