US2857261A - Herbicidal sulfoalkyl esters of phenoxyacetates - Google Patents

Description

United States Patent O HERBICIDAL SULFOALKYL ESTERS OF PHENOXYACETATES Milton Kosiniu, Dayton, Ohio, assiguor to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware No Drawing. Application April 27, 1954 Serial No. 426,026

12 Claims. (11. 71 2.6

The present invention provides new and hitherto unknown sulfoalkyl esters of certain aryloxy-substituted fatty acids, methods of preparing the same, herbicidal compositions comprising the new esters, and methods of destroying or preventing plant growth in which such compositions are used. I

An object of the invention is to provide improved herbicidally active compounds. Another object of the invention is to prepare esters of aryloxy-substituted fatty acids which esters are characterized by low volatility. Still another object of the invention is to provide watersoluble aryloxy-substituted fatty acid esters.

These and other objects hereinafter disclosed are provided by the following invention wherein there are prepared sulfo-esters having the formula RIII in which R, R, R and R' are selected from'ithe class consisting of hydrogen, chlorine and alkyl radicals of from 1 to 4 carbon atoms and in which at least one of R, R, R" and R' is chlorine, Y is selected from the class consisting of hydrogen, methyl radical and chlorine,

X is selected from the class consisting of hydrogen and the methyl radical, x is a number of from 1 to 2, n is a i number of from 0 to 14, and M is a water-solubilizing cation.

Compounds having the above formula are readily obtainable by the condensation of the appropriate hydroxyalkanesulfonic acid or (hydroxyalkoxy)alkane. sulfonic acid, e. g., isethionic acid or Z-methylisethionic acid, a

water-soluble salt thereof or the hydroxy ether of such an acid and a polyalkylene glycol with the appropriate aryloxy-substituted fatty acid or acyl halide thereof substantially according to the scheme:

2,857,261 Patented Oct. 21, 1958 acids having from 1 to 4 chlorine atoms andhaving in the benzene ring thereof at least one unsubstituted carbon atom in the position orthoto the oxy-linkage, such as 4- chloro-, 2,4-dichloro-, 2,4,5-trichloroor 2,3,4,5-tetrachlorophenoxyacetic acid. Another useful class of aryloxy fatty acids of the above general formula are archlorinated a-phenoxypropionic acids having from 1 to 4 chlorine atoms and having in the benzene ring thereof at least one unsubstituted carbon atom in the position orthoto the oxy-linkage, e. g., 3-chloro-, 2,3-dichloro-, 2,4,5- trichloro- .or 2,3,4,5-tetrachlorou-phenoxypropionic acid.

Still another class of suitable aryloxy fatty acids of the above formula comprises the ara1kylated-archlorinated phenoxyacetic acids having in the benzene ring thereof at least one unsubstituted carbon atom in the position orthoto the oxygen linkage, e. g., 4-chlor0-2-methylphenoxyacetic acid, 4,S-dichloro-Z-ethylphenoxyacetic acid, 3-isopropyl-2,4,5-trichlorophenoxyacetic acid, 2-butyl-4-chlorophenoxyacetic acid, etc.

Useful compounds of the above formula also are the corresponding u-aryloxypropionic acids, i. e., the ar-alkylated-ar-chlorinated a-phenoxypropionic acids, e. g., 2- chloro-4,S-diethyI-a-phenoxypropionic acid, 3-butyl-4- chloro 0c phenoxypropionic acid, 3 n propyl 2,4,5- trichloro-u-phenoxypropionic acid, 2-chloro-4-methyl-aphenoxypropionic acid, 3-chloro-2,4,5-trimethyl-a-phenoxypropionic acid, etc.

Another class of useful aryloxy-substituted fatty acids having the above general formula and useful for the present purpose includes the ar-chlorinated B-phenoxypropionic acids having in the benzene ring thereof at least one unsubstituted carbon atom in a position orthoto the oxy-linkage, e. g., fi-(2-chloro-, 2,3-dichloro-, 2,4,5-trichloroor 2,3,4,5-tetrachloro)phenoxypropionic acids. The corresponding aralkylated-ar-chlorinated fl-phenoxypropionic acids of the above general formula are likewise useful. Examples of such ar-chloro-ar-alkyl compounds are fl-(2-chloro-4-methylphenoxy)propionic acid, B-(4- dibutyl-Z,3-dichlorophenoxy)-propionic acid, 3-(3-ethyl- 2,4,5-trichlorophenoxy)propionic acid, B-(3-chloro-2,4,5- trimethylphenoxy)propionic acid, etc.

Other classes of useful aryloxy-substituted fatty acids of the above general formula are the ar-chlorinated fi-phenoxyisobutyric acids or the ar-chlorinated-ar-alkylated fiphenoxyisobutyric acids having in the benzene ring thereof at least one unsubstituted carbon atom in a position orthoto the oxy-linkage. Examples of the first of these classes are ,8-(2,4-dichlorophenoxy)-isobutyric acid and fi-ig ij-trichlorophenoxy)isobutyric acid. Examples of the other of these classes are ,8-(2-chloro-4-tolyloxy)-isoorthoposition in the benzene ring, e. g., 5-(2-chloro-,

halides thereof having the above formula and useful for l the present purpose are the air-chlorinated phenoxyacetic 2,4-dichloroor 2,3,4,S-tetrachlorophenoxy)butyric acid or 3-(4-chloro-o-tolyloxy)butyric acid or B-(B-isopropyl- 2,4-dichlorophenoxy)butyric acid.

Other aryloxy-substituted fatty acids embraced by the above general formula and useful in the preparation of the present herbicidally active compounds are the archlorinated or the ar-alkylated-ar-chlorinated n e-dimethyl-B-phenoxypropionic acids having a free orthoposition in the benzene ring, e. g., a,B-dimethyl-/8-(2- chlorophenoxy)propionic acid, a,B-dimethyl-(fl-2,4-dichlorophenoxy)propionic acid, a,/3dim6thyl-}9-(Z-ChlOI'O- 4-isopropylphenoxy)propionic acid, dichloro-3-methylphenoxy)propionic acid, etc.

Aryloxy-substituted chlorinated fatty acids useful for the preparation of the present herbicidally active compounds are, e. g., the ar-chlorinated or the ar-alkylated-archlorinated fl-phenoxy chloroacetic acids, the B-phenoxya-chloropropionic or butyric acids, the p-phenoxy-B- chloropropionic acids or butyric acids, and the fi-phenoxy-a,B-dichloropropionic or butyric acids. As examples of such aryloxy chlorinated fatty acids may be mentioned; 4-chlorophenoxychloroacetic acid, 2,4'-dichlorophen oxy,- chloroacetic acid, 2,4,5 trichlorophenoxychloroacetic acid,

4-chloro-o-toly1oxychloroacetic acid; p- (2,4-diphl6rophen1 oxy)-u-chloropropionic acid, B-(2,4,5-trichlorophenoxy,)r fl-chloropropionic acid, fl-(4,5-dichloro-o-tolyloxy)-u,fi-

dichloropropionic acid, t1(2,4-dlChlO1'OPheHOXy) -OPChIQ robutyric acid, etc.

Isethionic acid compounds having the above formula and reactive with the above aryloxy-substituted fatty acids to yield the present improved herbicidal compounds are isethionic acid, Z-methylisethionic acid and the watersoluble salts thereof, e. g., the alkali metal isethionates or Z-methylisethionates such as sodium, potassium or lithium isethionate or Z-methylisethionate, ammonium isethionate or Z-methylisethionate, organic amine salts of the isethionates such as the dimethylamine, the butylamine, the triethylamine, the ethanolamine, the isopropanolamine, the tri-n-propanolamine or the morpholino salts of isethionic or 2-methylisethionic acid. Hydroxy ethers;v

of such isethionic acid compounds obtainable, e. g., by reaction of said acid compounds with ethylene glycol, polyalkylene glycols or with from 1 to 15 moles of ethylene oxide are; particularly useful in the preparationv of the present esters. As examples of such hydroxy ethers may be, mentioned: 2-(2-hydroxyethoxy)ethanesulfonic acid and water-soluble salts thereof, the hydroxy ethers obtainable by reaction, of isethionic acid or Z-methylisethionic acid,or, the salts, thereof with diethylene glycol, pentaethylene glycol, octaethylene glycolor pentadecaethylene glycol; etc. etherszmayi also be prepared-by condensing from 2 to, 15

molesof-ethyleneoxide or isopropylene oxide with 1 mole.

of the isethionicacid or Zunethylisethionic, acid.

Compounds, obtainable by the condensation of saidaryloxy-substituted fatty acids. and: said isethionic acid,

compounds are, e. g;, salts. of 2 sulfoethyl or 2-sulfoisopropyl ar-chlorinated or ar-alkylated-ar-chlorinated phenoxyacetates, aor fi phenoxypropionates, fl-phenoxyisobutyrates, fi-phenoxybutyrates or a fl-dimethyl-firphenoxypropionateshaving from 1- to 4 carbon atoms in the alkyl radical and having in: the benzene ring thereof at least one carbon, atom in the position orthoto the oxy-linkage.

Asexamples, of such 2-sulfoethyl or 2-sulfoisopropyl ar-chlorinated;phenoxyacetates:may be mentioned:

As examples of such 2-sulfoethyl or 2-sulfoisopropyl ar-chlorinated-ar-alkylated phenoxyacetates may be mentioned:

Z-sulfoethyl 4-chloro-o-tolyloxyacetate 2-(amrnonium sulfo)ethyl 4-chloro-o-tolyloxyacetate.

2-(sodium su1fo)isopropyl 2,4-dichloro-3-ethylphenoxyacetate 2-(lithium sulfo)ethyl 2-butyl-3,5-dichlorophenoxyacetate Dibutylamine salt of Z-sulfoethyl,2,3t-dichloro-4-isopropylphenoxyaeetate The useful polyalkylene glycol Triethanolamine salt of 2-sulfoethyl 4-chloro-2,3,5-trimethylphenoxyacetate Morpholine salt of 2-sulfoethyl 3-chloro-ptolyloxyacetate Z-(sodium sulfo)ethyl 2-methy1-3,4,5-trichlorophenoxyacetate As examples of such 2-sulfoethyl or 2-sulfoisopropyl ar-chlorinated fl-phenoxypropionates may be mentioned: 2-sulfoethyl [3- (4,-chlorophenoxy) propionate 2-(sodium sulfo)isopropyl B-(3-chlorophenoxy)propionate 2-(potassium pionate sulfo)ethyl fl-(2,4-dichlorophenoxy)pro- Isopropanolamine-salt of 2-sulfoethyl p-(2,4,5-trichloro- Cal phenoxy)propionate. Triethylamine salt of 2-sulfoethyl fl-(2,3,4,5-tetrachlorophenoxy)propionate Examples of such 2-sulfoethyl or, 2-sulfoisoprojpyl archlorinated-ar-alkylated fi-phenoxypropionates are:

2-sulfoethyl fl-(2-chloro4-tolyl) propionate Z-(potassium sulfo)ethyl [3-(3,4-dichloro-p-tolyl)propionate.

2-(sodium sulfo)isopropyl ,3-(4-ethyl-2,3,S-trichlorophenoxy prop ionate Z-(ammomum sulfo)ethyl fi- (4-butyl-2,3-dichlorophenoxy) propionate Triethylenetetramine salt of 2-sulfoethyl fi-(2,3r-dichloro- 4,5 -dimethylphenoxy) propionate Morpholine salt of 2-sulfoethyl, B-('4-chloro-2,3,5-triethylphenoxy-)pr,opionate Examples of presently provided 2-sulfoethyl or 2-sulfoisoproyl ar-chlorinated fi-phenoxypropionates are:

0 2sulfoethy1 ,6-(4-chlorophenoxy)propionate 2-(sodium sulfo)ethyl fl-(3,4-dichlorophenoxy)propionate Z-(ammonium sulfo)isopropyl p-(3,4,5-trichlorophenoxy) propionate n-Butylamine salt of 2-sulfoethyl 8-(2,3,4,5-tetrach1orophenoxy)propionate Examples of the present 2-sulfoethyl or 2-sulfoisopropyl ar-alkylated-ar-chlorinated p-phenoxypropionates are:

2-.sulfoe thyl }3-(2-chloro-4-n-propylphenoxy)propionate 2 (p otassium sulfo)isopropyl fl-(3,4-dichloro-o-tolyloxy) propionate Triisopropanolamine salt of 2-sulfoethyl B-(Z-n-butyl-BA,

S-trichlorophenoxy propionate Examples; of thepresently provided 2-sulfoethyl or 2- sulfoisopropyl alt-chlorinated ,B-phenoxyisobutyrates are:

2-sulfoethyl B- (2,4-dichlorophenoxy isobutyrate 2- (sodium sulfo)ethyl fl (-4-chlorophenoxy)isobutyrate Diethylenetriamine salt of 2-sulfoisopropyl B-(2,4,5-trichlorophenoxy) isobutyrate As examples of the present 2-sulfoethyl or 2-sulfoisopropyl ar-alkylated-ar-chlorinated fi-phenoxyisobutyrates may be mentioned:

2-(sulfoethyl fl-(4-chloro-o-tolyloxy)isobutyrate 2-(sodium sulfo)ethyl fi-(2-chloro-4-ethylphenoxy)isobutyrate v Ethanolamine salt of 2-sulfoisopropyl fl-(ZA-dichloro-nbutylphenoxy) isobutyrate Examples of the present 2-sulfoethyl or 2-sulfoisopropyl-ar-chiorinated ix,;8-dimethyl-/3-phenoxy propionates are:

2-su 1foisopropyl a,fi-dimethy1-/3-( 3 chlorophenoxy)-propionate,

2-(potassium sulfo)ethyl a,[3-dimethyl [i (2,4-dich1orophenoxy)propionate Morpholine salt: of 2-sulfoethyl: a,fl-dimethyl'-[3-(2,4,5 tridichlorophenoxy)propionate Examples of the present 2-sulfoethyl or i-sulfoisopropyl ar-alkylated-ar-chlorinated a,p-dimethyl-p-phenoxypropionates are:

2-sulfoethyl a,fl-dirnethy1-,3-(2-chloro-4-n butylphenoxy)- propionate Z-(ammonium sulfo)ethyl a,[3-dimethyl-[3-(3,4-dichloro-otolyloxy) propionate 2-(sodium sulfo)isopropyl a,[i-dimethyl-fl-(2-isopropyl-3,

4,5-trichlorophenoxy)propionate As examples of the present 2-sulfoethyl or 2-sulfoisopropyl ar-alkylated or ar-alkylated-ar-chlorinated [Si-phenoxychloroacetates may be mentioned:

2-sulfoethyl 4-chlorophenoxychloroacetate 2-(potassium sulfo)isopropyl 3-chloro-o-tolyloxychloroacetate The di-n-butylamine salt of 2-sulfoethyl 2,4,5-trichlorophenoxychloroacetate As examples of the present 2-sulfoethyl or 2-sulfoisopropyl ar-chlorinated or a'r-alkylated-ar-chlorinated 13- phenoxy ot-chloropropionates may be mentioned:

2-sulfoethyl t?- 2,4-dichlorophenoxy) -u-chloropropionate 2-(sodium sulfo)ethyl fl-(2,4,5 trichlorophenoxy) achloropropionate Triisobutanolamine salt of 2-sulfoisopropyl fl-(4-chloro- Z-propylphenoxy)-u-chloropropionate As examples of the present Z-sulfoethyl or 2-sulfois0- propyl ar-alkylated or ar-alkylated-ar-chlorinated B-phenoxy-fl-chloropropionates may be mentioned:

2-sulfoisopropyl fl- 2-chlorophenoxy) -B-chloropropionate Z-(ammonium sulfo)ethyl ,B-(ZA-dichlorophenoxy)-,B-

chloropropionate The morpholine salt of 2-sulfoethyl ,6-(4-chloro-2-ethylphenoxy) -fi-chloropropionate Illustrative of the present 2-sulfoethyl or 2-sulfoisopropyl ar-alkylated or ar-alkylated-ar-chlorinated B-aryloxy a,fi-dichloropropionates are:

2-sulfoethyl ,8-(4-chlorophenoxy)-a,,8-dichloropropionate 2- (sodium sulfo ethyl 8- 3 ,4-dichloro-o-tolyloxy) -oc,]3-di chloropropionate The diethanolamine salt of 2-sulfoisopropyl ,8-(2,4,5-trichlorophenoxy -a,[i-dichloropropionate 2-(2-sodium sulfoethoxy)ethyl 2,4-dichlorophenoxyacetate 2-(2-ammonium sulfoisopropoxy)isopropyl B-(2-chloro-4- tolyl propionate The triethanolamine salt of 2-(2-sulfoethoxy)ethyl 2,4-

dichlorophenoxyacetate As examples of the esters of the present aryloxy substituted fatty acids and polyalkylene glycol ethers of isethionic or Z-methylisethionic acid may be mentioned:

The sodium salt of the ester of 2,4,5-trichlorophenoxyacetic acid and the pentaethylene glycol ether of isethionic acid.

The ammonium salt of the ester of 4-chloro-2-tolyloxy a-chlorcpropionic acid and the diethylene glycol ether of isethionic acid.

The isobutanolamine salt of the ester of B-(4-chloro-otolyloxy)isobutyrate and the decaisopropylene glycol ether of Z-methylisethionic acid.

ashr m The sodium salt of the ester of 2,4-dichlorophnoxy' acetic acid and the pentadecaethylene glycol ether of isethionic acid.

In preparing the present sulfoalkyl esters I operate substantially as follows: I heat a mixture of the isethionic acid compound, e. g., isethionic or Z-methylisethionic acid or salt thereof, with the ar-chlorinated aryloxy-substituted fatty acid compound at a temperature of from, say, C. to below the decomposition point of the reaction mixture, until formation of the sulfoalkyl ester has occurred. An inert diluent may or may not be employed. Since the reaction occurs by condensation of one mole of the isethionic acid compound with one mole of aryloxy-substituted fatty acid compound, equimolar proportions of the reactants generally may be employed. In practice, it may be preferable to use a slight excess of whichever component is more readily obtainable in order to assure complete reaction of the less readily obtainable reactant. The reaction may be effected at ordinary atmospheric, sub-atmospheric or superatmospheric pressures. Generally, in order to permit smooth and rapid reaction at the higher temperatures, e. g., at temperatures of from, say, 200 C. to 300 C., it is advantageous to operate at diminished pressure, say, it a presseure of from 10 to 100 mm. of mercury. Catalysts may or may not be employed. Useful catalysts comprise organic or inorganic acid or basic materials, e. g., sulfuric acid, 4- toluenesulfonic acid, sodium methoxide, etc. The reaction product, i. e., the sulfoethyl ester, is separated from the resulting reaction mixture by simply removing any unreacted constituents, e. g., by distilling, decanting, washing or extracting. Generally the use of substantially equimolar proportions of the isethionic salt and the aryloxy-substituted fatty acid compound and heating at temperatures of from 200 C. to 300 C. for a time of, say, from a few minutes to several hours, assures complete reaction of both components so that the reaction product consists of the substantially pure, crystalline salt of the sulfoethyl ester. In this case no further treatment of the product is required.

As may be apparent to those skilled in the art, use of isethionic acid or of Z-methylisethionic acid in the condensation reaction will result in the formation of the free sulfonic acd. While the free acid may be employed as the active ingredient in the formulation of herbicidal compositions, for ease in manipulation and storage, it is generally advisable to convert the 2-sulfoalkyl ester into the sulfonate. This may be effected by neutralizing;

the free sulfonic acid with an appropriate organic or inorganic basically reacting agent until a neutral product is obtained. Useful basic materials in the neutralizing step are alkali metal hydroxides or the basically reacting salts thereof, water-solubilizing alkyl or alkanolamines, ammonium hydroxide or basically reacting salts thereof, morpholine etc.

The present s-ulfoalkyl esters and the water-soluble salts thereof are generally substantially colorless, crystalline materials which are characterized by high, selective herbicidal efliciency and low volatility. In prior art, the

usefulness of chlorinated phenoxy-substituted fattyacids,-

e. g., 2,4-dichloroor 2,4,5-trichlorophenoxyacetic acid, in weed control has been somewhat limited in that, owing to their high volatility, they were readily transported from the unwanted weeds, upon which they had been applied, to neighboring fields of crops. The 2,4-D or the 2,4,5-T type of herbicides possess a selectivity of action against broad-leafed plants, and since the majority of horticultural and crop plants are also broad-leafed,

the utility of such herbicides for deweeding grass plots' adjacent to cultivated areas was problematic. Attempts to decrease the high volatility of the aryloxyacetic acid type of herbicides by variously substituting the nucleus or by esterifying the carboxy radical have been generally unsuccessful in that lowered volatility was often accompanied by a modification of herbicidal effect and an Example 1 To a 1-liter reaction vessel equipped with mechanical stirrer and thermometer there was charged a'mixture consisting of 246 g. (1.0 mole) of 2,4-dichlorophenoxyacetic acid (90% assay) and 148 g. (1.0 mole) of sodium isethionate. The total weight of reactor and charge was 967.3 g. The charge was melted and heating was continued to a temperatureoff210 C.,-at which point waterpump vacuum was applied. Heating at from 210 C. to 255 C. at a pressure of about 20 mm. of mercury was continued for 45 minutes. During this time, considerable evolution of water was noted. At the end of the heating timethere was a weight loss of 303g. A portion of the reaction mixture was removed and washed thoroughly with acetone to remove any unreacted material. Analysis of the washed and dried product gave 18.22% chlorine as against 20.20%, the theoretical chlorine value for C H Cl NaO S, i. e., 2-(sodium sulfo)ethyl 2,4-dichlorophenoxyacetate. Accordingly, the acetone-washed prodnot was dissolved in water, filtered to remove traces of insoluble material and slowly precipitated by gradual addition of ethanol in order to separate the water-soluble sodium isethionate. The precipitate which formed upon treatment with ethanol was filtered off and dried to give the substantially pure 2-(sodium sulfo)ethyl 2,4-dichloropheno-xyacetate, M. P. above 270 C., analyzing 19.35% chlorine. It is labelled Product I in the herbicidal evaluation tests of Example 6.

Example 2 To a 500 ml., 3-neck flask equipped with glass stirrer, thermometer and take-over head connected to a vacuum source there was charged 94.0 g. (0.338 mole based on 92% assay) of 2,4,5-trichlorophenoxyacetic acid and 50.0 g. (0.338 mole) of sodium isethionate. The temperature of the charge was raised rapidly to 200 C., and water-pump vacuum was gradually applied, so that within about 15 minutes the temperature of the reaction mixture had reached 250 C. After a total heating time of 20 minutes at a temperature of 215255 C., and a minimum vacuum of about 40 mm. of mercury, heating was discontinued. During this time water together with a small quantity of phenol distilled off. A total weight loss of 21.6 g. of the reaction mixture was noted. By the end of the heating period the reaction mixture had begun to solidify. The liquid portion of the reaction mixture was removed, and the residual solid was washed 3 times with an excess of acetone, dried and dissolved in hot water to give an approximately 20% solution. The hot solution was filtered to remove traces of water insoluble material. The precipitate which formed in the filtrate upon cooling was filtered ofi, dried, washed with acetone and dried to give the substantially pure 2-(sodium sulfo)ethyl 2,4,5-trichlorophenoxyacetate analyzing 27.61% chlorine as against 27.59% the calculated value for CIQHSCI3NQO5S.

Example 3 Employing the apparatus described in Example 2, a mixture consisting of 111.5 g. (0.5 mole based on 90% assay) of 4-chloro-o-tolyloxyacetic acid and 74.0 g. (0.5 mole) of sodium isethionate was heated to a temperature of 225 C., water-pump vacuum was applied and heating was continued to a temperature of 255 C., at a pressure of about 25 mm. of mercury, for 15 minutes. Attempted washing of the cooled reaction mixture with acetone was only partially successful in that swelling of the product caused difiiculty in filtration. The reaction mixture was extremely soluble in water and was not precipitated by ethanol-addition. Accordingly, after filtering the reaction mixture to remove traces 'of water insoluble material it wasconcentrated. *The' crystalline solid which formed in the concentrated solution was dried, washed twice with absolute-ethanol, filtered and dried to give the substantially pure 2-(sodium sulfo)ethyl 4-chloro-o-toyloxyacetate, analyzing 10.52% chlorine as against 10.72% the calculated chlorine'value for C H ClNaO S.

"Example 4 This example shows "esterification of 2,4-dichlorophenoxyacetic acid with s'odiumisethionate in the presence of an inert diluent. To a 1-liter reactor equipped with stirrer, thermometer, modified Dean and Stark trap, and a reflux condenser there was charged 400 g. of trichlorobenzene, 148 g. (1.0 mole) of sodium isethionate and 221.9 g. (1.0 mole based on 99.6% assay) of 2,4-dichlorophenoxyacetic'acid. The charge was rapidly brought to a pot temperature of 192 C. and maintained at a temperature of 192-215 C. for a time of 2 hours and 50 minutes. During this time a total of 17.3 g. (96.2% of theory) 'ofwaterw'as collected. At the end of the heating, the'reaction mixture was poured rapidly, with stirring, into 1600 g. of water and the reactor was washed with hot water and the "water washings combined with the main product. The whole was then allowed to stand overnight. The organic layer which formed upon standing was separated and the residual aqueous layer shaken with activated alumina and filtered to remove traces of insolublematerial. One-half (1210 g.) of the filtrate was drum dried at 60 lbs. steam pressure to give 165.0 g. (94.4% theoretical yield) of the substantially pure 2- (sodium sulfo)ethyl 2,4-dichlorophenoxyacetate. Onefou'rth (605 g.) of the filtrate was neutralized with 6.2 g. of 40% sodium hydroxide, filtered and drum dried at 60 lbs.- steam pressure to give 80.7 g. (92% theoretical yield) of the substantially pure Z-(sodium sulfo)ethyl 2,4-dichlorophenoxyacetate. Both products gave clear aqueoussolutions.

ExampleS To a 1-liter, 3-neck reactor fitted with glass paddle, thermometer and take-over head there was charged 256.5 g. (1.0 mole) of 2,4,S-trichlorophenoxyacetic acid and202 g. (1.05 mole) of sodium 2-(2-hydroxyethoxy) ethanesulfonate. The charge was heated to a temperature of 150 C. at which 'point it became fluid and water began to condense in the take-off condenser. Heating was then continued until a temperature of 250 C. was attained, and a water pump vacuum was then applied. After maintaining the reaction mixture for 15 minutes at a temperature of 250 C. and a pressure of 22 mm. of mercury the loss in weight of the charge was determined to be 30.8 g. The reaction mixture, a liquid having a freezing point of ISO- C. was stirred with 200 g. of acetone and filtered. There was thus obtained as the precipitate the substantially pure 2-(2-sodium sulfoethoxy)ethyl 2,4,5-trichlorophenoxyacetate.

Example 6 This example describes testing of the herbicidal activity of the compounds prepared in Examples 1-3. Aluminum pan flats, filled with 'mixtures consisting of 2 parts of top soil which had been screened through a M: wire mesh and 1 part of sand, were seeded to buckwheat, radish, wild oats and rye grass. Twenty seeds of each were used. The grass seeds were scattered randomly over one-third the area of the soil surface and the seeds of the broad-leafed plants were randomly scattered over the remaining twothirds of the soil surface. The seeds were covered with a layer of the soil. The seeded pans were placed in /2" of water and allowed to absorb moisture through the perforated bottom until the soil surface was completely moist. The pans were then transferred to a wet sandbench in the greenhouse for germination and growth. Respective 0.4percent (by weight) aqueous solutions of 2- (sodium sulfo)ethyl 2,4 dichlorophenoxyac'e'tate (Product I), 2-(sodium sulfo)-ethyl 2,4,5-trichlorophenoxyacetate (Product II) and 2-(sodium sulfo)ethyl 4-chloro-o-tolyloxyacetate (Product III) were prepared. When the test plants in the pan flats were from days to 2 weeks old, they were sprayed, respectively, by means of an atomizer, with 30 cc. of the solution. The sprayed pans of plants were then maintained in the greenhouse for 10 days. At the end of this time, observation of the sprayed plants showed the grass which had been sprayed with the solution of Product II and III to be entirely unharmed whereas that which had been sprayed with Product I showed slight injury. Broad-leafed plants which had been sprayed with the solutions of Product I and II were completely dead and those which had been sprayed with the solution of Product III showed severe injury.

Similar testing of Product I at a concentration of 0.13 percent showed no injury to grass at this concentration, whereas broad-leafed plants were completely dead.

Example 7 This example describes testing of the volatility characteristics of the compounds of Examples II and III, i. e., 2 (sodium sulfo)ethyl 2,4,5 trichlorophenoxyacetate (Product II) and 2-(sodium sulfo)ethyl 4-chloro-o-tolyloxyacetate (Product III).

Respective 1% aqueous solutions of each compound were prepared and 0.12 cc. of the solution of Product II was applied to a section of filter paper. To another filter paper there was applied 0.132 cc. of the solution of Product III, the quantity of solution employed in each case being gauged to provide comparable amounts of each chemical based on the acid equivalent.

Potted bush beans (Black Valentine variety) with first trifoliate leaves still unfolded were sealed in polyethylene bags X 8") inside of which had been attached (at the top) one of the treated filter papers. The sealed pots were then maintained for 48 hours at a temperature of 75-85 F. After 48 hours the plastic bags were removed and the plants placed in wet sandbenches in the greenhouse. Observation of the plants 9 days after the plastic bag had been sealed to the pots showed no visible effect of the test chemicals upon the plants. On the other hand, in a similarly conducted test with butyl 2,4-dichlorophenoxyacetate the use of an equivalent quantity (0.12 cc.) of this ester showed the plants to be completely dead 9 days after pots of the bush beans had been sealed.

The very good water-solubility of the present esters is of economic significance in that it permits easy and inexpensive formulation. Unlike the prior water-insoluble esters of the 2,4-D or 2,4,5-T type, the present sulfoethyl esters need not be dispersed or emulsified for use as sprays. They may be packaged in solid form for the user to incorporate into water in the useful concentrations, or they may be sold in concentrated aqueous solutions which need be merely diluted with water prior to use. organic solvents, emulsifying agents, or special formulating equipment is required.

While the present sulfoethyl esters are most advantageously employed as herbicides in aqueous solution, they may also be incorporated into solid carriers such as clay, talc, pumice and bentonite to give herbicidal compositions which may be applied to the living plants or to soil sur faces which are to be freed from broad-leafed plant growth. The present esters may also be mixed with liquid or solid agricultural pesticides, e. g., insecticides and fungicides. For specialty uses, oil-in-water emulsions of the sulfoethyl esters may be prepared, employing either ionic or nonionic emulsifying agents, e. g., the long chain polyalkylene glycols or the long chain alkyl sulf.succinates.

Because of the very high herbicidal efficiency of the present sulfoethyl esters, they are present in the herbicidal sprays or dusts in only very small concentrations, for example,-in concentrations of from 0.01 percent to 1.0 per- Neither cent by weight. The sulfoethyl esters possess at least the Rl m in which R, R, R and R are selected from the class consisting of hydrogen, chlorine and alkyl radicals of from 1 to 4 carbon atoms and in which at least one of R, R, R" and R is chlorine, x is a number of from 1 to 2, n is a number of from 0 to 1 and M is a water-solubilizing cation.

2. 2-(2-sodium sulfoethoxy)ethy1 2,4,5-trichlorophenoxyacetate.

3. Z-(sodium sulfo)ethyl 2,4-dichlorophenoxyacetate.

4. 2-(sodium sulfo)ethyl 2,4,5-trichlorophenoxyacetate.

5. 2-(sodium sulfo)ethyl 4-chloro-o-tolyloxyacetate.

6. A herbicidal composition comprising an inert carrier and as the essential active ingredient a phytotoxic quantity of a sulfo-ester having the formula:

in which R, R, R and R are selected from the class consisting of hydrogen, chlorine and alkyl radicals of from 1 to 4 carbon atoms and in which at least one of R, R, R and R' is chlorine, x is a number of from 1 to 2, n is a number of from 0 to 1 and M is a watersolubilizing cation.

7. A herbicidal composition comprising an inert carrier and a phytotoxic quantity of 2-(sodium sulfo)ethyl 2,4-dichlorophenoxyacetate as the essential active ingredient.

8. A herbicidal composition comprising an inert carrier and a phytotoxic quantity of 2-(sodium sulfo)ethyl 2,4,5-trichlorophenoxyacetate as the essential active ingredient.

9. A herbicidal composition comprising an inert carrier and a phytotoxic quantity of 2-(sodium sulfo)ethyl 4-chloro-o-tolyloxyacetate as the essential active ingredient 10. The method of destroying undesirable plants which comprises applying to said plants a phytotoxic quantity of a herbicidal composition comprising as the essential active ingredient a sulfo-ester of the formula:

in which R, R, R" and R are selected from the class consisting of hydrogen, chlorine and alkyl radicals of from 1 to 4 carbon atoms and in which at least one of R, R, R, and R' is chlorine, x is a number of from 1 to 2, n is a number of from 0 to 1 and M is a watersolubilizing cation.

11. The method of destroying undesirable plants which comprises applying to said plants a phytotoxic quantity of a herbicidal composition comprising 2-(sodium sulfo)- ethyl 2,4,5-trichlorophenoxyacetate as the essential active ingredient.

12. The method of destroying undesirable plants which comprises applying to said plants a phytotoxic quantity of a herbicidal comp tion co pri -(sod um ul a)- 2,390, 41 ethyl 4-ch1oro-o-tolyloxyacetate as the essential agtive i11- 2,523,228 sm qn 2, 96, 9

References Cited in the file ofythis .Patent 5 UNITED STATES PATENTS 2,179,209 Daimler Nov. 7, 1939 pp. 267-278.

OTHER REFERENCES Contrib. Boyce Thompson Institute," April-June 1951,

Claims (3)

1. A SULFO-ESTER HAVING THE FORMULA

6. A HERBICIDAL COMPOSITION COMPRISING AN INERT CARRIER AND AS THE ESSENTIAL ACTIVE INGREDIENT A PHYTOTOXIC QUANTITY OF A SULFO-ESTER HAVING THE FORMULA:

10. THE METHOD OF DESTROYING UNDESIRABLE PLANTS WHICH COMPRISES APPLYING TO SAID PLANTS A PHYTOTOXIC QUANTITY OF A HERBICAL COMPOSITION COMPRISING AS THE ESSENTIAL ACTIVE INGREDIENT A SULFO-ESTER OF THE FORMULA: