CA1063126A

CA1063126A - 2-halobenzyl ethers

Info

Publication number: CA1063126A
Application number: CA233,345A
Authority: CA
Inventors: Peter Kirby; Eirlys R. Barker-Isaac
Original assignee: Shell Canada Ltd
Current assignee: Shell Canada Ltd
Priority date: 1974-09-23
Filing date: 1975-08-12
Publication date: 1979-09-25
Also published as: GB1521685A; AU8505875A; FR2285387B1; FR2285387A1; IT1042758B; JPS5156449A; ES441149A1; BR7506091A; BE833582A; DD121595A5; DE2542212A1; NL7511145A; SU587839A3

Abstract

A B S T R A C T

Herbicidally active 2-fluorobenzyl ether derivatives having the following formula:-

Description

~33L26 This invention relates to 2-fluorobenzyl ether derivatives which are of interest as selective herbicides.
The present invention provides 2-fluorobenzyl ether compounds having the follo~lng formula:

I > \ ~I~
Rl - C - O 3 wherein Rl and R2 each individually represents an alkyl group of 1-6 carbon a~oms; R3 represents an alkyl group of 1-6 carbon atoms, a carboxyl group, an alkoxycarbonyl group of up to 6 carbon atoms, or a group of formuLa -CONR5R6, in which R5 is a hydrogen atom, R6 is a hydrogen atom, an alkyl group of 1-6 carbon atoms, a phenyl group, a halophenyl group, a phenyl group substituted with a lower alkyl or lower alkoxy group of up to 4 carbon atoms, a carbamoyl group, or a carbamoyl group substituted with a lower alkyl group o~ up to 4 carbon atoms, an aryl-substituted carbamoyl group; or R2 and R
may together represent a polymetylene group of up to 5 carbon atoms; and R4 represents a 2-fluorobenzyl group.
The preferred compounds according to the invention are those of formula (I) wherein Rl and R2 each individually represents an alkyl group of 1-6 carbon atoms, for example methyl, ethyl or propyl; R3 represents an alkyl group of 1-6 carbon atoms, for example methyl, a carboxyl group, an alkoxycarbonyl group of up to 6 carbon atoms, for example ethoxycarbonyl, or a group of formula -CONR5R6 (in which R5 is a hydrogen atom, R6 is a hydrogen atom, an alkyl group of 1-6 carbon atoms e.g. methyl or butyl, a phenyl group, a halophenyl group e.g. chlorophenyl or C r - 2-. . . ............... .

3 10f~3126 .`
fluorophenyl, an alkylphenyl group e.g. methylphenyl, an alkoxyphenyl group e.g. methoxyphenyl, a carbamoyl group, an alkyl-substituted carbamoyl group e.g.
N-butylaminocarbonyl, an aryl-substituted carbamoyl . , : .
group e.g. N-phenylarninocarbonyl, N-chlorophenylamino-carbonyl and N-alkylphenylaminocarbonyl~; or R2 and R
may together represent a polymethylene group of up to 5 carbon atoms e.g. a pentamethylene group; and RL~
represents a 2-fluorobenzyl group.
' 10 It will be appreciated that the 2-fluorobenzyl ether ; derivatives accordin~ to the invention may exhibit geometrical andtor optical isomerism. The individual isomers together with mixtures thereof are included with:in the scope of the invention. It will also be appreciated ;
that certain isomers of the 2-fluorobenzyl derivatives of the invention will have more activity than the others and that it may be desirable to effect separation of the more active component.

. .
The invention also provides a process for the -~

preparation of` compounds of formula ~I~ which comprises ;- -~ reacting a diol of` formllla ., CH20H
., R1 ~ C - OH (II) 1 ~ ~ . .. ,;
: CH20R4 , :`.-: '~

,' . . : .

L 10~i312~
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with a ketone compound of formula ~' ~ R2 0 = C \ (III) -' ~
(wherein X is a hydrogen atom, an alkyl, carboxyl~ or alkoxycarbonyl group, or R2 and X together represent a polymethylene group) in the presence of an acid, suitably an inorganic acid such as hydrogen chloride or an aryl-sulphonic acid such as ~-toluenesulphonic acid, and additionally~ if compounds of formula (I) wherein R~ is a -CONHR5R6 group (wherein R5 and R6 have the meaning specified above) are to be prepared, reactlng the resultlng compound of formula (I3 (wherein R3 is a carboxyl or alkoxy-carbonyl group? with ammonia or with the appropriate primary or secondary amine or with ammonia followed by the appro-priate isocyanate.
15In the reaction of Compound (II) with Compound (III) the reaction is preferably carried out in an aromatic solvent, for example benzene or toluene. Alternatively ln the reaction of Compound (II) with an alpha-keto carboxylic acid of formula (III) the catalyst may be boron trifluoride etherate in the absence of a solvent.
The compounds according to the invention have exhibited useful selectivity in cereal (especially wheatj ~ ~
crops and also in soya bean crops. An unusual feature of -- -this class of compounds is their ability to control blackgrass (Alopecurus mysosuroides) as well as annual ~, - 5- 10&~3~Z6 ;~ ~

~ broadleaf weeds including Stell _ a, Veronica, Matricaria - and Papaver. The invention therefore includes herbicidal compositions comprising a carrier and/or surface-active agent and as active ingredient, at least one 2-fluorobenzyl 5 ether derivative according to the invention. The invention :
includes also a method of combating weeds at a locus which ;
comprises applying to the locus a herbicidally effective amount of a 2-fluorobenzyl ether derivative or a composition containing such a compound. `~
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 liquid. Any of the materials usually applied in formulating pesticides, herbicides or fungicides may be used as carrier.
',I"':i: ~: -Suitable solid carriers are natural and synthetlc 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 j ~-example, kaolinites, montmorilloni~es and micas; calcium : ~
carbonates; calcium sulphate; synthetic hydrated silicon ',!~'"~, ' ".' .
2S oxides and synthetic calcium or aluminlum silicates; ~- -elements, for example, carbon and sulphur; natural and synthetic resins, for example, coumarone resins, polyvinyl ~

. ~ '' '~'' ~,'' ' i .: .
' :' f, ~
i31Z6 chlorlde and styrene polymers ancl copolymers; solid polychlorophenols; bitumen; waxes, for exam~le, beeswax, paraffin wax, and chlorinated mineral waxes; and solid fertilizers, for example, superphosphates.
` 5 Suitable liquid carriers are water, alcohols, or - example~ isopropanol and glycols; ketones, for example~ ;
acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ethers, aromatic hydrocarbons, for example, ; benzene, toluene and xylene; petroleum fractions, for example, kerosine and light mineral oils; chlorinated hydrocarbons, ~or example, carbon tetrachloride, per-chloroethylene and trichloethane; and lique~iecl~
normally vaporous, perchlorQethylene and trichloroethane;
and liquefied, normally vaporous, gaseous compounds.
Mixtures of different liquids are o~ten suitable.
. . .:: -The surface-active agent may be an emulsifying agent ~ ~
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 ~ -fungicides may be used. Examples o~ suitable surface-active agents are the sodium or calcium salts Or poly- -acrylic acids and lignin sulphonic acids; the condensation ;
products of fatty acids or aliphatic amines or amides con~
taining at least 12 carbon atoms in the molecule with ethylene oxide and/or propylene oxide; fatty acid esters of glycerol, sorbitan, sucrose or pentaerythritol; conden-sates of' these with thylene oxide and/or propyl-ne oxide;

;.' ,:~., , ........ ....... .................................................................... ..... .

~ ' . , - . . ... . ...

- 7 - ~63126 ` ; ~

condensation products of fatty alcohols or alkyl phenols, for example, p-octylphenol or p-octylcresol, with ethylene oxide and/or propylene oxide; sulphates or ~ ~;
sulphonates of these condensation products; alkali or alkaline earth metal salts, preferab~y sodium salts, of sulphuric of sulphonic acid esters 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; ;~
and polymers of ethylene oxide and copolymers of ethylene oxide and propylene oxide. ;
~he compositions of the invention may be formulated ~
as wettable powders, dusts, granules, solutions, ` ~; ;
emulsifiable concentrates, emulsions, suspension concen~
trates and aerosols. Wettable powders are usually com~
pounded to contain 25, 50 or 75~Wof toxicant and usually contain, in addition, to solid carrier, 3-10%w of a dispersing agent and, where necessary, 0-lO~w 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 diluted ;;
in the field with further solid carrier to give a composition usually containing 2-10%w o~ toxicant.
Granules are usually prepared to have a size between 10 and 100 BS mesh (1.676 - 0~152 mm)~ and may be manufactured : : .-.` ~ ` , ~ '' : , :,.~

- 8 - ~ ~S3~l26 : ~

by agglomeration or impregnation techniques. Generally, granules will contain 2-25% w of toxicant and 0-10% w of additives such as stabillzers, slow-release modiflers and binding agents. Emulsifiable concentrates usually contain, in addition to the solvent and, when necessary, co-solvent, 10-50% w/v of toxieant, 2-20% w/v of emulsifiers and 0-20% wtv of appropriate additives such as stabilizers, penetrants and corrosion inhibitors. ;
Suspension concentrates are compounded so as to obtain a stable, non-sedimenting flowable product and usually contain 10-75% w of toxicant, 0.5-15% w of dispersing .... .
agents, 0.1-10% w of suspending agents such as proteetive colloids and thixotropic agents, 0-10% w of appropriate additives sueh as detoamers, eorrosion inhibitors, stabilizers, penetrants and stiekers, and as earrier, water or an organie liquid in which the toxicant is .
substantially insoluble; certain organie solids or ~ ; ;
inorganic salts may be dissolved in the carrier to assist in preventing sedimentation or as antifreeze agents for ~;
water.
Aqueous dispersions and emulsions, ~or example, eompositions obtained by diluting a wettable powder or a eoncentrate aeeordin~ to the invention with water, also lie within the seope 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 thiek "mayonnaise"-like ;
eonsisteney.

,'' ~

. .. . .

9 11[~;3~Z6 ~ ~
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The compositions Or the invention may also contain other ingredients, for example, other compounds possessing -~
pesticidal~ herbicidal or fungicidal properties.
The invention is further illustrated in; the following exam~les.
EXAMPLE 1 Ethyl 4-(2-fluorobenzyloxymethyl)-4-ethyl-2- ;
methyl-1,3-dioxalan-2-carboxylate Dry hydrogen chloride was passed into a stirred solution of 3-(2-fluorobenzyloxy)-2-ethylpropane-1~2-diol (80 g) and ethyl pyruvate (41 g) and the solution stirred and kept at 0-5C for 3 3 hours. The reaction mixture ~;
was then poured into a suspension Or potassium carbonate (50 g) in methylene chloride at -10C. The solids were filtered off and the filtrate washed with 5% solution of potassium carbonate, followed by water and drled over anhydrous magnesium sulphate. After removal of solvent the residue was fractionally distilled to give the desired product as an isomer mixtl~, b.p. 145C at 0.4 mm Hg.
Analysis Calculated for C17H2~5F C 62-6; H 7~
Found : C 62.3; H 7.3.
EXAMPLE 2 4-(2-fluorobenzyloxymethyl)-4-methyl-?- ~ ;
- spirocyclohexane-1,3-dioxalane .
3-(2-fluorobenzyloxy)-2-methylpropane-i,2-diol Z5 (2.7 g), cyclohexanone (1.5 g) and p-toluenesulphonic ~ acid (100 mg) in toluene (25 ml) were heated together at :,.: ,, ~
'-.'' ~

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' .. : ,:

- 10 ~ 1~63~26 ~ ~

reflux temperature under a Dean and Stark trap for 16 hours. When the correct amount of water had been ~ -collected the solvent was removed from the reaction mixture and the residue chromatographed on silica gel i~
using a 4:1 mixture of methylene chloride and ether. '-The desired product was confirmed by NMR spectroscopy.
Analysis Calculated for C17H233~ C 69-4; H 7-9 ~ound : C 69.7; H 7.9.

EXAMPLES 3 and 4 4-(2-fluorobenzyloxymethyl)-4-ethyl-

2-methyl-1,3-dioxalan-2-(N-o-tolyl) carboxamide. Isomers I and II

o-Toluidine (1.97 g) was added to a stirred suspension of sodium hydride in dimethylsulphoxide and stirring was continued at room temperature for 1 hour. The mixture~was ~;
cooled to 15-20C and ethyl 4-(2-flùorobenzyloxymethyl)-4-ethyl-2-methyl-1,3-dioxalan-2-carboxylate (6 g, prepared as in Example 1) was added dropwise. Stirring was continued ;~
at room temperature for 16 hours. The reaction mixture ,~
was poured ~into crushed ice and extracted with chloroform (4 x 25 ml). The combined extracts were washed wIth 2N
hydrochloric acid, followed by potassium carbonate and water.
After drying over anhydrous magnesium sulphate the dried i~
extracts were chromatographed on silica gel, using a 3 mixture of petroleum ether and ether as eluant. The first fractions to be eluted from the column were collected and ,. . .
the solvent removed. The residue was recrystallized from ~ ~ -' ~

,~'

3~26 ~ -:
~, cyclohexane to give a product, identified as isomer (lI), m.p. 56-58C.
Analysis Calculated for C22H26NOLIF: C 68-3; H 6-7; N 3-6 Found : C 68.3; H 7.0; N 3.7. / -~
Further eluted fractions from the column were collected and the solvent removed. The residue was recrystallized from petroleum ether to give a product identified as isomer (I), m.p. 42-44C. Elemental analysis of the product ` -corresponded with that obtained above for isomer (II).
EXAMP~E 5 4-(2-fluorobenzyloxymethyl)-LI-ethyl-2-methyl-2-(N phenyl allophanoyl)-1,3-dioxalane ,... : .
ll-(2-fluorobenzyloxymethyl)-4-ekhyl-2-methyl-1,3~
dioxalan-2-carboxamide ( 4 g, prepared by reacting the com-pound produced in Example 1 with concentrated ammonia) and :~
phenyl isocyanate (1.6 g) in dry toluene (40 ml) were `~
,t'~
refluxed overnight. The solution was cooled and solvent removed under reduced pressure and the residue was recrystallized from ethyl alcohol to give the desired product as a mixture of isomers, m.p. 80-85C.
Analysis Calculated for C22H25N25F C 63.4; H 6-o; N 6-7 Found : C 63.5; H 6.1; N 6.6.
EXAMP~ES 6-19 Following procedures similar to those given in Examples 1-5 further compounds were prepared, whose physical charac- `
teristics and analyses are set out in Table 1. All the structures were confirmed by NMR techniques.
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16- 1063~26 EXAMPLE 20 Herbicidal activit~ ~ ;
To evaluate their herbicidal activity, the compounds of the invention were tested using as a representative range of plants:- maize, Zea mays (Mz); rice, Oryza sativa .. . .
(R), barnyard grass, Echinochloa crusgalli (BG); pea, Pisum sat~vum (P); linseed, Linum usitatissimum tL);
mustard, Sinapis alba (M); and sugar beet, Bet ~ ~ ;
(SB). ~-The tests fall into two categories, pre-emergence and post-emergence. The pre-emergence tests involved spraying a liquld formulation of the compound onto the soil in which the seeds of khe 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 soil drench tests the soil in which seedling plants of the above species were growing, was drenched with a liquid formulation contalning 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-steriliæed, 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 `~
., i, :
diluting with water solutions of~the compounds, in acetone ;~

- containing 0.4% by weight of an alkylphenol/ethylene oxide concentrate available under the trade name Triton X-155.

In the soil spray and foliar spray tests the acetone ~ rk : ~ ~
... ..

,. , . , .. ..
,. , ~: :

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solutions were diluted with an equal volume of water and the resulting formulations applied at two dosage levels corresponding to 10 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 10 kilograms of active material ; ~ .
per hectare in a volume equivalent to approximately 3,000 litres per hectare.
In the pre-emergence tests untreated sown soil and ;
in the post-emergence tests untreated soil bearing seedling plants were used as controls. ~ .
The herbicidal effects of the compounds were assessed visually seven days after spraying the foliage and drenching A"''~, '`~ ;
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.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. 2-Fluorobenzyl ether compounds having the following formula:

(I) wherein R1 and R2 each individually represents an alkyl group of 1-6 carbon atoms; R3 represents an alkyl group of 1-6 carbon atoms, a carboxyl group, an alkoxycarbonyl group of up to 6 carbon atoms, or a group of formula -CONR5R6, in which R5 is a hydrogen atom, R6 is a hydrogen atom, an alkyl group of 1-6 carbon atoms, a phenyl group, a halophenyl group, a phenyl group substituted with a lower alkyl or lower alkoxy group of up to 4 carbon atoms, a carbamoyl group, or a carbamoyl group substituted with a lower alkyl group of up to 4 carbon atoms, an aryl-substituted carbamoyl group; or R2 and R3 may together represent a polymethylene group of up to 5 carbon atoms; and R4 represents a 2-fluorobenzyl group.

2. Compounds according to claim 1 wherein R1 and R2 each individually represents methyl, ethyl or propyl; R3 represents methyl, carboxyl, ethoxycarbonyl or a group of formula -CONR5R6 in which R5 is hydrogen and R6 is hydrogen, methyl, butyl, phenyl, chlorophenyl, fluorophenyl, methylphenyl, methoxyphenyl, carbamoyl, N-butylaminocarbonyl, N-phenyl-aminocarbonyl, N-chlorophenylaminocarbonyl or N-alkylphenylaminocarbonyl; or R2 and R3 represent a pentamethylene group; and R4 represents a 2-fluorobenzyl group.

3. 4-(2-fluorobenzyloxymethyl)-4-ethyl-2-methyl-1,3-dioxalan-2-(N-o-tolyl)-carboxamide.

4. An isomer of 4-(2-fluorobenzyloxymethyl)-4-ethyl-2-methyl-1,3-dioxalan-2-(N-o-tolyl)-carboxamide having a melting point of about 42-44°C.

5. 4-(2-fluorobenzyloxymethyl)-4-ethyl-2-methyl-1,3-dioxalan-2-carboxamide.

6. 4-(2-fluorobenzyloxymethyl)-4-ethyl-2-methyl-2-(N-n-butyl-allophanoyl)1,3-dioxalane.

7. 4-(2-fluorobenzyloxymethyl)-4-ethyl-2-methyl-1,3-dioxalan-2-(N-3-methoxyphenyl)-carboxamide.

8. 4-(2-fluorobenzyloxymethyl)-4-ethyl-2-methyl-1,3-dioxalan-2-(N-4-fluorophenyl)carboxamide.

9. An isomer of 4-(2-fluorobenzyloxymethyl)-4-ethyl-2-methyl-1,3-dioxalan-2-(N-4-fluorophenyl)carboxamide having a melting point of about 85-87°C.

10. A process for the production of compounds having the general formula (I) as defined in claim 1, which comprises reactlng a diol of formula:- (II) with a ketone compound of formula:- (III) (wherein X is a hydrogen atom, an alkyl, carboxyl, or alkoxycarbonyl group, or R2 and X together represent a polymethylene group) in the presence of an acid, and additionally, if compounds of formula (I) wherein R3 is a -CONHR5R6 group (where R5 and R6 have the meaning hereinbefore specified) are to be prepared, reacting the resulting compound of formula (I) (wherein R3 is a carboxyl or alkoxycarbonyl group) with ammonia or with the appropriate primary or secondary amine or with ammonia followed by the appropriate isocyanate.

11. A method of combating weeds at a locus which comprises applying to the locus a herbicidally effective amount of a 2-fluorobenzyl ether compound as defined in claim 1.