GB2050168A

GB2050168A - Ethynyl compounds as herbicides

Info

Publication number: GB2050168A
Application number: GB8011108A
Authority: GB
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 1979-04-04
Filing date: 1980-04-02
Publication date: 1981-01-07
Also published as: GB2050168B

Abstract

A method of controlling undesired plant growth at a locus, which comprises applying to that locus a ketone of the general formula <IMAGE> in which A represents a thienyl group, or a phenyl group which may be unsubstituted or substituted by one or more of the same or different substituents selected from halogen atoms, hydroxy, nitro, alkyl, haloalkyl, alkenyl, alkoxy and alkenyloxy groups, and phenoxy and benzyloxy groups which may be unsubstituted or substituted by one or more of the same or different substituents selected from halogen atoms and hydroxy, nitro, alkyl, haloalkyl, alkenyl, alkoxy and alkenyloxy groups.

Description

SPECIFICATION Ethynyl compounds as herbicides This invention relates to a method of controlling undesired plant growth, to a composition for use in this method, to novel compounds have herbicidal properties and to a method of making said compounds.

The invention provides a method of controlling undesired plant growth at a locus, which comprises applying to that locus a ketone of the general formula

in which A represents a thienyl group, or a phenyl group which may be unsubstituted or substituted by one or more of the same or different substituents selected from halogen atoms, hydroxy, nitro, alkyl, haloalkyl, alkenyl, alkoxy and alkenyloxy groups, and phenoxy and benzyloxy groups which may be unsubstituted or substituted by one or more of the same or different substituents selected from halogen atoms and hydroxy, nitro, alkyl, haloalkyl, alkenyl, alkoxy and alkenyloxy groups.

Preferably any alkyl or alkenyl moiety present in the group A has up to 8, preferably up to 4, carbon atoms. Any halogen atom is preferably a bromine, fluorine or, especially, chlorine, atom.

A haloalkyl group is preferably a trifluoromethyl group.

A preferred group of compounds is that in which A represents a thienyl group, an unsubstituted phenyl group or a phenyl group substituted by one or more of the same or different substituents at least one of which is an optionally-substituted phenoxy or benzyloxy group or a nitro, haloalkyl, alkenyl or alkenyloxy group; especially preferred are those compounds in which A represents a phenyl group substituted, preferably monosubstituted, by a phenoxy group which may be unsubstituted or substituted by one or more of the same or different substituents selected from chlorine atoms and hydroxy, nitro, trifluoromethyl, C(1-4) alkyl and C(1-4) alkoxy groups.

A second preferred group of compounds is that in which A represents a phenyl group substituted by 1 or more, preferably 1 or 2, substituents at least one of which is present in the 2-position.

The ketone of the general formula I may be applied to the locus to be treated as such, but is preferably applied in the form of a composition which also contains one or more carriers. The invention also provides a herbicidal composition which comprises a carrier and, as active ingredient, a ketone of the general formula I in which A represents a thienyl group or a phenyl group which is substituted by one or more of the same or different substituents selected from halogen atoms, hydroxy, nitro, alkyl, haloalkyl, alkenyl, alkoxy and alkenyloxy groups, and phenoxy and benzyloxy groups which may be unsubstituted or substituted by one or more of the same or different substituents selected from halogen atoms and hydroxy, nitro, alkyl, haloalkyl, alkenyl, alkoxy and alkenyloxy groups with the proviso that A does not represent a 3,4,5trimethoxy group or a phenyl group bearing in the 3 and/or 4 positions 1 or 2 substituents selected from halogen atoms and hydroxy, alkyl and alkoxy groups.

Certain of the ketones of the general formula I are novel, and the present invention therefore provides a ketone of the general formula I in which A represents a phenyl group which is substituted by one or more of the same or different substituents selected from halogen atoms, hydroxy, nitro, alkyl, haloalkyl, alkenyl, alkoxy and alkenyloxy groups, and phenoxy and benzyloxy groups which may be unsubstituted or substituted by one or more of the same or different substituents selected from halogen atoms and hydroxy, nitro, alkyl, haloalkyl, alkenyl, alkoxy and alkenyloxy groups with the proviso that A does not represent a 3,4,5-trimethoxy group or a phenyl group bearing in the 3 and/or 4 positions 1 or 2 substituents selected from halogen atoms and hydroxy, alkyl and alkoxy groups, or a 2-methoxyphenyl, 2-hydroxyphenyl, 2-chlorophenyl, 4-methoxyphenyl, 4-chlorophenyl or 4-nitrophenyl group, or any phenyl group bearing a 4-hydroxy substituent.

The ketones of the general formula I may be prepared by oxidising the corresponding alcohol (A-CHOH-CCH). Any suitable oxidising agent may be used, for example chromium trioxide or manganese dioxide. Chromium trioxide in the presence of acetic acid or, especially, sulphuric acid, is an especially useful reagent. The reaction is preferably carried out in the presence of an inert solvent at a temperature in the range of from - 20 to 50"C, preferably from - S to 20"C.

Suitable solvents for chromium trioxide include hydrocarbons or ketones, for example benzene or, preferably, acetone. Suitable solvents for manganese dioxide include ethers, ketones, esters and halogenated hydrocarbons, for example methylene chloride or ethyl acetate.

The corresponding alcohol used as starting material may for example be prepared by reaction of an acetylide, such as sodium acetylide, or an ethynyl Grignard reagent such as ethynyl magnesium bromide, with the aldehyde of the general formula A-CHO. The reaction is preferably carried out using tetrahydrofuran as solvent, suitably at a temperature in the range of from - 20 to 50"C, preferably from - 5 to 20"C. Normally air and moisture are excluded from the reaction mixture by carrying out the reaction under an inert atmosphere, for example of nitrogen.

The compounds of the general formula I also exhibit fungicidal activity against a range of fungal diseases, including vine downy mildew and rice leaf blast. 2,4-dimethyoxypropiolophenone and 4-nitropropiolophenone are especially active. For example, 2,4-dimethoxypropiolophenone has translaminar activity against Plasmopora v., activity against Botrytis c. (on leaves and grapes) and protectant activity against Phytophtora i.

A carrier in a composition 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 form a liquid, and any of the carriers normally used in formulating herbicidal compositions may be used.

Suitable solid carriers include natural and synthetic clays and silicates, for example natural silicas such as diatomaceous earths; magnesium silicates, for example talcs; magnesium aluminium silicates, for example attapulgites and vermiculites; aluminium silicates, for example kaolinites, montmorillonites and micas; calcium carbonate; calcium sulphate; synthetic hydrated silicon oxides and synthetic calcium or aluminium 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, for example beeswax, paraffin wax, and chlorinated mineral waxes; and solid fertilisers, for example superphosphates.

Suitable liquid carriers include water; alcohols, for example isopropanol and glycols; ketones, for example acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ethers; aromatic or araliphatic hydrocarbons, for example benzene, toluene and xylene; petroleum fractions, for example kerosine and light mineral oils; chlorinated hydrocarbons, for example carbon tetrachloride, perchloroethylene and trichloroethane. Mixtures of different liquids are often suitable.

Herbicidal compositions are often formulated and transported in a concentrated form which is subsequently diluted by the user before application. The presence of small amounts of a carrier which is a surface-active agent facilitates this process of dilution. Thus preferably at least one carrier in a composition according to the invention is a surface-active 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 lignin sulphonic acids; the condensation products of fatty acids or aliphatic amines or amides containing at least 1 2 carbon atoms in the molecule with ethylene oxide and/or propylene oxide; fatty acid esters of glycerol, sorbitan, sucrose or pentaerythritol; condensates of these with ethylene oxide and/or propylene oxide; condensation products of fatty alcohol phenols, for example poctylphenol or poctylcresol, with ethylene oxide and/or propylene 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 carbon atoms in the molecule, for example sodium lauryl sulphate, sodium secondary alkyl sulphates, sodium salts of sulphonated castor oil, and sodium alkylaryl sulphonates such as sodium dodecylbenzene sulphonate; and polymers of ethylene oxide and copolymers of ethylene oxide and propylene oxide.

The compositions of the invention may for example be formulated as wettable powders, dusts, granules, solutions, emulsifiable concentrates, emulsions, suspension concentrates and aerosols.

Wettable powders usually contain 25, 50 and 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 formulated as a dust concentrate having a similar composition to that of a wettable powder but without a dispersant, and are diluted in the field with further solid carrier to give a composition usually containing 3-10% 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 manufactured by agglomeration or impregnation techniques. Generally, granules will contain i-25% w active ingredient and 0-10% w of additives such as stabilisers, slow release modifiers and binding agents.

Emulsifiable concentrates usually contain, in addition to a solvent and, when necessary, cosolvent, 10-50% w/v active ingredient, 2-20% w/v emulsifiers and 0-20% w/v of other additives such as stabilisers, penetrants and corrosion inhibitors. Suspension concentrates are usually compounded so as to obtain a stable, non-sedimenting flowable product and usually contain 10-75% w active ingredient, 0.5-15% w of dispersing agents, 0.1-10% w of suspending agents such as protective colloids and thixotropic agents, 0-10% w of other additives such as defoamers, corrosion inhibitors, 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 antifreeze agents for water.

Aqueous dispersions and emulsions, for example compositions obtained by diluting a wettable powder or a concentrate according to the invention with water, also lie within the scope of the present invention. The said emulsions may be of the water-in-oil or of the oil-in-water type, and may have a thick 'mayonnaise'-like consistency.

The compositions of the invention may also contain other ingredients, for example, other compounds possessing pesticidal, herbicidal or fungicidal properties.

The following Examples illustrate the invention. The identities of the products were confirmed by NMR and infra-red spectroscopy and by elemental analysis.

Example 1-Preparation of 2-ethoxypropiolophenone (i) A solution of ethynyl magnesium bromide (0.12 mole) in tetrahydrofuran (80 ml) was stirred at 0-5"C and treated dropwise with a solution of 2-ethoxybenzaldehyde (15.0 g) in tetrahydrofuran (50 ml). After four hours at ambient temperature, the reaction mixture was diluted with diethyl ether (250 ml) and saturated aqueous ammonium chloride (250 ml), shaken thoroughly, and the aqueous phase separated and re-extracted with diethyl ether (200 ml). The combined ethereal extracts were washed with brine, dried over sodium sulphate and evaporated to dryness under reduced pressure. The residue was chromatographed over silica gel using graded elution from toluene to methylene chloride.Later fractions gave 11.5 g of 2-ethoxy-aethynylbenzyl alcohol as an oil corresponding to a 65% yield. (Elemental Analysis: Found: C 75.4; H 6.9; C"H,202 requires: C 75.0; H 6.9%).

(ii) A solution of 2-ethoxy-cu-ethynylbenzyl alcohol (4.0 g) in acetone (50 ml) was stirred at 0-5'C and treated dropwise with a solution of chromium trioxide (1.5 g) in a mixture of water (4.4 ml) and concentrated sulphuric acid (1.3 ml). After 1 hours at 0-5"C, the solution was diluted with water (500 ml) and extracted with diethyl ether (2 X 200 ml). The combined extracts were washed five times with water and once with brine, dried (Na2SO4) and evaporated to give an orange oil (3.8 g). This was dissolved in methylene chloride and filtered through silica gel. Evaporation of the eluate gave 3.7 g of 2-ethoxypropiolophenone as a yellow oil, corresponding to 93% yield. (Elemental analysis: Found: C 75.7; H 6.0; C"H,002 requires: C 75.8; H 5.8%).

Example 2-Preparation of 4-(4 '-chloro)-phen oxy-propioloph enone (i) A solution of 4-chlorophenol (14.1 g) in xylene (125 ml) was stirred under nitrogen and to it was added a solution of sodium (2.65 g) in methanol (45 ml). The mixture was heated to reflux and xylene disfilled out, with continuous replacement by fresh, dry xylene until the total distillate was 200 ml. The mixture was cooled, cuprous chloride (3.0 g) and pyridine (50 ml) were added and the temperature was raised to boiling point. A solution of 4-bromobenzaldehyde (18.5 g) in xylene (25 ml) was added dropwise and the mixture was refluxed for 4 hours.It was then cooled, poured into water (250 ml) and diethyl ether (250 ml), acidified with dilute HCI and the ethereal solution separated, washed four times with dilute HCI, once with aqueous NaHCO3 and once with brine, dried (Na2SO4) and evaporated under reduced pressure to give an oil (26.7 g). This was distilled at 1.0 mm Hg until the distillate had a boiling point of 120"C.

The residue was then chromatographed over silica gel to give 4-(4'-chloro)phenoxybenzaldehyde as a crystalline solid (18.3 g), melting point 51-53", in 79% yield. (Elemental analysis: Found: C 67.5; H 4.2; Cl 15.2; C,3HgCI02 requires: C 67.1; H 3.9; Cl 15.2%).

(ii) 4-(4'-chloro)phenoxybenzaldehyde (16.0 g) in tetrahydrofuran (50 ml) was reacted with ethynyl magnesium bromide (0.077 mol) in tetrahydrofuran (50 ml) in the same way as described in Example 1 (i) above. 4-(4'-chloro)phenoxy-a-ethynylbenzyl alcohol was obtained as a crystalline solid (12.5 g), melting point 84-86"C, in 70% yield. (Elemental analysis: Found: C 70.1; H 4.3; Cl 14.1; C,5H"02 requires: C 69.6; H 4.3; Cl 13.7%).

(iii) 4-(4'-chloro)phenoxy-a-ethynylbenzyl alcohol (5.0 g) in acetone (50 ml) at 0-5"C was treated with a solution of chromium trioxide (1.3 g) in a mixture of water (3.8 ml) and concentrated sulphuric acid (1.1 ml). The reaction was worked up as described in Example 1 (ii) above to give 4-(4'-chloro)phenoxypropiolophenone as a pale yellow crystalline solid (4.6 g), melting point 72-74"C in 93% yield. (Elemental analysis: Found: C 70.1; H 3.4; Cl 13.5%; C,5HgCI02 requires: C 70.2; H 3.5; Cl 13.8%).

Examples 3 to 32 By methods analogous to those described in Examples 1 and 2, the following compounds were prepared

Elemental Analysis Example Calculated Found No. X C H C H 3 3-phenoxy 81.1 4.5 81.6 4.6 4 3-(CH2 = CH-CH2-O-) 76.6 5.3 77.3 5.7 5 3-(2-nitro-4-trifluoromethyl) 57.3 2.4 56.3 2.6 phenoxy (N:4.2) (N:4.0) 6 3-benzyloxy 81.4 5.1 81.4 5.5 7 3-(3,5-dimethylphenoxy) 81.6 5.6 81.6 6.0 8 3-(4-nitrophenoxy) 67.4 3.4 66.9 3.5 (N:5.2) (N::5.3) 9 4-phenoxy 81.1 4.5 10 2-phenoxy 81.1 4.5 80.9 4.7 11 3-(3-chlorophenoxy) 70.2 3.5 69.1 3.7 12 3-(3-trifluoromethylphenoxy) 69.1 3.2 69.9 4.0 1 3 3-(4-methoxyphenoxy) 76.2 4.8 14 2,4-dimethoxy 69.5 5.3 69.1 5.2 15 4-(4-methoxyphenoxy) 76.2 4.8 76.6 4.8 16 4-(2-methoxyphenoxy) 76.2 4.8 76.6 4.6 17 4-(2,4-dimethylphenoxy) 81.6 5.6 79.8 5.7 18 2,3-dimethoxy 69.5 5.3 69.1 5.4 19 2-octyloxy 79.0 8.6 79.2 8.8 20 4-(3,4-dichlorophenoxy) 61.9 2.8 61.9 . 2.7 (Cl:24.35) (Cl:24.6) 21 2,6-dichloro 54.3 2.0 54.3 1.9 (Cl:35.6) (Cl:35.8) 22 2-methoxy-5-chloro 61.7 3.6 62.1 3.7 (Cl::18.2) (18.2) 23 2-methoxy 5-bromo 50.2 2.95 50.6 2.9 24 4-(2,4dichlorophenoxy) 61.9 2.8 62.3 3.1 25 2-nitro 61.7 2.9 61.7 2.7 (N:8.0) (7.8r 26 3-methyl 83.3 5.6 27 2-methoxy 75.0 5.0 74.8 5.1 28 2-hydroxy 74.0 4.1 74.1 4.3 20 H 81.5 4.6 30 2-chloro 65.7 3.1 65.8 3.0 31 4-nitro 61.7 2.9 71.4 2.6 (N:8.0) (N:7.8) 32 Compound prepared: 61.7 3.0 60.7 2.9 ethynyl 2-thienyl ketone Example 33-Herbicidal activity To evaluate their herbicidal activity, compounds according to the invention were tested using as a representative range of plants: maize, Zea mays (Mz); rice, Oryza sativa (R); barnyard grass, Echinochloa crusgalli (BG); oat, Avena sativa (0); linseed, Linum usitatissimum (L); mustard, Sinapsis alba (M); sugar beet, Beta vulgaris (SB) and soya bean, Glycine max (S). The tests conducted were foliar spray tests, in which seedling plants were sprayed with a formulation containing the test compound.

The soil used in the tests was a steam sterilised, modified John Innes Compost mixture in which half the peat, by loose bulk, had been replaced by vermiculite.

The formulations used in the tests were prepared by diluting with water, solutions of the test compounds in acetone containing 0.4% by weight of an alkylphenol/ethylene oxide condensate available under the trade name TRITON X-1 55. The acetone solutions were diluted with an equal volume of water and the resulting formulations applied at dosage levels corresponding to 5 and 1 kg of active material per hectare in a volume equivalent to 400 litres per hectare.

Untreated seedlings plants were used as controls.

The herbicidal effects of the test compounds were assessed visually seven days after spraying the foliage and were recorded on a 0-9 scale. A rating 0 indicates no effect on the treated plants, a rating 2 indicates a reduction in fresh weight of stem and leaf of the plants of approximately 25%, a rating 5 indicates a reduction of approximately 55%, a rating 9 indicates a reduction of 95%, etc.

The results of the tests are set out in the table below.

Compound of Phytotoxicity Rating Foliar Spray Example Dosage No. (Kg/ha) Mz R BG O L M SB S 1 5 2 1 6 2 8 8 6 6 1 0 0 2 0 2 3 3 6 2 5 3 3 5 0 5 7 4 7 1 0 0 2 0 3 3 1 4 3 5 2 2 2 7 7 5 5 8 1 0 2 0 5 0 2 2 3 4 5 1 0 0 2 0 6 5 1 5 5 5 0 0 2 0 6 3 3 4 1 0 0 0 0 0 0 0 2 6 5 0 0 2 0 5 4 2 4 1 0 0 0 0 0 0 0 2 7 5 0 0 1 0 5 3 4 3 1 3 1 3 8 5 2 0 4 2 5 5 3 6 1 0 0 1 1 3 1 0 2 9 5 5 5 6 4 8 8 9 7 1 2 0 3 1 5 4 4 5 10 5 3 2 4 3 8 4 7 6 1 0 0 1 1 5 2 0 3 11 5 3 3 4 1 4 4 6 6 1 1 2 2 0 3 1 1 2 12 5 4 5 5 2 7 6 6 5 1 1 0 2 0 3 0 2 3 13 5 3 1 4 2 6 5 5 5 1 0 0 1 1 4 3 3 3 14 5 4 0 5 3 8 7 8 5 1 0 0 4 0 3 2 7 4 15 5 4 0 6 1 5 5 0 5 1 0 0 0 0 0 2 0 2 17 5 0 0 0 0 6 3 2 6 1 0 0 0 0 2 2 0 2 18 5 4 3 5 1 9 8 7 8 1 0 1 2 0 5 3 4 5 19 5 4 0 2 1 5 2 2 6 1 1 0 0 0 2 0 0 4 20 5 1 0 0 3 0 6 2 0 3 21 5 0 2 5 1 8 8 5 7 1 0 0 1 0 4 4 0 5 22 5 0 1 4 0 9 4 7 9 1 23 5 1 1 2 0 8 6 5 4 1 0 0 0 4 3 1 2 24 5 0 0 7 2 5 4 3 6 1 0 0 6 0 3 4 3 5 25 5 3 0 7 0 8 8 6 8 0 0 0 2 0 4 5 3 7 26 5 0 0 0 0 7 9 7 8 Compound of Phytotoxicity Rating Foliar Spray Example Dosage No. (Kg/ha) Mz R BG O L M SB S 1 0 0 0 0 5 4 5 6 27 5 6 4 8 5 9 9 9 9 1 2 1 3 3 7 7 6 7 28 5 3 0 5 1 6 5 2 4 1 0 0 0 0 0 0 0 0 30 5 4 2 8 5 8 9 6 5 1 2 0 3 2 7 8 5 6 31 5 3 0 7 2 7 6 3 6 1 0 0 6 0 6 4 0 5 32 5 1 4 5 4 9 9 9 8 1 0 0 3 3 8 9 5 6 29 5 5 5 7 5 8 9 9 8 1 0 4 2 4 5 7 4 5

Claims

1. A method of controlling undesired plant growth at a locus, which comprises applying to that locus a ketone of the general formula

2. A method as claimed in Claim 1, in which A represents a phenyl group substituted by one or more of the same or different substituents at least one of which is an optionallysubstituted phenoxy or benzyloxy group or a nitro, haloalkyl, alkenyl or alkenyloxy group.

3. A method as claimed in Claim 2, in which A represents a phenyl group monosubstituted by a phenoxy group which may be unsubstituted or substituted by one or more of the same or different substituents selected from chlorine atoms and hydroxy, nitro, trifluoromethyl, C(1-4) alkyl and C(1-4) alkoxy groups.

4. A method as claimed in any one of claims 1 to 3, in which A represents a phenyl group substituted by 1 or 2 of said substituents, at least one of which is present in the 2-position.

5. A method as claimed in Claim 1, which comprises applying to the locus a ketone of the general formula I named in any one of the Examples herein.

6. A herbicidal composition which comprises a carrier and, as active ingredient, a ketone of the general formula I given in Claim 1, in which A represents a thienyl group or a phenyl group which is substituted by one or more of the same or different substituents selected from halogen atoms, hydroxy, nitro, alkyl, haloalkyl, alkenyl, alkoxy and alkenyloxy groups, and phenoxy and benzyloxy groups which may be unsubstituted or substituted by one or more of the same or different substituents selected from halogen atoms and hydroxy, nitro, alkyl, haloalkyl, alkenyl, alkoxy and alkenyloxy groups with the proviso that A does not represent a 3,4,5-trimethoxy group or a phenyl group bearing in the 3 and/or 4 positions 1 or 2 substituents selected from halogen atoms and hydroxy, alkyl and alkoxy groups.

7. A herbicidal composition as claimed in Claim 6, which comprises a ketone of the general formula I as defined in any one of claims 2 to 4.

8. A herbicidal composition as claimed in claim 6, which comprises a ketone of the general formula I named in any one of Examples 1 to 25, 27, 28 and 30 to 32 herein.

9. A herbicidal composition as claimed in any one of claims 6 to 8, which comprises at least two carriers, at least one of which is a surface-active agent.

10. A ketone of the general formula I given in Claim 1, in which A represents a phenyl group which is substituted by one or more of the same or different substituents selected from halogen atoms, hydroxy, nitro, alkyl, haloalkyl, alkenyl, alkoxy and alkenyloxy groups, and phenoxy and benzyloxy groups which may be unsubstituted or substituted by one or more of the same or different substituents selected from halogen atoms and hydroxy, nitro, alkyl, haloalkyl, alkenyl, alkoxy and alkenyloxy groups with the proviso that A does not represent a 3,4,5trimethoxy group or a phenyl group bearing in the 3 and/or 4 positions 1 or 2 substituents selected from halogen atoms and hydroxy, alkyl and alkoxy groups or a 2-methoxyphenyl, 2hydroxyphenyl, 2-chlorophenyl, 4-methoxyphenyl, 4-chlorophenyl or 4-nitrophenyl group, or any phenyl group bearing a 4-hydroxy substituent.

11. A ketone as claimed in claim 10, in which A represents a phenyl group substituted by one or more of the same or different substituents at least one of which is an optionallysubstituted phenoxy or benzyloxy group or a haloalkyl, alkenyl or alkenyloxy group.

1 2. A ketone as claimed in claim 11, in which A represents a phenyl group monosubstituted by a phenoxy group which may be unsubstituted or substituted by one or more of the same or different substituents selected from chlorine atoms and hydroxy, nitro, trifluoromethyl, C(1-4) alkyl and C(1-4) alkoxy groups.

13. A ketone as claimed in claim 10 and named in any one of Examples 1 to 25 herein.

14. A process for the preparation of a ketone as claimed in any one of claims 10 to 13, which comprises reducing the corresponding alcohol.

15. A process as claimed in claim 14, carried out substantially as described in either Example 1 or Example 2 herein.