CA1270832A - Diphenyl ether herbicides - Google Patents

Abstract

ABSTRACT

DIPHENYL ETHER HERBICIDES

Herbicidal compositions comprising, as active ingredient, a diphenyl ether derivative of formula wherein R1 represents a hydrogen or halogen atom or an alkyl or haloalkyl group; R2 and R3 each independently represents a hydrogen or halogen atom or an alkyl, haloalkyl, nitro or cyano group; and the substituents A and B have the meanings as defined in the text; the use of such diphenyl ethers as herbicides;
certain novel diphenyl ethers within formula I and their preparation.

Description

This invention relates to a composition for and a method of controlling undesired plant growth and to compounds for use in such a composition or method.
Certain substituted phenoxy phthalates are disclosed as herbicides in United States Patent 4,334,915, along with the cor-responding phenoxy phthalic anhydride. That anhydride is disclosed only as being a useful intermediate in the preparation of the phthalates and no mention or suggestion is made that the anhydride itself may exhibit any biological activity. It has now been found that such phenoxy phthalic anhydrides, along with certain other diphenyl ethers which bear a fused ring substituent at the 3,4 position, show interesting herbicidal activity.
Accordingly, the present invention provides a herbicidal composition which comprises a liquid carrier comprising a surface-active agent or a solid carrier and, as active ingredient, a di-phenyl ether derivative having the general formula I:

R~
C

X

wherein Rl represents a hydrogen or halogen preferably chlorine atom or a Cl 10 alkyl or Cl 6 haloalkyl preferably trifluoromethyl group;

~" ~

3L27~

- 2 - 70474-152 R2 ancl R3, which may be the ~ame or di:Eferent, each indepen-dently r~present a hy~lro~en or ha.logen preferably chl.orine atorn or a Cl-10 a]kyl, Cl-6 hal.oalkyl, nitro or cyano group, ~ represents a ~ivalent group selecte~ from -X-, > C(R4)2 and > C=X, B represen~s a divalent grou~ selected from > C(R~)2; -X-, > N-R5; > C=X and > SO2, provided that when A represents -X-, then B must be different from A and cannot represent > C=X;
each R4, whi.ch may be the same or different, represents a hydrogen or halogen atom or an optionally substituted Cl_lo alkyl, C3_10 cycloalkyl, Cl_lo alkenyl, Cl_loalkynyl, phenyl, benzyl, Cl_lo a]kyl substituted phenyl, Cl_lo alkoxy, C3_10 cycloalkoxy, Cl_lo a].kenyloxy, Cl_lo alkynyloxy, Cl_lo alkoxycarbonyl- Cl_lo alkoxy, Cl_lo alky].th;.o, Cl_lo acyl (as herein defined), carboxyl, Cl_lo alkoxycarbonyl, Cl_lo acyloxy or pyrrolyl, pvrolidinyl, pyridyl, piperidyl, furyl or pyranyl, 5-(4-trifluoromethyl-phenoxy)phthalic anhydride and compounds in which Rl represents a hydrogen atom, a chlorine atom or a methyl group, R2 anc~ R3 each represent a hydrogen atom, A represents > C=O, X represents an oxygen atom and B represents ~ NRs (where Rs is methyl or phenyl), > CHR4 (where R4 is phenyl) or -O-, an amino group of formula NR6R7, or when one R4 represents a hydrogen atom, a Cl_4 alkoxy group or an above mentioned hydrocarbon group, then the other may represent a hydroxyl group, or both groups R4 together may represent an imino group of formula =NRs;
Rs represents a hydrogen atom, a carboxyl or hydroxyl group, or an optionally substituted Cl_lo alkyl, Cl_lo alkoxy, benzyl, lZ~8,3~

- 3 - 70474-152 Cl_lo alkoxycarbonyl. or Cl_lo alkoxycarbonyl Cl_lo aLkyl group, where;.n the optional substituents are selected from halogen, n;tro, cyano, hydroxy, alkoxy and ester groups derived from orga-nic aci.ds or an amino group o:f -Eormul.a NR6R7;
R6 and R7, which may be the same or d.ifferent, each repre-sents a hydrogen atom or an optionally substituted Cl_lo alkyl, phenyl or C1_1o alkanoyl group, where:in the opti.onal substituents are selected :Erom halogen, nitro, cyano, hydroxy, al.koxy and ester groups derived from organic acids; and X, both in formula I and in the definitions of the substi-tuents therein, represents an oxygen or sulphur atom.
The term "acyl" is used herein to denote the radical derived from an organic acid by the removal of a hydroxyl group;
the organic acid may be a carboxylic acid (including carbamic acid derivatives) or a su].phonic acid, examples of suitable acyl groups bei.ng alkylcarbonyl, alkylcarbamoyl and alkylsulphonyl, e.g.
acetyl,methylsulphonyl and dimethylcarbamoyl.
When any o.E the foregoing substituents represents or contains an alkyl, alkenyl or a]kynyl. substituent group, this may be linear or branched and may contain up to lO, preferably up to 6, carbon atoms, sui.table exampl.es being methyl, ethyl, propyl, allyl and propynyl. ~hen they represent or contain a cycloalkyl substituent group this may contain from 3 to 10, preferably 5 to 8, carbon atoms, and is suitably cyclohexyl. When they contain a haloalkyl substituent aroup, this suitably contains up to 6, preferably up to 4, carbon atoms and the halogen atom is suitably fluorine or chlorine, tr;.fluoromethyl being particularly prefer-~ ;Z7 ~3 8 3 l~d - 3a - 70474-152 recl. When any of the foregoing substituents are deslgnated as being opti.onal]y subst;.tuted, the substituent groups whic~h are optionally present may be any of those customarll.y employed in the deve].o~ment of pestic;dal compounds, ancd/or the modification of SUCll compounds to inr-luence their structure/activity, persistence, penetration or other property. Specifi.c examples of such substi-tuents incl.ude halogen, especial].y chlorine, atoms and nitro, cyano, hydroxyl, 127~bl32 alkoxy, e.g. methoxy, or es-ter, e.g. alkoxycarbonyl, groups.
Preferred compositions are those wherein the active ingre-dient is a compound of general formula I wnerein X represents an oxygen a-tom;
A represen-ts an oxygen atom, a carbonyl group, the group ~(R4)2 whereln one group R4 is a hydrogen atom, or an alkyl or alkoxy group of up to 4 carbon atoms, especially methyl or methoxy, or a phenyl, group, and -the other group R4 is a hydrogen or halogen, especially chlorine or bromine, atom, a hydroxyl group, an alkyl group of up to 4 carbon atoms, especially methyl, an alkoxy group of up to 4 carbon atoms, especially methoxy, ethoxy or propoxy, optionally substituted by a halogen, especially chlorine, atom, or a hydroxyl or alkoxy, especially methoxy, group, a cycloalkoxy group of 5 to 8 carbon atoms especially cyclohexyloxy, an al.kenyloxy or alkynyloxy group of up to 6 carbon atoms, especially allyloxy or propynyloxy, an alkoxycarbonylalkoxy wi-th up to 4 carbon atoms in the alkoxy moieties, especially ethoxycarbonylethoxy, group, an alkylthio group of up to 4 carbon atoms, especially methyl- or propyl- thio, an alkanoyl, especially acetyl, group of up to 4 carbon atoms, a pyridyl group, or an amino group of formula NR6R7 wherein R6 represents a hydrogen atom or an alkyl group of up -to 4 carbon atoms, especially methyl, and R7 represents an alkyl group of up to 4 carbon atoms, especially methyl, a phenyl. group optionally substituted by at least one halogen, especially chlorine, atom, or an alkylcarbonyl group with up to 4 carbon atoms in the alkyl moiety, especially acetyl;

~LZ~
- 4a - 70474-152 and ~ represents an oxygen atom, the group C(R4)2 wherein each group K4, which may ~e the same or different, independently represent a hydroqen at-om or an alkyl or alkoxy group of up to 4 carbon atoms, especially methyl or methoxy, or t'ne group NRs wherein Rs represent.s a hydrogen ~tom, an alkyl group of up to 4 carbon atoms, especially methyI, a benzyl group, or an alkoxy-carbonylalkyl group of Up to 8 car~)on atoms, especially ethoxy-carbonylmethyl or ethoxycarbonylethyl.
Particularly preferred compositions are those wherein the active ingredient is a compound in which Rl represents a tri-fluoromethyl group, R2 represents a halogerl, especia]ly chlorine, atom and R3 represents a hydrogen atom.
With some exceptions, the compounds of formula I are novel, and the invention therefore also extends to those novel compounds per se. The novel compounds are the diphenyl ether derivatives of formula I wherein the substituents A, B, Rl, R2, R3, R4, Rs, R6 and R7 have the meanings defined above, with the exception of 4 (2- chloro-4-trifluoromethylphenoxy)-phthalic an-hydride, 5-(4-trifluoromethylphenoxy)phthalic anhydride and com-pounds in which Rl represents a hydrogen atom, a chlorine atom ora methyl group, R2 and R3 each represent a hydrogen atom, A repre-sents > C=O, X represents an oxygen atom and B represents > NRs (where Rs is methyl or phenyl), > CHR4 (where R4 is phenyl) or --O-- .
It will be appreciated that when the nature of the substituents is such as to introduce an asymmetric carbon atom, then the resulting compound will exist in stereoisomeric forms.

lZ7083~

- 4b - 70474-152 Also, some substituent co~binations permit the existence of tauto-meric forms. The scope of the presen.t ;nvention lnc] udes these different forms of the compounds and their mixtures, and herbici-dal compositions contai.ning the acti~e ingredient in such ~LZ7~3~

iscmeric for~3 and mixtures.
The mvention further provides a process for the preparation of the no~Tel diphenyl ethers as defined above which ccmprises reac~ing a phthalide of Eormula:-Q ~ ~A \
B (II) X
with a c~mpcund of the formula^
l2 ~Z

wherein A, B, X, ~ , ~ and ~ have the meanings given above for formula I; one of Z and Q represents a halogen, suitably chlorine, atcm or nitro grOUD~ and the other represents a grcup of formNla -CM wherein M represents a hydrogen or alkali metal atom. Conveniently the reaction is carried out by reacting a ccmpound of formLla II wherein Q is hydroxy with an alkali metal hydr~xide m an alkanol, e.g. ethanol, solvent, thereby formLng the corresponding aLkali metal salt which is then reacted with a compound of formula III wherein Z represents a chlorine atom.
m e reaction of the said salt with the chloro- compound is preferably carried cut in a suitable organic solvent, eg dlmeth~rl sulphoxide, sulpholane, dimethyl formamide, or dimethyl acetamide at elevated temperature, e.g. above 25C and in particular between 40C and reflux, conveniently under reflux, and also under an inert atmosphere such as nitrogen.
Compounds wherein X in formLla I represents sulphur m~y be obtained from the corresponding oxygen analogues by reaction 2~ with phosphorus pen~asulphide. Ccmpounds wherein A represents a halomethylene group may suitably be obtained by reacting the corresponding methylene ocmpcund with an appropriate halcgenating agent. Thus, a oompound wherein A represents CHBr may be obtained by reacting the corresponding A=~CH2 compound with N-brcmo-succim ~ide, suitably in the presence of a B~28.00l ~L27~3,~

peroxlde s~lch as kenzoyl peroxide and in a solvent such as carbon tetrachloride. Compounds ~lerein A represents a hydroxymethylene grcup may be obtained by hydrolysis of the corresponding halomethylene co~Found.
Compcunds wherein X and s in formwla I both represent an oxygen atom, and A is the group C(R4)2 in which one group R4 is a hydrcgen atcm and the other has one of the meanings defined above excluding hydrogen or hydroxyl, may be obtained frcm the corresponding oompound wherein A represents CH(OH) by reaction with a reagent of formula HR4 wherein ~4 is as defined for formula I excluding hydrogen or hydroxyl or, when R4 is a carboxylic acyloxy group, an acyl anhydride of formLla Ac20 wherein Ac is c~n alkylcarbonyl group. The reactior. is suitcibly carried out by refluxing the reaction mixture. In some cases the reactant HR4 can be used in excess to provide a convenient reaction solveAnt; in other cases it may be convenient to introduce the reagent HR4 as a solution in an organic solvent, e.g. acetonitrile or methyl ethyl ketone.
The compcunds of the general formLla I have been found to show interesting activity as herbicides. Accordingly the invention also provides the use as a herbicide of such a compoNnd or composition according to the invention. Further in accordance with the invention there is provided a method of combating undesired plant growth at a locus by treating the locus with a compound or composition according to the invention.
Application to the locus may be pre-emergence or post-emergence.
The dosage of active ingredient used may, for examplel be from 0.05 to 4 kg/ha.
A carrier in a ccmposition according to the invention is any material with which the active ingredient is formulated to facilitate application to the locus to be treated, which may for example be a plant, seed or soil, or to facilitate storage, transport or handling. A carrier may be a solid or a liquid, including a material which is normally gaseous but which has been compressed to fonm a liquid, and any of the carriers ~N28.00l ~L27~3~

normally used in formNlating herbicidal compositions may be used. Preferably cc~positions acc~rding to the invention contain 0.5 to 95~ by weight of active ingredient.
Suitable solid carriers incl~lde natural and synthetic clays and silicates, ~or example natural silicas such as diatomaceous earths; magnesium silicates, for example talcs; magnesium alumunium silicates, for example attapulgites and vermiculites;
aluminium silicates, for example kaoiinites, montomorillonites and micas; calcium car~onate; calcium sulphate; ammonium 0 sulphate; synthetic hydrated silicon oxides and synthetic calcium or alumini~n silicates; elements, for example carbon and sulphur; natural and synthetic resins, for example coumarone resins, polyvinyl chloride, and styrene polymers and copolymers;
solid polychlorophenols; bitumen; waxes; and solid fertilisers, for example superphosphates.
Suitable liquid carriers include water; alcohols, for example isopropanol and glycols; ketones, for exlmple acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone;
ethers; arcmatic or araliphatic hy~lx~lr~ns, for example benzene, toluene and xylene; petroleum fractions, for example kerosine and light mineral oils; chlorinated hydrocarbons, for example carbon tetrachloride, perchlor~ethylene and trichloro-ethane. Mixtures of different liquids are often suitable.
Agricultural compositions are often formulated and transported in a concentrated form which is subsequently diluted by the user before application. The presence of small am~unts of a carrier which is a surface-active a~ent facilitates this process of dilution. Thus preferably at least cne carrier in a composition accor~ing to the invention is a surface-active 3o agent. For example the composition may contain at least two carriers, at least one of which is a surface-active agent.
A surface-active agent may be an emulsifying agent, a dispersing agent or a wetting agent; it may be nonionic or ionic. Examples of suitable surface-active agents include the sodium or calcium salts of polyacrylic acids and ligm n su~phonic acids; the oondensation of fatty acids or aliphatic BN28.00l ~2~

amines or amides containlng at leas, 12 carbon atoms in the m~ecule with ethylene oxide and/or prrJpylene oxide; fatty acid esters of g]ycerol, sorbit~n, sucrose or pentaerythritol;
condensates of these with ethylene oxide and/or propylene oxide;
condensation products of fatty alcohol or aIkyl phenols, for example ~-octylphenol or ~-octylcresol, with ethylene oxide and/or propy]ene oxide; sulphates or sulphonates of these condensation products; alkali or alkaline earth metal salts, preferably sodium salts, of sulphuric or sulphonic acid esters containing at least 10 OE bon atoms in the molecule, for example sodium lauryl sulphate, sodium secondary alkyl sulp~lates, sodium salts of sulphonated castor oil, and sodium alkylaryl sulphona~es such as dodecylbenzene sulphonate; and polymers of ethylene oxide and copolymers of ethylene oxide and propylene oxide.
The compositions of the invention may for example be for~ulated as wettable powders, dusts, granules, solutions, emulsifiable concentrates, emulsions, suspension concentrates and aerosols. Wettable powders usually contain 25, 50 or 75~ w of active ingredient and usually contain in addition to solid inert carrier, 3-10% w of a dispersing agent and, where necessary, 0-10% w of stabiliser(s) and/or other additives such as penetrants or stickers. Dusts are usually formLlated as a dust concentrate having a similAr composition to that of a wettable powder but without a dispersant, and are diluted in the field with ~urther solid carrier to give a composition usually containing ~-10% w of active ingredient. Granules are usually prepared to have a size between 10 and 100 BS mesh (1.676 -0.152 mm~, and may be mar.ufactured by agglomeration or 3o impregnation techniques. Generally, granules will contain ~-75% w active ingredient and 0-10% w of additives such as stabilisers, surfactants, slcw release modifiers and binding agents. me so-called "dLy flowable pcwders" consist of relatively small gra~ules having a relatively high concentration of active ingredient. Emulsifiable concentrates usually contain, in addition to a solvent and, when necessary, BN28.001 ~7~

g co-solven t, :LO-50~ w/v ac-tive ingredient, 2-20~ w/v ernulsifiers and 0-~0% w/v of other addi-tives such as stabilisers, penetrants and corrosion inhibitors. suspension concentra-tes are usually compolmded so as to obtain a s-table, non-sedimenting flowable product and usually contain :L0-75 w active ingredient, 0.5-15% w of dispersing agents, O.]-lO~o W oE suspending agents such as pro-tec-tive colloids arld thixotropic agents, 0-10% w of other additives such as deEoam~rs, corrosion inhibi-tors, stabilisers, penetrants and stickers, and water or an organic liquid in which the active ingredient is substantially insoluble; certain organic solids or inorganic salts may be present dissolved in the formulation to assist in preventing sedimentation or as anti-freeze agents for water.
Aqueous dispersions and emulsions, for example composi-tions obtained by diluting a wettable powder or a concentrate according to the invention with water, also lie within the scope of the invention. The said emulsions may be of the water-in-oil or of the oil-in-water type, and may have a thiclc 'mayonnaise'-like consistency.
The composition of the invention may also contain other ingredien-ts, for example other compounds possessing herbicidal, insecticidal or fungicidal properties.
The following Examples illustrate the invention.
Example 1 5-(2'-chloro-4'-trifluoromethyl phenoxy)phthalide 5-Hydroxy phthalide (5.5g) was dissolved in ethanol (50ml), 2.5g potassium hydroxide added and the solution refluxed for 3 hours. The solvent was removed, the residue dissolved in dimethylsulphoxide (50 ml) and 8.2g of 3,4 dichlorobenzotri-~2~7q~
- :~o -fluoride added. This mixture was stirred ~mder dry nitrogen at 160C for 18 hours, after wh:icll it was cooled, poured onto ice, neutralised with dilute hydrochloric acid and -the product extrac-ted with methylene ch]oride to yield the desired produc-t m.pt. 109-111C.

Analy~is: Calc- Eo~- C15H8O3ClF3 C 54.8 H 2.46 Found C 54.8 El 2.5o Example 2 5-(2'-Chloro-4'--trifluoromethylphenoxy)-3 bromo phthalide.
The product of Ex. 1 (1.5g) and ~I-bromo succinimide (0.82g) was dissolved in dry carbon tetrachloride (25 ml) and a small pellet of benzoyl peroxide added. The reac-tion mixture was refluxed with s-tirring under strong light, when succinimide began to precipita-te. The mixture was cooled, filtered, washed with carbon tetrachloride and the solvent removed. Chromatographic separation (silica column; methylene chloride eluant) yielded a pale orange viscous oil as the desired product.
Analysis: Calc for C15H7ClBrF3O3 C 44.2 H 1.7~o Found C 44.2 E~ 1.9%
Example 3 5-~2'-chloro-4'-trifluoromethylphenoxy)-1-thiophthalide The product of Example 1 (1.55g) and phosphorus penta-sulphide (2.2g) were refluxed in sodium dried dioxan (15ml) for 1 hour with stirring. The reaction mixture was cooled, filtered, dried, washed with methylene chloride, and chromatographically purified to yield a pale yellow solid, m.pt. 86-88C.
Analysis Calc for C15H8ClO2SF3 C 52-2 H 2-3 Found C 51.8 H 2.3 12~?~

Example 4 N-Benzyl-5-(2'-nitro-4'-trif] uoromethylph~noxy) phthalimide __ N-Benzyl-5-hydroxyphthalimide (0.84 g.) and potassium hydroxide (0.19 g.) were dissolved in ethanol (50 ml. ) and the solvent was evaporated. The residue was dissolved in dimethyl-sulphoxide (50 ml.) and 4-chloro-3-nitro benzotrifluoride (0.75 g.) was added. The mixture was heated at 180C for six hours and poured into water. The mixture was extracted with ethyl acetate, the ethyl acetate layer was separated, dried and evapora-ted to yield a pale yellow oil. The oil crystallised from ethanol as pale yellow prisms m.pt 166-167C.

Analysis; Calc :~or C22H13F3N2O5 FGund C 59.8 H 3.0 N 6.6 Example 5 N-Benzyl-5-(2'-chloro-4'-trifluoromethylphenoxy) phthalimide Following a similar procedure to that of Example 4, but using 3,4-dichlorobenzotrifluoride in place of 4-chloro-3-nitro-benzotrifluoride, -the desired product was obtained as a white solid m.pt. 119-121C.
Analysis: Calc for C22H13F3ClNO3 C 61.2 H 3.0 N 3.2S%
Found C 61.2 H 2.9 N 3.1%
Example 6 5- (2'-chloro-4'-trifluoromethylphenoxy)-3-hydroxyphthalide The product of Example 2, was refluxed with 20 ml water for 3 days, and the reaction mixture extracted with methylene chloride and dried. Removal of the solvent and chromatographic purification yielded the desired product, m.pt. 145-147C.

~7~
- lla -Analysis: Calc for Cl5~o4clF3 C 52.2 H 2.3%
Found C 51.9 H 2.4~
Example 7 5-(2'-chloro-4'-trifluoromethylphenoxy)-3-methoxy phtilal_cle _ _ __ ~ ) 5~ ydroxy pllthalide (5.5g) was dissolved in ethanol (50ml), 2.5g potassium hydroxide added and the solution refluxed for 3 hours. The solverlt was removed, -the residue dissolved in dimethylsulphoxide (5dml) and 8.2g of 3,4-dichlorobenzotrifluoride added. This mixture was stirred under dry nitrogen at 160C for 18 hours, after which it was cooled, poured on-to ice, neutralised with dilute hydrochloric acid and the product extracted wi-th methylene chloride.
B) The product of A (1.5g) and N-bromo succinimide (0.82g) was dissolved in dry carbon -tetrachloride (25ml) and a small pellet of benzoyl peroxide added. The reaction mixture was refluxed with stirring under strong light, when succinimide began to precipitate. The mixture was cooled, filtered, washed with carbon tetrachloride and the solvent removed. Chromatographic separation (silica column; methylene chloride eluant) yielded a pale orange viscous oil.

127q~B31~

C) me product of B was refluxed with 20ml water for 3 days, and the reaction mixture extracted with methylene chloride and dried. Re~oval of the solvent and chrcmatc~graphic purification yielded 5-(2'-chloro-4'-trifluoromethyl-phenoxy)~3-hydro~y~hthalide ~I.pt. 145-147C. This produc~
is referred to in the follcw~ng Examples 8-10 as "hydroxyphthalide".
D) Hydroxyphthalide prepQred as in steps A)-C) above (1.4g) was refluxed is methanol (20ml) with stirring for 2 hours.
Residual solvent was removed by evaForation, the product chromatographically purified over silica with methylene dichloride eluant to yield a clear oil, which was recrystallised to give the desired product, m.pt. 67c.
Analysis Calc- for C16H1oClF304: C 53.6; H 2.8; Cl 9.9~
Found C 53.6; H 2.9; Cl 9.9%
Example 8 5-l2'-chloro-4~-trifluorcmethylphenoxy)-3 acetoxy phthalide Hydr~xyphthalide, (0.7g) t~as refluxed in acetic anhydride (lOml~ with stirring for 5 hours. Excess acetic anhydride was removed by evaporation, the residue washed with saturated sodium bicarbonate solution, extracted with methylene dichloride and the organic layers washed with bicarbonate and dried with scdium sulphate. The solvent t~as removed, the product chromatographically purified and recrystallised to yield a solid, m.pt. 113C.
Analysis Calc- for Cl ~loClF305: C 52.8; H 2.6%
Found : C 53.0; H 2.7%
Example 9 5-(2'-chloro-4'-trifluoromethylphen~xy)-3-N',N' dimethylureido ~hthalide Hydrox~phthalide (0.7g) t~as added to a solution of 1,1-dimethyl urea (O.?g) in methyl ethyl ketone (2Cml) and the mixture refluxed for 2 hours, after t~hich a f~rther 0.2g of the urea were added. Pfter a further 6 hours reflux, the solvent t~as remov~d, the residue suspended m t~ater and shaken to reve any unre~cted urea, taken up in ethyl acetate and chromatographically purified to yield a ~olid, mOpt. 154C.
BN28.001 Analysis Calc- for Cl8HlaN204ClF3 C 52.7; H 3.4; N 6.8%
Found : C 52.0; H 3.2; N 6.4%
Example 10 _- 2~-chloro-4'-tri~3~lbL~
3,4-dichloroanilino phthalide Hydro~phthalide (1.Og) was adde~ to a solution of 3,4-dichloroaniline (O.Sg) in drv acetonitrile (lOml), and a crystal of p.toluene sulphonic acid added. The mi~ture was refluxed with stirring for 55 hours, the solvent removed, and the residue chromatcgraphically purified to yield a solid, m.pt. 168C.
Analysis Calc. for C~lHllN03C13F3: C 51.6; H 2.2; N 2.9 Fc~nd : C 51.6; H 2.1; N 2.7 Examp.le 11-40 Foll~Ying procedures similar to those described in the foregoing Examples, further compounds were prepared whose characteristics and analyses æe set out in Table 1. In all cases, the identity of the product was confirmed by n.m.r.
analysis. In those instances m æked "m.m.s." the empirical formula was confirmed by accurate mass measurement spectr~metry.
The compounds are identified by reference to substituent R2, A
and s in the follcwing formula:-C /

BN28.001 B;~

d~ d~ rJ~ o`. o~ d~
r-l r-l ~ O ~ I~
~r ~ ~' ~r ~ ~ri ZZ ZZ ZZ

U~ ~' ~r Ln ~ ~O Ln d, ~ Ln G ~ 1 ~ ~ ~D ~0 ~ r~) ~r-l t~ N ~i ~ ~ i ~ r~) (~ ~ ~ ~) ~) ~) ~7 ~ r~) r~ ~ ~C ~ ~C ~ X ~C ~ ~ ;~ ~: ~ ~ ~ ~ ~: :C ~
o ~1 Ln ~ ~ U:~ ~ 1--Ln co cs~ c~ o o~ a~ ~ ~
o a~ ~ ~ ~ ~ ~ ~ ~ ~r It~ ~ Ln Ln ~ ~D
Ln Ln ~o n ~ ~D Ln Ln ~n Ln Ln Ln Ln Ln Ln Ln n n ~) O ~ C~ C~ C~ C) C~ C~ U C~ C~ ~ ~ ~) C ) C~

,, ~ ,~ ,~ ~ r~ oo o ~g ,~ ~g ~`~
~ ~ ~ C ) c_) ~ r~ ~_) t_) C ) m o o ~ o o o o o o ~ ~ ~ ~ C) ~ ~ I~ ~ ~

r~ ~1 t~l ~) ~r U~ ~D 1_ ~70 a~ O
~i r--J ~--1 ~ 1_l ~1 ~ r--~ ~--1 ~

U~ ~ ~ c~ ~-1 ~ ~ C~ 1-- N (`~I i-- CO Il~ ) ~
,1 ~ ~ ~:r ~' ~ ~ ~ ~ ~ ~i ~ ~ ~ ~ ~ ~
~! ~ ;c ~ ;~ I :~ ~ ~ :C ~ ~
~ ,~ ~ ~ a~ CO ~ r~ oo ~ co ,~ o co u~ u~ ~ ~ ~ ~r ~ o ~ r~ o o ~, u~ In u~ ~ r In In u~ u~ In U~ U~ U~ Lt~ n C~ ~_) ~ U ~ C) C~ ~ C~ ~ C~ C~ C~ ~ C~ O

~ ~ ~ ~j ~ ~j ~ ~j ~ ~ ~ ~ ~ r~ ~

. 1~ ~1 l l O~ ~D
Q~ O c~ t'~l ~ 0-1 u-) a~ ~

U') ~

R~ ,~ ,~ ,~ ,1 ,~ ,~ ,~ ,~
~K ~ o r~ r~ r~ r~

o o o o o o o o ~ ~ I ~ l r~
~ ~ 3 ~N 3 8 _ Q 3 ~rl 3 ~ o ~1 ~ ~ ~r In ~ I~ CO

3 ~ 7~

~c l~a~ ~ r~
er~r ~, ~ ~ ~r~
Z Z ~Z Z Z Z Z Z Z ~7;
o a~ Ln (r~ c a~ ~r ~ o ,~ ~ ~ .~ o i ~ ~ ~ ~i r~ ~ ~ ~i ~'! ~ ~ ~ ~ _ ~ . .
I~ u~ ~ t-- ~ In ~ o o co co ~ ~ a~ . .
~ ~\i ~ ) ~ ~ ~r ~r 1` ~O ~ ~ ~ `i E~ E
L~ In ~ n ~ In L~ n u~ In u~ L(l L~
C~ ~ ~ O ~ ~ O
.~ .~ .~ .~ .~ .~ .
u~ ~ ~8 ~8 ~ ~,~ ~ ~ ~ ~ ~,~

t, . o . ~ ~) O O ~ In r-l r-l l r-l ~ ~ C~ ~ er ~ ~ 0 'O ~ 'O

.
~ ~ O ~) r~ r~ ~ rO O ~

~ ~ ~; Z Z ~ O H C f~ O
~3 o~
$~
~ ~ o o ~ ~ ~ ~ ~ ~

~ CO C;~ O ~ ~ ~ ~ U~ ~D
~ ~ ~ ~ ~ ~ ~ ~ r~ r~
~ I q ,~ ~i ~:

c~u v~

~ ~ u u u u a~

~ 1` ~ O

Example 41 EIerbicidal ~c-tivi-ty _ _ _ To evaluate their herbicidal activity, compounds accor-ding to the invention were tested using as representa-tive range of plants: maize, Zea mays (~z); rice, Oryza sa-tiva (R); barnyard grass, Echinochloa crusgalli (BG); oat, Avena sativa (O); linseed, Linum usitatissimum (L); mustard, Sinapsis alba (M); sugar beet, Beta vulgaris (SB) and soya bean, Glycine max (S).
The tests fall into two categories, pre-emergence and post-emergence. The pre-emergence tests involved spraying a liquid formulation of the compound on~o the soil in which the seeds of the plant species mentioned above had recently been sown.
The post-emergence tests involved two types of test, viz., soil drench and foliar spray tests. In the soil drench tests the soil in which the seedling plants of the above species were growing was drenched with a liquid formulation containing a compound of the invention, and in the foliar spray tests the seedling plants were sprayed with such a formulation.
The soil used in the tests was a prepared horticultural loam.
The formu]ations used in the tests were prepared from solutions of the test compounds in acetone containing 0.4% by weight of an alkylphenol/ethylene oxide condensate available under the trade mark TRITON X-155. These acetone solutions were diluted with water and the resulting formulations applied at dosage levels corresponding to 5 kg or 1 kg of active material per hectare in a volume equivalent to 600 litres per hectare in the soil spray and foliar spray test, and at a dosage of level equivalent to 10 kilograms of active material per hectare in a volume equivalent 3~

- 18a -to approximately 3,000 litres per hectare in the soil drench tests.
In the pre-emergence tests untreated sown soil and in the post-emergence tests untreated soil bearing seedling plants were used as controls.
The herbicidal effects of the test compounds were ass-essed visually twelve days after spraying the foliage and the soil, and thirteen days after drenching the soil and were recorded on a 0-9 scale. A rating O indicates growth as untreated control, ~2'7(~ 2 a rating 9 indicates death. An increase of 1 unit on the lin~ar scale appro~imates to a 10% increase in the level of effect.
m e results of ~he tests are set out in Table II below, in which the oomp~unds are identified by reference to the preceding examples.

BN28.001 ~Z7(3~3~

V~ L(l ~ 1 ~
U~ a~ o a~a~ co~l ~ a~co ~ro 1 r` LO O ~) ~ LD O ~D Lfl LD ~) ~r O
a~, OD Lr) O -- Lt~ ~D O LD L(~ O O O O
O CO 1-- O O 1~ t`') LD O ~D L~l LO ~1 O O
~ ~ a~G`. ~0~ ~ C~O ~ C~ ~10 P:; 1~ ~ Lt`, ~ D ~r 1-- 0 ~r ~r CO ~) O O
~ LO O 1~ 0 _ ~r 1-- 0 ~P ~`J Lt~ ~1 5~1 0 U~ ~ a~ U'~ L~ ~ 1~ 00 CO _ c~o~ If~fO _L~ a~ a~ coL~-) coLt~
X a~ 0~9 ~ 7 a~ C;~CIO ~0 COOO
.
U 1~¦ a~ a~ 1~ LD ~0 00 a~ 00 C~ ~ a~ 00 CO L9 L~ O ~I co ~ ~I ~ ~7 co ~9 ~ o~ 1_ ~ Lr'l ~) N ¦ ~ a~ ~ co Lt) CO ~ C5~ CO ~ OD a~ u~ I` ~D
t~; LO ~ t'~l _I er O ~ r 1--~D 1--L~l e~

i~ ~ t~ ~ ~ 1 r~ Ln co co 1~11') Ln L~
o ~ ~ u~ ~ ~ ~ n ~ :~ _I u~ ~ ~ ~ u~

NV~ N ~ ~r O O 1--l Ln ~3 ~D ~r ~ ~r er Ln er ~ ` X D Ln Ln ~ ~r L~') ~_ ~1 1~ L~) U~ ~~ (~1 Ln ~ O
5~ ~1 O Cl~ el~ Ln ~9 1_ ~ ~
O~ CO ~ Ln ~D ~D ~r ~_ 0:~ ~_ L.'~, ~ ~O ~
~0 ~ ~ 1~ t~ LC~ ~ O l_ ~
~9 ~ ~0 ~27~83,Z:
u~ ~a~ oo oo oo oo ,~,~
~ ~a~ r`~D ~D~ L~ 00 ~OD
~ ~ a~ 1- LS) el~ N ~r ~ o o ~
~ ~:1 o~ ~ ~r ~ o o ~ o o ~
~ O a~~ ~ ~,~ oo oo Ll~
~ a~ co~ ~ ~D-n 00 a~co P: a~:\ oo oo oo oo ~o . ~ ~ r~ ~0 00 00 ~0 U~ ~ 1~ u~er ~ ~0~0 ~o~ c~ ~r~ ~9~ ~ c~
a~a~ a~co ~o~r ooln a~ o~
. ~ ~ ~ 0~ ~-D a~ ~n~ c~a~
O O a~a~ o~o u~ ~o~ ~ a~a~
a~co co~r co~ c~co cr~

N ~ co CO ~ ~ ~ .-1 'r ~I ~ ~ ~D
r~ :~! ~ OD 00 ~r 1` ~) ~D ~ ~D IS') Cr~ X
~ ~ ----~ ~ u~ ~ u~ ---u~-~ ~-l ~ ~ U~ If ~ ~ N ~7 O U~
~53 ~ I-~ ~ ~ CD cn o X o~ L~ ~ ~ ~ r-~ ~ co u~ ~ ~ ~O a~
O r~ ~o ~r u~ o a~
.~ ~ co r- t- ~_ o ~
r~ ~r ~r ~r o ~
_ _ _ ~0 ~0 r- oo ~ ,1 _~ ~

~7V8~2, In~ 00 00 ~30 00 00 ~. CO CO ~ CO 1- CO ~D CO ~9 O O
a~ ~ ~ r~ r ~o r~ u~ r ~D ~o ~D o o ~ ~ I_ ~ r ~ ~ r~ r Lr) ~D ~ o o ~ O ~ In~ ~r~ ~ oo oo ~ o~o ~r~ CO~D ~ 00 00 . ~; ~ ~ O O ~-7 0 O O er ~ O O
oo oo ~o ~ oo _ ~n a~ a~ ~co r-l~ coco l-er ~a~ cna~ a~ o~a~ cooo u~er . ~ ~ a~a~ o~a a~a~ o~a~ ~o~
~o~ a~cn ~c~ ~ ~a~ r-~
O ~a~ a~a~ a~ c~co u7u~ u o~ ~co a~~ ~D~ CO~
8 K r ~ r ~D r u~ r ~D u~ u~ ~r ;~ g~ ~ ~ CO CO 0~ 1` I ~0 r` ~D U~ U~ D ~
11~1 IS)~ IS~I 1~ ~1 1~ ~1 1~
_ __ - !
U~ O N ~ N O N
~ g~ ~ a~ o~ c~ 0 ~
o ~E (~1 ~r In ~r N tr) ~ ~ ~ t- 1~ In t~ ~
O I~ I~ I~ ~ ~ U~
_~ ~ r t~ r u~ N I_ Il~ 1~ ~ O ~D
~r ~9 ~ ~ o D ~0 ~0~ _ __ _, _ O
l~i I` CCI ~ N ~1 ~1 u~ oo oo ~o ~o r~o ~o oo 1~1_ r-l- I_t~ 1_0 a~Ln 00 ~D~ ~D ~ ~ ~ ~O O CO~
00 00 00 1_~ 00 CO~D
o oo oo ~,, ~ oo ~o oo ~ COu~ ~ oo ~o~
oo oo oo oo oo ~ oo oo oo oo oo ~ro U~ In U~ CO CO CO ~ ~ ~D ~ ~ a~ ~D
~ r~ o\a~ ~ a~ r-~ ~
~ æ co co a~ ~ r~ ~ a~ ~ co r- c~ ~D
~ ~ oo o~ cOO:~ a~o a:~D a~
O ~ a~r~ I`r oou~ r~ I`~r i~ ~ ~ oo co~ ~D~D CO~ ~D~ a~u~
~ ~; o o ~ ~r u~ ~ ~ ~ ~ ~ ~ ~
~O~D ~ (n~ I

~1 u~,l ~ 1~ m u~ I
t~l U~ O O ~D In O U~
~ ~ o a~ ~D ~ O ~r o ~ o ~r ~ r- o o ~ ~ O ~ ~ ~D O ~9 O O ~ ~ ~o o CO
f 1~ 1~ ~ o a; o ~ ~ ~ o ~
~ ~ ~ ~ ~ ~ ~o ~0~ _ ~ ~' ~ 1- r 1~

12~Q8~

u~ o ¦m ~ o o ~ ~ c o o o U~ O ~ ~ In in In Ir~ O O O O
8 ~ o ~ co ~ oo oo ~ ~ o ~o oo ~ oo oo ~ o o C~ ~ o o o o o o o o O ~ 00 D~ 00 00 ~ o cor~ oo oo oo oo _ ~ o 1~ oo oo oo oo u~ ~ a~ a. el~ ~ In ~ U~ m ~ n ~ a~ ~o ~r 1--In I_ ~ er r~
i~ a~ Ln O~ u)~ ~ m~r t~
~ ~ ~D C~ ~ U~ ~ CO CO CO n I_ ~
O ~ ~ ~ u~r Ln~r ~r !i 1~ ~ ~ a~a~ ~ ~Der Ih~ r`~D

~r o~r~ U~Ul ~r~
o~u~ U~ ~D~r ~ l~

~r R ~ _ m ~ ~ ~ u~ _l ~ ~1 u~ ~ ~n U~ In ~ O O O
:~ g3 r~ ~ ~ c o ol ~ t- ~ o o o ~ ~ ~ o o o ~
.~ O co O ~ o ~r ~ ~ a~ ~ r~ o ~

1~; CO o o o ~
_~ _ =~ o o o ~ o ~-0~
=~ , 1~ ~o co O a~ N
l 3 ~ ~ ~ ~ ~ N ~1 U~ 1`0 CO~X~
~co a~
X u~r a~
C0~9 G~
~ O C~CO COI-~ ~c~ ~a~

N O ~ ~
l~D
.. ~ . a~co a~
~ ~ O ~a~ o~a~

N 1~ 8 a~ a~ a~ cn _ . a~ co CD
. ~ o~ C~
r~ o ~0~ c~ ~n ~

Claims (15)

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

1. A herbicidal composition which comprises a liquid carrier comprising a surface-active agent or a solid carrier and, as active ingredient, a diphenyl ether derivative having the general formula I:

(I) wherein R1 represents a hydrogen or halogen atom or a C1-10 alkyl or C1-6 haloalkyl group;
R2 and R3, which may be the same or different, each inde-pendently represent a hydrogen or halogen atom or a C1-10 alkyl, C1-6 haloalkyl, nitro or cyano group;
A represents a divalent group,selected from -X-, ?C(R4)2 and ?C=X;
B represents a divalent group selected from ?C(R4)2;
-X-; ?N-R5; ?C=X and ?SO2, provided that when A represents -X-, then B must be different from A and cannot represent ?C=X;
each R4, which may be the same or different, represents a hydrogen or halogen atom or an optionally substituted C1-10 alkyl, C 3-10 cycloalkyl, C1-10 alkenyl, C1-10 alkynyl, phenyl, benzyl, C1-10 alkyl subsituted phenyl, C1-10 alkoxy, C3-10 cyclo-alkoxy, C1-10 alkenyloxy, C1-10 alkynyloxy, C1-10 alkoxycarbonyl-C1-10 alkoxy, C1-10 alkylthio, C1-10 acyl, carboxyl, C1-10 alkoxy-carbonyl, C1-10 acyloxy or pyrrolyl, pyrolidinyl, pyridyl, piperidyl, furyl or pyranyl, wherein the optional substituents are selected from halogen, nitro, cyano, hydroxy, alkoxy and ester groups derived from organic acids, an amino group of formula NR6R7, or when one R4 represents a hydrogen atom, a C1-4 alkoxy group or an above mentioned hydrocarbon group, then the other may represent a hydroxyl group, or both groups R4 together may represent an imino group of formula =NR5;
R5 represents a hydrogen atom, a carboxyl or hydroxyl group, or an optionally substituted C1-10 alkyl, C1-10 alkoxy, benzyl, C1-10 alkoxycarbonyl or C1-10 alkoxycarbonyl C1-10 alkyl group, wherein the optional substituents are selected from halogen, nitro, cyano, hydroxy, alkoxy and ester groups derived from organic acids, or an amino group of formula NR6R7;
R6 and R7, which may be the same or different, each repre-sents a hydrogen atom or an optionally substituted C1-10 alkyl, phenyl or C1-10 alkanoyl group, wherein the optional substituents are selected from halogen, nitro, cyano, hydroxy, alkoxy and ester groups derived from organic acids; and X, both in formula I and in the definitions of the substi-tuents therein, represents an oxygen or sulphur atom.

2. Compositions as claimed in claim 1 wherein the active ingredient is a compound of general formula I, wherein X represents an oxygen atom;
A represents an oxygen atom, a carbonyl group, the group C(R4)2 wherein one group R4 is a hydrogen atom, an alkyl or alkoxy group of up to 4 carbon atoms, or a phenyl group, and the other group R4 is a hydrogen or halogen atom, a hydroxyl group, an alkyl group of up to 4 carbon atoms, an alkoxy group of up to 4 carbon atoms, optionally substituted by a halogen atom, or a hydroxyl or alkoxy group of up to 4 carbon atoms, a cycloalkoxy group of 5 to 8 carbon atoms, an alkenyloxy or alkynyloxy group of up to 6 carbon atoms, an alkoxycarbonylalkoxy group with up to 4 carbon atoms in the alkoxy moieties, an alkylthio group of up to 4 carbon atoms, an alkanoyl group of up to 4 carbon atoms, a pyridyl group, or an amino group of formula NR6R7 wherein R6 represents a hydrogen atom or an alkyl group of up to 4 carbon atoms and R7 represents an alkyl group of up to 4 carbon atoms, a phenyl group optionally substituted by at least one halogen atom, or an alkylcarbonyl group with up to 4 carbon atoms in the alkyl moiety; and B represents an oxygen atom, the group C(R4)2 wherein each group R4, which may be the same or different, independently repre-sent a hydrogen atom or an alkyl or alkoxy group of up to 4 carbon atoms, or the group NR5 wherein R5 represents a hydrogen atom, an alkyl group of up to 4 carbon atoms, a benzyl group, or an alkoxycarbonylalkyl group of up to 8 carbon atoms.

3. Compositions as claimed in claim 2 wherein B represents an oxygen atom and A represents the group C(R4)2 in which R4 is as defined in claim 2.

4. Compositions as claimed in claim 1, 2 or 3 wherein R1 represents a trifluoromethyl group, R2 represents a halogen atom, and R3 represents a hydrogen atom.

5. A composition as claimed in claim 1, 2 or 3 which comprises at least two carriers, at least one of which is a surface-active agent.

6. A composition as claimed in claim 1, 2 or 3 wherein R1 represents a trifluoromethyl group, R2 represents a halogen atom, and R3 represents a hydrogen atom which comprises at least two carriers, at least one of which is a surface-active agent.

7. A diphenyl ether derivative of the formula I as shown in claim 1, wherein the substituents have the meanings defined in claim 1, with the exception of 4-(2-chloro-4-trifluoromethyl-phenoxy)phthalic anhydride, 5-(4-trifluoromethylphenoxy)phthalic anhydride and compounds in which R1 represents a hydrogen atom, a chlorine atom or a methyl group, R2 and R3 each represent a hydrogen atom, A represents >C=O, X represents an oxygen atom and B represents > NR5 (where R5 is methyl or phenyl), > CHR4 (where R4 is phenyl) or -O-.

8. A diphenyl ether derivative of the formula I as defined in claim 1, 2 or 3, wherein R1 represents a trifluoromethyl group, R2 represents a halogen atom, and R3 represents a hydrogen atom with the exception of 4-(2-chloro-4-trifluoromethylphenoxy) phthalic anhydride.

9. A process for the preparation of a diphenyl ether of the formula I as defined in claim 1 with the exception of 4-(2-chloro-4-trifluoromethylphenoxy) phthalic anhydride, 5-(4-trifluoro-methylphenoxy)phthalic anhydride and compounds in which R1 repre-sents a hydrogen atom, a chlorine atom or a methyl group, R2 and R3 each represent a hydrogen atom, A represents >C=O, X repre-sents an oxygen atom and B represents >NR5 (where R5 is methyl or phenyl), >CHR4 (where R4 is phenyl) or -O- which comprises reacting a phthalide of formula II:

(II) with a compound of the formuIa III:

(III) wherein - 30a - 70474-152 A, B, X, R1, R2 and R3 have the meanings defined in claim 1;
and one of Z and Q represents a halogen atom or nitro group and the other represents a group of formula -OM wherein M represents a hydrogen or alkali metal atom, followed, when the thiophthalide is required, by reaction with phosphorus penta-sulphide, or when the desired compound is a halo or hydroxy methylene group by reaction with a halogenating agent and, for the hydroxymethylene derivative, hydrolysis of the resultant halo-methylene derivative with the proviso that when the reaction of the compound of formula II with the compound of formula III is not followed by reaction with phosphorus pentasulphide to obtain the thiophthalide then, in the starting materials, R1 cannot be tri-fluoromethyl when A is >C=O, B is -O-, X is O and one of R2 and R3 is chlorine and the other is hydrogen.

10. A process as claimed in claim 9 wherein the initial reaction is carried out by reacting a compound of formula II wherein Q is hydroxy with an alkali metal hydroxide in an alkanol solvent, followed by reaction of the resultant alkoxide with a com-pound of formula III wherein Z represents a chlorine atom.

11. A process as claimed in claim 10 wherein the reaction of the alkoxide with the chloro compound III is carried out in an organic solvent at elevated temperature and under an inert atmos-phere.

12. Method of combating undesired plant growth at a locus, which comprises treating the locus with a composition as claimed in claim 1, 2 or 3.

13. Method of combating undesired plant growth at a locus, which comprises treating the locus with a composition as claimed in claim 1, 2 or 3 wherein R1 represents a trifluoromethyl group, R2 represents a halogen atom, and R3 represents a hydrogen atom.

14. Method of combating undesired plant growth at a locus, which comprises treating the locus with a compound of the formula I

as defined in claim 1, 2 or 3 with the exception of 4-(2-chloro-4-trifluoromethylphenoxy) phthalic anhydride, 5-(4-trifluoro-methylphenoxy)phthalic anhydride and compounds in which R1 repre-sents a hydrogen atom, a chlorine atom or a methyl group, R2 and R3 each represent a hydrogen atom, A represents >C=O, X repre-sents an oxygen atom and B represents >NR5 (where R5 is methyl or phenyl), >CHR4 (where R4 is phenyl) or -O-.

15. Method of combating undesired plant growth at a locus, which comprises treating the locus with a compound of the formula I as defined in claim 1, 2 or 3 wherein R1 represents a trifluoromethyl group, R2 represents a halogen atom, and R3 represents a hydrogen atom with the exception of 4-(2-chloro-4-trifluoromethylphenoxy) phthalic anhydride, 5-(4-tri-fluoromethylphenoxy)phthalic anhydride and compounds in which R1 represents a hydrogen atom, a chlorine atom or a methyl group, R2 and R3 each represent a hydrogen atom, A represents >C=O, X
represents an oxygen atom and B represents >NR5 (where R5 is methyl or phenyl), >CHR4 (where R4 is phenyl) or -O-.