WO1998013341A1

WO1998013341A1 - Hydroxybenzophenone derivatives as herbicides

Info

Publication number: WO1998013341A1
Application number: PCT/EP1997/005210
Authority: WO
Inventors: Susan Mary Cramp; Fabrice Viviani
Original assignee: Rhone Poulenc Agriculture Ltd
Current assignee: Bayer Agriculture Ltd
Priority date: 1996-09-27
Filing date: 1997-09-23
Publication date: 1998-04-02
Anticipated expiration: 1999-03-27
Also published as: GB9620202D0; AU4705197A; ID19545A

Abstract

The invention relates to hydroxybenzophenone derivatives of formula (I), wherein R?1, R2, R3, R4, R5, R6, R7 and R8¿ are as defined in the description, and to their use as herbicides.

Description

HYDROXYBENZOPHENONE DERIVATIVES AS HERBICIDES

This invention relates to novel hydroxybenzophenone derivatives, compositions containing them, processes and intermediates for their preparation, and their use as herbicides.

The present invention provides hydroxybenzophenone derivatives of formula (I):

(Ii wherein:

R¹ represents :- straight- or branched- chain halogenated alkyl containing up to four carbon atoms and at least two halogen atoms; or a member of the group consisting of -N0 , R⁹S(0)_m-, R⁹S0₂-0-, R⁹S(0)_m-CH(R¹⁰) -, (R⁹0) (R^1:L0)P(0) -, (R⁹0) (R^ι:0)P(0) -CH(R¹⁰) -, R¹⁰R¹²NC(O)N(R¹⁰) -, R¹³XCCO)N(R¹⁰) -, R⁹R^1:LNS0₂-, R¹⁴S0₂N (R¹⁰) - , -SF₅, Het-CH(R¹⁰) -, R⁹S(0)_m-CH₂CH₂- and benzyl optionally substituted by one or more groups R¹⁵ which may be the same or different;

R² and R³ independently represent : -

R¹, hydrogen, halogen, straight- or branched- chain alkyl containing up to four carbon atoms optionally halogenated with one halogen; straight- or branched- chain optionally halogenated alkoxy containing up to four carbon atoms; straight- or branched- chain alkyl containing up to six carbon atoms which is substituted by one or more -OR¹^ groups,- or a member of the group consisting of cyano, R⁹C(0)-, R⁹XC(0)-, R¹⁰R¹²NC(O) -, R¹³C (0) N (R¹⁰) - and NR¹⁰R¹²; wherein the ortho position of the phenyl ring is substituted by a non-hydrogen substituent;

R⁴ represents :- hydrogen, R¹³, straight- or branched- chain alkyl containing up to six carbon atoms which is substituted by one or more -XR¹⁶ groups; or a member of the group consisting of R⁹S0₂-, R⁹C(0)- and R¹⁰C(O)C(R¹⁰) (R¹²) -;

R⁵, R⁶ and R⁷ independently represent: - hydrogen, halogen, hydroxy, R¹⁶SO_m-, R¹³, straight- or branched- chain optionally halogenated alkoxy containing one to four carbon atoms; straight- or branched- chain alkyl containing up to six carbon atoms which is substituted by one or more -OR¹⁶; or a member of the group consisting of -N0₂, cyano,

R¹⁴S0₂N(R¹⁰) -, R⁹C(0)-, R⁹XC(0)-, R⁹C (0) N (R¹⁰) - , R¹⁰R¹²NC(O) -, R¹⁰R¹²NC(O)N(R¹⁰) -, R¹⁰R¹²NS0₂-, and cycloalkyl containing from three to six ring carbon atoms,- R⁸ is as defined for R⁵ with the exclusion of hydroxy;

R⁹ and R independently represent : - straight- or branched- chain optionally halogenated alkyl containing up to four carbon atoms ; or phenyl or benzyl which are optionally substituted by one to five groups R¹⁵ which may be the same or different;

R¹⁰ and R¹² independently represent hydrogen or R⁹;

R¹³ represents straight- or branched- chain optionally halogenated alkyl containing up to four carbon atoms; R¹⁴ represents straight- or branched- chain alkyl containing up to four carbon atoms;

R¹⁵ represents halogen, optionally halogenated methyl; or R¹⁴SO_m- ; R¹⁶ represents straight- or branched- chain alkyl containing up to six carbon atoms,-

Het represents a five me bered aromatic heterocyclic ring containing from one to three ring nitrogen atoms which is attached to the -CH(R¹⁰)- group via one of the ring nitrogen atoms ;

X represents oxygen or sulphur; m represents the values 0,1, or 2; with the proviso that: (a) when R¹ represents nitro it is located at the 2 -position of the phenyl ring and that at least one of R² and R³ represents halogen, R⁹S(0)_m-, or straight- or branched- chain halogenated alkyl containing up to four carbon atoms;

(b) when each of R² to R⁶ and R⁸ represent hydrogen and R⁷ represents methyl, R¹ is not 2-SOMe, 2-S0₂Me or 2-S- (4-methylphenyl) ;

(c) when R², R³ , R⁵, R⁶ and R⁸ each represent hydrogen and R⁴ and R⁷ each represent methyl, R¹ is not 2-SMe;

(d) when R¹ represents 2-CF3 and each of R² to R⁶ and R⁸ represent hydrogen, R⁷ is not chloro or hydroxy; (e) when R¹ represents 2-CF3. R² , R³ , R⁴,

R⁷ and R⁸ each represent hydrogen and R⁵ represents chloro, R⁶ is not methoxy;

(f) when R¹ represents 2-CF3 and R², R³ , R⁴, R⁵, R⁷ and R⁸ each represent hydrogen, R⁶ is not hydroxy;

(g) when R¹ represents 2-CF3; R² , R³ , R⁵ and R⁸ each represent hydrogen and R⁶ represents methoxy, R⁴ is not hydrogen or methyl; (h) when R¹ represents 2-CF₃; R² , R³ , R⁵ , R⁶ and R⁸ each represent hydrogen and R⁴ represents methyl, R⁷ is not methoxy;

(i) when R¹ represents 2-CF3; R² , R³ and R⁷ each represent hydrogen; R⁴ represents methyl and R⁵ and R⁶ each represent methoxy, R⁸ is not methyl; and agriculturally acceptable salts thereof, which possess valuable herbicidal properties. In certain cases a number of the substituents may result in the compounds of the invention existing as optical and/or stereo isomers. All such forms are embraced by the present invention. By the term "agriculturally acceptable salts" is meant salts the cations or anions of which are known and accepted in the art for the formation of salts for agricultural or horticultural use. Preferably the salts are water-soluble. Suitable salts with bases include alkali metal (e.g. sodium and potassium), alkaline earth metal (e.g. calcium and magnesium), ammonium and amine (e.g. diethanolamine, triethanolamine, octylamine, morpholine and dioctylmethylamine) salts.

Suitable acid addition salts, e.g. formed by compounds of formula I containing an amino group, include salts with inorganic acids, for example hydrochlorideε, sulphates, phosphates and nitrates and salts with organic acids for example acetic acid.

It will be understood that while compounds of formula (I) listed in the provisos (a) to (i) above are not considered per se part of the invention, their use as herbicides does form part of the invention. In addition it will be understood that compositions of compounds of formula (I) above including those in the provisos (a) to (h) also form part of the invention.

Compounds of formula (I) above in which R¹ is straight- or branched- chain haloalkyl containing up to four carbon atoms; or R⁹S(0)_m- wherein m is as defined above and R⁹ is straight- or branched- chain alkyl containing up to four carbon atoms are preferred. Preferably R¹ or R² (with the exclusion of hydrogen) occupies the ortho- position of the phenyl ring (compounds in which R occupies the ortho- position are especially preferred) .

Compounds of formula (I) above are preferred in which: R² is optionally halogenated alkoxy or (most preferably) hydrogen; and/or R³ is hydrogen, halogen or haloalkoxy.

Compounds of formula (I) above in which R⁴ represents hydrogen are preferred. Compounds of formula (I) above in which at least one of R⁵, R⁶, R⁷ and R⁸ represents halogen are also preferred.

Compounds of formula (I) above in which one or two of the groups R⁵, R⁶, R⁷ and R⁸ are not hydrogen are preferred.

Compounds of formula (I) above in which R⁸ represents hydrogen are preferred.

Compounds in which one or more of the following features are present are also preferred:

R¹ represents C1-C3 alkyl containing at least two halogen atoms (for example trifluoromethyl) , -S(0)_mR⁹ (wherein R⁹ represents C1-C3 alkyl), -CH(R¹⁰) -S (0)_m-R⁹ (wherein R⁹ represents C1-C3 alkyl or phenyl, and R¹⁰ represents hydrogen or methyl) , N0 or R¹⁴S0₂N(R¹⁰) - (wherein R¹⁴ and R¹⁰ represent Cl- C3 alkyl) ;

R² and R³ independently represent C1-C3 optionally halogenated alkyl (for example methyl or trifluoromethyl) , hydrogen, halogen, C1-C3 optionally halogenated alkoxy or -S(0)_mR⁹ (wherein R⁹ represents C1-C3 alkyl) ;

R⁴ represents hydrogen, C1-C3 alkyl, R⁹S0 - (wherein R⁹ represents C1-C3 alkyl or phenyl optionally substituted by one to five halogen, methyl or R¹ S(0)_m- groups wherein R¹⁴ represents C1-C3 alkyl), R⁹C(0)- (wherein R⁹ represents C1-C3 alkyl or phenyl optionally substituted by one to five halogen or C1-C3 alkyl groups), R¹⁰C(O)CH₂- (wherein R¹⁰ represents phenyl optionally substituted by one or more halogen or C1-C3 alkyl groups) , or methyl substituted by -XR¹⁶ wherein R¹⁶ represents C1-C3 alkyl; R⁵, R⁶ and R⁷ independently represent hydrogen, halogen, hydroxy, C1-C3 alkoxy or R¹⁶S(0)_m- wherein R¹⁶ represents C1-C3 alkyl; and R⁸ represents hydrogen or halogen.

Compounds in which the para-position of the phenyl ring is occupied by R² which represents hydrogen, halogen or Cl-C3-haloalkyl are also preferred.

Compounds in which the ortho-position of the phenyl ring is occupied by R¹ which represents -S(0)_m-R⁹ (wherein R⁹ represents Cl-C3-alkyl) , -CH(R¹⁰) -S(0)_m-R⁹ (wherein R⁹ represents C1-C3- alkyl or phenyl and R¹⁰ represents hydrogen or methyl), or R¹⁴S0₂N(R¹⁰) - (wherein R¹⁰ and R¹⁴ represent C1-C3 alkyl) are also preferred. A preferred class of compounds are those in which:

R⁴ represents hydrogen; R⁵ , R⁶ and R⁷ represent hydrogen, halogen, hydroxy, R¹⁶S(0)_m-, R¹³ , straight- or branched- chain optionally halogenated alkoxy containing up to four carbon atoms, straight- or branched- chain alkyl containing up to six carbon atoms which is substituted by one or more OR¹⁶ groups, -N0₂, cyano, or R¹⁰R¹²NSO₂- ; and

R⁸ is as defined for R⁵ excluding hydroxy.

A further preferred class of compounds are those having one or more of the following features :

R¹ represents MeS(0)_m- or -CF3.

R² , R⁴ and R⁸ each represent hydrogen;

R³ represents hydrogen or -CF₃; R⁵ represents hydrogen, halogen, hydroxy or methoxy;

R⁶ represents hydrogen or MeS(0)_m-; and

R⁷ represents hydrogen, halogen or methyl.

A further preferred class of compounds are those in which: the ortho- subεtituent of the phenyl ring bearing R¹, R² or R³ is -S(0)_mR⁹ (wherein R⁹ represents C1-C3 alkyl), -CH (R¹⁰) -S (0)_m-phenyl (wherein R¹⁰ repreεentε hydrogen or methyl) , Cl- C3 haloalkyl (for example trifluoromethyl) ,

R¹⁴S0₂N(R¹⁰) - (wherein R¹⁴ and R¹⁰ represent Cl- C3 alkyl) or C1-C3 alkyl (for example methyl) ; the para-substituent of the phenyl ring bearing R¹, R² or R³ iε hydrogen, halogen, C1-C3 haloalkyl (for example trifluoromethyl) or

-S(0)_mR⁹ (wherein R⁹ represents C1-C3 alkyl); the meta-substituent of the phenyl ring is selected from hydrogen, halogen, C1-C3 optionally halogenated alkoxy (for example methoxy or 2, 2-difluoroethoxy) and C1-C3 alkyl;

R⁴ represents hydrogen or C1-C3 alkyl (for example methyl) ; R⁵ represents hydrogen, halogen, hydroxy or C1-C3 alkoxy (for example methoxy) ^■

R^ represents hydrogen, halogen or R¹⁶S(0)_m- wherein R¹⁶ represents C1-C3 alkyl; R⁷ represents hydrogen, halogen or C1-C3 alkoxy (for example methoxy) ; and

R⁸ represents hydrogen.

The following table includes representative compounds of formula (I) . In the table that follows it will be understood that 'Me' means methyl, 'Et' means ethyl, 'Pr' means n-propyl, 'nBu' means n-butyl and 'Ph' means phenyl. Also, where numbers appear directly after atoms or groups they are understood to be subscript (e.g. 'N02' means -N0₂, 'CF3' means -CF3, ^*S02Me' means -S0 CH₃ etc.) .

Cpd Rl, R2, and R3 definitions R4 R5 R6 R7 R8 No

179 2-S02Me 3-OMe 4-Br H Cl H H H

180 2-OCH2CH2F 3-SOMe 4-Br H Cl H H H

181 2-N02 H 4-S02Me H Cl H H H

182 2-C1 3-OCH2CH20Me 4-S02Me H Cl H H H

183 2-SMe 3 -SMe 4-CF3 H Cl H SMe H

184 2-SMe 3 -SMe 4-C1 H Cl H SMe H

185 2-N02 3 -SMe 4-C1 H Cl H SMe H

186 2-Me 3 -SMe 4-C1 H Cl H SMe H

187 2 -Me 3-S02Me 4-C1 H Cl H SMe H

188 2 -Me 3 -SMe 4-Br H l H SMe H

189 2 -Me 3-S02Me 4-Br H Cl H SMe H

190 2 -Me 3 -SMe H H Cl H SMe H

191 2-Me 3-S02Me H H Cl H SMe H

192 2 -SMe 3 -SMe H H Cl H SMe H

193 2-Me 3 -SMe 4-CF3 H Cl H SMe H

194 2-Me 3-S02Me 4-CF3 H Cl H SMe H

195 2 -Me 3 -SMe 4-CF3 H Cl H SMe H

196 2 -Me 3-S02Me 4-CF3 H Cl H SMe H

197 2-OMe 3 -SMe 4-C1 H Cl H SMe H

198 2-OMe 3-S02Me 4-C1 H Cl H SMe H

199 2-OMe 3-SMe 4-F H Cl H SMe H

200 2-OMe 3-S02Me 4-F H Cl H SMe H

201 2-C1 H 4 -SMe H Cl H SMe H

202 2-C1 H 4-S02Me H Cl H SMe H

203 2-NMeS02Me H 4-C1 H Cl H SMe H

204 2-NMeS02Me H 4-CF3 H Cl H SMe H

205 2-NMeS02Me 3-Br 4-Br H Cl H SMe H

206 2-NMeS02Me H 4-F H Cl H SMe H

207 2-NMeC02Me H 4-C1 H Cl H SMe H

Compounds of formula (I) above may be prepared by the application or adaptation of known methods (i.e. methods heretofore used or described in the literature) .

It is to be understood that in the descriptions of the following processes the sequences may be performed in different orders, and that suitable protecting groups may be required to achieve the compounds sought .

According to a feature of the present invention compounds of formula (I) may be prepared by the reaction of a compound of general formula (II):

wherein R⁴,

as defined above and Y represents a leaving group (for example chlorine or -NR¹⁷R¹⁸ wherein R¹⁷ represents lower alkyl, preferably methyl, and

R¹⁸ represents lower alkyl or preferably alkoxy, methoxy being especially preferred) , with an organometallic reagent of formula (III):

wherein R¹, R² and R³ are as defined above and M is a suitable metal, preferably lithium. The reaction is generally performed in an inert solvent (for example ether) at a temperature from -78°C to 30°C.

According to a further feature of the present invention compounds of formula (I) may be prepared by the reaction of a compound of general formula (I la) :

(Ha) wherein R⁴ , R⁵, R⁶ , R⁷ and R⁸ are as defined above and M represents a suitable metal or metal halide for example lithium or magnesium bromide, with a compound of formula (Ilia) :

wherein R¹, R² , R³ and Y are as defined above . The reaction is generally performed in an inert solvent (for example ether or tetrahydrofuran) at a temperature from -78 °C to 30°C.

Those skilled in the art will appreciate that some compounds of formula (I) may be prepared by the interconversion of other compounds of formula (I) and such interconversions constitute yet more features of the present invention.

The above reactions to form compounds of formula (I) by the reaction of compounds of formula (II) and (I la) with compounds of formula (III) and (Ilia) are particularly useful for preparing compounds in which R⁴ represents alkyl (preferably methyl) which may function as valuable intermediates for preparing yet further compounds of the invention. As outlined in the process descriptions which follow the alkyl group R⁴ (preferably methyl) may subsequently be cleaved to provide the corresponding phenol derivative which may in turn be further reacted to provide compounds incorporating other R⁴ values .

According to a further feature of the present invention compounds of formula (I) wherein R¹, R² , R³ , R⁵ , R⁶, R⁷ and R⁸ are as defined above and R⁴ represents hydrogen may be prepared by de-etherification of the corresponding compound of formula (I) in which R⁴ represents R¹³, preferably methyl. This reaction is generally carried out with a boron trihalide of formula BZ3 wherein Z represents halogen, preferably bromine. The reaction is generally performed in an inert solvent, for example dichloromethane, at a temperature from -78°C to 30°C.

According to a further feature of the present invention compounds of formula (I) wherein R¹, R², R³, R⁵, R⁶, R⁷ and R⁸ are as defined above and R⁴ represents R⁹S0 may be prepared by reaction of the corresponding compound of formula (I) in which R⁴ represents hydrogen with a sulphonyl chloride of formula R⁹S0 C1 in which R⁹ is as defined above. The reaction is generally performed in the presence of a base, for example pyridine, in an inert solvent, for example dichloromethane, at a temperature from 0°C to 30°C. According to a further feature of the present invention compounds of formula (I) wherein R¹, R² , R³ , R⁵ , R⁶ , R⁷ and R⁸ are as defined above and R⁴ represents R¹⁰C(0)C(R¹⁰) (R¹²)-, wherein R¹⁰ and R¹² are as defined above may be prepared by the reaction of the corresponding compound of formula (I) in which R⁴ represents hydrogen, with a compound of formula (IV) :

R¹⁰C(O)C(R¹⁰) (R¹²) -Z

(IV)

in which R^l-> and R¹² are as defined above and Z represents halogen preferably chlorine. The reaction is generally performed in the presence of a base, for example potassium carbonate, in an inert solvent, for example acetone, at a temperature from 20°C to 120°C. According to a further feature of the present invention compounds in which m is one or two may be prepared by the oxidation of the sulphur atom of the corresponding compounds in which m is zero or one. The oxidation of the sulphur atom is generally carried out using for example 3-chloroperoxybenzoic acid in an inert solvent such as dichloromethane at a temperature from -40°C to room temperature.

Intermediates of formula (II) , (Ila) , (III) , (Ilia) and (IV) are known or may be prepared by known methods .

Compounds of formula (I) can be converted into agriculturally acceptable salts thereof by known methods or by the adaptation of known methods . The following non-limiting examples illustrate the preparation of compounds of formula (I) and the Reference Examples illustrate the preparation of intermediates in their synthesis. NMR Spectra are recorded in ppm in deuterochloroform as solvent. In the tables that follow it will be understood that 'Me' means methyl, 'Et' means ethyl, 'Pr' means n-propyl, 'nBu' means n-butyl and 'Ph' means phenyl. Also, where numbers appear directly after atoms or groups they are understood to be subεcript (e.g. 'N02' means N0 , 'CF3' means CF3 etc. ) .

Where MS/ [M] + appears this refers to the observed molecular ion (or characterising fragment) in the electron impact mass spectrum for the compound.

Example 1

Boron tribromide (0.3ml of a 2M solution in dichloromethane) was added dropwise to a εtirred solution of 3 -chloro-2 -methoxy- 2 ' -methylthio-4 ' - trifluoromethylbenzophenone (O.lg) in dichloromethane at -78°C. After 1 hour the mixture was allowed to warm to room temperature. A drop of hydrochloric acid (2M) was added and the εolution filtered through a εilica gel column eluting with ethyl acetate/petroleum ether to give 3 -chloro-2 -hydroxy- 2 ' -methylthio- 4 ' -trifluoromethylbenzophenone ( Compound 1, 50mg) , NMR 2.41 (s,3H), 6.72 (t,lH), 7.09 (m,lH), 7.3 (m, IH) , 7.4-7.53 (m,3H), 12.3

(S,1H) .

By proceeding in a similar manner the compounds of formula (I) shown in the following table wherein R⁴ and R⁸ represent hydrogen were also prepared.

Notes : (a) [M-CF3]⁺ 231/233 b) [M-CF3] ⁺ 300/302

C) 3.38(s,3H), 7.20-7.34 (m,2H) , 7.44-

7.53 m,2H), 7.95-8.01(m,2H) , 8.48-8.51 ( , IH) . d) 3.42(s,3H), 6.95(d,lH), 7.16(dd,lH),

7.32 dd,lH), 7.96-8.01(m, IH) , 8.34-8.42 (m, IH) . e) 2.53(ε,3H), 2.68(ε,3H), 6.79-

6.85 m,lH), 7.01-7.08 (m,2H) , 7.20-7.28 (m, 2H) , 7.47- 7.51(m,2H) . f) 5.10(ε,2H), 6.77-6.87 {m, IH) , 6.98-

7.05 m,lH), 7.34-7.68 (m, 9H) , 8.02-8.07 (m, 2H) . g) 5.09(s,2H), 6.96(d,lH), 7.16(dd,lH),

7.33 d,lH), 7.49-7.69(m,7H) , 8.00-8.05 ( , IH) . h) 1.67(d,3H), 5.70(q,lH), 7.14-

7.35 m,8H), 7.40-7.58 (m, 3H) . 7.74-7.79 (m, IH) , 7.98- 8.03 (m, IH) . i) 1.65(m,2H), 5.69(q,lH), 6.88-

7.00 m,lH), 7.15-7.36(m,6H) , 7.42-7.59 (m, 2H) , 7.65- 7.79(m,2H), 7.95-7.99(m,lH) . j) 2.48(s,3H), 6.78-6.94(m,2H) , 7.32-

7.49 m,4H) , 8.11-8.18(m,lH) . k) 2.49(s,3H), 4.29-4.40(m,2H) ,

6.24 tt,2H), 6.81-7.11(m,2H) , 7.19-7. 2 (m, 2H) , 7.58 d,lH) , 7.66-7.72(m,lH) .

1) 1.22(t,3H), 1.41(t,3H), 2.36(ε,3H),

2.98- 3.10(m,4H), 6.84-6.95 (m, IH) , 7.12- 7.39 m,2H), 7.49-7.61(m,lH) , 8.00-8.04 (m, IH) . m) 4.58(s,2H), 6.85-6.90 (m, IH) , 6.99-

7.05 m,lH), 7.17-7.44(m,9H) , 7.89-7.97 (m, IH) . n) 1.79(d,3H), 6.08(q,lH), 6.85-

6.95 m,3H), 7.00-7.08 (m,2H) , 7.16-7. 5 (m, 7H) . o) 1.20(t,3H), 1.41(t,3H), 2.16(ε,3H),

2.92 3.09(m,4H), 7.11(d,lH), 7.26-7.40 (m, 2H) , 7.81 d,lH) .

Bvaτnpl B 2 sec-Butyllithium (3.4 ml of a 1.3M solution in cyclohexane) was added during 3 minutes to a stirred solution of 2-methylthio-4- trifluoromethyl-bromobenzene (1.09 g) at -78°C under an inert atmosphere. After 3 hours at that temperature the above mixture was added slowly to a stirred solution of N-methoxy-N-methyl-3- chloro-2-methoxybenzamide (0.92 g) in ether at -78°C under an inert atmosphere. After 1 hour at -78°C the mixture was warmed to ambient temperature, stirred overnight and evaporated. Chromatography on silica gel eluting with ethyl acetate/petroleum ether gave 3 -chloro-2 -methoxy- 2 ' -methylthio-4 ' -trifluoromethylbenzophenone (Compound 18, 0.783g), NMR 2.45 (s,3H), 3.62 (s,3H), 7.09 (t,lh), 7.3-7.5 (m, 5H) .

By proceeding in a similar manner the compounds of formula (I) shown in the following table were also prepared.

Cpd NMR/MS No. Rl R2 3 4 R5 6 R⁷ δ [M] ⁺

19 2-CF3 H H Me Cl H Cl H (a)

20 2 -SMe H 4-CF3 Me H SMe H H 372

21 2 -SMe H 4-CF3 Me H H Me H 340

22 2 -SMe H 4-CF3 Me OMe H H H 356

23 2 -SMe H 4-CF3 Me H Cl H H 360/362

24 2-CF3 H H Me H SMe H H 326

25 2-CF3 H H Me H H Me H 294

26 2-CF3 H H Me OMe H H H 310

27 2-CF3 H H Me Cl H H H 314/316

28 2-CF3 H H Me H Cl H H 314/316

29 2 -SMe H H Me Cl H Cl H 326/328

30 2 -SMe H H Me H SMe H H (b)

31 2 -SMe H H Me H H Me H 272

32 2 -SMe H H Me OMe H H H 288

33 2 -SMe H H Me Cl H H H 292/294

34 2 -SMe H H Me H Cl H H 292/294

35 2 -SMe H 4-CF3 Me Cl H Cl H 394/396 (a) NMR 3.5 (s,3H) , 7.3 (m, IH) , 7.4-7.6 (m,4H) , 7.7 (m, IH)

(b) [M-C7H7S]⁺ 181

Example 3

A εolution of 2-bromoaniεole (0.15g) in dry tetrahydrofuran was added dropwise during 0.5 hour to a stirred mixture of magnesium turnings and dry tetrahydrofuran at 50°C under an inert atmosphere. After a further 0.5 hour the mixture was coooled and added via a syringe to a solution of N-methoxy-N-methyl-2-methyl-4- (methylthio)benzamide (0.16g) stirred in tetrahydrofuran at -78°C under an inert atmosphere. The mixture was allowed to warm to 20 °C during 18 hours, poured onto a mixture of ice-cold hydrochloric acid (2M) and ethanol, stirred for 0.3 hour and extracted (ether/dichloromethane) . The organic phase was washed (brine) , dried (magnesium sulphate) and evaporated. Purification by chromatography on silica gel eluting with i-hexane/ethyl acetate gave 2-methoxy-2 ' -methyl-4 ' -

(methylthio) benzophenone (Compound 244, 0.17g), NMR 2.48 (S,3H) , 2.57(s,3H), 3.87(s,3H), 6.77- 6.90(m,2H), 7.02-7.09 (m, 2H) , 7.20- 7.29 (m, IH) , 7.48-7.52 (m,lH) , 7.82-7.87 (m, IH) .

By proceeding in a similar manner the compounds of formula (I) wherein R⁴ represents methyl and R⁸ represents hydrogen shown in the following table were also prepared.

Cpd NMR/MS No. Rl R R3 R5 R6 R⁷ [M] ⁺

249 2-CF3 H H H H H

250 2-NEtS02Me 3 -OMe 4-Br H H H 442/444

251 2-CH2SPh H H H H H (e)

252 2-CHMeSPh H H H H H ( f )

253 2-Et 3-Me 4-SEt Cl H H ⁽g⁾

254 2-CH2SPh H H Cl H H (h)

255 2-CHMeS02Ph H H Cl H H (i)

256 2-CHMeSPh H H Cl H H ⁽j⁾

257 2-S02Me H 4-CF3 Cl H Cl (k)

258 2-CH2S02Ph H H Cl H Cl (1)

259 2-Et 3 -Me 4-SEt Cl H Cl (m)

260 2-Et 3 -Me 4-SEt H H H (n)

261 2-NEtS02Me 3 -OMe 4-Br Cl H H (o)

262 2-S02Me 3-OCH2CHF2 4-Br Cl H Cl ⁽p⁾

(a) 2.42(ε,3H), 3.83(s,3H), 6.71- 6.95(m,2H), 7.29-7.33 (m, 2H) , 7.38-7.48 (m, 2H) , 8.10 (d, IH) .

(b) 3.32(s,3H), 3.85(s,3H), 6.81- 6.95(m,2H), 7.19-7.30 ( , 2H) , 7.72-7.79 (m, IH) , 7.88-7.94 (m, IH) , 8.41-8.44 (m, IH) .

(c) 2.48(s,3H), 3.92(s,3H), 4.29- 4.40(m,2H), 6.27(tt,lH), 6.90-6.99 (m, 3H) , 7.24- 7.30(m,lH), 7.58(d,lH), 7.61-7.64 (m, IH) .

(d) 3.82(5,3H), 5.08(S,2H), 6.87- 7.01(m,3H), 7.23-7.34 (m, 2H) , 7.40-7.50 (m, 3H) , 7.58-7.69(m,3H) , 7.87-7.92 (m, 2H) .

(e) 3.81(ε,3H), 4.59(ε,2H), 6.90- 6.99(m,3H), 7.20-7.48 (m, 10H) .

(f) 1.66(d,3H), 3.83(s,3H), 5.59(q,lH), 6.86-7.03 (m,3H) , 7.14-7.37 (m, 5H) , 7.44- 7.57(m,2H), 7.60-7.80(m,2H) , 7.95-8.00 (m, IH) .

(g) m.p. 134-139°C.

(h) 3.91(s,3H), 4.59(ε,2H), 6.88- 6.98(m,2H), 7.18-7.54 (m, 9H) , 7.89-7.95 ( , IH) . (i) 1.76(m,3H), 3.91(s,3H), 6.08(q,lH), 6.87-6.98 (m,3H) , 7.20-7.95 (m, 9H) .

(j) 1.65(m,3H), 3.90(s,3H), 5.69(q,lH), 6.88-6.95(m,2H) , 7.19-7.41 (m, 6H) , 7.43- 7.56(m,lH), 7.60-7.69 (ra, IH) , 7.71-7.79 (m, IH) ,

7.94-8.00(m, IH) .

(k) 3.39(s,3H), 3.90(s,3H), 6.83(d,lH), 7.19(dd,lH), 7.48(d,lH), 7.91- 8.00 (m, IH) , 8.31- 8.41(m,lH) . (1) 3.89(s,3H), 5.08(ε,2H), 6.85(d,lH),

7.19(dd,lH), 7.37(d,lH), 7.40-7.69 (m, 7H) , 7.86- 7.90 (m,lH) .

(m) 1.12(t,3H), 1.34(t,3H), 2.29(ε,3H), 2.84-3.05(m,4H) , 3.84(s,3H), 7.01-7.06 (m, IH) , 7.13(dd,lH), 7.31(d,lH), 7.75(d,lH).

(n) m.p. 146.5-148.5°C.

(o) 1.12-1.19(m,6H) , 3.10(s,3H), 3.64- 3.78(m,4H), 3.90(s,3H), 4.07(s,3H), 6.88- 6.98(m,2H), 7.20-7.39 (m, 2H) , 7.62(d,lH). (p) 2.52(S,3H), 3.90(s,3H), 4.27-

4.39(m,2H), 6.28(tt,lH), 6.88(d,lH), 7.20(dd,lH), 7.39(d,lH), 7.61-7.64 (m, IH) .

Example 4 sec Butyllithium (0.7mmol) was added dropwiεe to a stirred solution of N,N,N',N'- tetramethylethylenediamine (0.7mmol) in dry tetrahydrofuran at -78°C under an inert atmosphere. A solution of phenyl N,N- diethylcarbamate (O.Smmol) in dry tetrahydrofuran was added and the mixture stirred at -78°C for 1.25 hours. A solution of N-methoxy-N-methyl-3, 4-dichloro-2- (methylthio)benzamide (0.85mmol) in dry tetrahydrofuran was added and stirred at -78°C for 3 hours. The mixture was warmed to 20°C and stirred for 2 days. Hydrochloric acid (2M) was added, the mixture heated at 50°C for 1 hour, then extracted (ethyl acetate) , dried (sodium sulphate) and purified by chromatography on silica gel eluting with ethyl acetate/cyclohexane to give 2-hydroxy-3 ' , 4 ' - dichloro-2 ' - (methylthio)benzophenone (Compound 42, O.llBg), NMR 2.37 (s,3H), 6.75 (m, IH) , 7.0 ( , IH) , 7.08 (d, IH) , 7.22 (d, IH) , 7.39 (d, IH) , 7.5 (d, IH) , 11.8 (s, IH) .

By proceeding in a similar manner the following compound was also prepared:

2 -hydroxy- 5 -methoxy-3 ' , 4 ' -dichloro-2 ' - (methylthio)benzophenone (Compound 263), NMR 2.3 (s,3H), 3.55 (ε,3H), 6.45(d,lH), 6.95 (d,lH), 7.08 (d,2H), 7.49 (d,lH), 11.4 (S,1H).

Reference Example 1 Oxalyl chloride (2.8ml) and N,N- dimethylformamide (1 drop) was added to a solution of 3-chloro-2-methoxybenzoic acid (6.5g) in dichloroethane and stirred at room temperature for 1 hour. The mixture was partially evaporated, diluted with dichloroethane and N, O-dimethylhydroxylamine hydrochloride (3.0 g) followed by pyridine (3ml) added. The mixture was stirred overnight and then partitioned between ethyl acetate and water. The organic phase was washed with water and sodium bicarbonate solution, dried (magneεium sulphate) and evaporated to give N- methoxy-N-methyl-3-chloro-2 -methoxybenzamide

(6.71g) as a yellow gum, NMR 3.28 (br s,3H), 3.4 (br s,3H), 3.82 (s,3H), 7.0 (m, IH) , 7.12 (m, IH) , 7.35 (m,lH) .

By proceeding in a similar manner the following compounds were also prepared: N-methoxy-N-methyl-2-methoxy-4- (methylthio)benzamide, NMR 2.41 (s,3H), 3.2 (br s , 3H ) , 3 . 5 (br s , 3H ) , 3 . 76 ( ε , 3H ) , 6 . 75 (m, 2H ) , 7 . 1 - 7 . 2 (m, lH) ;

N-methoxy-N-methyl- 2 -methoxy- 5 - methylbenzamide, NMR 2.21 (s,3H), 3.22 (br S,3H), 3.5 (br s,3H), 3.74 (s,3H), 6.73

(d,lH), 7.0-7.2 (m,2H);

N-methoxy-N-methyl-2, 3-dimethoxybenzamide, NMR 3.29 (br ε,3H), 3.41 (br ε,3H), 3.8 (ε,3H), 3.81 (ε,3H), 6.8-7.1 (m,3H); N-methoxy-N-methyl-4-chloro-2- methoxybenzamide, NMR 3.29 (br s,3H), 3.4 (br ε,3H), 3.82 (ε,3H), 7.0 (m, IH) , 7.1 (m, IH) , 7.35 (m,lH) ;

N-methoxy-N-methyl -3, 5-dichloro-2~ methoxybenzamide, NMR 3.36 (br s,3H), 3.5

(br S,3H), 3.9 (s,3H), 7.18 (d,lH), 7.41 (d, IH) ;

N-methoxy-N-methyl- 2 -methyl-4 - (methyl hio)benzamide, m.p .140-143 °C;:

N-methoxy-N-methyl-2- trifluoromethylbenzamide, NMR 3.25(s,3H),

3.76(ε,3H), 7.85-7.94 (m, IH) , 8.09-8.19 (m, IH) , 8.42-8.69(m,2H) ;

N-methoxy-N-methyl-4-bromo-2- (N-ethyl-N- methylsulphonyl ) amino- 3 -methoxybenzamide , NMR l.ll(t,3H), 3.10(s,3H), 3.26(s,3H), 3.69(q,2H),

3.74(s,3H), 4.05(ε,3H), 7.49(d,lH), 7.61(d,lH);

N-methoxy-N-methyl-4-bromo-3 - (2,2- difluoroethoxy) -2-methylsulphonylbenzamide, NMR 2.45(S,3H), 3.28(s,3H), 3.79(s,3H), 4.29- 4.40(m,2H), 6.24(tt,lH), 7.25(d,lH), 7.55(d,lH);

N-methoxy-N-methyl-2 -methyl ulphonyl-4 - trifluoromethylbenzamide, NMR 3.22(s,3H), 3.33(s,3H), 3.75(ε,3H), 7.81(m,lH), 7.94- 8.09(m,2H) ; N-methoxy-N-methyl-2 -methylthio-4 - trifluoromethylbenzamide, m.p .131-144°C (dec) ,-

N-methoxy-N-methyl-2- phenylthiomethylbenzamide, NMR3.24 (ε, 3H) , 3 . 75 ( s , 3H ) , 4 . 51 ( s , 2H) , 7 . 18 - 7 . 44 (m, 8H) , 7 . 89 - 7 . 94 (m, lH ) ;

N-methoxy-N-methyl-2- [1 ( - phenylthio) ethyl] benzamide, NMR 1.62 (d,3H), 3.25(s,3H), 3.76(ε,3H), 5.69(q,21H), 7.16-

7.32(m,5H), 7.44-7.55 (ra, IH) , 7.59-7.79 (m, 2H) , 7.94(dd,lH) ;

N-methoxy-N-methyl-2 -ethyl-4 -ethylthio-3- methylbenzamide, NMR 1.21 (t, 3H) , 1.39(t,3H), 2.39(s,3H), 2.91-3.10(m,4H) , 3.26(s,3H), 3.76(ε,3H), 7.10(d,lH), 7.81(d,lH);

N-methoxy-N-methyl-2- (1- phenylεulphonylethyl) benzamide, MS/ [M] + 334; and

N-methoxy-N-methyl- 2- phenylεulphonylmethylbenzamide, NMR 3.25(s,3H), 3.78(s,3H), 5.08(s,2H), 7.40-7.71 (m, 8H) , 7.89(m,lH) .

Reference Example 2 A solution of 4-methoxyphenol (20mmol) in dry N,N-dimethylformamide waε added dropwise to a εtirred εuspension of εodium hydride (60%, 22mmol) in dry N,N-dimethylformamide at 60°C. When hydrogen evolution had ceaεed the mixture waε εtirred at 60 °C for 0.3 hour and diethylcarbamoyl chloride (20mmol) added dropwise. The mixture was slowly warmed to 90°C and stirred for 18 hours, then cooled and diluted with ether and water. The organic phase was washed (2M sodium carbonate solution and water) , dried (magnesium sulphate) and evaporated to give 4 -methoxyphenyl N,N- diethylcarba ate (3.97g), NMR 1.2 (m, 6H) , 3.4 (m, 4H) , 3.8 (s, 3H) , 6.82 (d, 2H) , 7.02 (d, 2H) .

According to a further feature of the present invention, there are provided compositions suitable for herbicidal use comprising one or more of the hydroxybenzophenone derivatives of formula I or an agriculturally acceptable salt thereof, in association with, and preferably homogeneously dispersed in, one or more compatible agriculturally- acceptable diluents or carriers and/or surface active agents [i.e. diluents or carriers and/or surface active agents of the type generally accepted in the art as being suitable for use in herbicidal compositions and which are compatible with compounds of formula I] . The term "homogeneouεly diεperεed" iε used to include compositions in which the compounds of formula I are dissolved in other components. The term "herbicidal compositions" is used in a broad sense to include not only compositions which are ready for use as herbicides but also concentrates which must be diluted before use. Preferably, the compositionε contain from 0.05 to 90% by weight of one or more compounds of formula I .

The herbicidal compositions may contain both a diluent or carrier and surface-active (e.g. wetting, dispersing, or emulsifying) agent.

Surface-active agents which may be present in herbicidal compositions of the present invention may be of the ionic or non-ionic types. Suitably, the herbicidal compositions according to the present invention may comprise up to 10% by weight, e.g. from 0.05% to 10% by weight, of surface-active agent but, if desired, herbicidal compositionε according to the preεent invention may compriεe higher proportions of surface-active agent, for example up to 15% by weight in liquid emulεifiable suspension concentrates and up to 25% by weight in liquid water soluble concentrates. Examples of suitable solid diluents or carriers are aluminium silicate, microfine silicon dioxide, talc, chalk, calcined magnesia, kieεelguhr, tricalcium phoεphate, powdered cork, adεorbent carbon black and clayε such as kaolin and bentonite. The solid compoεitionε (which may take the form of dustε, granuleε or wettable powders) are preferably prepared by grinding the compounds of formula I with solid diluents or by impregnating the solid diluents or carriers with solutionε of the compoundε of formula I in volatile solvents, evaporating the solventε and, if neceεεary, grinding the productε εo aε to obtain powders. Granular formulations may be prepared by absorbing the compounds of formula I (dissolved in suitable εolventε, which may, if desired, be volatile) onto the solid diluents or carriers in granular form and, if desired, evaporating the solventε, or by granulating compositions in powder form obtained aε described above. Solid herbicidal compositions, particularly wettable powders and granules, may contain wetting or dispersing agents (for example of the types described above) , which may also, when solid, serve as diluents or carriers. Liquid compositions according to the invention may take the form of aqueous, organic or aqueous-organic solutionε, εuεpensions and emulεionε which may incorporate a surface-active agent. Surface-active agents, which may be preεent in the liquid compoεitions, may be ionic or non-ionic and may, when liquid, also serve as diluents or carriers.

Powders, dispersible granules and liquid compositions in the form of concentrates may be diluted with water or other suitable diluents, for example mineral or vegetable oils, particularly in the case of liquid concentrates in which the diluent or carrier is an oil, to give compositions ready for use.

When desired, liquid compositions of the compound of formula I may be used in the form of self -emulεifying concentrates containing the active substanceε dissolved in the emulsifying agents or in solvents containing emulsifying agents compatible with the active substances, the simple addition of such concentrates to water producing compositions ready for use.

Liquid concentrates in which the diluent or carrier is an oil may be used without further dilution using the electrostatic εpray technique . Herbicidal compoεitions according to the present invention may also contain, if deεired, conventional adjuvantε εuch aε adhesives, protective colloids, thickeners, penetrating agents, spreading agents, stabiliserε, εequestering agents, anti-caking agents, colouring agents and corrosion inhibitors. These adjuvants may also serve as carriers or diluents .

Preferred herbicidal compositionε according to the present invention are aqueous suspenεion concentrateε, wettable powderε, water εoluble or water dispersible powders, liquid water soluble concentrates, liquid emulsifiable suspension concentrates, water disperεible granuleε and emulεifiable concentrates.

Herbicidal compoεitionε according to the present invention may also comprise the compounds of formula I in association with, and preferably homogeneously dispersed in, one or more other pesticidally active compoundε and, if desired, one or more compatible pesticidally acceptable diluents or carriers, surface-active agents and conventional adjuvants as hereinbefore described.

Examples of other pesticidally active compounds which may be included in, or used in conjunction with, the herbicidal compositionε of the present invention include herbicides (which are preferred partners), insecticides, fungicides and plant growth regulators . Peεticidally active compoundε and other biologically active materials which may be included in, or used in conjunction with, the herbicidal compositions of the present invention and which are acids, may, if desired, be utilized in the form of conventional derivatives, for example alkali metal and amine salts and esters.

Examples of suitable herbicidal partners include aclonifen, alachlor, amitrole, atrazine, bentazone, bifenox, bromojcynil, chlortoluron, 2,4-D, dicamba, dichlobenil, dichlorprop, difenzoquat, diflufenican, dithiopyr, dimefuron diuron, ET-751, flampropme hyl , fluometuron, fluoroxypyr, glyphosate and glyphosate trimeεium (sulfosate) salt, hexazinone, imazapyr, isoproturon, isoxaben, MCPA, mecoprop, metolachlor or alpha- metolachlor, norflurazon, oryzalin, oxadiazon, oxyfluorofen, pendimethalin, εimazine, εulcotrione, εulfonyl ureaε εuch as rimsulfuron, terbuthylazine and triclopyr.

The following non-limiting examples illustrate herbicidal compositions according to the preεent invention. The following trade markε appear in the description: Ethylan, Soprophor, Sopropo, Rhodorsil, Atagel, Synperonic, Solvesεo, Arkopon, Tixoεil.

Example Cl:

A suspension concentrate is formed from: Compound 1 20%

Ethylan BCP (surfactant) 0.5%

Soprophor FL 0.5%

Sopropon T36 (Disperεant) 0.2% Rhodorεil 426R (Antifoaming agent) 0.01%

Propylene glycol (antifreeze) 5.0% Atagel 50 (anti-εettling agent) 2.0 Water to 100%

Similar εuεpension concentrates may be prepared by replacing Compound 1 with other hydroxybenzophenone derivatives of formula I .

Example C2

An emulsion concentrate is formed from the following:

Compound 1 10%

Synperonic NPE1800 (surfactant) 4.9% Arylan CA (surfactant) 5.0%

Cyclohexanone (solvent) 9.8% NMP (solvent) 9.8%

Solvesso 150 (blending agent) 5.0% Water to 100%

Note: NMP means N-methylpyrrolidinone Similar emulsion concentrates may be prepared by replacing Compound 1 with other hydroxybenzophenone derivatives of formula I .

Example C3

A wettable powder is formed from the following:

Compound 1 20.0%

Arylan SX flake (surfactant) 3.0%

Arkopon T (surfactant) 5.0% Sodium polycarboxylate (disperεant) 1.0% Tixoεil 38 (flow aid) 3.0%

China Clay 68.0% Similar wettable powders may be prepared by replacing Compound 1 with other hydroxybenzophenone derivatives of formula I .

According to a feature of the present invention, there is provided a method for controlling the growth of weeds (i.e. undesired vegetation) at a locuε which compriεeε applying to the locuε a herbicidally effective amount of at leaεt one hydroxybenzophenone derivative of formula I or an agriculturally acceptable salt thereof. For this purpose, the hydroxybenzophenone derivatives are normally used in the form of herbicidal compositions (i.e. in association with compatible diluents or carriers and/or surface active agents suitable for use in herbicidal compositions) , for example as hereinafter described.

The compounds of formula I show herbicidal activity against dicotyledonous (i.e. broad- leafed) and monocotyledonous (e.g. grass) weeds by pre- and/or post-emergence application.

By the term "pre-emergence application" is meant application to the soil in which the weed seeds or seedlings are present before emergence of the weeds above the surface of the soil . By the term "post-emergence application" is meant application to the aerial or exposed portions of the weeds which have emerged above the surface of the soil. For example, the compoundε of formula I may be used to control the growth of : broad-leafed weeds, for example, AbutiIon theophrasti, Amaranthus retroflexus, Bidens pilosa, Chenopodium album, Galium aparine, Ipomoea spp ■ e.g. Ipomoea purpurea. Sesbania exaltata, Sinapiε arvensis. Solanum nigrum and Xanthium strumarium, and grass weeds, for example Alopecurus mvosuroides , Avena fatua, Digitaria sanguinalis. Echinochloa crus-galli, Eleusine indica and Setaria spp, e.g. Setaria faberii or Setaria viridis, and sedges, for example, Cyperus esculentus. The amounts of compounds of formula I applied vary with the nature of the weeds, the compositions used, the time of application, the climatic and edaphic conditions and (when used to control the growth of weeds in crop-growing areas) the nature of the crops. When applied to a crop-growing area, the rate of application should be sufficient to control the growth of weedε without cauεing εubεtantial permanent damage to the crop. In general, taking these factors into account, application rates from about 0.01 to about 4.0kg (preferably from 0.01 to 1.0 kg) of active material per hectare give good results. However, it is to be underεtood that higher or lower application rates may be used, depending upon the particular problem of weed control encountered. Typically the compounds of the invention exhibit herbicidal propertieε at a dose rate of 250g/ha or lower. The compounds of formula I may be used to control selectively the growth of weeds, for example to control the growth of those specieε hereinbefore mentioned, by pre- or post- emergence application in a directional or non- directional fashion, e.g. by directional or non- directional spraying, to a locus of weed infeεtation which is an area used, or to be used, for growing crops, for example cereals, e.g. wheat, barley, oats, maize and rice, soya beans, field and dwarf beans, peas, lucerne, cotton, peanuts, flax, onions, carrots, cabbage, oilseed rape, sunflower, sugar beet, and permanent or sown grassland before or after sowing of the crop or before or after emergence of the crop. For the selective control of weeds at a locus of weed infestation which is an area used, or to be uεed, for growing of cropε, e.g. the crops hereinbefore mentioned, application rates between 10 g and 500 g, and preferably between 25 g and 250 g, of active material per hectare are particularly suitable. The compounds of the invention are especially useful for controlling grass weed specieε .

The compounds of formula I may also be used to control the growth of weeds, especially those indicated above, by pre- or post-emergence application in establiεhed orchards and other tree-growing areas, for example forests, woods and parks, and plantations, e.g. sugar cane, oil palm and rubber plantations. For this purpoεe they may be applied in a directional or non- directional fashion (e.g. by directional or non- directional spraying) to the weeds or to the soil in which they are expected to appear, before or after planting of the trees or plantations at application rates between 50 g and 5000 g, and preferably between 50 g and 2000 g, most preferably between 100 g and 1000 g of active material per hectare.

The compounds of formula I may also be used to control the growth of weeds, especially those indicated above, at loci which are not crop- growing areas but in which the control of weeds is nevertheless desirable.

Examples of such non-crop-growing areas include airfields, industrial sites, railways, roadside verges, the verges of rivers, irrigation and other waterways, scrublandε and fallow or uncultivated land, in particular where it is desired to control the growth of weeds in order to reduce fire riskε . When uεed for εuch purposes in which a total herbicidal effect is frequently deεired, the active compounds are normally applied at dosage rates higher than those used in crop-growing areas as hereinbefore described. The precise dosage will depend upon the nature of the vegetation treated and the effect sought. Pre- or post-emergence application, and preferably pre-emergence application, in a directional or non-directional faεhion (e.g. by directional or non-directional εpraying) at application rateε between 50 g and 5000 g, and preferably between 50 g and 2000 g, moεt preferably between 100 g and 1000 g of active material per hectare are particularly suitable for this purpose.

When used to control the growth of weeds by pre-emergence application, the compounds of formula I may be incorporated into the soil in which the weeds are expected to emerge. It will be appreciated that when the compounds of formula I are used to control the growth of weeds by post-emergence application, i.e. by application to the aerial or exposed portions of emerged weeds, the compounds of formula I will also normally come into contact with the soil and may also then exercise a pre-emergence control on later-germinating weeds in the εoil. Where eεpecially prolonged weed control is required, the application of the compounds of formula I may be repeated if required.

METHOD OF USE OF HERBICIDAL COMPOUNDS:

TEST METHOD a) General Appropriate quantities of the compounds used to treat the plants were dissolved in a solution of acetone/water (80:20 by volume) containing 0.1% Ethylan BCP as a wetter, so as to give a dose rate of 250g test compound per hectare.

These solutionε were applied from an automatic sprayer delivering the equivalent of 800 litres of spray fluid per hectare. b) Weed control : Pre-emergence The seeds were sown in 70 mm square, 75 mm deep plastic pots in non-sterile loam, 3 species per pot and the seedε covered with the loam. The quantitieε of εeed per pot were aε follows : -

Weed species Approx no. of seeds/species

1) Broad- leafed weeds

.Abutilon theophrasti 7-8

Amaranthus retroflexus 20 (pinch)

Galium aparine 4-5

Ipomoea purpurea 5

2) Grass weeds

Alopecuruε myoεuroides 15-20

Avena fatua 10

Echinochloa crus-galli 15

Setaria viridiε 15

Crop

1) Broad-leafed

Soya 2

2) Grass

Maize 2

Rice 5

Wheat 5

The compounds of the invention were applied to the soil surface, containing the seeds, as described in (a) . Pots containing the species represented were allocated to each treatment, with unsprayed controls and controls sprayed with acetone/water alone. After treatment the pots were placed on capillary matting kept in a glass house, and watered by overhead sprinkler (pre- emergence) and sub-irrigation, supplemented overhead (post- emergence) . Visual assessment of weed control and crop damage was made 12 days (post- emergence) and 17 days (pre- emergence) after spraying. The results were expresεed aε the percentage reduction in growth or damage to the crop or weeds, in compariεon with the plants in the control pots.

When applied at 250 g/hectare or less pre- or post-emergence, compound numbers 1, 3, 10, 14, 35, 239, 249-251 and 260 gave at least 90% reduction in growth of one or more of the weed specieε liεted above.

Claims

1. A method for the control of weeds at a locus which comprises applying to said locus a herbicidally effective amount of a Kydrox-'benzo- ^■^henonα derivative of formula (I) :

(I) wherein:

R¹ represents :- straight- or branched- chain halogenated alkyl containing up to four carbon atoms and at least two halogen atoms; or a member of the group conεisting of -N0₂, R⁹S(0)_m-, R⁹S0₂-0-, R⁹S(0)_m-CH(R¹⁰) -, (R⁹0) (R¹¹0)P(0)-, (R⁹0) (R¹¹0)P(0) -CH(R¹⁰) -, R¹⁰R¹ NC(O)N(R¹⁰) -, R¹³XC(0)N(R¹⁰) -, R⁹R¹¹NS0₂-, R¹⁴S0₂N (R¹⁰) - , -SF₅, Het-CH(R¹⁰) -, R⁹S (0)_m-CH₂CH₂- and (benzyl optionally substituted by one or more R-¹-⁵ which may be the same of different) ^■

R² and R³ independently represent : -

Rl, hydrogen, halogen, straight- or branched- chain alkyl containing up to four carbon atoms optionally halogenated with one halogen; straight- or branched- chain optionally halogenated alkoxy containing up to four carbon atoms; straight- or branched- chain alkyl containing up to six carbon atoms which is substituted by one or more -OR ^ groups; or a member of the group consisting of cyano, R⁹C(0)-, R⁹XC(0)-, R¹⁰R¹²NC(O) -, R¹³C (0) N (R¹⁰) - and NR¹⁰R¹²; wherein the ortho position of the phenyl ring is substituted by a non-hydrogen substitutent ,-

R⁴ represents :- hydrogen, R¹³, straight- or branched- chain alkyl containing up to six carbon atoms which is substituted by one or more -XR¹⁶ groups; or a member of the group consisting of R⁹S0₂-, R⁹C(0)- and R¹⁰C(O)C(Rl0) (Rl ) -_; R⁵, R⁶ and R⁷ independently represent :- hydrogen, halogen, hydroxy, R¹⁶SO_m-, Rⁱ³ , straight- or branched- chain optionally halogenated alkoxy containing one to four carbon atoms; straight- or branched- chain alkyl containing up to six carbon atoms which is substituted by one or more -OR¹⁶; or a member of the group consisting of -N0₂, cyano, R¹⁴S0₂N(R¹⁰) -, R⁹C(0)-, R⁹XC(0)-, R⁹C (0) N (R¹⁰) - , R¹⁰R¹ NC(O) -, R¹⁰R¹²NC(O)N(R¹⁰) -, R¹⁰R¹²NSO₂-, and cycloalkyl containing from three to six ring carbon atoms ,-

R⁸ is as defined for R⁵ with the exclusion of hydroxy;

R⁹ and RU independently represent :- straight- or branched- chain optionally halogenated alkyl containing up to four carbon atoms ; or phenyl or benzyl which are optionally substituted by one to five groups R¹⁵ which may be the same or different;

R¹⁰ and R¹² independently represent hydrogen or R⁹;

Rl³ represents straight- or branched- chain optionally halogenated alkyl containing up to four carbon atoms;

R¹⁴ represents straight- or branched- chain alkyl containing up to four carbon atoms; R¹⁵ represents halogen, optionally halogenated methyl; or R¹⁴SO_m-,-

R¹⁶ represents straight- or branched- chain alkyl containing up to six carbon atoms; Het representε a five membered aromatic heterocyclic ring containing from one to three ring nitrogen atoms which is attached to the -CH(R¹⁰)- group via one of the ring nitrogen atoms ; X represents oxygen or sulphur; and m repreεentε the values 0,1, or 2; or an agriculturally acceptable salt thereof .

2. A method according to claim 1 wherein the locus is an area used, or to be used for the growing of crops and the hydroxybenzophenone derivative iε applied at an application rate of from about 0.01 to about 4.0kg/ha.

3. A compoεition comprising a hydroxybenzophenone derivative as defined in claim 1 with the proviso that when R¹ represents 2 -trifluoromethyl; R² , R³ and R⁷ each represent hydrogen; R⁴ represents methyl and R⁵ and R⁶ each represent methoxy, R& does not repreεent methyl; or an agriculturally acceptable salt thereof, in asεociation with an agriculturally acceptable diluent or carrier and/or surface active agent.

4. A hydroxybenzophenone derivative of formula (I) as defined in claim 1 or an agriculturally acceptable salt thereof, with the proviso that:

(a) when R¹ represents nitro it is located at the 2 -position of the phenyl ring and that at least one of R² and R³ represents halogen, R⁹S(0)_m-, or straight- or branched- chain halogenated alkyl containing up to four carbon atoms ;

(b) when each of R² to R⁶ and R⁸ represent hydrogen and R⁷ represents methyl, R¹ is not

2-S0Me, 2-S0₂Me or 2-S- (4-methylphenyl) ;

(c) when R² , R³ , R⁵, R⁶ and R⁸ each represent hydrogen and R⁴ and R⁷ each represent methyl, R¹ iε not 2-SMe,- (d) when R¹ represents 2-CF3 and each of R² to R⁶ and R⁸ represent hydrogen, R⁷ is not chloro or hydroxy;

(e) when R¹ represents 2-CF3 R² , R³, R⁴, R⁷ and R⁸ each represent hydrogen and R⁵ representε chloro, R⁶ is not methoxy;

(f) when R¹ represents 2-CF3; and R² , R³ , R⁴, R⁵, R⁷ and R⁸ each represent hydrogen, R⁶ iε not hydroxy;

(g) when R¹ represents 2-CF3; R² , R³, R⁵ and R⁸ each represent hydrogen and R⁶ represents methoxy, R⁴ is not hydrogen or methyl;

(h) when R¹ repreεentε 2-CF3; R² , R³ , R⁵ , R⁶ and R⁸ each represent hydrogen and R⁴ representε methyl, R⁷ iε not methoxy; (i) when R¹ represents 2-CF3; R² , R³ and R⁷ each represent hydrogen; R⁴ representε methyl and R⁵ and R⁶ each repreεent methoxy, R⁸ is not methyl.

5. A compound according to claim 4 in which R¹ is straight- or branched- chain haloalkyl containing up to four carbon atoms; or R⁹S(0)_m- wherein m iε aε defined in claim 4 and R⁹ is straight- or branched- chain alkyl containing up to four carbon atoms.

6. A compound according to claim 4 or 5 in which R⁴ represents hydrogen.

7. A compound according to claim 4, 5 or 6 in which at leaεt one of R⁵ , R⁶ , R⁷ and R⁸ repreεents halogen.

8. A compound according to any one of claims 4 to 7 in which one or two of the groups R⁵, R⁶, R⁷ and R⁸ are not hydrogen.

9. A compound according to claim 4 in which:

R¹ repreεentε C1-C3 alkyl containing at least two halogen atoms, -S(0) R⁹ (wherein R⁹ represents C1-C3 alkyl), -CH (R¹⁰) -S (0)_m-R⁹ (wherein R⁹ represents C1-C3 alkyl or phenyl, and R¹⁰ repreεentε hydrogen or methyl) , N0₂ or R¹⁴S0₂N(R¹⁰) - (wherein R¹⁴ and R¹⁰ represent Cl- C3 alkyl) ;

R² and R³ independently represent C1-C3 optionally halogenated alkyl, hydrogen, halogen, C1-C3 optionally halogenated alkoxy or -S(0)_mR⁹ (wherein R⁹ represents C1-C3 alkyl) ;

R⁴ representε hydrogen, C1-C3 alkyl, R⁹S0₂- (wherein R⁹ represents C1-C3 alkyl or phenyl optionally subεtituted by one to five halogen, methyl or R¹⁴S(0)_m- groups wherein R¹⁴ representε C1-C3 alkyl), R⁹C(0)- (wherein R⁹ represents C1-C3 alkyl or phenyl optionally substituted by one to five halogen or C1-C3 alkyl groups), R¹⁰C(0)CH₂- (wherein R¹⁰ represents phenyl optionally substituted by one or more halogen or C1-C3 alkyl groups) , or methyl subεtituted by -XR¹⁶ wherein R¹⁶ repreεents C1-C3 alkyl; R⁵, R⁶ and R⁷ independently represent hydrogen, halogen, hydroxy, C1-C3 alkoxy or R^lβS(0)_m- wherein R¹⁶ represents C1-C3 alkyl; and R⁸ represents hydrogen or halogen.

10. A compound according to claim 4 in which the para-position of the phenyl ring is occupied by R² which represents hydrogen, halogen or Cl-C3-haloalkyl .

11. A compound according to claim 4 in which the ortho-position of the phenyl ring is occupied by R¹ which represents -S(0)_m-R⁹ (wherein R⁹ represents Cl-C3-alkyl) ,

-CH(R¹⁰) -S(0)_m-R⁹ (wherein R⁹ representε C1-C3- alkyl or phenyl and R¹⁽-⁾ represents hydrogen or methyl), or R¹⁴S0₂N(R¹⁰) - (wherein R¹⁰ and R¹⁴ represent C1-C3 alkyl) .

12. A compound according to claim 4 in which: -

R⁴ representε hydrogen;

R⁵, R⁶ and R⁷ repreεent hydrogen, halogen, hydroxy, R¹⁶S(0)_m-, R¹³ , εtraight- or branched- chain optionally halogenated alkoxy containing up to four carbon atoms, εtraight- or branched- chain alkyl containing up to six carbon atoms which is subεtituted by one or more OR¹⁶ groups, -N0₂, cyano, or R¹⁰R¹²NSO₂-_; and

R⁸ is as defined for R⁵ excluding hydroxy.

13. A compound according to claim 4 having one or more of the following features : - R¹ representε MeS(0)_m- or -CF₃.

R² , R⁴ and R⁸ each repreεent hydrogen;

R³ repreεents hydrogen or -CF3;

R⁵ representε hydrogen, halogen, hydroxy or methoxy; R⁶ repreεentε hydrogen or MeS(0)_m-,- and

R⁷ represents hydrogen, halogen or methyl.

14. A process for the preparation of a hydroxybenzophenone derivative of formula (I) as defined in claim 4 which comprises : -

(a) reacting a compound of general formula (ID :

wherein R⁴, R⁵ , R⁶ , R⁷ and R⁸ are as defined in claim 4 and Y representε a leaving group, with an organometallic reagent of formula (III) :

wherein R¹, R² and R³ are as defined in claim 4 and M is a metal;

(b) reacting a compound of general formula

(Ha) :

(Ila) wherein R⁴, R⁵ , R⁶, R⁷ and R⁸ are as defined in claim 4 and M represents a suitable metal or metal halide, with a compound of formula (Ilia) :

(Ilia) wherein R¹, R² and R³ are aε defined in claim 4 and Y is a leaving group; (c) where R⁴ representε hydrogen and R¹, R² ,

R³, R⁵, R⁶, R⁷ and R⁸ are defined in claim 4, de-etherification of the correεponding compound of formula (I) in which R⁴ represents R¹³;

(d) where R⁴ representε R⁹S0 and R¹, R² , R³ , R⁵, R⁶, R⁷, R⁸ and R⁹ are defined in claim 4, the εulphonation of the correεponding compound of formula (I) in which R⁴ represents hydrogen with a εulphonyl chloride of formula R⁹S0₂C1 wherein R⁹ is aε defined in claim 4; (e) where R⁴ represents R¹⁰C (O) C (R¹⁰) (R¹²) - in which R¹, R² , R³ , R⁵ , R⁶ , R⁷ , R⁸ , R¹⁰ and R¹² are defined in claim 4, the alkylation of the corresponding compound of formula (I) in which R⁴ represents hydrogen with a compound of formula (IV) :

R¹⁰C(O)C(R¹⁰) (R¹²) -Z (IV) in which R¹¹-¹ and Rl² are defined in claim 4 and Z represents halogen;

(f) where m is one or two, the oxidation of the corresponding compound of formula (I) in which m is zero or one; optionally followed by the converεion of the compound of formula (I) thuε obtained into an agriculturally acceptable εalt thereof .