CA1246601A - Herbicides - Google Patents

Abstract

ABSTRACT

Compounds of the formula wherein A is hydroxy; alkoxy of 1 to 4 carbon atoms;
mercapto; alkylthio, alkylsulphinyl, or alkylsulphonyl of 1 to 4 carbon atoms;
mono- or dialkylamino with alkyl groups of 1 to 4 carbon atoms;
methyl; or trifluoromethyl;
B is fluorine or chlorine;
C is hydrogen;
D is trifluoromethyl;
E is hydrogen;
and F is hydrogen, chlorine, or fluorine and salts, esters, and amides thereof;
useful as selective herbicides.

Description

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HE~BICIDES

This invention relates to chemical compounds use~ul as herbicides, and to herbicidal compositions and processes utilising them.
In our European Patent No. 0003416 there are claimed herbicidal diphenyl ether compounas of the formula (I), R CONSO R

5 4 ~ ~ O ~ ~ - R

and salts thereof, wherein R is an alkyl group of 1 to 6 carbon atoms optionally su~stituted by one or more fluorine atoms, or 10 by a phenyl group optionally substituted by one or more - - halogen atoms; R is a hydrogen a'com, a fluorine, chlorine, bromine, ox iodine atom, or a nitro group"
R is a hydrogen atom, a fluorine, chlorine, bromine, or iod ine atom, an alkyl group of 1 to 6 carbo4n atoms, a trifluoromethyl group, or a cyano group; R is a hydrogen atom, a fluorine, chlorine,5bromine~ or io~ine atom, or a trifluoromethyl group; R is a fluorine, chlorine, bro6ine, or iodine atom or a trifluoromethyl grQUp; and R is a ~ydrogen atom or an alkyl group o~

2 0 1 to 4 carbon a toms .
In the present appl ication we make no claim to any compound claimed in aforesaid European Paten~ No.

,3 . ~ .

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0003416. Subject to this disclaimer, the present invention provides diphenyl ether compounds of formula (II) C B / R

D~

E F
~II) wherein A i5 hydrogen; halogen; NO ; N-N-CF ;
S PO H and C to C4 alkyl esters thereof; a carboxy group or a functional derivative thereof; NH ;
N~OH; -N2 ; mono or dialkylamino; NHCOR wherein R is alkyl or alkoxy or mono- or dialkylamino, 2alkyl;
mono- 2 dialkylamino; trialkylammonio; ~HSO R
where R is2an alkyl or phenyl radical;
~NHCONHSO R , alkylthio; alkylsuIphinyl; al~yl-sulphonyl; dialkylsulphonio; cyanosulphonyl; hydroxy;
alkano~loxy; alkoxy, alkoxy substituted by alkoxy carbonyl; -S~; ~N=O; -SCN; N ; CF ;
O
15: -N=N-P-(OCH ) ; or acyl; ~
B is hydrogen, fluorine; chlorin ; bromine; iodine;
alkyl; alkoxy; alkylsulphinyl; llkylsulphonyl; CF ;
: NO ; CM; NH2; NHCOR where R is defined as above; or CONH2;
~: 20~ C is hydroyen, halogen, alkyl, or dialkylamino;
~D is CF ; alkylthio; alky}sulphinyl, alkylsulphonyl;
halogeno; alkyl; sulphamoyl; ~ormyl; alkylcarbonyl; CN;
or M(CH ) ;
E is hyd~ogen, halogeno, alkyl, aikloxy; alkylsulphinyl;
25 ~ alkylsulphonyl; CN; CF3; NH2; NHCOR ; or CONH ;

:., .

~ 3 F is defined as for B above;

and R i5 a group -CONR SO R where R is hydro~en or an alkyl group of 1 to 4 carbon atoms and R is a phenyl, pyridyl or thienyl radical optionally substituted by one or more halogen atoms, alkyl groups, or nitro 5 groups ~ or an alkenyl or alkynyl radical of 2 to 4 carbon atoms or an alkyl radical of 1 to 4 carbon atoms optionally substituted by one or more atoms of chlorine, bromine, or iodine, or by one or more of the following substituents, carboxyl; alkoxycarbonyl of two to five carbon atoms; alkylcarbonyl, of two to five carbon atoms; mono~ or di alkyl carbamoyl in which the alkyl groups have from one to four carbon atoms; alkoxy of one to four carbon atoms; alkylthio, alkylsulphinyl, or 15 alkylsulphonyl all of one to four carbon atoms; alkyl-carbonyloxy of two to five carbon atoms; alkylcarbonyl-amino of two to f ive carbon atoms; or cyano.
In the foregoing definition, the expression l'carboxyl group or a functional derivative thereof" is intended to include esters, amides, and salts of the carboxylic function, inclu3ing for example substituted amides of formula CONHSO R as defined above and oximes of the formula -C-N-OR
~ wherein X is chlorine, cyano, nitro, or an acyl group -C-R wherein R is an alkyl group-of o 1 ts 4 carbon atoms.
Where reference is made above to alkyl radicals or radicals containing one or more alkyl groups, for example 3û mono- and di-alkylamino, or alkoxy~ the alkyl raaical may be for example a lower alkyl radical having for example 1 to 6 carbon atoms.

One sub-group of compounds according to the invention com~rises compounds of formula (II) wherein A is hydrogen, fluorine, chlorine, bromine9 iodine or a nitro group;
B is a nitro group;
C is hydrogen;
D is fluorine, chlorine, bromine, iodine, or a CF
group;
E is hydrogen;
F is hydrogen, fluorine, chlorine, bromine, iodine, or and R is a -CO~HSO2R group wherein R is an alkenyl or alkynyl group of 2 to 4 carbon atoms or an op~ionally substituted alkyl group of 1 to 4 carbon atoms.

Another sub group comprises compounds in which the group A is methyl or tri~luoromethyl;
B is fluorine or chlorine~
C is hydrogen;
D is fluorine, chlorine, bromine, iodine, or CF ;
E is hydrogen;
F is hydrogen, ~luorine, chlorine, br~mine, iodine, or CF3; 3 . 3 .
and R i5 a -CONHSO R group whereln R 1S an alkynyl or alkenyl group of 2 to 4 carbon atoms or an optionally substituted alkyl group of 1 to 4 carbon atoms.
Examples of compounds of the invention are listed in '~able 1 below~

_ . ___ _ _ ~ ~ ~ I
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æ :

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~ H o o o ~ , CC~ " ~, ~ o ~ _ ._ _ i ~ ~ $ ~ C~ U
l _ ~
t~ ~ , ~ ~ x ~
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¦ ~ ~ o U o ~ Z Z ~ ~ N o ~

~ ~ D ¦

,. i ~L~7 ,. _ L~) V O r ~ L"
Z O ' ~ L~) L'~ L~ N

_ , _ ~ ~V ~ V ~ t~ rl _ ._ l 1~4 ~ X ~
r.1 ~ U ~ D:
~1~ ~ r~ - l fd I I (~ ~ f~ rq ~ ~~ N
~/ ~ Q I U~ L~

a ~ æ ;~ æ~ C) h C) ~ t.) ~ _ ~

~ ~ O:
~ ~ ~ ~ ~) N ~ o N C\ ~`I
_ j L~ j R N~ N N ~ N N .1 --I r~ a ¦ :

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_ 9 _ TABI,E I I

C B ~ CONHSO CH3 D ~ O {~ A

- ! i .
~OMPOUND A B C D E F
NO _ _ _ .
4 3 NO 2 H ~ H 2 3 H lEI

No2 CEI3 H CH SO IH CH3 46 No2 CH3 H 3 2 }I CE13 47 ~o2 H 3 H 3 :~ H E}
48 ~o2 Cl H CH3$2 . H H
49 . No2 NO H Cl ~ H
No2 2 H CON ( C~3 ) ~H E~
51 No2 CH O ~ Cl ~ . ~
52 No2 C~3C) H ~ H }I H
53 No2 . H H 2 2 ~ H .
54 N~2 NO~ H CH3 H H
5 5 No2 H H A 9 H H
56 No2 E~ H 3 H a 57 No2 Cl H 4 9 H }I
58 NO El H CN H H
59 No2 Cl H CF3 H N~2 ~o2 ~ F ~1 CF3 ~ N~2 6~1 No2 H H SCH3 ~ : H
6 2 2 H ~1 SOCH H H
_ ~O~ i _ 11 _ C ( CH3 )3 H

.. ..

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TABLE I I CONTD v COMPOUND A B C D E
_~ ~ l I
6 4 NO Cl H OCEI 3 H H
6 5 2 5 C1 H C F 3 11 ~I
66 SH Cl H CF3 H E~
67 SCE~ Cl H CF3 E H
6 8 SOCH Cl H CF3 H H
69 SO C~l C1 H CF3 H H
2 3 Cl H CF3 H H
71 3 Cl H C~3 H H
72 OCH3 Cl H CF3 . H
CH
7 3 OCHCO CH Cl H CF3 H ~
7 4 OCOCH Cl E~ CF3 H H
L 75 I M(CH3~ 2 L~ 3 C 3 ~ __ Further examples of compounds falling within the scope of the inve-tion are listed in T-ble IIA.

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TABLE I IA

C B / C~HSO

S'--~ ~
E F

~ _ _ _ _ _. . . --_ I
COMPOUND A ¦ B C D E F R
NO __ _ ~ __ _ 7 6 NO 2 CF 3 H Cl H H 3 2 3 77 NO Cl H Cl . H H . C~2CE~2Cl 7 8 No2 Cl E~ CF H H . CHCl 2 79 Cl 2 Cl H CF3 H El . CH C0~3 ( CE~3) 2 8 0 NO Cl H CF H H 3-pyridyl 81 No2 CF H C13 H H 2 2 3 82 No2 C13 H CF H H .CH CH Ol::H3 8 3 Cl 2 CF3 H Cl 3 H H 2 2 3 84 NO ~ H CF3 H H ~,CH(CH3)C~
8 5 NO Cl H CF3 H H . CH 2COCH3 86 NO Cl H CF3 H H .CH CH SH
87 No2 Cl H CF H H .CH CH SOCH
8~8 No2 Cl ~ CF H H 2 2 2 3 :8 9 No2 Cl H CF3 H ~ 6 4 --9 0 NO Cl E~ CF 3 H H . C H . OCH3 91 NO Cl H CF3 H H 2-pyridyl 92 NO Cl H CF3 H H 2-thlenyl ~3 N2 Cl H ~ CF3 H . F .CH CEI~OC~3 9 4 NO Cl H CF H H O CH=C:E~2 NO Cl H CF :H F C~2C CH
96 C l 2 Cl H CF3 H H .C112CH=CH2 * 97 NO2 Cl H CF3 H F 2 2 2 : ~__ o - ~ _ _ *~ Melting poln-c 150-I51 , . ..

V~

As explained below, the compounds of the invention may in general be made from the corresponding compounds of formula II above wherein R is a carboxyl gr~up.
Table III below gives melting poinl:s for compounds.
which may be u~ed as intermediates for the synthesis of the compounds listed in Table II.

TABLE I I I

C ~ ~

D ~ O - ~ ~ A
~<~
E F
, INTERMEDIATE FOR Z MELTING POINT
COMPOUND MO . .
~see Table II) __ _ _ _ 43 ~2C~3 8fi-90 44 CO ~H 68-6~

~8 CO2~ 187-189 : CO2N(CH3~2 141-145.
51 ~O CH 64~65 53~ C2c~3 149~153 . .. _ .

.
.

.
. . ~ .

.

TABLE III CONTD.

_ .
INTER~IEDIATE FOR Z MELTING POINT
COMPOUND NO C
~see Table II) _ ._ 5~ C2C~13 99-100 57 CO CH 94-g6 59 co2c~3 168-170 2 3 138-139 .

71 Cc2Cc~3 137 , _ ~ j O l~b.~180 ~1 Torr ~, Most of the compounds listed in Table III are esters, with one amide. The esters and th~ amide ~ay be hydrolysed to the cor~esponding carboxylic acids ~Formula II, R=CO H) by conventional acid or base hydrolysis ana the acids converted to the sulphonamide derivatives o, the invention as described below. Certain of the carboxylic acids are new compounds, and form a further part of the present invention, together with their salts~
esters (e.gO alkyl esters), and amides.
These compounds are themselves herbicidal and may be useful as herbicides, as well as being useful as intermediates for the compounds of the invention~ In particular, the compound 5-(2-chloro-4-trifluoro~ethyl phenoxy)-2-trifluoromethylbenzoic acid, described in Example 18 as an intermedi~te for compound 37 of the invention, is belièved to be a new compound and together with its salts, esters, and amides, forms a further part of the invention.
The compounds of the inven~ion may be prepared by a variety of methods. In one method outlined in Sch~me A below, a suitably substituted diphenyl ether derivative ~ bearing a carboxyl group is converted ~ the corresponding carbonyl chloride by reaction with a chlorinating agent according to standard methods. The carbonyl chloride tIv~ 3so obtained is then reacted with an alkanesulphonamide R SO NH in the presence of an acid acceptor~ to give the compound of the învention.
Examples of acid acceptors include tertiary amines ~ for example pyridine and triethylamine. Other acid acceptors include alkali metal carbonate5, e.g. anhydrous potassium carbonate. Alkali metal fluoridPs~ especially caesium fluoride, may also be used.

6~i~3 ~ 15 ~

Scheme A

C B CO H C BCOCl D ~ ~ O - ~ ~ 33 D ~ o - ~ A

F E F

(III) tIv~ ~~

~IV) + ~ S2NH Acid ~I3 Acceptor In Scheme A, the starting material lIII~ may be one that contains all the required substituents for the final product (II). Alternati~ely, one or more of the substituents may be introduced after the -C~NHSO R
S substituent has been built on to the molecule. Thus, if the substituent A is to be a nitro group in the fina~
pr~duct, the reaction Scheme A may start with a compound in which the substituent A is hydrogen and the nitro group may be introduced by a conventional nitration procedure at the last step, following the second reaction shown in Scheme A. In another approach, a compound II may be prepared and one or more of the substituents m~y be modified by conventional chemical procedures. Thus compounds (II) wherein A is an amino ~roup may be prepared by reduction o compounds (IIj wherein A is a nitro group.

....

The carboxyl~substituted diphenyl ether derivatives (III) may be obtained by various synthetic methods. In one method, an appropriately substituted phenol may be reacted in salt form with an ester (e.g. the methyl ester) of 3-carboxy-4-nitrofluorobenzene as described in Example 8 for compound 38 of Table 1. The ester so obtained may then be hydrolysed (e.g. by treatment with a mixture of acetic acid and aqueous hydrobromic acid) to the corresponding carboxylic acid (III) 7 In another method, the same reaction sequence may be carried through, but using an ester of 3-carboxy-4-nitrochlorobenzene instead of an ester of 3-carboxy~4-nitrofluorobenzene, as described in Example 6.
In another method, 3-hydroxybenzoic acid or a ~
substituted-5-hydroxybenzoic acid may be reacted in the form of its di-salt with an appropriately substituted fluoro- or chlorobenzene, as described in Examples 17 and 5.
By way of Eurther illustration of the methods of preparing the compounds of the invention, the ollowing - description gives details of the preparation of a number of compounds of formula ~III). Each preparation is prefixed by the word "Intermediate" and the number o~ the compound in ~able I or Table II for which the compound is an intermediate. Thus "Intermediate 65" means that ~he compound prepared is the carboxylic acid of formula III (or its ester) which can be used in the preparation of compound 65 of Table II.

Intermediate 35 .

3-Hydroxybenzoic acid t13.8 g) in dry dimethyl-30 formamide ~100 ~1) was heated and stirred or 7 hours at 100 with anhydrous potassium carbonate (26 9~ and . . .

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4-chloro-3-ni~robenzotrifluoride (22.S 9). The mixt-lre was then evaporat~d to a small volume under reduced pressure and diluted with water. With warming, a dark solution was obtained. Acidification gave a white precipitate; this was washed with water and recrystall-ised from a mixture of methanol and water to give 3(2-nitro-4-trifluoromethylphenoxy~ benzoic acid (24 9).

Intermediate 59 (a) Preparation of 2-amino-6-chloro-4-trifluoromethyl-phenol Solid sodium dithionite (10 9) was added in portions ~o a stirred solution of 2-chloro-6-nitro-4-trifluoro-~ethylphenol t4.5 g) in a mixture of ethanol (20 ml~ and water (30 ml). The solution was stirred for 2 hours, left overnight, filtered, and evaporated. The resiaue was mixed with toluene and the toluene removed under reduced pressure. The residue was extracted with boiling chloroform ~3 x 100 ml) and the chloroform extracts evaporated to give a yellow oil identified as the required substituted phenol.

~b) Pr~paration of meth~l 5-(2-amino-6-ohloro-4-trifluoromethylphenoxy)-2-nitroben20ate The phenol prepared in (b) (l.~ g~ was stirred wit~
methyl S-fluoro-2-nitrobenzoate (1.~ gj and anhydrous potassium carbonate t2 0 g) in dry dimethylsulphoxide ~20 ml~ for 3 hours at lS0 . The mixture was then cooled, diluted with water, neutralised with dilute hydrochloric acid. The solid which separated was dissolved in dilute sodium hydroxide solution~ The solution was extracted twice with ether and then brought to p~ 5-6 (HCl). The solid which separated was identified as the required Intermediate 59.

,~, ~66~

Intermediate 65 2-Iodo-5-(2-chloro-4-trifluoromethylphenoxy) benzoic acid (0.1 mole) in dimethyl~ormamide (500 ml) was co~led to 0 . Cuprous oxide ~0.11 mole) was added, follo~ed by ethyl ~ercaptan (0.1 mole). The mixture was stirred while sodium hydride tO.25 mole) was added in portions.
~fter 15 minutes the temperature was raised to 80 for 6 hours. The mixture was cooled and poured into hydro~
chloric acid (2 molar)O ~he mixture was twice extracted with ether. The ether extract was washed with water, dried (Na SO~) and evaporated. ~he residue was recrystallised from ether to give 2-ethylthio-5-~2-chloro-4-trifluoromethylphenoxy)ben~oic acid, with a melting point o~ 153-155 .

Intermediate 6_ Methyl 2-diazo-5(2-chloro-4-trifluoromethylphenoxy) benzoate tetrafluoborate (15.0 ~, prepared as described in Example 18) was added portionwise at 30 to a stirred solution of tetramethylthiourea ~4~0 g~ in acetonitrile (S0 ml). The mixture was stirred for a further forty-five minutes at 50 , an excess of sodiu~
iodide added to decompose any remaining diazoni~m salt and the solvent removed in ~acuo~ The residue was triturated many times, first with water, then ether. The oil was dissolved in dichloromethane, dried and evaporated to give a solid salt.
This salt (3.65 g) was stirred with N sodium hydroxide sol~tion until homogeneous (approximately thirty minutes~. The solution was extracted with ether, acidified with 2N hydrochloric acid and again extracted with ether. The latter extracts were washed with water and brine, dried and evaporated to give Intermedia~e 66 ( 1 .11 9) .

Intermediate 6?

A solution o~ methyl 2-mercapto-5(2-chloro-4-tri-fluoromethylphenoxy)benzoate (1.76 g, prepared as described in Intermediate 66) in N,N-dimethylacetamide (10 ml) was treated with sodium hydride (0.24 g~ 50~, o prewashed with petroleum b.p. 40-60 ). The mixture was stirred for ten minutes, treated with methyl iodide (0.5 ml, excess~ and stirred for a further f:ifteen minutes.
It was then diluted with water and extracted with ether.
The extracts were washed with water and brine, dried and evaporated to give Intermediate 67.

Intermediate 68 A solution of methyl 2-methylthio-5(2-chloro-4-tri-fluoromethylphenoxy) benzoate (1.55 gl in methanol tS0 ml) was treated with sodium metaperiodate ~0 9 g) in - water (10 ml). The mixture was heated at 80 for one hour/ cooled, diluted with water and extracted with ethyl acetate. The extracts were washed with water, dried, evaporated and the residue chromatographed on silica in ether to give Intermedia~e ~8 IQ.65 9, mp 130 ).

Intermediate 69 .

A solution of methyl 2-methylthio-5(2-chloro-4 trifluoromethylphenoxy)benzoate (1.55 g) and m-chloro-perbenzoic acid (3.42 9, excessj in dichloromethane (50 : ml~ was refluxed for four hours, cooled, diluted with - dichloromethane and washed with sodium bicarbonate solution, water and brine. The extracts were dried, evaporated and triturated with petroleum ~b.p. 40-~0 ) to give Int~rmediate 69 (1.1 9, .p. l25 ).

- 2~ -Intermediates 70 and 75 A ~ixture of methyl 2-amino-5~2 chloro-4-trifluoro~
methylphenoxy)benzoate (3.0 g) and dimethylmethyl-phosphonate (10 ml) was heated at 120 for four hours It was then cooled, diluted with waterf Ibasified with 2N
sodium hydroxide solution and extracted with ether. T~e extracts were washed with water and brine, dried and evaporated in vacuo to give a brown oil. Trituration ~ith methanol gave Intermediate 70 ~0.4g g, m.p~ 94 A similar experiment was carried out with the 10 exception that the reaction period was extended to twenty hours at 170 . The mixture was cooled, diluted with water and sodium hydroxide solution and extracted with ethyl acetate. The extracts were washed with water ana brine, dried and evaporated in vacuo. ~he residue was triturated with methanol to give Intermediate 75 (1~83 g, m.p. 76 ). Tntermediate 7S was also prepared by reductive alkylation. Thus treatment o~ the amine ~0.43 g) with formaldehyde (40~, 1.5 ml~, sodium cyano~oro-hydride (0025 9) and acetic acid lO.13 ml) ~ave rise to ~0 0.30 g of crude material contaminated with approximately 10% of Intermediate 70.
, Intermediate 71 2,5-Dihydroxybenzoic acid (1.68 9) was added portionwise to a stirred suspension of sodium hydride (1.6~ g, 50~, prewashed with petroleum b.p. 40-60 ) in N,N-dimethylacetamide ~50 ml~. The mix~ure was stirred for a ~urther thirty minutes, then treated with 3-chloro-4-fluorobenzotrifluOride* ~2.24 9). It was then heated at I20 for one hourl cooled, diluted with water, acidified with 2N hydrochloric acid and extracted with ethyl acetate. The extracts were washe~ with water an~

6~

brine, dried and evaporated in vacuo. The residue was triturated with petroleum (b.p. 40~60 ~ and the resultin~ solid recry~stallized from petrole~m (b.p~ 8n -100 ) to give Intermediate 71 ~1.55 g, m.p. 137 ~, * 3,4-Dichlorobenzotrifluoride can also be employed but the period of reaction is extended to thirteen hours at lS0 and purification more complex.

~ mixture of this mater;al (1,35 g)j methanol ~2~
ml) and borontrifluoride etherate (2 ml) was refluxed for twelve hours, treated with a further portion of the catalyst ~1 ml) and refluxing continued for six hours more. Water was then added and the mixture extractecl with ether. The extracts were washed wikh water and brine t dried, evaporated and the residue recrystallized rom methanol to give the methyl ester of Intermediate 71 (1.04 g, m.p. 75 ). -/

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Intermediates 72, 73 and 74 Methyl 2-hydroxy-5t2-chloro-4- trifluoromethyl-phenoxy)benzoate ~0.35 g, prepared as above was adde~
portionwise to a stirred suspension of sodium hydride (0~05 9, 50~, prewashed with pe-troleum b.p. 40-60 ~ in dimethylacetamide (5 ml). The mixture was stirred ~or a further thirty minut~s, treated with methyl iodide (0.1 ml, excess), and heated at 60 for one ~hour. It was then diluted with water and extracted with ether. The extracts were washed with water and brine~ dried an~
evaporated and the residue recrystall-ized from petroleum (b p. 40-60 ) to give Intermediate 72 (250 mg, M.p.
73 ) A similar reaction utilising methyl alpha bromo-propionate in place of methyl iodide and extending the reaction period to two hours at 90 gave Intermediate 73 (m.p. 73 ~.
A similar reaction utilising acetyl chloride in place of methyl iodide proceeded instantaneously to ~i~e Intermediate 74 lb.P. lS0 (bath)/l mml.
The compounds of the invention arè useful both as pre- and post~emergence herbicides. Pre-emergence herbicides are usually used to treat the soil in which a crop is to be plantedl by application before or durin~
seeding, or after seeding and before the crop emerges~
~5 Post-emergence herbicides are applied after the crop plants have emerged from the soil. Compounds of the invention may be used as selective herbicides in a variety of crops~
including for example cotton, soya bean, peanuts, peas, ~ wheat, sugar beet, barley and rioe. Compounas of the invention may also be used as total herbicides~ The compounds of the inv~ntion may be applied by any o~ the conventional techniques for applying herbicides. ~hen applied as pre-emergence herbicides they may ~or example .

....

6~

~e sprayed on the surEace oE the soil before or during seeding, or after seeding and before emergence of the crop. In some situations for example in pre-emergence applica~ion to soya bean crops it may be advantAgeous ~o incorporate the compound of the invention into the soil before planting the crop. This may be done by applying the compound to the surface of the soil and then discing or harrowing the soil to mix the compound with the soil.
Alternatively use may be made of the applicators which have been developed for placing herbicides in a band beneath the surface of the soil.
In another aspect~ therefore, the inven~ion provides a 1~ process of killing or severely injuring unwanted plants, which comprises applying to the plants or to the locus thereof, a compound of the formula ~II) or a salt there~
as hereinbefore defined.
As will be understood by those skilled in the art, the amount of the compound ~II) applied will depend upon a variety of Eactors, for example the particular compoun~
chosen for use and the identity of the unwant~d plan~s~
By way of general guidance, however, an amount of from 0.1 to 5.Q kilograms per hectare is usually s~itable~
while from 0.25 to 1.0 kilograms per hec~are i3 preferre~O
The compounds used in the process of the invention are preferably applied in the form of a composition, in which the active ingredient is mixed with a carrier comprising a solid or liquid diluent. In another aspectr therefore, the invention provides a herbicidaal compositior., comprising as an active ingredient a compound of the formula (II~ as hereinbefore defined~ in admixture with a solid or liquid diluent. Preferably the composition al50 comprises a surface-active agent~
The solid compositions of the invention may be for example, in the form o dusting pvwders7 or ~ay take the form of granules~ suitahle solid diluents include, for .. . .

.

. , , ~.2~

example, kaolin, bentonite, kieselguhr, dolomitel calcium carbonate, talc, powdered magnesia, and Fuller's earth.
Solid compositions also include soluble powders and granules which may comprise a salt of a compound of the invention in admixture with a water-soluble carrier, or a mixture of a compound of the invention with an alkali for example sodium or potassium carbonate; when m;xed with water the composition gives a solution of a sal~
of the compound of the invention.
Solid compositions may also be in the form of dispersible powders or grains comprising in addition to the active ingredient, a wetting agent to facilitate the dispersion of the powder or grains in liquids~ Such powders or grains may include fillers D suspending agents and the like.
Liquid compositions include aqueous solutions~
dispersions and emulsions containing the active ingreaient preferably in the presence of one or more surface active agents. Water or organic liquids may be used to prepare solutions, dispersions, or emulsions of the active ingredient. The liquid compositions of the invention ma~ also contain one or more corrosion inhibitors for example lauryl isoquinolinium bromide.
Surface active agents may be of the cationic, anionic or non-ionic type. Suitable agents of the cationic type include for example quaternary ammonium compounds, for example cetyltrimethyl ammonium bromide. Suitable agents of the anionic type include for example soaps, salts of aliphatic mono-esters of sulphuric acid, for example sodium lauryl sulphate; and salt5 of sulphonated aromatic compounds, for example dodecylbenzene-sulphonate, sodium, calcium and ammonium lignosuIphonate, butylnaphthalene sulphonate, and a mixture of the sodium salts of diisopropyl- and triisopropyl-naphthalenesulphonic acia.
Suitable agents of the non-ionic type includer for example~

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.

the condensation products of ethylene oxide with fatty alcohols such as oleyl alcohol and cetyl alcohol, or with alkyl phe~ols such as octyl-phenol, nonylphenol, and octylcresol~ Other non-ionic agents are the partial esters derived ~rom long chain fatty acids and hexitol anhydrides, for example sorbitol monolaurate; t~e condensation products of the said partial esters with ethylene oxide and the lecithins.
The compositions which are to be used in the form of aqueous solutions, dispersions or emulsions are generally supplied in the form o~ a concentrate containing a high proportion of the active ingredient, the concentrate being diluted with water before use~ These concentrates are usually required to withstand s-torage for prolonged periods and after such storage to be capable of dilu~ion with water in order to form aqueous preparations which remain homogeneous for a sufficient time to enable the~
to be applied by conventional spray equipment.
The compositions of the invention may contain3 in addition to carriers and surface-active agents, various other constituents to increase their usefulness. They may contain, for example, buffering ~alts to maint~in ~he pH of the composition within a desired range;
antifreeze agents, for example urea or propylene glycol;
adjuvants, for example oils and humectants, and sequestrants, ~or example citric acid an~ ethylenediamine-tetracetic acid, which help to prevent the formation of insoluble precipitates when the compositions are diluted with hard water. Agueous dispersions may contain anti-settling agents and anti-caking agents. ~The ~ompositions may in general contain a dye or pigment to impart a c~aracteristic colour. Agents for increasing ~iscosity may be added to reduce the ormation of fine droplets during spraying, a~d thereby reduce spray drift. Other additives useful for particular purposes will be known ,~

to those skilled in the forrnulation art.
In general concentrates ~ay conveniently contain from 10 to 8S% and preferably from 25 to 60~ by weight of active ingredient. Dilute preparations ready for use may contain varying amounts of the active ingredient, depending upon the purpose for which the~ are to be used;
however, dilute preparations suitable ~or many uses contain between 0.01% and 10% and preferably between 0~1% and 1% by weight of the active ingredient.
The invention is illustrated by the following ~xamples, in which all parts are by weight and all temperatures in degrees Centigrade unless otherwise stated.

This Example illustrates the preparation of Compound nos. 12 to 16 of Table I.
A vigorously stirred solution of 2~nitro-5t2-chloro-4-trifluoromethylphenoxy)N-methanesulphonylbenzamide ~40~0g~
in acetone (1250 ml) was treated slowl~ with titani~m ~richloride ~450 ml, 30~ w/v solution in hydrochloric o acid) whilst maintaining the temperature below 15 .
The reaction mixture was stirred for a urther thirty minutes at-room temperature, neutralised by the addi~ion of sodium hydroxide solution tto p~ 5) and excess sodium bicarbonate solution, and extracted with dichloromethane.
The extracts were washed with water, dried and evaporated to give the corresponding 2-amino derivative ~30.26g, m.pO 184-185 ).
A mixture of this material 11.69), acetic anhydride (0.4 ml) and acetonitrile (15 mlj was heated under reflux for 2~5 hours, evaporated in vacuo and the residue re-crystalllsed from methanol to give Compound No.12 tl.5g, .

~24~6~

m.p~ 201 ) of Table I.
Compound Nos. 13, 14 and 15 were prepared similarly using the appropriate anhydride ~r chloroformate. Compound No~ 16 resulted from the reaction of the amine with dimethyl-ammonium N,N-dimethylthiolcarbamate in ~,N-dimethyl-formamideO
The 2-nitro-5(2-chloro-4-~rifluoromethylphen~xy)N-methanesulphonylbenzamide required as starting ma~erial was prepared as follows:

5~2-chloro-4-trifluoromethylphenoxy)-2-nitrobenzQic acid (1~58g) was heated under re1ux in an excess of thionyl chloride (20 ml) for 30 minutes. The excess of thionyl chloride was removed in a vacuum and the remaining oil taken up in dry pyridine (20 ml). Methanesulphonamide (0.45g) was added and the mixtu~e stirred at room temperature overnight. The pyridine was removed in a vacuum and the remaining oil mixed with 2-molar hydrochloric acid and extracted with ether ~2 x 100 ml~.
The ether extraots were washed with water llO0 ml)~ drie~, and evaporated in a vacuumO The residual solid wa5 recrystallised from isopropanol to give 5-~2-chloro-4-trifluoromethylphenoxy)-~-n tro-N-~ethanesulphonylbenzamid~
with a melting point of 201 C.
The ether extracts were washed with water (100 ml~, dried, and evaporated in a vacuum. The residual solid was recrystallised from isopropanol to give 5-(2-chloro-4-trifluoromethylphenoxy)-~-n tro-N-methanesulphonylben~amide with a melting point of 201 C.

q'his Example illustrates the preparation of Compound No.17 of Table lo

6~9~

- 28 ~

2-Amino-5(2-chloro-4-trifluoromethylphenoxy)N-methanesulphonylbenzamide (3.0g, prepared as described in Example 1) was added to a solution of sodium met~oxide (from l90mg oE sodium) in methanol (60ml). The mix~ure was warmed until dissolution was complete, cooled to 0 and treated with trifluoronitrosomethane until starting material had been consumed. It was then diluted with water~ acidified with 2N hydrochloric acid and ~xtracted wi~h ether. The extracts were washed with water and brine, dried and evaporated and the residue recrystallised from o toluene/petroleum (b.p. 80-100 ) to give Compound No.17 (3.39) of Table I.

This Example illustrates the preparation of Compound No.18 of Table I.
A vigorously stirred solution o 2-nitro-5~2-chloro~4-tri1uoromethylphenoxy)~-methanesulphonylbenzamide ~4,4g~
in 0.5N sodium hydroxide solution (20mll was treated successively with sodium hypophosphite (4.49) and 10~
palladiu~ on car~on (440mg). After one hour, the mixture was diluted with water and extracted with ethyl acetate.
The extracts were washed with water and brine, dried and evaporated. The residue was triturated with petroleum (b.p. 40-60 ) and recrystallised from acetonitrile to give Co~pound No.18 (950mg) of Table I.

..

This Example illustrates the preparation of Compound No.l9 of Table I~
: A solution of 2-amino-5(2-chloro-4-trifluoromethyl-phenoxy)N-methanesulphonylbenzamide (2.03g) in N sodium hydroxide solution (5ml) was treated with a solution o~
sodium nitrite (400mg) in water (5ml). The resulting solution was added dropwise to a stirred mixture of concO
hydrochloric acid ~7.5ml~ and water (2.5ml) cooled to 5 0 The diazonium chloride was filtered off, washed with ether and heated in water (20ml), on a steam bath, for thirty minutes. The mixture was cooLed and filtered.
The solid was dried and recrystallised from toluene to give Compound ~o.l9 (1.06g) of Table I.

EXAMPLE S

This Example illustrates the preparation of Compound Wo.20 of Table I.
A mixture of sodium hydride (2.3g, ~0% dispersion in mineral oil, prewashed with petroleum, b.p. 40-6~ ) and 4-hydroxy-2-methylben~oic acid (3.49) in dry N,~-dimethylformamide (30ml) was stirred for thirty minutes, then treated with 3-chloro-4-fluorobenzotrifluoride ~4~5g).
o The ~ixture was heated at 13G for five hours, coolea, diluted w}th water~ acidified with 2M hydrochloric acid and extracted with ethyl acetate. The extracts were washed with water and brine, dried and evaporated~ The residue was recrystallised from petroleum (b,p. 80-100 3 to give 2-methyl-5(2-chloro-4-trifluoromethylphenoXy)-benzoic acid 12.06g, m.p. 113 ~. A suspension of this material (1.34g) in thionyl chloride (5ml) was heatèd under re~lux for one hour and the excess reagent removed in vacuo The residue was dissolved in acetonitrile and again ; evaporated to give crude acid chloride.
A mixture of methanesulphonamide ~0.41g), potassium carbonate ~1.15g~ and methyl ethyl ketone (lOml) was heated under reflux for thirty minutes, khen treated dropwise ~;;. . .

~6~

over a period oE two hours with a solu.ion of the acid chloride in methyl ethyl ketone (lOml~. After heating for a further one hour, the mixture was cooled, diluted with water, acidified with 2N hydrochloric acid ~nd S extracted with ethyl acetate The extracts were washed with water and brine, dried and evaporated and the residue recrystallised from toluene/petroleum to give Compound No.20 (0O56g) of Table I.

This Example illustrates the preparation of Compound lQ No. 22 of Table I.
(a) 2,4,5-Trichlorophenol ~20g) in dry dimethylaceta~ide (49ml) was treated with sodium hydride.~5.28~ of 50%
dispersion in o;1) in portions and the resulting mlxture heated to 120 C. Ethyl-5-chloro~2-nitrobenzoate ~16~5g~
was added in solution in dry dimethylacetamide (60ml~
o and the mixture heated at 160 C for ten.hours. The solvent was removed and the residue washed with water and extracted with ether. The ether solution was extracted with ether. The ether solution was evaporated. The remain:ing oil solidified and wa~ recrystallise~ ~rom ethanol to give ethyl 5(2,4,5-trichlorophenoxy)-2-nitro-benzoate (10.99) with a melting point of 99-102 C.

: (b~ The product from (a) was heated at 70 C in iso-: propanol (50ml) with a~solution of sodium hydroxide ~1.02g?
in water (30ml) for eight hours. The isopropanol was : removed;and the res~idue acidified with dilute hydrochloric acid and extracted with methylene dichloride. The ~ methylene dichlcride ext~act yielded an:oil which : crystallised and was recrystallised from toluene t~ gi~e 2 nitro-5(2,4,5-trichlorophenOxy)benzoic acid:(5.5g) with a ., ." :
.

L6~

melting point oE 1~7-161 C.

(c) The product from (b) (4g) was heated under reflux in thionyl chloride (20ml) Eor four hours. ~emoval o~
the excess oE thionyl chloride gave an oil i49) which solidiEied on standing.

~d) The acid chloride (2g) prepared in (c) above in dry methyl ethyl ketone (20ml) was added dropwise over a period of two hours to a solution of methanesulphonamide ~0.7~g?
in dry methyl ethyl ketone ~lOml) containing anhydrous potassium carbonate (l.lg) and maintained at reflux temperature. The mixture was heated for another three hours and then left overnight. The mixture was stirred with dilute hydrochloric acid (lOOml)and extracted with ethyl acetate (150ml). Evaporation of the ethyl acetate gave an oil which solidified when triturated with dilute hydrochloric acid. The solid was recrystallised from toluPne to give Compound No. 22, with a melting point o of ~70-17} C.

This Example illustrates the preparation of Compound No. 23 of Table I.

(a) 2-Nitro-5~2-c~loro-4-trifluoromethyphenoxy)benzoic acid ~lOg) in a mixture of 1,2-dichloroethane (50ml~ and concentrated sulphuric acid (50ml) was cooled ta -~ C
and potassium~nitrate (2.79g~ added slowly, keeping the temperature below O C. The mlxture was stirrèd for another 1~5 hours, allowed t~ warm to room tempera~ure and stirred for another hour. The mixture was pourea on to ic~ and the resulting mixture extracted with ,.,:
.

chloro~orm. The chloroform extract yave an oil which was shaken with ether and sodium bicarbonate solution.
The bicarbonate solution was washed with ether and acidified to give an oil. The oil was extracted with ether. The extract gave a pale yellow oil (8~1g). This was dissolved in ether/hexane and cooled, when the product crystallised out. The carboxylic acid was convertea to the acid chloride by treatment with thionyl chloride~
as in Example 6(c).

(b~ The product from (a3 ~3g) in dry pyridine (15ml) was cooled to 0 C and treated with methanesulphonamide.
The mixture was left at room temperature for ~4 hours and poured on to ice~ Acidification gave a brown solid.
This was taken up in ether, and the solution filtered and added to hexane with stirring to give a white solid (0.7g). Recrystallisation from chloroorm/hexane gave Compound No. 23 ~0.53g) with a melting point of 206 C
(softened and resolidified at 120 C).
This compound was also prepared by nitrating 5-~2-chloro-4-trifluoromethylphenoxy)-2-nitro-N-methane-sulphonylbenzamide by the method described in-paragraph (a) above.

:
This Example illustrates the preparation of Compound No~ 38 of Table I.
~ethyl 5-f}uoro-2 nitrobenzoate was reacted with the sodium salt of 4-chloro-3-methylphenol ~prepared from sodium hydride and the phenol~ in dimethyl~ormamide at 100 C for 2.5 hours and the res:ulting methyl 5~4-chloro-3-methylphenoxy~-2-nitroben~oate isolated in the usual way; the ester had a melting point oE 85~87 C, ~2~

The ester was then hydrolysed to the correspondin~
carboxylic acid. This was converted to the corresponding carboxylic acid chloride and reacted with methanesulphonamide in the presence of pyridine as acid acceptor to give Compound No. 38.

EXAMPLF g This Example describes the preparation of Compound 26 of Table Io Copper chrornite ~0 r 159) was adde~ to a stirred solution of the tetrafluoroborate salt of Compound 19 (1.43g) and tetrabutyla~monium thiocyanate (l~lg) in acetonitrile (lOml). After 1 hour, the mixture was poured into water and extracted with ethyl acetate~ The extrac~s were washed with water, dried and evaporated The oil so obtained was chrornato~raphed on silica ~el in acetonitrile to give an oily product (l.Og).
Trituration with isopropanol gave compound no. 26 (0~429) with a ~elting point of 135 ~ecomp.
.

This Example describes the preparation o~ compound 27 of Table I.
Sodium azide ~1.691 was added in one portion to a solution of the tetrafluoroborate salt o~ compound 19 i~.O9) in acetone (80ml). After thirty minute~ the acetone (80ml). After thirty minutes the acetone was removed under reduced pressure. The residue was sha~en with ethyl acetate and water and the ethyl aceta~e extracts washed with water and brine, dried, and evapurated. The resldue was triturated with ether/petroleum (b.p. 40-60 ). The solid so obtained was recrys~allised from carbon tetrachloride to give compound 27 (1.02~) with a melting point of 119 ~decomp.~

This Example describes the preparation of compound no. 29 of Table I. The tetrafluoroborate salt of compound no. 19 ~4.39) was added in portions to stirred trimethylphosphite (50ml) while the temperature was kept at 25-30 by external cooling. After a further hour, the mixture was diluted with water and extracted with e~hyl acetate. The extract was washed with water and then with brine, dried, and evaporated. The residue was ~riturated with ether to give comp~und no. 29 (0.8g) with a melting point of 159 tdecomp.).

This Example illustrates the preparation of N-: (methoxycarbonylmethanesulphonyl)-5-(2-chloro-4-trifluoro-methylphenoxy~-2-nitrobenzamide (compound no. 7 of Table I)~
5-~2 chloro-4-trifluoromethylPhenOXy)-2-nitrObenzoic acid (2.36 g) was heated under re1ux in thionyl chloride (20 ml~ for 90 minutes. ~he mixture was cooled and the excess ~f thionyl chloride removed under reduced pressure.
Toluene was twice added and removed under reduced pressure~
The remaining oil was diluted with butyl acetate (35 ml) and heated under reflux with methoxycarbonylmethane-sulphonamide ~1 g) and caesium 1uoride (3 g) for 20 hours~
The mixture was poured in~o water and extractèd with ethyl L6~

-- 35 ~

acetate. The extracts ~ere washed with water, drîed, and evaporated to give a oil. This was diluted wi~h ethee and the ether solution treated with charcoal and diluted with 1 ight petroleum . The yellow solid which separated was puri~ied by thin layer chromatography using silica gel as the solid phase and acetonitrile as the eluent. The chromatography gave an oil which crystallised on addition of etherJlight petroleum to give the required compound (0.31 g) with a melting point of 158-160 C.

10 This Example illustrates the preparation of compound no. 6 of Table l~
5-(2~chloro-4-triEluoromethylphenoxy) 2-nitro benzoic acid (3.62 g~ was heated under reflux in thionyl chloride (30 ml) for 2 hours. The excess of thionyl chloride was removed and the residue twice evaporated with toluene. The remaining oil was diluted with butyl acetate and hea~e~
under reflux with 3-chloropropanesulphonamide (l.S8 93 and caesium fluoride (3 g) for g hours. The cooled reaction mixture was diluted with water and extrcted with ethyl acetate. The aqueous solution was acidified with dilute hydrochloric acid and extracted with more ethyl acetate.
The combined extracts were dried and evaporated to give an oil~ This was taken up in carbon tetrachloride and the solution decolourised with charcoal and cooled. Slow addition of petroleum ~b.p. 40-60) gave an oily solid.
This was taken up in a mixture of chloroformr acetone, and acetic acid ~90:10:5) and the solu-~ion passed ~hrough a column of silica gel. The solution was e~aporated and the residue purifi2d by thin layer chroma~ography on silica ge~
pla'ces, using a mixture of chloroEormr acetone, and acetic:
acid (90-10:5) as eluent~ The principal component was 6(~3L

extracted fro~ the silica gel plates with ethanol. The ethanol was evaporated and the residue agitated with dilute hydrochloric acid and ethyl acetate. The ethyl acetate extract was washed with water~ dried, and evaporated. The residue was crystallised from a mixture of ether and petroleum (b.p. 30-40 ) and the required compound obtained (0.9 g) as a solid of melting point 116-119 .

This Example illustrates the preparation of N-benze~e-sulphonyl-5-~2-chloro-4-trifluoromethylphenoxy)-2-ni~ro-benzamide (Compound no. 1 of Table 1)~
5-(2-Chloro-4-trifluoromethylphenoxy)-2-nitrobenzoic acid (2 9) was heated under reflux in thionyl chloride ~15 ml) for 90 minutes. The excess of thionyl chloride was removed under reduced pressure and the residue diluted with toluene. The toluene was removed under reduced pressure and the remaining oil taken up in butyl acetate. Benzene-sulphonamide (1.3 g~ and caesium fluoride (4.0 9) were added and the mixture was stirred and heated under reflux for 90 minutes. The mixture was cooled, diluted with waterd acidified (HCl) and extracted with ethyl acetate.
The extract was washed with water, dried, and evaporated to give an oil. Trituration with carbon tetrachloride and petroleum gave a solid. This was recrystallised from a mixture of carbon tetrachloride, ether, and petroleum to give the required compound (1.11 9), with ~ melting point ~of 123-125 .

EXAMP~E lS
.
This Example illustrates the preparation of ~-methane-sulphonyl-5-(2-methanesulphinyl-4-triflùoromethylphenoxy)-2-nitrobenzamide (compound 28 of Table I).

, . . .

(a) Preparation of methyl 5-(2-methanesulphinyl-4-trifluoromethylphenoxy)-2-nitrobenzoate.

Methyl 5-(2-amino-4-trifluoromethylphenoxy)-2-nitro~
benzoate (8 g) in concentrated hydrochloric acid (35 ml~
was cooled to 0-5 and stirred vigorously while a solution of sodium nitrite (1.86 g) was added dropwise, keeping the temperature at 0-5 . The ~ixture was stirred for 30 minutes and then filtered into a solution Qf sodium fluoborate ~5.44 g) in water (6 ml30 The precipitated dia~oniur fluoborate salt ~8~74 g~ was washed with aqweous sodium fluoborate, cold ethanol~ and ether.
The diazonium salt so prepared (8.74 9~ in dry dimethylsulphoxide (20 ml) was added dropwise to a stirred solution of potassium iodide (6.38 g) in dry dimethyl sulphoxide (30 ml) and the mixture stirred for 1 hour at room temperature. The mixture was then poured into water and extracted with e~ter. The ether extract was washed with water, dried, treated with charcoal, and evaporated to give an oil. This was extracted several times with petroleum (b.p. 60-80 ~. The petrQleum extracts yielded methyl 5-(2-iodo-4-trifluoromethylphenoxy)-2-nitro ben~oate upon evaporation. The residue ~rom the ex~raction was taken up in ether and applied to preparative chromato-graphic plates coated with silica gel. The plates were eluted with chloroform containing 2% of ethanol. Two products were separated; the first was the iodo compound 16 g~ referred to above. The second product (0~95 g~ was identiEied as the required methanesulphinyl compound.
.
(b) Preparation of compound 28.

The methanesulphinyl compound ~0.95 g) from (a) was hydroly5ed to 5-(2-methanesulphinyl-4-trifluoromethyl-phenoxy~-2 nitro benzoic acid by treatment with a mixture of acetic acid and aqueous hydrobromic acid as described in parayrapb ~c) of Example 16. The substituted ben~oic acid so obtained was converted to its acid chloride and treated wi-th methanesulphonamide and caesium fluoride in refluxing butyl acetate as described in paragraph ~dl of Example 16 to give compound 28 wi h a melting point of 158-160.

This Example illustrates the preparation of N-methane-sulphon~l-5-(2,3,5,6-tetrafluoro-4-trifluoromethylphenoxyl-2-nitrobenzamide (compound 30 of Table I~.

~a) Preparation of ethyl 5-(2,3,576-tetrafluoro-4-- trifluoromethylphenoxy)benzoate, Pentafluorobenæotrifluoride ~11.8 ~ was stirred in dry dimethylsulphoxide (75 ml~ with ethyl 3-hydroxy benzoate (8.3 g) and anhydrous potassium carbonate (7,0 93 for 2 hours and then kept overnight9 The mixture was poured into water (600 ml~ and extracted with ether (2 x 25~ ml). The extract was washed with water (~00 mll, dried, and evaporated to give a colourless liquid (18,4 9 identifi.ed as the required ester.

1~) Preparation of ethyl 5-t2,3,5,6-te~rafluoro-4-trifluoromethylphenoxy)-2-nitro benzoate~

The ester from (b) ~15.28 9~ in 1,2-dichloroethane (100 ml) was cooled to 0 C and stirred while concentrated sulphuric acid (1~0 ml) was added in portions, keeping the temperature below 5 . The mixture was then cooled to O and potassium nitrate (4~44 g) added in portions over . ,. ~

_ 3 a period of 75 minutes~ keeping the temperature belo~
5 C. The mixture was then stirred for another hour at and poured on to ice (500 ml). The mixture was extracted with ether t3 x 200 ml). The ether extract was washed with water (5 x 500 ml~ until the washings were neutral. The extract was dried (MgSO ~ and evaporated to give an oil which solidified on cooling. This was washed with petroleum (b.p. 30-40 ) to give a colourless solid (13.4 g) identified as the required nitro co poundO
A sample recrystallised from petroleum tb~p. 60-80 ) had a melting point o 77~7~ .

(c) Preparation of 2-nitro-5-(2,3,5,6~te~rafluoro-4-trifluoromethylphenoxy)ben~oic acid.

The product from (b) (~.0 g) was stirred and heated under reflux with a mixture of acetic acid (180 ml) and 40%
aqueous hydrobromic acid (90 ml) for 6.25 hours~ The mixture was cooled, left overnight, and evaporated under reduced pressure. Toluene was twice added to the resiaue and evaporated off under reduced pressure. The remaining solid was recrystallised from a mixture o toluene (80 ml) and petroleum (b.p. 80-100 , 120 ml), giving the required acid ~6.5 g) with a melting point of 138.5-139.5 .

~d) Preparation of compound 30.

- The product from (c) (3.5 9) was heated under reflux in thionyl chloride (60 ml~ for 3 hours. The excess of thionyl chloride was removed under reduced pressure and the residue heated and stirred under reflux with dry caesium 1uoride (3.3 g) and methanesulphonamide ~1.67 g) in dry butyl acetate ~50 ml) fQr 2.5 hours. The solution was cooled, and diluted with ethyl acetate, (150 ml) and dilute hydrochloric acid. The organic layer was ~eparated, washed , _ 4O -with water (3 x 200 ml) and dried. Removal of the solvent ~lnder reduced pressure gave a colourless solid (3.~ gl, which was washed with petrole~m ~h.p. 30 40 ) and recrystallised from isopropanol to give compound no30 with a meltiny point of 177-177.5 .

EX~MPLE 17 This Example illustrates the preparation of N-methane-sulphonyl S-(2-chloro-5-trifluoromethylphenoxy~-2-nitro benzamide (compound 32 of Table I) and N-methane-sulph~nyl-3-(2-chloro-5-tr;fluoromethylphenoxy3benzamide (compound 31).

(a) Preparation of 4-chloro-3-fluorobenzotrifluoride.

3-Amino-4-chlorobenzotriEluoride was diazotised by the standard procedure and the diazonium salt isola~ed as the fluoborate. This material was heated to decomposition with :a Bunsen burner flame. The 4-chloro-3- fluorobenzo-trifluoride distilled off and was redistilled at atmospheric pressure (b.p. 128 ).
/

/
'~

66~

(b) Prepar~tion of 3(2-c'nloro-5-trifluOromethylphenoxy) benzoic acidO

3-Hydroxybenzoic acid (3.45 9) was added to a solution of potassium hydroxide (2.8 g) in methanol. The solution was evaporated under reduced pressure to give a white solid. T'nis was taken up in dry dimethyl-sulphoxide (25 ml). The resulting solution was stirred and heated at 170 with anhydrous potassium carbonate (1~25 g) and 4-chloro-3-fluorobenzotrifluoride ~5 9] for 12 hours. The mixture was then cooled and poured into water, (500 ml). The mixture was extracted with ether and then acidified (HCl). The precipitate which forme~
was recrystallised from petroleum (b.p. 60-80 ) to give the required acid ( 4 . 5 g) with a melting point of 142-1~3 .

(c~ Preparation of 5~ chloro-5- trifluoromet~yl-phenoxy)-2-nitrobenzoic acid.

The acid from ~b) (2.0 g~ was added to a mixture of concentrated sulphuric acid ~15 ml) and 1,2-dichloro-ethane (1~ ml) kept at 0 c Potassium nitrate (1.~ g)~was then added in portions with stirring over a perioa oE 30 minutes, keeping the temperature at 0 . The mixture was stirred for a further hour a~ 0 and then for 3 hours at room temperature. The mixture was then poured on to ice and extracted with ethyl acetate. The extract was washed with water, dried, and evaporated to gi~e a dark gum. This wa~ extracted several tImes with boiling cyclohexane. The residue crystallised on cooling and was identified as the re~uired nitro-acid~ with a melting point of 147-148 .

4~

- ~2 -(d) Preparatlon of compound 32.

The nitro-acid from (c) (0.8 g3 ~.~as heated under reflux with thionyl chloride (25 ml~ for 3 hours. The excess of thionyl chloride was removed under reduced pressure and the remaining oil taken up in pyridine (2 ml), Methanesulphonamide (0.5 g) was added and the mixture stirred and heated under reflux for 3 hours. The pyridine was removed under reduced pressure and the residue agitated with ethyl acetate and dilute hydro-chloric acid. The ethyl acetate layer was washed withwater, dried, and evaporated to give a brown gum.
Trituration with cold ether ~ave a beige solid id ntified as compound 32, having a melting point of 204-205 .

(e) Preparation of compound 31.

The acid from (b) (0.8 g) was treated with thionyl chloride followed by methanesulphonamide and pyridine as ~escribed in paragraph (d) above for compound 32. The product was recrystallised from a mixture of ether an~
petroleum (b.p. 40-60 ) to give compound 31 with a melting point of 132-133 .

This Example illustrates the preparation of N-methanesulphonyl-5--(2-chloro-4-trifluoromethylphenoxy3-2-trifluoromethylbenzamide (Compound 37 of Table I).
Finely powdered methyl 2-amino-5(2-chloro-4-tri-fluoromethylphenoxy)benzoate ~16~5 g3 was sus~ended in 1uoboric acid (120 ml, 40~), treated with ethanol tlO0 ml) - ~3 -and coolecl to 0 . A sol~tlon o~ sodium nitrite ~4.5 ~3 in water (20 ml) was added dropwise -~o the stirred reaction mixture. A~ter a further fifteen minutes at O, the crystalline precipitate was filtered o~f and washed wi~h ether to give the diazonium fluoborate (L2.32 g~
Sodium iodide ~4.5 g) was added to a stirred solution of the diazonium salt (11.7 g) in acetonitrile tl ml~.
After stirring at 20 for fiten minutes, effervescence had ceased. The solvent was removed in vacue and the residue partitioned between dichloromethane and water. The extracts were washed with water, dried and evaporated. The cr~de product was flash chromatographed on silica in ether to give 10.2 g of a mixture of methyl 2-iodo-5(2-chloro-4-trifluoromethylphenoxy)ben~oate and its 2-H derivative t80:20 by GLC~.
This material t2.0 g) was heated in a sea~ed Teflon lined pressure vessel for eighteen hours at 150 together with trifluoromethyl iodide t5 ml), acetonitrile ~15 ml), dry pyridine (~ ml~ an~ dry, freshly precipitated, copper powder t2O5 g). The crude reaction mixture was filtere~
through Supercel, evaporated in vacuo, dissolved in ether, washed with 2N hydrochloric acid and water, dried and chromatographed on silica in ethyl acetate/petroleum, b Dp~
60-80 tl 3)o Pure methyl 2-trifluoromethyl-5(2-chloro-4-trifluoromethylphenoxy)benzoate t600 mg.), was obtained together with material contaminated with 2~-derivative.
Rechromatography of the latter gave an additional 250 mg o~
pure material b The 2-CF ester tl.62 g) was treated with potassium hydroxide (230 mg), water t3 ml~ and methanol (40 ml3 ana stirred at 60 for six hours. ~h~ mixture was cooled, diluted-with water, extracted wit~ ether to remo~e unchan~ed ester, acidified with 2N hydrochloric acia ana extracted - 4~ -with ethyl acetate. The latter extracts were washed with water and brine, dried and evaporated and the residue chromatographed on silica gel in dichloromethane to give an oil which crystallized slowly on standing to a white solid 1.08 g, m.p~ Bl identified as 5-(2-chloro~4-trifluoro-methylphenoxy~-2-trifluoromethylbenzoic acid.
This material (0.69 g) was converted into its acid chloride and then by treatment of the latter with methane-sulphonamide in methyl ethyl ketone in the presence of anhydrous potassium carbonate into compound 37, following the procedures described in paragraphs (c) and (d) o Example 6.

This Example illustrates the herbicidal properties of compounds of Table I. The compounds were submitted to herbicide tests as described below~
Each compound was formulated for test by mixing an appropriate amount of it with Sml of an emulsion prepared by diluting 160ml of a solution containing 21.1 grams per litre of Span 80 and 78.2 grams per litre of 20 r~ween 20 in methylcyclohexanone to 500 ml with water.
Span 80 is a Trade Mark for a surface-active agent comprising sorbitan monolaurate. Tween 20 is a Trade Mark for a surface-active agent comprising a condensate of 20 molar proportions of ethylene oxide with sorbitan monolaurate. The mixture of the compound and the em~lsion was then shaken with glass beads and diluted to 40 ml with water. The spray composition so prepared - was sprayed on to young pot plants (post-emergence test~

6~
~s of the species named in Table IV belowr at a rate equivalen~ to 1000 litres per hectare~ Dama~e to plants was assessed 14 days after spraying by comparison with untreated plants, on a scale of 0 to 5 where 0 is 0 to 20~ damage and 5 is complete kill. In the table of results, a dash (-~ means that no test was made.
A test was also carried out to detect pre-emergence herbicidal activity. Seeds of the test speoies were placed on the surface of fibre trays of soil and were sprayed with the compositions at ~he rate of ~000 litres per hectare. The seeds were then covered with further soil. Three weeks after spraying, the seedlings in the sprayed fibre trays were compared with the seedlin~s in unsprayed control trays, the damage being assessed on the same scale of 0 to 5.
The results of the tests are given in Table IV
below. - 7 6~
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- 5~ -Table V gives herbicide test results for 5-(2-chloro-4-trifluoromethy.lphenoxyj-2-trifluoromethyl benzoic acid, useful as an intermediate for compound 37 of Table I. The test procedures were the same as fcr Table IV. This compound is referred to in Table V as compound A. Other intermediates are referred ~o in Tabl V under the following code numbers:

Intermediate 67 Compound E~
69 " C
" 70 " D
~' 71 " E
,~ , /

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Names of test plants in Table IV and V

Sb Sugar beet Rp Rape Ct Cotto~
Sy Soya bean 5 Mz Maiæe Ww Win~er wheat Rc Rice Sn Senecio vulgaris Ip Ipomoea purpurea 10 Am _aran~hus retroflexus Pi Pol~gonum aviculare Ca Chenopodium album Po Portulaca oleracea Xs Xanthium spinosum 15 Ab Abutilon theophrastii Cv Convolvulus arvensis Ot/Av Oats (cultivated in pre-emergence test and Avena fatua (~ild oats) in post-emergence test) 23 Dg Digitaria sanguinalîs Pu Poa annua St Setaria viridis Ec Echinochloa crus-galli Sh Sor~hum halepense 25 Ag ropyron repens Cn ~perus rotundus Subject to the foregoing disclaimer regarding the contents of European Patent Application 79300098.5, what we claim is:-_ JED~149/ayl SPECS 39,40 & 41 ~: ~ 23 June 1980 .
... . .

Claims (2)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Compounds of the formula wherein A is hydroxy; alkoxy of 1 to 4 carbon atoms;
mercapto; alkylthio, alkylsulphinyl, or alkylsulphonyl of 1 to 4 carbon atoms;
mono- or dialkylamino with alkyl groups of 1 to 4 carbon atoms;
methyl; or trifluoromethyl;
B is fluorine or chlorine;
C is hydrogen;
D is trifluoromethyl;
E is hydrogen;
and F is hydrogen, chlorine, or fluorine and salts, esters, and amides thereof.

2. A process of inhibiting the growth of unwanted plants, which comprises applying to the plants, or to the locus thereof, a herbicidal amount of at least one compound of the formula as defined in Claim 1.