GB2135993A - Herbicidal and acaricidal dinitrophenol derivatives - Google Patents

Abstract

2-Trifluoromethyl-4,6-dinitro-phenol compounds of formula (I> <IMAGE> wherein X stands for hydrogen, alkali metal, alkaline earth metal, C1-10 alkyl, alkylcarbonyl, alkenylcarbonyl, phenylcarbonyl, halogen-substituted phenylcarbonyl or halophenyl or a group of the general formula (a> <IMAGE> wherein R1, R2 and R3 are the same or different and can stand for hydrogen, alkyl, alkoxyalkyl, alkenyl hydroxyalkyl, cycloalkyl, phenyl or substituted phenyl, have herbicidal, acaricidal or crop regulating properties.

Description

SPECIFICATION Phenol, derivatives thereof, processes for their preparation and compositions containing them The present invention relates to new 2-trifluoromethyl-4, 6-dinitro-phenol and derivaties thereof, herbicidal, acaricidal and crop regulating compositions containing same as active ingredient and process for the preparation of the compounds.

The new 2-trifluoromethyl-4,6-dinitro-phenol and derivatives thereof can be characterised by the general formula I

wherein X stands for hydrogen alkali metal, alkali earth metal, C1 10 alkyl, alkyl-or alkenyl-carbonyl, phenyl-carbonyl, halogen-substituted phenylcarbonyl, halophenyl, or a group of the general formula (a) H N R, R2 R3 (a) wherein R1, R2 and R3 are the same or different and stand for hydrogen, alkly, alkoxyalkyl, alkenyl, hydroxyalkyl, phenyl or substituted phenyl.

The compounds of the general formula I show herbicidial and acaricidal and crop regulating activity.

The preferred forms of substituent X in the compound of Formula I are: alkylcarbonyl, e.g. methyl-, ethyl- or propyl-carbonyl; alkenylcarbonyl, e.g. vinylcarbonyl, isopropenylcarbonyl or allylcarbonyl; halophenyl, e.g. chlorophenyl or 2,4-dichiorophenyl; and the group of Formula (a) in which R1, R2, R3 are the same or different and stand for: alkyl, e.g. methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl or sec.butyl; alkoxyalkyl, e.g. methyloxyathyl or ethoxyethyl; alkenyl, e.g. allyl, 2-methyl-allyl; hyd roxyalkyl, e.g. 2-hydroxyethyl; cycloalkyl, e.g. cyclopentyl or cyclohexyl; substituted phenyl, e.g. 2-trifluoromethylphenyl, 3-trifluoromethylphenyl, 2-chloro-5-trifluoro methylphenyl; or 3-trifluoromethyl-4-chloro-phenyl.

The compounds can be formulated to herbicidal, acaricidal or crop regulating compositions which preferably contain 0.1 to 80% by weight of active ingredient and the usual carriers and excipients.

The compositions may be prepared in the form of emulsifiable concentrates, aqueous suspensions, spray in the form of dust, oily paste, granulates etc., The present invention further provides a process for the preparation of the compounds of the general formula I by alkaline hydrolysis of 2-chloro-3,5-dinitro-benzotrifluoride in aqueous medium without catalyst, and if desired, followed by the conversion of the obtained phenolate to the end product by method known per se.

The structurally similar 2-methyl-4, 6-dinitrophenol, i.e. the so-called dinitro-ortho-cresol/ DNO- C/and alkali metal salts thereof are known to show herbicidal and acaricidal activity.

Known compositions containing such active ingredients are Novenda and Krezonit. Similarly 2-sec.-butyl-4,6-dinitro-phenol /DNBP/ of similar chemical structure is a known herbicide, used at smaller dosis as biostimulator in corn cultures /Ohlrogge, A.J.: the Development of DNBP /Dinoseb/ as a Biostimulant for Corn in Plant Growth Reguiators, editor: Stutte, C.A. 79-87 pp. Advances in chemistry series, 1 59. American Chemical Society, Washington, 1977./ No technical reference could be found concerning the preparation or bioiogical activity of the compounds of the general formula I according to the invention only for similar compounds. In GB PS 1 378 994 the preparation of 2,4-bis-/trifluoromethyi/-6-nitro-phenol and derivatives thereof is disclosed.In US PS 3813446 the preparation of 2,6-dinitro-4-trifluoromethyl-phenol and derivatives thereof is described. The known processes are performed in an organic solvent, optionally in the presence of phasis transfer catalysts. In said processes undesired side-reactions take place, such as ether derivative formation in methanol or hydrolysis of the trifluoromethyl group into carboxylic group. According to the present invention no such side reactions occur.

The process of the invention is suitable for the preparation of the compounds of the general formula I at industrial scale economically and in pure state.

We have also found that the new compounds show a surprisingly good biological activity.

After subjecting the various compositions of the invention containing the new compounds as active ingredient we have found that new herbicidal, acaricidal and crop regulating compositions were obtained.

When preparing the compounds of the general formula I-wherein X stands for hydrogen, alkali metal, alkali earth metal, C,1O alkyl, or alkenylcarbonyl, phenylcarbonyl, halogensubstituted phenylcarbonyl, or a group of the general formula /a/, wherein R1, R2 and R3 are the same or different and stand for hydrogen, alkyl, alkoxyalkyl, alkenyl, hydroxyalkly, cycloalkyl, phenyl or substituted phenylne may proceed by first preparing an alkali metal or alkali earth metal phenolate by reacting 2-chloro-3,5-dinitro-benzotrifluoride with alkali metal or alkali earth metal hydroxide.The reaction is conducted in an aqueous medium without catalyst at 20-100"C, preferably at 60-80"C at an alkali concentration of 5 to 20 % by weight preferably 10 to 1 5 % by weight. The phenolate formed during the alkaline hydrolysis is, if desired, converted to phenol with an acid by method known per se. The phenol is, if desired, converted to a phenolate derivative by using a base corresponding to the substituents of the general formula I latter being used as pesticidal active ingredient after isolation from the mixture.

The pesticidal composition is prepared by using the conventionally used carriers and excipients. The active ingredient content can vary within a range of 0.1 to 80 % by weight depending on the formulation type and method of application. The composition is used as herbicide, acaricide or crop regulating agent.

The process of the invention is simple, economical and reproduceable and suitable for the preparation of the new compounds of the invention which broaden the selection of pesticide agents due to their bioactivity.

The details of the invention are illustrated by the following Examples which serve merely for illustration and not for limitation.

Preparation of the compounds of the general formula I.

Example 1 To a 1000 cm3 flask equipped with a stirrer, dropping funnel, reflux and thermometer 300 g /0.75 mole/ of a 10 % by weight NaOH solution are added. 81.3 g /0.3 mole/ of 2-chloro 3,5-dinitro-benzotrifluoride of a purity of 95 % are added under stirring. The temperature is raised to 60 C and the reaction mixture is stirred at 60-65 "C for 4 hours, while the aqueous suspension forms an emulsion. The reaction mixture is then cooled to room temperature /20-25 "C/ under stirring and within 1 hour a 37 % hydrochloric acid solution corresponding to 0.82 mole HCI is added in equal portions under vigorous stirring.The precipitated product is filtered, washed with water and dried to constant weight at room temperature. 2-Trifluoromethyl-4,6-dinitro-phenol is obtained /68.19., purity: 94 %/ Identification was carried out by a mass spectrometer connected to a gas chromatograph.

Yield: 90 %.

Example 2 To 250 1 enamelled reactor equipped with a mixer, and reflux 60 kg. of water are added and under stirring 32.5 kg. of 2-chloro-3,5-dinitro-benzotrifluoride are added through a powder funnel. The reaction mixture is heated to 75 C and at equal rate 65 kg. of a 20 % NaOH solution are pumped in while the temperature is maintained at 75-80 "C. The reaction mixture is stirred at 75-80 "C for 3.5 hours. The reaction mixture is cooled to room temperature and within 1 hour 9.5 cc. HCI are added at equal rate. The precipitated product is centrifuged, washed with water and dried at room temperature to constant weight. The obtained product is 2trifluoromethyl-4, 6-dinitro-phenol, /28 kg./.

Purity: 94.3 %, yield: 92.4 %.

Preparation of the composition Example 3 60 % by weight emulsifiable concentrate /EC/ 433 g. of 97 % 2-trifluoromethyl-4,6-dinitro-phenol are dissolved at 40 "C in a mixture of 200 g. of isophoron and 25 g. of xylene. The solution is cooled to room temperature and filtered through 0.1 micrometer GAF filter. To the filtrate 36 g of Tensiofix B 7425 and 6 g. of Tensiofix LS emulsifier are added under stirring.

Example 4 60 % by weight of emulsifiable concentrate /EC/ One proceeds as disclosed in Example 3 but isophoron is replaced by cyclohexanone and xylene is replaced by aromatol solvent and the following emulsifying agents are used: A B C Tensiofix AS g. 18 - 10 Tensiofix LS g. 24 - - Emulsogen EL g. - 12 25 Sapoegenat T 180 g. 10 - Sapoegenat T 500 g. - 20 7 Example 5 20 % by weight of water soluble concentrate /WSC/ To 300 g. of a 30 % by weight of 2-trifiuoromethyl-4,6-dinitro-phenol-Na aqueous solution 50 g. ethylene glycol and 4 g. of Tensiofix CG-21 emulsifiers are added. The solution is supplemented to 450 g. with ionexchanged water under stirring.

Example 6 20 % by weight of oily paste 620 g. of 97 % 2-trifluoromethyl-4,6-dinitro-phenol are dissolved in 500 g. of cyclohexanone and to this solution 1 20 g. of cosmetic vaseline oil are poured. The obtained solution is emulsified with a 10 % solution of Tensiofix PO-132 emulsifier by means of Ultra-turrax mixer while the temperature is maintained at 30 "C. After cooling to 1 5 "C 50 g. of 0.2 % by weight of Kelsan S-ethylene glycol solution is dispersed in the mixture within 1 hours under slow stirring.

Example 7 Herbicide activity test in green house In culture dishes white mustard, pig weed, fat hen, autumn wheat, Italian grass and corn seeds were sown. When the seeds were sprouted 10 % EC and 10 % WSC were prepared from the compounds to be tested, and after dilution with water 0.2 % spray was prepared. 2-4 leaves plants were sprayed with this liquid so that for each compound a dose corresponding to 2.5-5-10 kg./ha active ingredient was used. On the 14th day after the treatment the extent of the injury of the plants was evaluated and expressed in %. The results are summarized in Table 1.

Table 1 Compound Dose white pig fat Italian autumn corn kg/ha nustard weed hen grass wheat 2-trifluoromethyl- 1.25 45 50 75 0 0 0 4,6-dinitro-phenol 2.55 75 85 90 10 5 5 5.0 95 100 100 30 10 15 2-trifluoromethyl- 1.25 40 50 70 0 0 0 4,6-dinitro-phenol- 2.5 60 60 75 - - - diethyl-amine 5.0 80 85 80 10 10 10 2-trifluoromethyl- 1.25 45 50 70 0 0 0 4,6-dinitro-phenol- 2.5 55 65 75 0 0 0 dimethyl-amine 5.0 75 80 85 20 10 10 2-trifluoromethyl- 1.25 50 60 70 0 0 0 4,6-dinitro-phenol- 2.5 80 85 90 10 0 10 -Na 5.0 100 100 100 15 15 15 2-trifluoromethyl- 1.25 65 45 70 0 0 0 4,6-dinitro-phenol 2.5 75 85 90 10 0 10 -K 5.0 90 100 100 15 15 15 Example 8 Determination of Hill-reaction inhibition By means of the method of Arnon et. al. spinach chloroplastises were isolated.To 1 g. of leaves freed from the ribs 6 ml. of a 0.35 molar solution of NaCI and 0.6 ml. of 0.2 molar TRIS-buffer were added, the mixture was ground, and the homogenizate was filtered through a gauze of several layers and centrifuged for 5 minutes at a rate of 2000 rotations. The chloroplastis precipitate was suspended in a 0.035 molar NaCI, homogenized in a Potter tube and the thus obtained chloroplastis suspension was held at O "C until use.A reaction mixture of the chloroplastis suspension K2Fe/CN/6, K2HPO4, TRIS.HCI buffer, MgCI2 of suitable concentration and ratio and a solution of the compounds of the general formula /I/ as inhibitors and N /3,4-dichloro-phenyl/-N', N'-dimethyl-urea /DCMU/ and dinitro-ortho-cresol /DNOC/ as standards of a molar concentration of 1 x 10-' -1 x 10-3 were subjected to an exposure of 5000 lux light intensity for 20 minutes whereafter the reaction was quenched with 25 % trichloroacetic acid solution /TCA/. The precipitate was removed by centrifuging and the extinction of the solution was measured at 420 nm, with a photometer of type Spektromom 204. The measuring series was conducted also with reaction mixtures held in the dark.Hill-reaction inhibition was determined on the basis of the extinction differences measured in dark and light reactions and converted to ,ug/ml potassium ferricyanide concentration on the basis of calibration curve. The % values of the inhibition are plotted against concentration and concentrations belonging to 50 % inhibition were read from this curve /Iso/.

Results are shown in Table 2.

Table 2 Compound 15o micromole/dm3 2-trifluoromethyl- 0.21 4,6-dinitro-phenol 2-trifluoromethyl- 0.57 4,6-dinitro-phenoldiethanol-amine 2-trifluoromethyl- 0.52 4,6-dinitro-phenoldimethyl-amine 2-trifluoromethyl- 0.25 4,6-dinitro-phenol-N H4 2-trifluoromethyl- 0.20 4,6-dinitro-phenol-Na 2-trifluoromethyl- 0.31 4,6-dinitro-phenol-K dinitro-ortho-cresol-Na standard 0.86 N-/ 3,4-dichloro-phenyl/-N ',N'- 0.071 dimethyl urea One can see that 2-trifluoromethyl-4,6-dinitro-phenol and salts thereof are similarly to N-/3,4dichloro-phenyl/-N',N'-dimethyl-urea inhibitors of the 2. photochemical system and their effectivity is in between the effectivity of N-/3,4-dichloro-phenyl/-N',N'-dimethyl-urea and dinitroortho-cresol.Among the 2-trifluoromethyl-4,6-dinitro-phenol compounds the amine salts are less effective than the alkali and ammonium salts.

Example 9 Herbicide test in corn field The test was carried out with 2-trifluoromethyl-4,6-dinitro-phenol-Na 20 WSC formulated according to Example 5 and with 2-trifluoromethyl-4,6-dinitro-phenol 60 EC formulated according to Example 3. The test performed on a brown forest soil containing 1.8 % of organic substance. The soil was seeded on April 25th and 26th with corn of type Pioneer 3950 with a gern number of 73000/ha to a depth of 8 to 10 cm. Spraying was conducted on May 30th at 1.5 atm. by means of a parcel spraying machine equipped with a sprinkler of type Tee-Jet 11002 with water at a rate of 300 liter/ha. At this time the corn had 3-4 leaves, the main part of the weeds had 2-4 leaves. The tests were repeated 4 times. At spraying the field was covered with weeds in 87.5 %, in 58% with pig weed, in 27 % with fat hen and the residue was covered with barnyard grass. The activity was evaluated on June 15th. The weed killing activity and the phytotoxic symptoms observed in corn were evaluated by EWRC scale.

The EWRC scale needed for evaluation is contained in Table 3 and the results are summarized in Table 4. Data in Table 4 are average values obtained from 4 repetitions.

Table 3 EWRC value scale Value Weed killing effect Killing Effect on domesticated plants scale: injury killing % 1. excellent 100 no O 2. excellent 99 very slight 1 3. good 98 slight 2 4. satisfactory 95 slightly 5 moderate 5. sufficient 90 moderate 10 6. insufficient 75 average 25 7. bad 50 strong 50 8. very bad 25 very strong 75 9. unsuitable 0 complete 100 killing Table 4 EWRC values Composition Dose pig fat Barnyard corn l/ha weed hen grass 2-trifluoromethyl- 5 3 2 5 1.5 4,6-dinitro-phenol- 10 1.5 1 2 1.5 Na 20 WSC 2-trifluoromethyl- 1.6 4 3.5 7 4,6-dinitro-phenol- 3.2 2 1 3.5 60 EC Example 10 Crop regulation of corn Test compound: 2-Trifluoromethyl-4,6-dinitro-phenol-Na 20 % WSC Corn of the type MVSC 3780 with a germ number of 55000/ha was seeded on April 20th.

Spraying from helicopter was carried out on July 22nd at the beginning of the blooming of the corn at a beard height of 4-5 cm. Application rate 0.25 liter/ha+0.05 kg./ha active ingredient). The lands of parcels were 4 ha and the test was repeated twice. For each ha 50 liters of water was used. Corn was harvested on November 3rd.

Results are summarized in Table 5.

Table 5 length of length of corn-ear weight of corn-ear covered by grains corn-ear cm cm dkg 1. repetition 16.07 + 2.19 14.52 + 2.80 22.96 + 6 62 % of the ears is 90.35 % of defective the corn-ear length is covered by grain 2. repetition 17.06j2.71 15.35+3.93 20.84j5 66 % of the ears is 93.34 % of the defective ears is covered by grain control 17.33+i.87 15.33+2.48 19.16+4 84 % of the corn-ears 89.97 % of the is defective ears is covered by grain Crop averages: 1. repetition: 4.25 to/ha = 119.7 % 2. repetition: 4.08 to/ha = 114.9 % 8 control: 3.55to/ha=100%.

According to the test 2-trifluoromethyl-4,6-dinitro-phenol-Na 20WSC could induce a significant crop increase due to its effect on the increase of the grain-size and on the better graindensity.

Example 11 Acaricide activity test The test was adjusted on apples of Golden delicious type planted in a 7.5 m X 4.5 m field in parcels of 5 trees arranged in rows. Spraying was carried out on March 16th before budding at a pressure of 20 bar by a manual high pressure spraying gun of Haflinger spraying car. Testcompounds: 2-trifluoromethyl-4,6-dinitro-phenol-Na 20 % WSC and 2-trifluoromethyl-4, 6-dini- tro-phenol 60 % EC. Protective activity against eggs of spider mite living through the winter was evaluated by collecting 5 X 10 pieces of fruit-buds from the treated and untreated parcels 48 hours after the treatment. Observations were continued in the laboratory until the mite hatching terminated /12 days/. Mortality % was determined on the basis of the number of the hatched mites and expressed in the % of the control. Results are shown in Table 6.

Table 6 Composition Concentration of number of egg infection the composition in hatched mortality in % of the spray liquid mites in % the % 5 x 10 fruit- control buds pieces 2-trifluoromethyl 2.5 19 96.35 3.65 4,6-dinitro-phenol Na 20 WSC 2-trifluoromethyl- 0.8 23 95.59 4.41 4,6-dinitro-phenol 60 EC Dinitro-ortho-cresol 2.0 27 94.82 5.18 /DNOC-25/paste Untreated control - 521 0 100 Compounds of the general formula I achieved the activity of Novenda-25 paste containing dinitro-ortho-cresol.

Claims (11)

1. 2-Trifluoromethyl-4,6-dinitro-phenol and derivatives thereof of the general formula I

wherein X stands for hydrogen, alkali metal, alkali earth metal, C1 lO alkyl, alkylcarbonyl, alkenylcarbonyl, phenylcarbonyl, halogen-substituted phenylcarbonyl, or halophenyl or a group of the general formula (a) 8 H N R1 R2 R3 wherein R1, R2 and R3 are the same or different and can stand for hydrogen, alkyl, alkoxyalkyl, alkenyl, hydroxyalkyl, cycloalkyl, phenyl or substituted phenyl.

2. Herbicidal, acaricidal or crop regulating composition comprising as active ingredient a compound as claimed in Claim 1.

3. Process for the preparation of 2-trifluoromethyl-4,6-dinitro-phenol and derivates thereof of the general formula I-wherein X is as given in Claim 1, which comprises hydrolysing 2-chloro 3,5-dinitro-benzotrifluoride with alkali metal hydroxide or alkali earth metal hydroxide in aqueous medium without catalyst and, if desired, converting the obtained phenolate to phenol and, if desired, converting the obtained phenol to phenolate of the general formula I.

4. Process as claimed in claim 3, which comprises conducting the hydrolysis at an alkali concentration of 5 to 20% by weight.

5. Process as claimed in claim 4, wherein the said alkali concentration is from 10 to 15% by weight.

6. Process as claimed in any of claims 3 to 5, which comprises performing the hydrolysis at 20-1 OO"C.

7. Process as claimed in claim 6, wherein said hydrolysis is performed at 60-80"C.

8. Process substantially as hereinbefore described in Example 1 or 2.

9. A compound made by the process as claimed in any one of claims 3 to 8.

10. An agricultural composition substantially as hereinbefore described in any one of Examples 3 to 6.

11. An agricultural method comprising treating a plot infected by weeds with a composition as claimed in claim 2 or claim 10.

1 2. An agricultural method as claimed in claim 11 substantially as hereinbefore described in any one of Examples 7 to 11.