5-IMINOMETHYL-HALOACYLOXAZOLIDINES HAVING AN INHIBITING ACTION ON THE PHYTOTOXICITY OF HERBICIDES

Abstract: Compounds of formula: where R is alkyl having from 1 to 8 carbon atoms, alkenyl, cyclohexyl or arylalkyl; R₁ is alkyl having from 1 to 8 carbon atoms, alkenyl, cyclohexyl or arylalkyl; R and R₁ being apt to form a -(CH₂)- n group. These compounds can be used as phytotoxicity antidotes for thiol­ carbamate and/or acetanilide herbicides for use on maize cultivations.

Description: There are known to be numerous thiolcarbamate and acetanilide herbicides which are highly effective against weeds infesting maize fields. However, these herbicides are frequently phytotoxic towards maize. On the other hand, those infesting weeds most difficult to destroy are not sufficiently controlled by herbicides which are less phytotoxic towards maize, as certain derivatives of the S-triazine or substituted urea families. It is therefore very important to provide antidotes particularly effective in inhibiting the phytotoxicity of the thiolcarbamates and acetanilides used as selective herbicides for maize. It is known from literature that various classes of products having this inhibiting action exist. Among the successfully tested compounds described in literature (EP 0021759, or British Patent 2043447) there are variously substituted haloacyloxazolidines(EP-A-136016; US-A-3959304). The present invention relates to a haloacyloxazolidine family never previously described in literature, namely 5-iminomethyl-haloacyloxazoli-dines, having the general formula: where R is alkyl having from 1 to 8 carbon atoms, alkenyl, cyclohexyl or arylalkyl; R₁ is alkyl having from 1 to 8 carbon atoms, alkenyl, cyclohexyl or arylalkyl. These compounds are very effective as phytotoxicity antidotes or inhibitors both towards thiolcarbamate herbicides, such as: di-propyl-S-ethyl-thiolcarbamate (EPTC) di-isobutyl-S-ethyl-thiolcarbamate (Butylate) di-propyl-S-propyl-thiolcarbamate (Vernolate), and towards acetanilide herbicides, such as: 2-chloro-N-(ethoxymethyl)-2'-methyl-6'-ethyl acetanilide (ACETOCHLOR) 2-chloro-N-(pyrazol-1-yl-methyl)-2', 6'-dimethylacetanilide (METAZACHLOR) The compounds of formula (I) according to the invention are synthesized in accordance with the following reactions: The reaction 1) between epichlorhydrin and secondary amine may be preferably carried out in 1-5 hours, at a temperature of between 70° and 100°C, without the need to use solvents. The reaction 2) between compound (II) and potassium phthalimide may be advantageously carried out in an alcohol at a temperature of between 65° and 80°C, in 5-10 hours. The reaction 3) between compound (III) and hydrazine may be preferably carried out in an alcohol at a temperature of between 65° and 80°C in 2-4 hours. The reaction 4) between compound (IV) and acetone may be suitably carried out by azeotropic distillation of the water formed, using an organic solvent capable of forming an azeotrope with water. The reaction 5) between compound (V) and dichloroacetyl chloride may be preferably carried out in an organic solvent, normally that used in the preceding reaction 4), in the presence of an acid acceptor (NaOH, KOH, tertiary amines or others) at a temperature of between -10° and +10°C in 15 minutes - one hour. The compounds of formula (I) can be mixed with the aforesaid active herbicide substances to obtain new selective herbicide compositions for maize cultivations. These herbicide compositions can also contain other selective maize herbicides such as S-triazine herbicides (for example atrazine, simazine, terbutylazine, cyanazine), substituted urea herbicides (for example linuron, metabenzthiazuron), dinitroaniline herbicides (for example pendimethalin), or other herbicides. These herbicide compositions are obtained by mixing and possibly grinding the active substances with inert substances and adjuvants, and can be formulated either as water-emulsifiable liquids or as fluid suspensions (for example, water-based or organic solvent-based "flowables"). They can also be prepared in the form of granular compounds or as dry or wettable powders. The formulation methods for such herbicide compositions are well known to the expert in the art, as are the type of inert substances (liquids or solids) to be used and the various most suitable adjuvants. The ratio between antidote compounds of formula (I) and active thiolcarbamate and/or acetanilide herbicide substances, phytotoxic to maize, can vary within very wide limits, but is generally between 1:1 and 1:160. Herbicide compositions containing compounds of formula (I) with thiolcarbamate and/or acetanilide herbicides can be used before sowing the maize, generally by incorporation into the soil by means of suitable equipment, whereas herbicide compositions containing compounds of formula (I) and herbicide acetanilides can also be used on the soil surface after sowing the maize, without further incorporation, but being careful to use them within a few days from sowing (and anyhow before birth of the infesting weeds, i.e. at their initial appearance on the soil surface). The aforesaid herbicide compositions are distributed over maize fields by suitable equipment, so as to generally apply a total quantity of herbicides plus antidotes, which may vary from 1 to 17 kg. of active substances per hectare. A further method of application of the antidote compounds of formula (I) is to treat maize seeds before sowing, and then sowing the seeds treated with antidote compounds in fields which have already been deweeded with phytotoxic thiolcarbamate and/or acetanilide herbicides, or in fields which are to be deweeded, after sowing, with phytotoxic acetanilide herbicides. If used for seed treatment, the compounds of formula (I) are formulated in suitable liquid, fluid or powder compositions comprising active substances mixed with inert liquids or solids and/or adjuvants, well known to experts in the art, the compositions containing from 1 to 99% of active substances. The preparations obtained in this manner are applied to the seeds by standard equipment available in agriculture, using from 12.5 grams to 400 grams of antidotes per 100 kg of seeds. The examples given hereinafter allow to better illustrate the invention, but without limiting it in any way. PREPARATION EXAMPLE 1 Preparation of 2.2-dimethyl-N-dichloroacetyl-5-diisobutylamino methyl oxazolidine 129.2g of diisobutylamine are reacted for 3 hours at 80°C with 101.7 g of epichlorhydrin. After purifying by distillation, 199.5 g of N-(3-chloro-2-ol) propyl diisobutylamine are obtained. This product is then reacted at 80°C for 10 hours with 166.5 g of potassium phthalimide in 450 ml of anhydrous ethanol. After filtering off the formed potassium chloride, the mass is concentrated and left to crystallize. 261 g of N-(3-diisobutylamino-2-olpropyl) phthalimide are obtained. The product obtained is hydrolysed by reaction for 3 hours at 80°C in 1600 ml of ethanol with 44.1 g of hydrazine monohydrate. After acidification with hydrochloric acid, the ethyl alcohol is distilled off, adding water. The phthalhydrazide is separated by filtration. The 3-diisobutyl-2-ol-propylamine is recovered from the mother liquors by alkalising with NaOH and extracting with toluene. After drying with toluenic mass, 91 g of acetone are added and the mixture is heated to boiling, azeotropically distilling off the water formed in the reaction. In this manner a toluenic solution of 0,2-dimethyl-5-diisobutylaminomethyl oxazolidine is obtained, which is reacted with 121 g of dichloroacetylchloride and 110 g of 30% NaOH, at 0-5°C, for 30 minutes. Water is added to dissolve the sodium chloride formed. The organic layer is separated from the aqueous layer, and the solvent is removed by distillation to obtain 235 g of 2,2-dimethyl-3-dichloroacetyl-5-diisobutylamino methyl oxazolidine, in the form of a yellow-brown oil partially solid at ambient temperature. The IR, NMR, elementary and gas chromatography analyses have confirmed the structure of the product obtained. This product is indicated hereinafter by the code number 0134. PREPARATION EXAMPLES 2-9 The following products were synthesized using the method described in Example 1: 2,2-dimethyl-3-dichloroacetyl-5-ethyl cyclohexylamino methyl oxazolidine 200.1 g obtained (code number: 0 135) 2,2-dimethyl-3-dichloroacetyl-5-dimethylamino methyl oxazolidine 248.5 obtained (code number: 0 170) 2,2-dimethyl-3-dichloroacetyl-5-di-n-octylamino methyl oxazolidine 283.8 g obtained (code number: 0 171) 2,2-dimethyl-3-dichloroacetyl-5-di-n-propylamino methyl oxazolidine 139.8 obtained (code number: 0 187) 2,2-dimethyl-3-dichloroacetyl-5-di-sec-butylamino methyl oxazolidine 215.4 obtained (code number: 0 182) 2,2-dimethyl-3-dichloroacetyl-5-diallylamino methyl oxazolidine 77.04 g obtained (code number: 0 186) A water-emulsifiable liquid is obtained, which can be used for seed treatment. Analogous compositions can be obtained using the compounds of Preparation Examples 2-9. APPLICATION EXAMPLE 1 Aqueous emulsions of the herbicides indicated in the following Table A are distributed over plastic bowls containing sandy loam soil, the emulsions being mixed before use with aqueous emulsions of compounds of formula (I), prepared in accordance with the preceding Formulation Examples, the quantities being widely varied. After distributing the mixtures of herbicides and compounds of formula (I), these products are incorporated by being mixed with the soil to a depth of 10 cm. ALBION maize is then sown together with infesting weed seeds, the bowls being then kept in a greenhouse at temperatures suited for maize and weed growth, irrigating every two days. 30 days after sowing, one observes the phytotoxicity level on the maize and weed growths emerging from the soil, said level being considered by the E.W.R.S. (European Weed Research Society) scale, as follows: Level 1 = no phytotoxicity, healthy plants Level 2 = about 2.5% phytotoxicity Level 3 = about 5% phytotoxicity Level 4 = about 10% phytotoxicity Level 5 = about 15% phytotoxicity Level 6 = about 25% phytotoxicity Level 7 = about 35% phytotoxicity Level 8 = about 62.5% phytotoxicity Level 9 = plants totally destroyed. In the following Table A, the infesting weeds considered are: 1. Echinochloa crus galli 2. Setaria viridis 3. Amaranthus retroflexus 4. Chenopodium album TABLE A Results of phytotoxicity levels 1-9, observed 30 days after sowing - by the E.W.R.S. method - on ALBION maize and various infesting weeds sown on soil treated with various mixtures of herbicides and compounds of formula (I). The results reported in Table A clearly indicate that mixtures of formula (I) compounds with herbicides, which are normally phytotoxic towards maize when not containing the formula (I) compounds, eliminate maize phytotoxicity or reduce it to negligible levels, without reducing effectiveness towards weeds. APPLICATION EXAMPLE 2 In plastic bowls containing sandy loam soil - kept in a greenhouse and irrigated every two days - one sows maize of the DEKALB XL 69 variety and seeds of various infesting weeds, and the next day the soil surface is sprayed with mixtures of aqueous acetochlor emulsions and aqueous emulsions of formula (I) compounds, prepared in accordance with the preceding Formulation Examples, the quantities being widely varied. 30 days after sowing, the phytotoxicity 1-9 towards maize and infesting weeds is considered by the E.W.R.S. method (as described in detail in the preceding example). The results observed are reported in the following Table B, in which the compound code numbers have the same meaning as in the preceding Table A. TABLE B Phytotoxicity 1-9 considered by the E.W.R.S. method 30 days after sowing, having used herbicide mixtures of acetochlor and formula (I) compounds one day after sowing. The results reported in Table B clearly indicate that compounds of formula (I) eliminate phytotoxicity of ACETOCHLOR or reduce it to negligible levels when used after sowing, but before appearance of the maize and infesting weeds, without reducing the effectiveness of the herbicide towards weeds. APPLICATION EXAMPLE 3 Aqueous emulsions of herbicides phytotoxic towards maize are distributed in various quantities - as reported in the following Table C - over plastic bowls containing sandy loam soil, in which infesting weed seeds have been placed, said herbicides being then incorporated into the soil to a depth of 10 cm. Maize seeds of the ISCHIA variety are separately treated with aqueous emulsions of formula (I) compounds, prepared as indicated in the preceding Formulation Examples, using decreasing quantities of compounds per weight unit of seeds. These seeds, treated with antidote compounds, are sown in the bowls treated with the various herbicides, and the phytotoxicity 1-9 towards maize and weeds is considered after 30 days by the E.W.R.S. method (as described in detail in Application Example 1). The results observed are reported in the following Table C, in which the compound code numbers have the same meaning as in Tables A and B. TABLE C Phytotoxicity 1-9 considered by the E.W.R.S. method, 30 days after sowing, using herbicide mixtures of acetochlor and formula (1) compounds one day after sowing. The results reported in Table C clearly indicate that the compounds of formula (I), when applied directly to maize seeds, eliminate or reduce to negligible levels the phytotoxicity of thiolcarbamate or acetanilide herbicides used before maize sowing and incorporated into the soil, without reducing their effectiveness towards weeds.

Claims: Compounds of formula: where R is alkyl having from 1 to 8 carbon atoms, alkenyl, cyclohexyl or arylalkyl; R₁ is alkyl having from 1 to 8 carbon atoms, alkenyl, cyclohexyl or arylalkyl. A method for synthesizing the compounds of formula: where R is alkyl having from 1 to 8 carbon atoms, alkenyl, cyclohexyl or arylalkyl; R₁ is alkyl having from 1 to 8 carbon atoms, alkenyl, cyclohexyl or arylalkyl; characterised in that it is carried out in accordance with the following reactions: A synthesis method as claimed in claim 2), wherein the reaction 1) between epichlorhydrin and secondary amine is carried out in 1-5 hours, at a temperature of between 70° and 100°C, without the need to use solvents. A synthesis method as claimed in claim 2), wherein the reaction 2) between compound (II) and potassium phthalimide is carried out in an alcohol at a temperature of between 65° and 80°C, in 5-10 hours. A synthesis method as claimed in claim 2), wherein the reaction 3) between compound (III) and hydrazine is carried out in an alcohol at a temperature of between 65° and 80°C in 2-4 hours. A synthesis method as claimed in claim 2), wherein the reaction 4) between compound (IV) and acetone is carried out by azeotropic distillation of the water formed, using an organic solvent capable of forming an azeotrope with water. A synthesis method as claimed in claim 2), wherein the reaction 5) between compound (V) and dichloroacetyl chloride is carried out in an organic solvent, normally that used in the preceding reaction 4), in the presence of an acid acceptor (Na0H, KOH, tertiary amines or others), at a temperature varying between 10° and +10°C, in 15 minutes ÷ one hour. A selective herbicide composition for maize, containing compounds of formula: where R is alkyl having from 1 to 8 carbon atoms, alkenyl, cyclohexyl or arylalkyl; R₁ is alkyl having from 1 to 8 carbon atoms, alkenyl, cyclohexyl or arylalkyl; R and R₁ being apt to form a -(CH₂)- n group; together with thiolcarbamate and/or acetanilide herbicides and inert substances. A composition as claimed in claim 8), wherein the compound of formula (I) is 2,2-dimethyl-3-dichloroacetyl-5-diisobutylamino methyl oxazolidine, and the herbicide is di-propyl-S-ethyl-thiolcarbamate. A composition as claimed in claim 8), wherein the compound of formula (I) is 2,2-dimethyl-3-dichloroacetyl-5-diisobutylamino methyl oxazolidine, and the herbicide is di-isobutyl-S-ethyl-thiolcarbamate. A composition as claimed in claim 8), wherein the compound of formula (I) is 2,2-dimethyl-3-dichloroacetyl-5-diisobutylamino methyl oxazolidine, and the herbicide is 2-chloro-N-(ethoxymethyl)-2′-methyl-6′-ethyl acetanilide. A composition as claimed in claim 8), wherein the ratio between compounds of formula (I) and thiolcarbamate and/or acetanilide herbicides is between 1:1 and 1:160. A method for the selective deweeding of maize cultivations, consisting in using - in quantities varying from 1 to 17 kg/ha of active substances - a herbicide composition containing compounds of formula: where R is alkyl having from 1 to 8 carbon atoms, alkenyl, cyclohexyl or arylalkyl; R₁ is alkyl having from 1 to 8 carbon atoms, alkenyl, cyclohexyl or arylalkyl; R and R₁ being apt to form a -(CH₂)- n group; together with thiolcarbamate and/or acetanilide herbicides and inert substances. A maize seed treatment composition, containing from 1 to 99% of the compounds of formula (I) claimed in claim 1). A method for deweeding maize fields by using thiolcarbamate and/or acetanilide herbicides which are phytotoxic towards maize, together with maize seeds treated with antidote compounds of formula (I), as claimed in claims 8) and/or 14), in quantities of between 12.5 g and 400 g per 100 kg of seeds.

Inventors: RONCHI, NELLO
Applicants: OXON ITALIA S.P.A.
Application year: 1987
Main classification: C07D263
IPC codes: A01N25, C07D263, A01N43