US3520674A - Carboxamidooxyacetate ester herbicides and method of combating weeds - Google Patents

Description

a ed ews Pm CARBOXAMIDOOXYACETATE ESTER HER- BlClDES AND METHOD F COMBATING 'RalphP-glNeighbors, Olathe, Kans.,,assignor to Gulf Re- I search,.& Development I Company, Pittsburgh, 1 Pa., a c orporat ion of Delaware ,7 q v No Drawing. Continuation-impart of applications Ser. No. ,374,813, June l2, 19,64, and Ser. No. 641,487, May 26,

'1 l1967.",lhis application Sept. 15,1967,Ser. No. 668,180

The portion of the term of the patent subsequent lto June 10, 1986, has been disclaimed Int. Cl. Aflln 9/20, 9/22; C07c83/08 3Claims The method of the present invention comprises applying to the ,locusyof the weeds a herbicidal quantity of a com- 'tur'al' formula example, one of the following:

' 1 Summary of invention L his, applicationis a continiiation-in-part of :U.S. Ser. No. 374, 8.l3,.file d lune 12, 1964now US. Pat. 3,457,- 063 which disclosed that various aminooxy compositions pound selected from the group represented by the struc- Patented July 14, 1970 ice are useful as selective herbicides, including alkyl phthalimidooxyacetates. This application is also a continuationin-part of US. Ser. No. 641,487, filed May 26, 1967 now U.S. Pat. 3,449,113 which is directed to carboxamidooxyalkanoic acids and their salts and their use as selective herbicides. The herbicidal esters of the present application include esters of some of the acids disclosed in US. Ser. No. 641,487 now US. Pat. 3,449,113. However, the esters being non-ionic, differ from both the free acids and their salts which are substantially ionic, so that there are signifi cant differences in physical behavior, in selectivity of herbicidal action and chemical properties which critically affect the utility of the compositions. By way of illustration, the

- compound having the structural formula is useful in post-emergent control of weeds in legumes such as soybeans and alfalfa, whereas the free acid is very injurious to these crops but is useful in controlling weeds in sugar beets.

Although the amidooxy structure appears to be important to the herbicidal properties of the compositions, certain substituents can apparently cancel out the desirable effect. For example, the compound with the following structural formula appears to be practically non-phytotoxic:

The phytotoxicity of the compounds apparently decreases with increasing molecular weight of the alcohol group of the ester, the toxicity of the ester of the following alcohols decreasing in the order in which they are listed:

Butanol Cyclohexanol 2-ethylhexanol Dodecanol Of these esters, the butylesters are sufficiently active to possess interesting utility, particularly in view of their selectivity. The dodecyl esters, however, only appear to be active against a few grasses and for this purpose there are much cheaper compounds available. Although there is no specific molecular weight of the alchol group at which phytotoxicity can be said to terminate abruptly, only the lower alkyl esters possess sufficient activity to be economically competitive. The methyl and ethyl esters are most active and are therefore preferred.

. Briefly, the method of thepresent invention comprises applying to the locus of the weeds a herbicidal quantity of au pmnound 29 .from structural formula 11 XOOHz-COR in which X is one of the following;

the groupmrepresented by. the.

FaC

and R is lower alkyl.

In a preferred embodiment of the method, weeds -are combated in fields of grain crops such as oats, wheat and corn (maize) by applying to the locus of the weeds a herbicidal quantity of methyl or ethyl 2,4-dichlorophenoxyacetamidooxyacetate.

The practice of the invention is described in greater detail and specifically exemplified in the discussion which follows.

DETAILED DESCRIPTION OF THE INVENTION (A) Synthesis of herbicides The carboxamidooxyacetates are conveniently manufactured by reaction of the corresponding hydroxamic acid with a chlo ro or bromoacetate, asexemplified-by. the-following procedure for preparation of dodecyl benzamidooxyacetate:

To a solution of benzohydroxamic acid (13.7 g.,"0.1 mole) in 200 ml. of 0.5 N NaOH was added a' solution of dodecyl chloroacetate (26.3 g., 0.1 mole) in ethanol (1200 ml.). The mixture was refluxed 4 hrs., cooled and concentrated ,to one-half volumc. The concentrate. was diluted with water (500 ml.) and extracted with hexane and (500 ml.). The hexane extractwas concentrated under reduced pressure and the residual oil was dissolved ag ain in hexane (SOOmL) and chilled to 2 C.. tO. P ,cipitate dodecyl benzamidooxyace'tate (27.8 g.; 60%)- ll Benzohydroxamic. acid is readily prepared bylknqw n procedures(Organic Synthesis, Coll. vol." II p. 6,7).The chloroacetate ester may .be prepared also by' flrriown methods, utilizing chloroacet c acid, which is an article of commerce. Other hydroxamic acids used for synthesis or tr atmen the fla s,..w e am ed. a

the garboxamidppxyacetates are also readily. mademb known procedures, with only such modifications as lie within the ordinary skill of the art.

The phthalimidooxyacetate esters are readily prepared from N-hydroxyphthalimide as illustrated by the following procedure, which was disclosed in U.S. Ser. No. 374,813: I

A mixture of N-hydroxyphthalimide (0.1 mol, 16.3 g.), ethyl bromoacetate (0.1 mol, 16.7 g.) and dimethylformamide (200 ml.) wasfstirred at room temperature while triethylamine (0.1 mol, 10.1 g.) was added over a period of minutes. Atter addition of the triethylamine the mixture was stirred at v.a rihient temperattire. an additional 5 hours. The; -rea'ction-. :mixture 1' ariasdiluted with water (600 ml.) and the crude pr'o'dti movedby filtratiom. Washed' With .sedifim solution,' water ,"-then""'witlrhexane a There wasnbtainqd 18.2 g. 'q 'ta :I.-9 C- ield Ajrialysm Calodifor Ci H Nfk. c H, A; .N, 5.6 2 Foundn(percent 5- .2 -ar All of the necessary intermediates :for synthesis of the novelherbicides of this invention may be 'eithei pdr'ch'aseld or made by published procedures. jlhe general synthesis proceduresexemplified above were employ ed to prepare the novel compounds which were evaluated as herbicides as discussed-below: i

(B) Use of carboxamid'o'oxyand carboximidooxy' Specific compounds were employed as agents on a variety of representative plant species under carefully controlled conditions so as to evaluate both activity and selectivity of herbicidal action, according to the following procedures:

(1) Post emergentnactivity; An aqueousrdispersion of each active compound was prepared by combining 0.4 gram of the compound with about 4 ml. of a solventemulsifier mixture (3 parts of a commercial polyoxyethylated vegetable oil emulsifier, one part xylene, one part kerosene) and then adding water, with stirring, to a final volume of 40 ml; I

The species of plants on which each compound was to be tested were planted in four-inch pots in a greenhouse. Ten to eighteen days after emergence of the plants, three pots were sprayed with an aqueous dispersion of the active compound prepared as described above, at a rate of 5 lb. of active compound per acre and at a spray volume of gallons per'acre. Approximately one week after the spray application the plants were observed and the results rated according to the following schedule:

Herbicidal effect The same rating schedule was employed to judge preemergent results obtained according to the procedure below.

(2) Pre-emergent activityz' A solution of each active compound was prepared by dissolving 290 mg. of the compounds to be tested in 200 ml. of acetone. Disposable paper half-flats were prepared and seeded wth a variety of species of plant seeds, then sprayed with the acetone solution at the rate of 10 lb. of active "dherhical peiacre of sprayed area. One flat,-.which..had been seeded with alfalfa, brome, flax, oats, radishes and sugar beets was held at F. -"day""temperature?-atibthcr seeded with co rs co bl. c ttomsrflsra e ill t and ybe was held at Twenty-one day fte was rated according to the above schedule.

Both post-emergent and pre-emergent results are set forth in the following table. v

I claim:

RESULTS OF HERBICIDE TESTS The species of plants employed in the tests described above are selected so as to be representative of a great variety of families of related species and to give an indication of etfects on common crops. The test data are indicative of the elfects on individual, vigorous plants grown under beneficial conditions of temperature, moisture, fertility and illumination. In the field, weeds and crops are competing with each other, subject to varying weather and soil conditions. Usually no more than two or three species of weeds are a major problem in these competitive situations, so a herbicide which happens to be effective against only two species or even a single weed may be useful, providing substantial injury to the crop can be avoided. I

Crop injury can be minimized by reducing the rate of application overall, or by application at the locus of the weeds between the rows at a higher rate than on the rows of crop plants. These techniques are well known. Since the objective of weed control is to alleviate the loss of crop yield resulting from competition with weeds, the decision is often made to accept minor crop injury in order to eliminate the weeds. For this reason, application rates may vary with the situation, according to prevailing farming practices. The tabulated data may be used as a guide in adjusting herbicide application rates in the practice of the method of this invention, taking into consideration the fact that herbicides are utilized somewhat less efficiently in the field than when used in carefully controlled experiments on a small scale.

1 Plant Species Typeof Grain I Aetiv- Crab- Cox- Mil- Soy- Cot- Rad- Sugar Sorflompound ity grass comb Brome letbean ton Alfalfa Oats Corn Flax ish Beet Wheat ghum Ethyl phthalimidooxy- Post 4 a o 1 2 a o 4 *1 ...i acetate, M.P.95-7" 0. Pre 0 0 0 0 0 0 0 0 0 a 0 0 0 o I 0 Ethyl 2,4-dichloro- 4 Post '4 4 4' 1 a '4 14' "phenoxyacetamldo- Pre.'...- 4 4 4 4 4 4 4 3 2 4 4 oxyacetate, M.P. -7 0.

N-carbethoxymethoxy- Post 4 2 3 0 2 2 1 2 4 2 1 maleamicacid,M.P. Pre 1 4 0 2 3 2 1 0 1 0 2 4 {JG-8C. r

Ethyl cyclopropane- 4 2 1 0 2 1 0 1 0 2 1 carboxamidooxyace- 3 1 2 1 0 0 0 1" v3 1 tate,M.P.12s1a0o.. 4 j j v I Ethylbenzamidooxy- 4 2 2 1 1 4 1 4 4 4 2 acetate, M.P. 86- 2 3 2 0 0 0 0 1 3 87.5 C.

Mefhylbenzamidooxy- Post 4 3 4 2 1 4 1 1 4 2 2 acetate, M. Pro..." 1 4 0 2 3 2 1 0 1 0 1 4 Ethyl 3-trifluoro- Post 4 2 3 2 2 1 a a 4 1 2 methylbenzamido- Pre 1 4 0 2 2 2 1 1 1 2 2 4 oxyaeetate, M.P.

Ethyl phenoxyacet- Post 3 3 2 2 1 1 1 1 4 0 1 4 amidooxyacetate, Pre- 1 3 0 2 1 3 1 0 0 1 3 3 M.P. 77-9 C.

2-ethylhexyl benz- Post 4 1 1 0 1 4 1 1 3 3 2 amidooxyacetate, Pre 0 1 0 2 0 0 0 0 0 0 0 1 210 15020.

Oy'clohexylbenzamid0- Post 4 2 1 0 0 1 0 1 4 1 0 oxyaeetate, M. re.... 0 2 0 3 0 1 0 0 0 0 0 1 64-6" Dodecyl benzamido- Post 4 1 0 0 1 2 0 0 1 0 0 oxyaeetate, M.P.- Pre 0 1 0 1 0 0 0 0 0 0 0 1 67-9 C.

Butyl benzamidooxy- Post 4 1 1 1 1 2 4 3 4 1 1 acetate, N 1.5432. Pre 0 2 0 2 2 2 0 0 0 0 0 1 which comprises applying to the locus of the plants a herbicidal quantity of a compound selected from the group represented by the structural formula H XOCHzCOR in which X is a member of the group consisting of and I T 5 which comprises applyin'gxtd 'the"1'6eus f th'e VljICdClS a fwhich lcomprises applying 10 the locus of the plants a i Friankel etral-i chef-I'l- Q 1 3 -393 @C-NH- M References Cited g I -:UNITED STATES PATENTS l i 6 Q71: T. 3;1'A6'2,5'25 12 /1964 Leasiii'e l; L:; 7l- 1 13 1 3,282,987 11/1966' Ellis 260-471 -o gH=c-NH1 3,396 009 8/1968 Neighbors 71-115 "8,420,824-51/1969 Ellis; '260-244 and R is ldweflalkjrl. 1 8 .8 r 2. .The method of'combatingTmdesired plan1; grpwfl3 OTHER REFERENCES herbicidal quahtity ()f a cbmpound represented by he 6507586, ds, @PBHQf Structural formula: 5 Chemical Investors (assignee), 71, 96.

H E: LEWIS Go'ITs PrimaryExa mi ri'er Q 9 '.3? M. KASSENOFE, AssistantvExanfiner in which'Risldwer alkyl. l l 20. L, US- Cl- .11. 3. The method of combating yveeds in legume crops 7196, 106, 107, 108; 260-468, 47l, -482, 32 6 453 &3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,520 ,674 .D d July 14, 1970 Inventor(s) Ralph P. Neighbors It is certified that error appears in theaboveidentified patent and that said Letters Patent are hereby corrected as shown below:

I" -l Column 6, approximately line 63, Claim 1, the third formula which reads [Cl O-CH C-NH-] should be deleted. Column 7, approximately line 8, Claim 1, the eighth formula which reads OCH C-NH] should be deleted.

Sl'hiiiEB MD m mm 1. mm, m. L AW flomissioner of Patents J Edmflufletchenlrq