Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D213/00—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members
  • C07D213/02—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members
  • C07D213/04—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom
  • C07D213/60—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
  • C07D213/62—Oxygen or sulfur atoms
  • C07D213/63—One oxygen atom
  • C07D213/68—One oxygen atom attached in position 4
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D213/00—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members
  • C07D213/02—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members
  • C07D213/04—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom
  • C07D213/60—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
  • C07D213/61—Halogen atoms or nitro radicals

Definitions

• This invention relates to brominated and iodinated fiuoro-4-pyridinol derivatives having herbicidal properties, to methods for their manufacture and to herbicidal compositions containing the said brominated and iodinated fluoro-4-pyridinol derivatives.
• the 4-hydroxypyridine may contain bromine and fluorine or iodine and fluorine substituent only or may additionally contain other substituents for example chlorine.
• the 4-hydroxypyridine carries substituents 111 each of the 2, 3, 5 and 6 positions of the ring, but the invention also includes compounds having an unsubstituted ring position, that is to say a ring position occupied by a hydrogen atom.
• Preferred compounds according to the invention are those having fluorine atoms in the 2- and/or 6-positions of the pyridine ring.
• Especially preferred compounds are those set forth in Table 1 below, and salts, esters and ethers thereof.
• Compound No. 9 comprises a 1:1 mixture of 3-bromo-2- chloro-6-fiuoro 4 hydroxy 5 iodopyridine and 5- bromo-2-chloro-6-fluoro-4-hydroxy-3-iodopyridine.
• Salts according to the invention include metal salts, for example, alkali metal salts, alkaline earth metal salts, and amine salts, for example salts formed from primary, secondary and tertiary alkylamines in which the alkyl groups preferably have from 1 to 4 carbon atoms.
• Ethers according to the invention comprise compounds in which the hydrogen atom of the 4-hydroxy group of the 4-hydroxypyridine is replaced by an etherifying radical comprising an unsubstituted or substituted hydrocarbyl group.
• Preferred etherifying radicals are aliphatic radicals, particularly alkyl radicals of from 1 to 4 carbon atoms, op-
• Esters according to the invention are compounds in which the hydrogen atom of the 4-hydr0xy group of the 4-hydroxypyridine is replaced by an esterifying radical comprising an acyl group.
• Preferred acyl groups are alkylcarbonyl and alkylsulphonyl groups particularly those having from 2 to 4 carbon atoms and l to 4 carbon atoms respectively.
• Bromofiuoroand iodofluoro-4-hydroxypyridines or salts thereof may conveniently be prepared from the corresponding 4-fiuoro derivatives by conventional methods, for example, by hydrolysis with an alkali metal hydroxide. It is preferred, however, to prepare the bromofluoroand iodofluoro-4-hydroxy compounds of the invention by reacting the corresponding 4-fluoro derivatives with a metal carboxylate in a non-hydroxylic solvent.
• the bromo-fluoro derivatives required as intermediates may conveniently be prepared by vapour phase bromine.- tion of the appropriately substituted fiuoropyridine, or by conventional methods.
• the iodofiuoropyridine derivatives required as intermediates may be prepared by iodination of the appropriate fluoropyridine in the presence of fuming nitric acid.
• the processes used to prepare the compounds of the invention usually provide the compounds in the form of their metal salts.
• the free 'bromofluoroor iodoiluoro-4-hydroxypyridines may be obtained from their metal salts, for example, by hydrolysis of the metal salts with water (i.e.
• the free bromofluoroor iodofluoro-4-hydroxypyridine so obtained my be converted into a salt which may be the same or dilferent from the salt obtained as described above, by conventional methods such as neutralisation with an alkali metal hydroxide.
• the invention provides a method of inhibiting the growth of unwanted vegetation which comprises applying to the locus of the vegetation, or the locus of seeds thereof, a bromofluoroor iodofiuoro-4- hydroxypyridine or a salt, ester or ether thereof as hereinbefore defined.
• a bromofluoroor iodofiuoro-4- hydroxypyridine or a salt, ester or ether thereof as hereinbefore defined.
• the amount of bromofiuoro or iodofluoro- 4-hydroxypyridine applied will depend for example on the particular 4-hydroxy compound chosen for use and the identity of the vegetation to be treated.
• the compounds of the invention are applied at the rate of from 0.2 to 10 kilograms per hectare. A rate of from 1 to 5 kilograms per hectare is particularly preferred.
• the compounds of the invention are capable of inhibiting the growth of a wide variety of plants.
• the compounds In general for a given rate of application, the compounds have a greater herbicidal effect when applied to the foliage of plants than when applied to soil containing the seeds of plants whose germination and growth it is desired to inhibit.
• Application to soil may nevertheless be preferred in some circumstances, for example when it. is desired to take advantage of the selective herbicidal. action which the compounds display in certain crops.
• Compounds of the invention may be used selectively to inhibit the growth of weeds in cereal crops, for example rice, and in cotton.
• the compounds of the invention are applied in admixture with a carrier.
• the invention provides a herbicidal composition comprising as an active ingredient a bromofluoroor iodofluoro-4-hydroxypridine or a salt, ester or ether thereof as hereinbefore defined, in admixture with a carrier comprising a solid or liquid diluent.
• the herbicidal composition further comprises a surface active agent.
• compositions according to the invention include both compositions which are ready for immediate use and concentrated compositions which require to be diluted before use.
• the compositions contain from 0.01% to 90% by weight of the active ingredient.
• Dilute compositions ready for use preferably contain from 0.01% to 2% of the active ingredient, while concentrated compositions may contain from 5% to 90% of active ingredients although from 20% to 70% is usually preferred.
• Solid compositions may be in the form of a powder in which the active ingredient is mixed with a solid diluent.
• Suitable solid diluents include, for example, Fullers earth, powdered kaolin, gypsum, chalk and kieselguhr.
• Liquid compositions may comprise a solution or dispersion of an active ingredient in water optionally containing a surface active agent, or may contain a solution or dispersion of an active ingredient in an organic diluent, which may optionally contain a surface active agent.
• Another form of liquid composition comprises a solution of an active ingredient in a water immiscible solvent which is dispersed as droplets in water.
• Examples of surface-active agents which may be used in the compositions of the invention include the products of condensation of ethylene oxide with the following substances: alkyl substituted phenols for example p-octyl phenol and p-nonyl phenol: sorbitan monolaurate; oleyl alcohol, and propylene oxide polymer.
• alkyl substituted phenols for example p-octyl phenol and p-nonyl phenol: sorbitan monolaurate; oleyl alcohol, and propylene oxide polymer.
• a particular example of such a surface active agent is the condensate of p-nonyl phenol with from 7 to 8 molar proportions of ethylene oxide sold under the name of Lissapol NX (LissapoP is a trademark).
• Other surface active agents include calcium dodecylbenzenesulphonate and calcium, sodium and ammonium lignosulphonates. The choice of a suitable surface active agent is of course within
• compositions of the invention are conveniently transported and stored as concentrates, which are compositions containing a high proportion of active ingredient, and which therefore require to be diluted, usually with water, before application.
• a particularly preferred form of concentrate comprises a salt of a bromofiuoro or iodofiuoro-4-hydroxypyridine dissolved in water containing a surface active agent.
• the salt is an alkali metal salt, for example the potassium salt.
• Another form of concentrate comprises a "wettable powder that is to say, a mixture of the finely divided active ingredient with a solid surface active agent, either with or without the addition of a solid diluent.
• a wettable powder that is to say, a mixture of the finely divided active ingredient with a solid surface active agent, either with or without the addition of a solid diluent.
• the surface active agent assists in the dispersion of the finely divided active ingredient.
• the compounds according to the invention may be applied in conjunction with other herbicidal agents, either in combination or sequentially.
• the invention provides a herbicidal composition
• a herbicidal composition comprising a bromofiuoroor iodofluoro-4- hydroxypyridine in admixture with a herbicide which is a diazine, a triazine, a urea, a carbamate, an amide, a phenol, a nitrile, a benzoic acid, a phenoxyalkanoic acid, a nitro-aniline or a bipyridylium quaternary salt.
• a herbicide which is a diazine, a triazine, a urea, a carbamate, an amide, a phenol, a nitrile, a benzoic acid, a phenoxyalkanoic acid, a nitro-aniline or a bipyridylium
• composition further comprises a diluent or carrier.
• EXAMPLE 1 This example illustrates the preparation of 3,5-dibromo- 2,6-difiuoro-4-hydroxypyridine.
• the starting materials for compounds 2, 3 and 4 were prepared by vapour phase bromination of 2,4-difluoropyridine; 2,4,5,6 tetrafluoro 3 chloropyridine; and 3,5 dichloro 2,4,6 trifl'uoropyridine respectively.
• the remaining starting materials were prepared as follows:
• 6-Chloro-3,5-dibromo-2,4-difluoropyridine A mixture of 6-chloro-2,4-difiuoropyridine (15 g.) bromine (30 g.) and fuming nitric acid (45 ml.) was heated under reflux for 24 hours. The mixture was poured into water and extracted with methylene chloride, and the extracts washed with sodium hydroxide solution. Evaporation of the extracts and distillation of the residual oil gave 6 chloro 3,5 dibromo 2,4 difiuoropyridine (25.2 g.) having a melting point of 46 C. when recrystallised from chloroform.
• 3,5-Diiodotrifiuoropyridine A mixture of 2,4,6-trifiuoropyridine (20 g.) iodine g.) and fuming nitric acid ml.) was heated under gentle reflux for 12 hours. The mixture was poured into water and extracted with methylene chloride. The extracts were washed with aqueous potassium iodide solution and water. Evaporation of the solvent and recrystallisation from petroleum ether (b.p.
• EXAMPLE 4 This Example illustrates the selective herbicidal effect of several compounds according to the invention. For comparison, the results of tests wtih 3,5-dichloro-2,6-difiuoro- 4-hydroxypyridine, disclosed as a herbicide in UK. Patent Specification 1,161,491, are included. This compound is referred to in Table 3 below by its: common name, haloxydine. Plots of ground were sown with seeds of the plant species listed in Table 3 below. On the day after sowing, the plots were sprayed with aqueous solutions of the potassium salts of the compounds listed in the table. The volume of spray solution applied was 400 litres per hectare, and the solution contained 0.1% by weight of Agral as a wetting agent.
• EXAMPLE 5 This Example illustrates the selective herbicidal activity of 3-bromo 5 chloro-2,6-difluoro 4 hydroxy pyridine (compound No. 4 of Table 1) against couch grass (Agropyron repens) growing among barley plants.
• couch grass Agropyron repens
• haloxydine 3,5-dichloro- 2,6-difluoro-4-hydroxypyridine
• three single pieces of couch grass and five barley seeds were sown 1 centimetres deep in separate 3 inch pots.
• the pots were then sprayed with haloxydine and with compound No. 4 of Table 1, both in the form of aqueous solutions of their potassium salts containing 0.1% of Agral 90 as a wetting agent. After spraying a further layer of soil (0.5 centimetres thick) was placed over the sprayed surface.
• the soil used was a compost comprising:
• the damage to the plants was assessed 21 days after spraying, on a scale of 0 to 100 where 0 is no effect and 100 is complete kill.
• EXAMPLE 7 This Example illustrates the pre-emergence and postemergence herbicidal activitiy of compounds according to the invention.
• the preand post-emergence tests were carried out as described in Example 3, using as the plant growth medium the compost described in Example 5.
• the damage to the plants was assessed 28 days after spraying, on a scale of 0 to 9 where 0 is no effect, and 9 is complete kill. The results are given in Table 6 below.
• the compounds of the present invention are relatively more active by post-emergence application than by pre-emergence application, while the previously known herbicide haloxydine is only slightly less active when applied as a preemergence spray than when applied to foliage. As compared with haloxydine therefore, the compounds of the present invention have the advantage that they may be useful as post-emergence sprays to control weeds in orchard or plantation crops.
• a selective herbicidal pyridine compound selected from the group consisting of 2-fluoro-3,5,6-tribromo-4- 9 10 hydroxy-pyridine, 2,5,6-trifluoro 3 br0mo-4-hydr0xy- References Cited pyridine, 2,6 difluoro 3 bromo-4-ch1oro-4-hydroxy- UNITED STATES PATENTS pyridine, 2 fluoro 3,5 dibromo-6-ch1oro-4-hydroxypyridine and 2,6-difluoro-3,5-diodo-4-hydroxy-pyridine, 3249419 5/1966 Martm 260 297 R 3,545,955 12/1970 Bracknell 26(]-297 R and the alkyl ethers of 1 to 4 carbon atoms 1n the alkyl 5 3 654 292 4/1972 R b 260 29 R radical of the said substituted 4-hydroxypyridines. o erts 7 2.
• a herbicidal pyridine compound according to claim 1 which is S-bromo-S-chloro-2,6-difluoro-4-hydroxypyri- 10 dine. 260295 R, 270 R; 71-94 ALAN L. ROTMAN, Primary Examiner

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Pyridine Compounds (AREA)
• Agricultural Chemicals And Associated Chemicals (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (11)

Cited By (3)

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• 0
  • BE BE787805D patent/BE787805A/xx unknown
• 1972
  • 1972-03-15 GB GB1208172*[A patent/GB1403195A/en not_active Expired
  • 1972-08-11 AU AU45501/72A patent/AU4550172A/en not_active Expired
  • 1972-08-14 US US00280198A patent/US3850943A/en not_active Expired - Lifetime
  • 1972-08-14 IL IL40128A patent/IL40128A0/xx unknown
  • 1972-08-23 IT IT28423/72A patent/IT964189B/it active
  • 1972-08-24 DE DE2241665A patent/DE2241665A1/de active Pending
  • 1972-08-24 EG EG347/72*UA patent/EG10573A/xx active
  • 1972-08-24 FR FR7230199A patent/FR2150499B1/fr not_active Expired
  • 1972-08-25 NL NL7211614A patent/NL7211614A/xx unknown
  • 1972-08-25 JP JP47084686A patent/JPS4828640A/ja active Pending

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