IL30804A - Phosphorus-containing oxazolidines and their use for controlling pests or weeds - Google Patents

Description

Β*Ρ*Ϊ e»a»yi o» »tD tmtnV una PosphcruB-containiJig oxaaolidines and their us© for controlling peets or veerts STAUFFER CHEMICAL COMPA Ci 29031 The present invention is concerned with a novel group of thiophoephoryl, phosphonyl, thiophoaphony1, ploaphinyl and thiophoephinyl imino oxazolidines , their method of preparation, and their use as pesticides especially effective against insects, acarids and as herbicides.

The novel compounds are represented by the general formula wherein and are independently lower lkyl, lower nlkoxy or lower alk lthio; F.^ and are independently hydrogen, lower alkyl or lower alkenyl, and R¾ may also be phenyl; R_, Rg and R^ are independently hydrogen or lower i-lkyl; and X is oxygen or sulfur.

The lover rLkyl, lower ylkenyl, lower alkoxy rind lower alkylthio radicals which are suitable for ^, R3» ^ » ^5» and R are the straight rnd branched chain aliphatic radicals having from 1 to 6 carbon atoms -nd include, for example, methyl, ethyl, propyl, isopropyl, hex l and the like. 30804/2 In general, compounds of the present invention are prepared by reacting the appropriate organo substituted phosphorus chloride with an alkali metal tbiocyanate using acetone or acetonitrile as solvent. The isothiocyanate thereby produced is then reacted with the appropriate beta-hydroxy amine to give a thio urea which in the presence of mercuric ojiide undergoes cyclicization with the loss of the elements of hydrogen sulfide and yields the desired phosphoryl, thiophosphoryl, phosphonyl, thiophosphonyl, phosphinyl or thiophosphinyl imino oxazolidine. The desired product is isolated by thin layer chromatography using methods well known to those skilled in the art. The following example is illustrative of the above general method. , > EXAMPLE I Preparation of 2- fN-(0,0-Diethylphosphonothiono)-imino -3- ethyl-5-methyl-r,3-oxazolidine. To a solution of 38,8 grams (0.4 mole) of potassium thiocyanate in 395 ml. of acetone containing 6 grams of pyridine is added 75.4 grams (0.4 mole) of diethyl chlorothiophosphate over a 2 hour period. The mixture is stirred another hour at room temperature, then at 45-50 °C. for forty-five minutes. It is filtered from the precipitate of potassium chloride and the solvent removed in vacuo. The residue is taken up in benzene and the insoluble material removed. The benzene is removed in vacuo and the product distilled twice, the second time through a Vigreux column. 5.3 grams (0.025 mole) of this product is dissolved in 42 ml. of benzene 2.7 g. (0.025 mole of ethyl ^-hydroxypropylamine in 10 ml. of benzene is added over 15 minutes. After letting the mixture stand overnight, the solvent is removed in vacuo leaving a crystalline product. To a solution of 3.3 grams (0.011 mole) of the above product in 50 ml. of benzene is added 3.7 grams (0.0167 mole) of mercuric oxide.

The mixture is stirred and refluxed for 3.5 hours. The mixture is filtered and the filtrate dried over magnesium sulfate. The benzene is removed in vacuo leaving a crude viscous product. Thi product is taken up in 35 ml. of benzene and refluxed with 2.0 grams of mercuric oxide for another five hours. The mixture is again filtered, dried and the solvent removed. Pure 2-[N-(0,0-Diethyl-phosphonothiono)-imino] -3-ethyl-5-methyl-l,3-oxazolidine is isolated from the crude product by thin layer chromatography, using solvent systems 90:10 chloroform:acetone v/v on silica gel. Instrumental analysis establishes the above structure and elemental analysis shows 43.18% C, 7.53% H, 9.82% N, 11.23% P, and 11.27% S as compared with theoretical values of 43.20%, C, 7.55% H 10.00% N, 11.10% P and 11.40% S.

Another general method for the preparation of the 0,S-phos-phorylimino oxazolidines of the present invention consists of reacting the product resulting from the reaction of the appropriate 0,0-phosphorodithioic acid and cyanogen bromide in the presence of triethylamine with the appropriate beta-hydroxyamine and isolating the desired product by thin layer chromatography using methods well known to those skilled in the art. The follo ing example is illustrative of the above general method.

Example 2 Preparation of 2- [N-(Q,S-Dimethylphosphonothiolo)-imino]-3-ethyl-5-methyl-l,3-oxazolidine. To a solution of 79.0 grams (0.5 mole) of 0,0-dimethylphosphonodithioic acid in 100 ml, of benzene is added 50.5 grams (0.5 mole) of triethylamine at 15 to 2 °C. A solution of 53 grams (0.5 mole) of cyanogen bromide in 75 ml. of benzene is then added over 1.5 hours at 15°C. The reaction mixture is then stirred two more hours at room temperature, during which time the precipitate of amine hydrobromide becomes thicker. The mixture is filtered and the benzene removed from the filtrate in vacuo. The product is distilled at 55-58 °C. .75-1.0 mm. yielding 44.0 grams. 5.5 grams of this intermediate product is dissolved in 44 ml. of dry acetone and to the solution is added a solution of 3.1 grams of ethyl /$ -hydroxypropylamine i is stirred for 1.5 hours. The acetone is removed in vacuo and the residue pumped out at 0.4 mm. for 1.5 hours, yielding 8 grams. Upon standing, the product partially crystallizes. After the crystals are removed, the mixture is placed in 30 ml. of water and the mixture is extracted twice with 80 ml, portions of chloroform. The extract is dried over magnesium sulfate, filtered, and the solvent removed in vacuo. The residual oil is pumped out at 1 mm. up to 55 °C. It is then seeded with one of the spontan-eously formed crystals removed above and allowed to stand until all of the second component has crystallized out. The mixture is then filtered and the oily filtrate subjected to thin layer chromatography using 90:10 chloroform: acetone v/v and 95:5 ethanol: water v/v solvent systems on silica gel, giving pure 2- [N-(0,S-dimethylphosphonothiolo)-imino]-3-ethyl-5-methyl-l,3-oxazolidine. Instrumental analysis establishes the above structure and elemental analysis shows 12.30% P compared to 12.30¾> P theoretical.

Another general method for the preparation of the 0,S-phosphoryl imino oxazolidines of the present invention consists of reacting the appropriate 0,0-thiophosphonylimino oxazolidine with the appropriate alkyl or alkenyl iodide to form the desired product, which is isolated by thin layer chromatography using methods well known to those skilled in the art. The following example is illustrative of the above general method.

EXAMPLE 3 Preparation of 2- fN-(0, S-Dimethylphosphonothiolo)-imino'| -3-ethyl-5-me hyl-l , 3-oxazolidine. A solution of 7.6 g. (0.03 mole) of 2- [N-(0,0-dimethylphosphonothiono)-imino] -3-ethyl-5-methyl-1,3-oxazolidine and 4.4 g. (0.031 mole) of methyl iodide in a mixture of 25 ml. of hexane and 5 ml. of benzene is refluxed for 5 hours. The mixture is cooled and filtered and the solvent removed in vacuo.

EXAMPLE 4 Preparation of Diethylthiophosphinoisothiocyanatothioate. Potassium thiocyanate (65.6 g. , 0,75 mole) and a trace of potas-sium iodide are placed in 500 ml. of dry acetone and warmed to 45°. Diethylthiophosphinochloridothioate (78.3 g. , 0.5 mole) is added dropwise at 45-50°. A precipitate of potassium chloride appeared. The mixture is then refluxed for 15 minutes. It is cooled, filtered, and the solvent removed in vacuo. The residue is treated with water and the oil extracted with hexane. The extract is washed with sodium bicarbonate solution and with water, dried, and the solvent removed in vacuo. The residue is distille twice in vacuo. The product has a boiling point of 79-80°/.3 mm. Yield: 49.0 g. (55% of theory). Its IR spectrum showed a band characteristic of the isothiocyanate group at 2000-2050 cm Preparation of N-Diethylthiophosphinyl-N' -Methyl-N' -j9 -hydroxyethyl thiourea. The above-mentioned thioate (26.9 g. , .15 mole) is dissolved in 75 ml. of benzene and a solution of N-methylethanolamine (12.0 g. , .16 mole) added dropwise. The temperature increased to 33° during the addition. Stirring is continued 1 hour at room temperature, 1 hour at 65-70°. The reaction mixture is filtered through Celite and evaporated in vacuo. Upon trituation with hexane the residue solidified. It is recrystallized from benzene-hexane, and has a m.p. 68-73°. Yield: 23.4 g. (61% of theory).

Preparation of 2-(Diethylthiophosphinoimino)-3-methyl oxazolidine. The above-mentioned thiourea (15.6 g. , 0.07 mole) dissolved in 150 ml. of benzene is stirred and refluxed V7ith mercuric oxide (32.6 g. , 0,15 mole) under a Dean-Stark trap until no more water is given off (about 3 hours). Black mercuric sulfide appears. The mixture is cooled, filtered, and the filtrate dried over magnesium sulfate. Removal of the solvent left a yellow oil nj° = 1.5563. Yield: 7.8 g. (51% of theory).

The following is a table of compounds representative of those embodied in the present invention. Compound numbers have been assigned to them and are used for identification throughout the balance of the specification.

Systemic Evaluation Test. This test evaluates the j systemic toxicity by root absorption and upward translocation J of the candidate systemic compound. The two-spotted mite, j Tetranychus urticae (Koch) and the bean aphid, Aphis fabae (Scop.), j are employed in tests for systemic activity. Young pinto bean plants in the primary leaf stage are used as host plants for the two-spotted mite. The pinto bean plants are placed in bottles containing 200 ml. of the test solution and held in plac with cotton plugs. Only the roots are immersed. The solutions are prepared by dissolving the compounds to be tested in a suitable solvent, usually acetone, and then diluting with distilled water The final acetone concentration never exceeds about 1%. Immediately after the plants are placed in the test solution, they are infested with the test species. Mortalities are determined after seven days. The percentage kill is determined by comparison with control plants which are placed in distilled ater only.

The LD-50 value is calculated using well-known procedures. LD-50 values for the two-spotted mite are found in Table II under column 2SM-SYS; and for bean aphid under column BAS.

Young nasturtium plants (Tropaeolum sp.) are used as the host plants for the bean aphid. The host plants are transplanted into one pound of soil that has been treated with the candidate compound. Immediately after planting in the treated soil the plants are infested with the aphids. Concentrations of tpxiqants in the soil ranged from 10 ppm per pound of soil downward until an LD-50 value is obtained. Mortality is recorded is made with control plants placed • .*'■'¾·■' Insectlcidal Evaluation Tests* The following insect species are subjected to evaluation tests for insectlcidal activity. (1) Housefly (HF) - Musca domestica (Linn.) (2) Lygus Bug (LB) - Lygus Hesperus (Knight) Aliquots of the toxicants, dissolved in an appropriate solvent, are diluted in water containing 0.002% of a wetting agent, Sponto 221®- (a polyoxyether of alkylated phenols blended with organic sulfonates). Test concentrations range from 0.05% downward to that at which 50% mortality is obtained. In the tests, for these species, 10 one-month old nymphs of the Lygus Bug are placed in a circular cardboard cage sealed on one end with cellophane and covered by a cloth netting on the other.

Test concentrations for the Lygus Bug ranged from.0.05% downward to thaft at which 50% mortality was obtained. Each of the aqueous ί ' suspensions of the candidate compounds are sprayed onto the insects through the cloth netting by means of a hand spray gun.

Percent mortality in each case is recorded after 72 hours, and the LD-50 values expressed as percent of toxicant in the aqueous spray are recorded. The results are in Table II under Column LB. 1 The following procedure is used to test houseflies.

INSECTICIDAL EVALUATION RESUL LD-50 VALUES 6 7.5 .0005 .0003 .3 14 45.0 .0008 .0005 .05 10.0 .0008 .0003 .03 I »-» 100.0 .05 > .05 00 16 17 HOO.O .05 > 100.0 .03 .003 .8.0, 22 5.5 .00005 .0001 .008 23 85.0 .01 .05 . 5.0 24 40.0 .0005 .001 .3 40.0 .0003 .0003 .1 26 65.0 .01 .03 >10.0 37 18.0 .001 .005 8.0 8.0 > 100.0 - .005 .03 8.0 >10.0 31 5.5 .0003 .0003 .02 32 70.0 .03 .01 8.0 33 15.0 .0008 .001 .5 3.0 I 34 >100.0 > ·05 O 6.0 .0005 .0003 .3 10.0 36 ϊ ; 100.0 . .05 .03 3.0 37 18.0 .0003 .0008 .3 8.0 '3.

HF LB BA Compound BAS SYS Numbe fue/25°-) (%) I%1 -iPPm) (pom) 38 100.0 .03 .03 10.0 39 * . 30.0 .001 .001 8 _>10.0 40 ; - >ioo.o .03 .008 3.0 .0 ' .001 .003 .3 > o.o 40.0 .008 .003 1.0 > 10.0 ' 42 1 43 · 100.0 .03 .03 3.0 > io.o 44 > 100.0 .05 .03 8·°.„ ? 10.0 45 ^100.0 .003 .003 •8 >10.0 46 100.0 .03 .003 • 10.0 47 .0 . .003 . .0005 .3 8.0 48 49 > 100.0 .05 ~ .005 50 > 100.0 .01 .005 3.0 > 100.0 .01 .005 10.0 52 ' > loo. b >.05 53 > 100.0 .003 >.05 54 100.0 > .05 55 100.0 > .05 56 20.0 .0001 .0001 .03 3.0 6$ > 100.0 .05 > .05 65 . 30.0 .01 .03 1.0 10.0 66 3.7 - .001 .0003 .03 1.0 67 1.0 .0001 .00003 .005 .3 68 > 100.0 ' ·05 69 15.0 .001 .003 .08 ^10.0 . 70 70.0 .03 .008 •5 71 . 30.0 .001 .0008 .3 72 100.0 .005 .008 1.0 73 8.0 .001 .0003 As previously mentioned, the herein described compounds produced in the above described manner are phytotoxic compounds which are useful and valuable in controlling various' pla'nt species Compounds of this inventioh are tested as herbicides in the follow ing manner.

Pre-emergence herbicide test. On the, day preceding treatment, seeds of seven different weed species are planted in individual rows using one species per row across the width of the flat. The seeds used are hairy crabgrass (Digitaria sanguinatis (L.) Scop. ) , yellow foxtail (Setaria glauca (LS) Beauv.)» water-grass (Echinochloa crusgalli (L.) Beauv.)> wild oat (Avena f tua (L.))> redroot pigweed (Amaranthus retroflexus (L.))> Indian mus-tard (Brassica juncea (L.) Coss.) and curly dock (Rumex crispus (1..))· Ample seeds are planted to give about 20 to 50 seedlings per row, after emergence, depending on the size of the plants. The flats are watered after planting. The spraying solution is prepared by dissolving 50 mg. of the test compound in 3 ml. of a solvent such as acetone containing 1% Tween 20® (polyoxy-ethylene sorbitan monolaurate) and diluting with a small amount of water. The following day each flat is sprayed at the rate of 20 pounds of the candidate compound per 80 gallons of solution per acre. An atomizer is used to spray the solution on the soil sur-face. The flats are placed in a greenhouse at 80°F. and watered regularly. Two weeks later the degree of weed control is deter-mined by comparing the amount of germination and growth of each weed in the treated flats with weeds in several untreated control flats. The rating system is as follows: - = no significant injury (0-15 percent control) + = slight injury (25-35 percent control) ++ = moderate injury (55-65 percent control) .+++ = severe injury or death (85-100 percent control) An activity index is used to represent the total activity on all seven weed species. It is the sum of the number of plus marks, so that an activity index of 21 represents complete control of all seven weeds.

Post-emergence herbicide test. Seeds of five weed species including hairy crabgrass, watergrass, wild oats, Indian mustard, and curly dock and one crop pinto beans (Phaseolus vulgaris) , are planted in flats as described above for pre-emergence screening. The flats are placed in the greenhouse at 72-85 °F. and watered daily with a sprinkler. About 10 to 14 days after planting" when the primary leaves of the bean plant are almost fully expanded and the first trifoliate leaves are just starting to form, the plants are sprayed. The spray is prepared by weighing out 50 mg. of the test compound, dissolving it in 5 ml. of acetone containin 17o Tween 20® (polyoxy-ethylene sorbitan monolaurate) and then adding 5 ml. of water. The solution is sprayed on the foliage using an atomizer. The spray concentration is 0. 57o and the rate would be approximately 20 lbs. /acre if all of the spray were re-tained on the plant and the soil, but some spray is lost so it is estimated that the application rate is approximately 12. 5 lbs./ acre.

Beans are used to detect defoliants and plant growth regulators. The beans are trimmed to two or three plants per flat by cutting off the excess weaker plants several days before treat-ment. The treated plants are placed back in the greenhouse and care is taken to avoid sprinkling the treated foliage with water for three days after treatment. Water is applied to the soil by means of a slow stream from a watering hose taking care not to wet the foliage.

Injury rates are recorded 14 days after treatment. The rating system is the same as described above for the pre-emergence test where (-), (+) , (-H-) , and (+-H-) are used for the different rates of injury and control. The injury symptoms are also recorded. The maximum activity index for complete control of all the species in the post-emergence screening test is 18 which represents the sum of the plus marks obtained with the six plant species used in the test.

The concentration of a compound of the present invention constituting an effective amount and the best mode of administration to an insect or acarid pest or its habitat may be easily determined by those skilled in the art of pest control, as exemplified by the procedures described hereinabove. As shown above, the compounds of the present invention are also useful as pre-emergence or post-emergence herbicides, and can be applied in a variety of ways at various concentrations. In practice the compounds are formulated with an inert carrier utilizing methods well known to those skilled in the art, thereby making them suitable for application as dusts, sprays, drenches and the like. The amount applied depends upon the nature of the seeds or plants to be controlled and the rate of application may vary from one to 50 lbs. per acre. One particularly advantageous way of applying the compound is as a narrow band along the row crop, straddling the row.

Various changes and modifications can be made without departing from the spirit and scope of the invention described herein as will be apparent to those skilled in the art to which it pertains. It is accordingly intended that the present invention shall only be limited by the scope of the claims. 26. 30804/2

Claims (1)

1. CLAIMS Compounds of the formula wherein and independently lower lower or lover and are independently lover alkyl or lower and may also be are independently hydrogen or lower and is oxygen or of formula I in in which is lower and are lover Rg and are each is lower and X is The compound according to Claim in which is methoxy and is is ethyl and The compound according to Claim in which is 2 is is ethyl and is The compound according to Claim which is methyl is ethyl is Compounds of formula I in Claim in which nnd are each lower Rg and are and are each lower and X is The compound according to Claim in which is is methyl and and are Compounds of I in Claia in which is lower are e ch lower Rg are each and X is Compounds of I in in which and are lower and are each and is The compound according to Claim in which and are each ethyl and is acaricidal and compositione comprising an effective amount of compound having the formula I in Claim Compositions according to Claim in which in the of I is and are lower 3 4 g is lower and each and is A composition according to Claim in in the compound of formula I is is is A composition according to Claim in which in the compound of formula I is is ethyl 1 and is A composition according to in which in the of formula I is g is is ethy and is A composition according to Claim in which in the compound of formula I and are each lower and are each lower g and are is composition according to Claim in which in the of formula I is is methyl and are A ition to Claim in which in the compound of formula I is are each lower are e and X is composition to in which in the of formula I and are lower g and are and X is Λ composition according to 19 in which in the compound of formula I and ethyl is A method for controlling and applying to the of pests effective amount of a compound having the I in Claim method according to Claim in in the of formula I is and lower are ch and is method according to Claim which in the compound of formula I is and is ethyl and is A according to Claim in which in the compound of formula I is is ethylth is ethyl and is A according to Claim in which in the compound of formula I is is is ethyl and is A method according to Claim in which in the compound of formula I and are each lower and are each and are each and X ie Λ method according to Claim in which in the compound of formula I is is methyl and and g ore erch A method according to Claim in which in the compound of formula I is lower and R are lower and are each and X is according to in which in the compound of formula I each Rg and are each and is A method according to Claim in which in the of formula I and g are ethyl and is A method of controlling vegetation prising applying thereto effective amount of a having the formula I in Claim A n the of formula X io end are each lower is lower Rg and are each and X is A method according to Claim in which in the compound of formula I is methoxy and is 2 is A method according to Claim in which in the compound of formula I is g is is ethyl and is to Claim in v ich in of I in ic A to in in the I r are each lower X is recording to in in the compound of formula I is and ore netted to Claim in which in the of I ir lovrcr lower and e each X to in which in compound of formula I and are and a d X is method to C ain in the compound of fornula I R ethyl is 1 2 5 insufficientOCRQuality