Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
3~
2,6-DIHALOBENZYL ESTERS AND THEIR U3E AS PESTICIDES
This inver.tion relates to 2,6-dihalobenzyl esters,
to their preparation, and to compositions containing them
for use as pesticides, especially as insecticides and
acaricides.
~elgian Patent Specification No~ 862,10g (Bayer
A.G.) relates to a general class of compounds of formula
R
H /CH_C
~:~ 10 3 ~ CO - O - CH, ~ y
CH3 H Fn
where the R moieties, which may be the same or different,
are qelec:ted from fluoro~ chloro and bromo, and when R is
fluoro or bromo, rn is O to 5 and n i~ O to 5 provided
, ~
-~ 15 that _ and n cannot both be 0; when R is chloro, m is O
~ to 4 and n is 1 to 5; and ~hen m is O and n is 5, R may
-~ be methyl in addition to the other moieties. This Belgian
Patent also mentions generally the existence in the prior
art of similar compounds in which the benzyl moiety is
sub~tit;uted exclusively with chlorine atoms.
It has now surprisingly been discovered that a novel
group of compounds ~alling within the broad group of
compoun-ls discu~sed above has especia11y useful pes-
ticida~ activity, in particular surprising miticidal
activity in addition to insecticidal activity.
~` ':
l~J33
: ~ 2
:: .
Acccrding to the in~ention therefore there are
provided 2,6-dihalobenzyl esters of formula I:-
.~ / R
H C=C
CH3 ~ \ ` R2 y (I)
CH3 ~2
: where R1 and R2 are independently selected from fluoro,
chloro and bromo, y1 i~ chloro, and y2 is fluoro or
chloro, provided that when R1 and R2 are both bromo y2 i3~luoro and when neither of R1 and R2 is bromo, at least
: one of R1 and R2 i9 the same as at least one of y1 and
,
... .
:'?: ~ ' y C
The compounds of form~la I may exist as geometrical
and optical isomers, ~ixture~ of isomer~ and racemates,
there being two centres of asymmetry in the substituted
~ cyclopropyl ring system, as will be readi}y apparent to
.,: those skilled in the ,~rt. The preferred compounds of the
invention are the ci~-compounds of formula I, tho~e which
are conventionally designated 1,R-cis-compounds being the
most preferred.
Advantageou~ly in the co~pounds of formula I, R1,
R2 and y2 ar0 each fluoro or chloro, and yl is chloro, at
leas~ one of R1 and R' being the same as at least one of
25 y1 and y2. The compou~(ds wherein at least two of R1, R2
and Y are chloro, the! other being fluoro or chloro~ are
- particularly advantageou3.
., 1
'
:' '
;,
3~3
: 3
- The 2,6-dihalobenzyl esters of formula I ~ay be
prepared by analogous methods to tho~e used for known
. compounds. A convenient process comprises reaction of a
compound of formula II~-
; 5 / R1
H CH=C
~' \ j \R2
~ (II)
;~ CH ~ \ -COZ
CH3 H
with a compound of formula III:-
-~' y1
. \
~ Q - CH2 ~ ~ (III)
y2/
where R1, R2, y1 and y2 are as de~ined above, one of Q
and Z represents a halogen atom, pre~erably a chlorine or
bromine atom) and the other represents a hydroxy group.
The reaction is preferably carried out in the presence of
a suitable base, for example a tertiary amine 3uch as
triethylamine or an alkali metal carbonate such as
potassium or sodium carbonate, in the presence o~ an
inert solvent. Conveniently Z represents a hydroxy group
and Q represents a chlorine or bromine atom.
The compounds of formula II above and their indi-
viduaI isomers are conveniently prepared in kno~n manner,
for example as described in U.K. Patent Specifications
Nos. 1,413,491 and 1,4489228.
s
.
The compounds of formula III above are readily
prepared from 2,6-dichlorotoluene and 2-chloro-6-fluoro-
toluene, which are known compounds, by conventional
halogenating techniques e.g. reaction with N-bromo-
succinimide, and subsequent hydrolysis if desired.
The 2,6-dihalobenzyl esters according to the in-
vention are of interest as pesticides especially as
insecticides and acaricides for domestic and agricultural
outlets. The invention therefore includes within its
scope pesticidal compositions comprising a carrier and~or
a surface-active agent together with, as active ingre-
dient, a 2,6-dihalobenzyl ester of formula I. The in-
vention also includes a method of combating insect, tick
and/or acarld pests, particularly mites, at a locu~ which
comprises applying to the locus a pesticidally effective
amount of a 2,6-dihalobenzyl ester of the invention or
composition containing such a compound.
The term "carrier" as used herein means a material,
which may be inorganic or organic and o~ 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,
transpor~ or handling. The carrier may be a solid or a
liquid. Any of the materials usually applied in for-
mulating pesticides, herbicides, or fungicides may be
used as the carrier.
",
3QO
Suitable solid carriers are natural and synthetic
clays and silicates, for example natural silicas such as
diatomaceous earths; magnesium silicates, for example,
talcs; magnesium aluminium silicates, for example,
attapulgites and vermiculites; aluminium silicates, for
example, kaolinites, montmorillinites and micas; calcium
carbonates; calcium sulphate; synthetic hydrated silicon
oxide~ and synthetic calcium or aluminium Qilicates;
elements for example, carbon and sulphur; natural and
synthetic resins such as, for example coumarone resins,
polyvinyl chloride and ~tyrene polymers; solid poly-
chlorophenols; bitumen; waxes such as for example,
beeswax, paraffin wax, and chlorinated mineral waxes; and
solid fertilisers, for example superphosphates.
Suitable liquid carriers are water, alcohols, for
example, isopropanol and glycols; ketones for example,
acetone, methyl ethyl ketone, and cyclohexanone; ethers;
aromatic hydrocarbons, for example benzene, toluene and
xylene; petroleum fractions, for example kero~ine and
light mineral oils; chlorinated hydroaarbons, for example
carbon tetrachloride, perchloroethylene, trichloro-
ethane; and liquefied normally vaporous, gaseous com-
pounds. Mixtures of different liquids are often suitable.
The surface-active agent may be an emulsifying ~gent
or a dispersing agent or a wetting agent; it may be
nonionic or ionic. Any of the surface-active agents
usually applied in formulating pesticides,herbicides or
~ 3~ ~
fungicides, may be used. Examples of suitable surface-
active agents are the sodium or calcium salts of poly-
acrylic acids and lignin sulphonic acids; the conden-
sation products of fatty acids or aliphatic amines or
amides containing at least 12 carbon atoms in the mole-
cule with ethylene oxide and/or propylene oxide; fatty
acid esters of glycerol, sorbitan, sucrose or penta-
erythritol; condensates of these with ethylene oxide
and/or propylene oxide; condensation products of fatty
alcohols or alkyl phenols for example _-octylphenol or
p-octylcresol, with ethylene oxide and~or propylene
oxide; sulphates or sulphonates of these condensation
products; alkali or alkaline earth metal salts, prefer-
ably sodium salts, or sulphuric or sulphonic acid esters
containing at least 1~ 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 dodecyl-
benzene sulphate; and polymers of ethylene oxide and
copolymers of ethylene oxide and propylene oxide.
The compositions of the invention mav be formulates
as wettable powders, dusts, granules, solutions, emul-
sifiable concentrates, emulsions, suspension concentrates
and aerosols. Wettable powders are usually compounded to
contain 25, 50 and 75% of toxicant and usually contain,
in addition, to solid carrier, 31-0% w of a dispersing
agent and, where necessary, 0-10% w of stabiliser(s)
3~0
and~or other additives such as penetrants or stic~ers.
Dustq are usually formulated as a dust concentrate having
a similar composition to that of a wettable powder but
without a disperQant, and are diluted in the field with
further solid carrier to give a compositlon usually
containing ~-10S w of toxicant. ~ranules are usually
prepared to have a size between 10 and 100 BS mesh
(1.676-0.152 mm), and may be manufactured by agglomer-
ation or impregnation techniques. Cenerally, granules
will contain ~-25S w toxicant and 0-10% w of additives
such as stabilisers, slow release modifiers and binding
agentQ. Emulsiriable concentrates usually contain, in
addition to the solvent and, when necessary, co-solvent,
10-50S w toxicant, 2-20% w/v emulsiriers and 0-20S w/v of
appropriate additives such~as stabiliQers, penetrants and
corrosion inhibitors. Suspension concentrates are com-
pounded so as to obtain a stable, non-sedimenting
flowable product and uqually contain 10-75S w toxicant,
0.5-15S w of dispersing agents, 0.1-10S w of suspending
agents such as protective colloidq and thixotropic
agents, 0-10% w of appropriate additives such as de-
foamers, corrosion inhibitors, stabili~ers, penetrants
and stickers, and as carrier, water or an organic liquid
in which the toxicant is substantially insoluble; certain
organic solids or inorganic salts may be dissolved in the
carrier to assist in preventing sedimentation or as
anti-freeze ag~nts for water.
:~ :
3~0
Aqueous dispersions and emulsions, for example,
compositions obtained by diluting a wettable powder or a
concentrate according to the invention with water, also
lie within the scope of the present invention. The said
emulsions may be Or the water-in-oil or of the oil-in-
water type, and may have a thick "mayonnaise"-like
consistency.
The compositions Or the invention may also contain
other ingredients, ~or example, other compounds pos-
se~sing pesticidal, herbicidal or fungicidal properties.
The invention will be better understood from thefollowing Examples.
ExamDle 1 - Pre~aration Or 1,R-cis-2-ohloro-6-rluoro-
benzyl 2-(2,2-dichlor_vinyl)-3,3-dimethyl-
c~cloprop_ne_carboxylate
(a) Pre~aration Or 2-chloro-6-fluoroben~lbromide
2-chloro-6-fluorotoluene (14.45g) and N-bromo-
succinimide (19.6g) were stirred together with azo-bis-
i~obutyronitrile (O.lg) in anhydrous carbon tetrachloride
under rerlux ror 18 hours expo~ure to radiation ~rom an
infra-red lamp. The resulting solution was cooled in ice,
~iltered and evaporated to leave a pale orange liquid
which was distilled under reduced pressure of nitrogen to
yield the title product (20.lg, 90%) b.p. 74C/3.00 mm Hg.
(b) Preparation o~ 1,R-ci~-2-chloro-6-fluorobenzyl
2-(2,2-dichlorovinyl)-3,3-dimethylcy-cloDropane
carboxylate
3~0
1,R-cis-2-(2,2-dichlorovinyl)-3,3-dimethylcyclo-
propane carboxylic acid (1,1g), 2-chloro-6-fluorobenzyl-
bromide (1,1g) and anhydrous potassium carbonate (0.7g)
were stirred together in acetone under reflux for 2
hours. The reaction mixture was cooled, diluted with
water and extracted 3 times with 50 ml portions of
diethyl ether. The combined extracts were washed with
aqueous sodium bicarbonate solution, dried over magnesium
sulphate, evaporated and purified on an SiO2 column,
eluting with toluene and evaporating to yield 1.8g (100%)
of the title product.
Refractive index nD9 = 1.5420
[~ D24= _22.4 (C2, CHCl3)
Example 2 - Preparation o ~ is-2,6-dichlorobe_zyl
2-(2,2-dichlorovinyl)-3,3-dimethy1cyclo-
propane carboxylate
1,R-ciQ-2(2,2-dichlorovinyl)-3,3-dimethylcyclo-
propane carboxylic acid (3.5g~, 2,6-dichlorobenzyl-
chloride (3.0g), potassium iodide (0.5g) and potassium
2Q carbonate (2.3g) were stirred together in acetone under
reflux for 2 hours. The reaction mixture was treated as
in Example 1 to yield 5.6g (100%) of the title product.
Refractive index nD23 = 1.5638
[o~lD25= -26.50 (C2, CHCl3)
Exam~ 3 to_11
The following compounds were prepared in similar
manner to those of Examples 1 and 2:-
: ~ ' -
~5~3~0
cis-2,6-dichlorobenzyl 2-(2-chloro-2-fluorovinyl)-3,3-di-
methylcyclopropanecarboxylate (86% yield) nD8 = 1.541
cis-2-chloro-6-fluorobenzyl 2-t2,2-dichlorovinyl)-3,3-di-
methylcyclopropanecarboxylate (98S yield) nD9 = 1.5401
trans-2-chloro-6-fluorobenzyl 2-(2,2-dichlorovinyl)-3,3-
dimethylcyclopropane carboxylate (98% yield) nD9 = 1.5360
cis-2-chloro-6-fluorobenzyl 2-(2,2-dibromovinyl)-3,3-di-
methylcyclopropane carboxylate (98% yield) n23= 1.5664
Cis-2,6-dichlorobenzyl 2-(2,2-dichlorovinyl)-3,3-di-
methylcyclopropane carboxylate (87S yield) m.p. 91-95C
cis-2-chloro-6-fluorobenzyl 2-(2-chloro-2-fluorovinyl)-
3,3-dimethylcyclopropane carboxylate (72S yield) nD9 =
1.521
1,R-cis-2-chloro-6-~luorobenzyl 2-(2,2-difluorovinyl)-
3,3-dimethylcyclopropane carboxylate (91S yield) nD22 =
1.4987,[~]D4 = -9.50 (C2 CHCl3)
1,R-cis-2-chloro-6-fluorobenzyl 2-(2,2-dibromovinyl)-
3,3-dimethylcyclopropane carboxylate (63S yield) nD9 =
1.565,[~ D25 = -7.69 (C2 CHCl3)
1:1-cis/tran~-2,6-dichlorobenzyl 2-(2,2-dichlorovinyl)-
3,3-dimethylcyclopripane carboxylate (70S yield)
Pesticidal Tests
The insectlcidal and tickicidal activity of the
compounds according to the present invention was assessed
employing the following pests:
Insects: Musca dom_s_ica (M.d.)
Spodoptera littoralis (S.l.)
; : '''
.
1300
Aphis fabae (A.f.)
Heliothi~ zea (H.z.)
Mites: Tetranychus urticae (T.u.)
Ticls: Boophilus microplus (~.m.)
The test methods employed for each species appear
below:-
(i) Musca domestica (M.d.)
A 0.4% by weight solution in acetone of the compound
to be tested was prepared and taken up in a micro-
meter syringe. Two to three day old adult female
houseflies (Musca domestica) were anaesthetiqed with
carbon dioxide, and 1~1 of the test solution was
applied to the ventral side of the abdomen of each
fly, 20 flies being tested. The treated flies were
held in glass jars covered with paper tissue held by
an elastic band. Cotton-wool pads soaked in dilute
sugar solution were placed on top of the tissue as
food. After 24 hours the percentage of dead and
moribund flies were recorded.
(ii) Spodoptera~littoralis (S.l.)
Pairs of leaves were re~oved from broad bean plants
and placed on filter paper inside plastlc petri
dishes. The leaves were sprayed on the undersurface
with an aqueous formulation containing 20% by weight
of acetone, 0.05% by weight of TRITON X-100 (Trade
Mark) as wetting agent and 0.4% by weight of
. .
. ~ .. . . .
,
Q3~30
12
the compound to be tested. V~rying concentrations
were obtained by diluting the formulation. After
spraying the leaves were left to ~-1 hour drying
period and then each leaf pair was infested with ten
larvae of the Egyptian cotton leafworm (Spodopte~a
littoralis). After 24 hours the percentage of dead
and moribund larvae were recorded.
(iii) Aphis fabae (A.f.)
Tests were carried out on adult aphids (Aphis
fabae) by similar methods to that used for
Spodoptera littoraliq in (ii) above.
(iv) Heliothis zea (H.z.)
The compounds to be tested were incorporated in
aqueous solutions containing 20% by weight of
acetone, 0.04S by weight of Atlox 1045A (Trade Mark)
and 0.2% by weight of the test compound, more d~lute
solutions for dosage-mortality curves being made by
diluting the 0.2% solution with an aqueou~ solution
of 0.05% by weight of Atlox 1045A. Cut Windsor broad
bean plants were placed on a turntable and sprayed
with 4 ml of test solution. Immediately after
spraying. 5 corn earworm larvae ( ~ zea) were
transferred to each plant which was inserted into
water through a hole in a test board and the en-
vironment was maintained at a temperature of 27C
and 40-50~ relative humidity. Mortality was assessed
after 44 to 46 hours.
13
(v) Tetranychus urticae (T.u.)
Discs were cut from the leaves of French bean plants
and were placed on filter paper kept moist by a
cotton-wool wick dipping into water. Each disc was
infested with ten adult mites, and the discs were
then sprayed with a solution or suspension of the
test co~pound in acetone-water (20:80) containing
0.05~ of TRITON X-100 (Trade Mark) as wetting agent.
(vi) Boo~hilus m~ lus (B.m.)
A 0.1% by weight solution of the compound to be
tested was prepared in acetone containing 10% by
weight of polyethylene glycol. Varyin~ concen-
trations were obtained by diluting this solution. 1
ml of test solution was applied evenly to a filter
paper inside a petri dish. When sufficiently dry,
the filter paper was folded in half and crimped
along part o~ its outer edge to form a packet. About
80-100 two to three week old one-host cattle tick
larvae tBoophilus microplus) were transrerred into
the packet, which was then completed sealed. The
packet was then pl~ced in an incubator at 27C and
80% relative humidity. After 24 hours the packet was
opened and the percentage of dead and moribund
larvae was assessed.
The results are shown in Table I in which the test
species are identified by the initials noted above and the
activity of the compound is expressed in the form of its
S433~0
Toxicity Index (T.I.) which is calculated from the fol-
lowing equation:-
LC50 of ethyl parathion (standard)
Toxicity Index (T.I.) =
LC50 f test compound
The knockdown activity of the compound~ according to
the invention was assessed employing the common housefly
(Musca domestica) by means of the Kearns-March chamber
test.
The Kearns-March chamber consists of a 2 foot x 1
foot transparent glass cylinder into which flies can be
introduced through a sliding panel at one end. 0.2 ml of a
20% MeCl2/80S Shellsol K solution containing active
material was sprayed for 1~ seconds into the chamber at 10
psi and the air supply kept on for a further two seconds
to facilitate even distribution of the spray. About 70
flies were used in each treatment and knockdown counts
made at 1, 2, 3, 4, 5, 7 and 10 minutes after spraying.
Compounds are graded into six classes according to the
concentration of toxicant required to achieve 90% knock-
down after ten minutes, that is to say
Class 0 90S at 10 minutes = concentration 0.025%
Clas~ 1 90% at 10 minutes = concentration 0.05%
Class 2 90% at 10 minutes = concentration 0.1%
Class 3 90% at 10 minutes = concentration 0.2%
Class 4 90% at 10 minutes = concentration 0.4%
Clas~ 5<90S at 10 minutes = concentration 0.4S
Class 6 No knockdown at 0.4%
The results of these tests are also given in Table I.
~:~5~3~0
TABLE I
~ . _
Compound Toxicity Index Knock-
o~ ~ _ _ _ down
Example M.d. S.l. A.~. H.z. T.u. B.m. Class
.. _ . _
1 44 96 26 30 98 908 0
2 44 98 12 28 33 1110
3 13 44 5 + 34 1200 2
4 23 41 22 34 72 400
32 24 9 25 31 57 1
6 14 35 20 53 20 _ 2
7 17 107 26 80 61 381 2
8 12 79 29 + 19 482 0
9 17 121 19 19 4 240
32 137 75 + 10 343 0
11 21 77 Z6 -_ 17 178
. . - _ _ _ _
+ not yet te~ted
