GB1580880A - 4-alkylthio-2-trifluoromethyl-alkanesulphonalides and derivatives thereof - Google Patents

Abstract

2-Trifluoromethylalkanesulphonanilides substituted in the p position have the following formula <IMAGE> in which R<1> and R<2> denote an alkyl group having from 1 to 4 carbon atoms and n is 0 or 1 or 2, with the proviso that R<1> and R<2> are not simultaneously the methyl group. The compounds of the formula I may also be present as salts. An agent for modifying the growth of higher plants contains as active component at least one new compound of the formula I. In a method of modifying the growth of higher plants, a compound of the formula I is applied to the plants.

Description

(54) 4-ALKYLTHIO-2-TRIFLUOROMETHYL-ALKANESULFONANILIDES AND DERIVATIVES THEREOF (71) We, MINNESOTA MINING AND MANUFACTURING COMPANY, a corporation organized and existing under the laws of the State of Delaware, United States of America, of 3M Center, Saint Paul, Minnesota 55101, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to compounds of the formula

wherein Rl and R2 are independently alkyl groups containing from 1 to 4 carbon atoms and n is 0-2, provided that Rl and R2 are not both methyl, and agriculturally acceptable salts thereof.

These compounds are active as plant growth modifying agents, including as herbicidal agents. A particularly valuable property of the compounds is their ability to control rhizomatous Johnsongrass, Sorghum halepense (L. Pers.), often at application rates tolerated by particular crops which it commonly infests, such as cotton. Compounds disclosed in U.K. Specification No. 1,520,149, which conform to formula l above, except that both R' and R2 are methyl. also exhibit selective control of rhizomatous Johnsongrass in cotton but do not share other properties of the more similar compounds of the invention, such as selective activity against rhizomatous Johnsongrass in other crops, and/or particularly high specific plant growth modifying or herbicidal activity.

The invention also relates to plant growth modifying and herbicidal compositions comprising the compounds of the invention (including compositions consisting essentially of a compound of the invention dispersed in an agricultural extending medium), to the use of the compounds to modify (regulate, control, kill) higher plants and to methods for preparing the compounds and intermediates in their preparation.

The compounds of formula I, above, can form salts, i.e. compounds of the above formula wherein the sulphonamide H is replaced by an agriculturally acceptable cation. These are generally metal, ammonium and organic amine salts and can be prepared by treating the acid-form compound with an appropriate base under mild conditions. Among the salts of the invention are alkali metal (e.g. lithium, sodium and potassium), alkaline earth metal (e.g. barium, calcium and magnesium) and heavy metal (e.g. iron) salts as well as other metal salts such as zinc and aluminum. Appropriate bases for use in preparing the metal salts include metal oxides, hydroxides, carbonates, bicarbonates and alkoxides. Some salts are also prepared by cation exchange reaction (by reacting a salt of the invention with an organic or inorganic salt in a cation exchange reaction). The organic amine salts include the salts of aliphatic (e.g. alkyl), aromatic and heterocyclic amines, as well as those having a mixture of these types of structures. The amines useful in preparing the salts of the invention can be primary, secondary or tertiary and preferably contain not more than 20 carbon atoms. Such amines include, for example, morpholine, methyl cyclohexylamine, glucosamine and amines derived from fatty acids. The amine and ammonium salts can be prepared by reacting the acid form with the appropriate organic base or ammonium hydroxide. Any of the salts of the types set out above are agriculturally acceptable, the one chosen depending upon the particular use and upon the economics of the situation. Of particular utility are the alkali metal, alkaline earth, ammonium and amine salts.

The salts of the invention are frequently formed by reacting the precursors in aqueous solution. This solution can be evaporated to obtain the salt of the compound, usually as a dry powder. In some cases, it may be more convenient to use a non-aqueous solvent such as alcohols, acetones, etc. The resulting solution is then treated to remove the solvent, for example, by evaporation under reduced pressure.

The compounds of the invention can be prepared according to the following reaction sequences. The compound (or class of compounds) listed behind each numbered step is the product of that step (and the starting material for the next step, if any).

Method 1 Starting compound: 5-chloro-2-nitrobenzotrifluoride (1) 2-nitro-5-alkylthiobenzotrifluoride (containing the R2 group) (2) 4-alkylthio-2-trifluoromethylaniline (3) N-alkylSulfonyl-4-alkylthio-2-trifluoromethylalkanesulfonanilide (containing the moiety -N(SO2R')2) (4) the compound of formula I wherein n is zero (5) the compound of formula I wherein n is 1 or 2 Method 2 Starting compound: 2-aminobenzotrifluoride (1) 4-thiocyano-2-trifluoromethylaniline Note: this compound can be converted directly to the product of step (2) of Method 1.

(2) N-alkylsulfonyl-4-thiocyano-2-trifluoromethylalkanesulfonanilide (containing the moiety -N(502R')2) (3) the compound of formula I wherein n is zero Method 3 Starting compound: 2-aminobenzotrifluoride (1) 2-trifluoromethylalkanesulfonanilide (containing the R' group) (2) 4-bromo-2-trifluoromethylalkanesulfonanilide (3) the compound of formula I wherein n is zero The final product of Methods 2 and 3 as shown is, of course, the same as the product of step (4) of Method 1 and can be converted to the product of step (5) of Method 1.

Step (1) of Method 1 is carried out by heating 5-chloro-2-nitrobenzotrifluoride together with a slight excess of an alkanethiol in a suitable solvent in the presence of the appropriate amount of base. The solvent is one in which the reactants are soluble such as lower alkanol, e.g. ethanol. The base is a strong organic or inorganic base. Suitable organic bases are tertiary amines such as N,N-dimethylaniline, triethylamine, pyridine, and alkoxides such as sodium ethoxide. Suitable inorganic bases are alkali metal hydroxides such as sodium and potassium hydroxides, and calcium hydride. The product is isolated by conventional methods.

Alternatively, step (1) can be carried out by stirring a methylene chloride solution of 5-chloro-2-nitrobenzotrifluoride and a phase transfer catalyst with an aqueous base solution of the alkanethiol. Other solvents, such as benzene and dichlorobenzene, and various catalysts, such as organic ammonium salts, can also be utilized. Ordinarily the alkanethiol in dilute (approximately 4 percent) aqueous base is reacted with one-half an equivalent of 5-chloro-2-nitrobenzotrifluoride dissolved in methylene chloride in the presence of triethylbenzylammonium chloride (the phase transfer catalyst). However. when a branched thiol. such as 2-propanethiol or 2-methyl-2-butanethiol. is utilized. additional quantities of base and thiol are required for the best yields due to side reaction with the methylene chloride. This phase transfer reaction is ordinarily preferred when mercaptans other than methanethiol are utilized due to substantial amounts of by-products which form in the first-described process (which are frequently difficult to separate from the desired product).

The reaction of step (2) is a reduction of the nitro group of the intermediate 2-nitro-5-alkylthiobenzotrifluoride. Chemical or catalytic methods well known to the art are successful. Raney nickel is one suitable catalyst for the reduction. Product is isolated by conventional methods.

In step (3) of Method 1, the bis(alkylsulfonylation) is obtained utilizing two or more equivalents of the alkanesulfonyl chloride and excess base. Step (4) is the partial hydrolysis of the intermediate bis(alkylsulfonyl) compounds. This is a high yield base hydrolysis reaction using a strong base such as potassium hydroxide in methanol.

Alternatively the precursor of step (3) can be converted directly to the product of step (4) by means of a mono(alkylsulfonylation) reaction using one equivalent of the alkanesulfonyl chloride and one equivalent of base. The two-step process is, however, ordinarily more easily carried out and it is preferred. Suitable bases for step (3) and for the mono(alkylsulfonylation) are organic or inorganic bases such as pyridine, triethylamine, dimethylcyclohexylamine and substituted pyridines.

Step (5) of Method 1 is carried out using conventional oxidation methods such as hydrogen, peroxide in acetic acid or sodium metaperiodate. The sulfoxide compound (n=1) is produced when equimolar amounts of the oxidizing agent and the reactant are utilized, whereas the sulfone (n=2) is prepared directly utilizing 2 moles (or a slight excess) of the oxidizing agent per mole of the reactant.

The reaction of step (1) of Method 2 involves reacting 2-aminobenzotrifluoride with hydrocyanic acid or a salt thereof to form 4-thiocyano-2-trifluoromethylaniline. Suitable salts include alkali metal (sodium or potassium), cuprous and ammonium thiocyanates. The reaction is carried out in the presence of bromine or chlorine and commonly also in the presence of an alkali metal bromide or chloride and a suitable solvent, such as methanol.

Also, the 2-aminobenzotrifluoride can simple be reacted electrolytically with the thiocyanate.

Step (2) involves reacting the product of step (1) with an alkanesulfonyl chloride (R1S02C1) to form the corresponding 4-thiocyano-2-trifluoromethylalkanesulfonanilide or with an excess of the alkanesulfonyl chloride to form the N-alkylsulfonyl-4-thiocyano-2trifluoromethylalkanesulfonanilide, utilizing the general procedure and reaction conditions of step (3) of Method 1.

Step (3) involves alkylating the thiocyano moietv of the product of the previous step in the presence of a strong base and the alcohol R20H. When the previous product is the N-alkylsulfonyl-4-thiocyano-2-trifluoromethylalkanesulfonanilide, the bisfalkylsulfonyl) group is simultaneously partially hydrolyzed. The conditions under which this reaction is carried out are analogous to those of the hydrolysis reaction of step (4) of Method 1.

It can be seen from the foregoing reaction scheme that 4-alkylthio-2trifluoromethylanilines can be formed directly from the corresponding 4-thiocyano-2trifluoromethylaniline which is produced by step (1) of Method 2. This reaction can be carried out utilizing various conventional techniques. For example the thiocyano moiety can be alkylated in an alcoholic sodium cyanide solution. In this reaction the alcohol determines the alkyl group. Alternatively, a sodium mercaptide can be first formed from the thiocyano moiety and it can then be alkylated utilizing an alkylating agent such as an alkyl iodide (methyl iodide). The resulting compound is the same as the product of step (2) of Method 1 and can, of course, be further processed by the procedures of Method 1.

Step (1) of Method 3 is carried out utilizing procedures identical with those of steps (3) and (4) of Method 1. Alternatively, this can be carried out in a single step, as noted previously in discussing steps (3) and (4) of Method 1. The bromination of the 4 position of the ring and the reaction to replace the 4-bromine atom by the 4-alkylthio moiety (steps (2) and (3) of Method 3 are accomplished utilizing known procedures. For example, bromine can be added to a stirred solution of the 2-trifluoromethylalkanesulfonanilide in a water-alcohol solvent, and the thioalkylation step can be carried out by heating a mixture of cuprous thioalkoxide, the 4-bromo compound, pyridine and quinoline, and thereafter pouring it into a 12N hydrochloric acid-wet ice mixture and the desired product recovered therefrom, e.g. by extraction, distillation and/or recrystallization techniques.

The various steps of the processes of the invention as described herein are normally carried out at from about 0 to 50 C. except for the oxidation steps (for producing the compounds of formula I in which n is 1 or 2), which are conveniently carried out at the reflux temperature. All of the steps are ordinarily carried out at atmospheric pressure.

As noted previously, the compounds of this invention (formula I) have plant growth modifying, including herbicidal, activity (which is conveniently determined by screening tests against greenhouse plantings using the test procedure described in U.S. Patent No.

3,996,277). Plant growth modification as defined herein consists of all deviations from natural development, for example, defoliation, stimulation, stunting, retardation, dessication, tillering, dwarfing and regulation. This plant growth modifying activity is generally observed as the compounds of the invention begin to interfere with certain processes within the plant. If these processes are essential, the plant will die if treated with a sufficient dose of the compound.

The type of growth modifying activity observed varies widely among types of plants.

Among the particularly important activities are the following: Selective control of thizomatous Johnsongrass in crops which it commonly infests, such as cotton.

Increasing the sucrose yield in sugar cane. In this application the compound is applied, usually at a rate of about 0.1 to 2 pounds of active ingredient per acre at from about 3 to 12 weeks prior to harvesting the cane.

Retarding the growth of grass (which is valuable since it reduces the number of times the grass must be mowed). Activity is obtained at rates as low as 1/30 pound of active ingredient per acre on growing grass. The maximum application on grass depends upon the sensitivity of the grass under the particular conditions. For reasons of economy, the lowest effective rate is chosen, usually from about 0.1 to 3 pounds of active ingredient per acre.

The compounds of formula I in which R1 is methyl and R2 is ethyl and those compounds in which R is methyl or ethyl and R2 is tert-butyl constitute preferred classes due to their high degree of activity.

The compounds of formula I in which R1 is ethyl and R2 is methyl constitute a preferred class due to their ability to control rhizomatous Johnsongrass selectively in corn fields.

The compounds of formula I in which Rl is ethyl and R2 is ethyl constitute a preferred class due to their ability to control rhizomatous Johnsongrass selectively in corn and/or soybean fields.

The compounds of formula I in which Rl is methyl and R2 is isopropyl constitute a preferred class due to- their ability to control rhizomatous Johnsongrass selectively in soybean fields.

The folowing examples are given for the purpose of further illustrating the present invention but are not intended, in any way, to be limiting on the scope thereof. All parts are given by weight unless otherwise specifically noted.

EXAMPLE 1 2-Nitro-S-ethyhhiobeizot'ifiuoride A solution of 5-chloro-2-nitrobenzotrifluoride (150 g., 0.67 mole) and benzyltrimethylammonium chloride (15 g., 0.067 mole) phase transfer catalyst in methylene chloride (1500 ml.) is added to a cold (0-5" C.) stirred solution of sodium hydroxide (53.2 g., 1.33 moles) and ethanethiol (97.47 g. 1.57 moles) in water (1200 ml.) over a 1.5-2 hour period. The reaction mixture is allowed to come to room temperature and is stirred for 17 hours. Thin layer chromatography on silica gel with 10 percent ether-90 percent petroleum ether (b.p.

30-60 C.) diluent indicates all of the 5-chloro-2-nitrobenzotrifluoride has reacted. The methylene chloride layer is then separated from the aqueous layer and washed with water.

The methylene chloride is removed by evaporation leaving 2-nitro-5 ethylthiobenzotrifluorid as an oil.

This compound is also prepared utilizing the general method of Example 1 of U.S. Patent 3,996,277.

Additional compounds also prepared using the general method of Example 1 hereof are as follows: 2-nitro-5-isopropylthiobenzotrifluoride, an oil, 2-nitro-5-tert-butylthiobenzotrifluoride, an oil.

EXAMPLE 2 4-Ethyitli io-2 -tnfI1oronielliyIaniIin e A solution of 64 percent aqueous hydrazine (48.4 g. 1.5 moles) is added dropwise to a warm (50 C.) stirred solution of 2-nitro-5-ethylthiobenzotrifluoride in 95 percent ethanol (1200 ml.). After all of the hydrazine has been added, the reaction mixture is heated under reflux overnight. Thin layer chromatography indicates all of the nitro compound is reduced.

The reaction mixture is then filtered and concentrated under reduced pressure. The residual golden colored liquid is taken up in methylene chloride and washed with water.

The methylene chloride is removed by evaporation leaving the product, 4-ethylthio-2trifluoromethylaniline.

This compound is also prepared utilizing the general method of Example 2 of U.S. Patent 3,996,277.

Additional compounds also prepared utilizing the general method of Example 2 hereof are as follows: 4-isopropylthio-2-trifluoromethylaniline, an oil, 4-tert-butylthio-2-trifluoromethylaniline, m.p. 68-70"C.

EXAMPLE 3 N- Ethylsulfonyl-4-methylthio-2-trifluoromethylethanesulfonanilide Ethanesulfonyl chloride (16.1 g., 0.125 mole) is added dropwise to a cold (0.5"C) stirred solution of 4-methylthio-trifluoromethylaniline (10.4 g., 0.05 mole) in pyridine (31.6 g., 0;4 mole). The solution is stirred at room temperature overnight, poured into ice water and 12 N hydrochloric acid (100 ml.) with stirring to give N-ethylsulfonyl-4-methylthio-2 trifluoromethylethanesulfonanilide as an oil.

Additional compounds prepared using the same general method are as follows: N-methylsulfonyl-4-ethylthio-2-trifluoromethylmethanesulfonanilide, m .p. 130- 135 C.

N-methylsulfonyl-4-n-propylthio-2-trifluoromethylmethanesulfonanilide, a solid N-methylsulfonyl-4-tert-butylthio-2-trifluoromethylmethanesulfonanilide, m.p. 91-93"C.

N-ethylsulfonyl-4-ethylthio-2-trifluoromethylethanesulfonanilide, a solid N-ethylsulfonyl-4-isopropylthio-2-trifluoromethylethanesulfonanilide, an oil N-n-propylSulfonyl-4-methylthio-2-trifluoromethylpropanesulfonanilide, an oil N-n-butylSulfonyl-4-methylthio-2-trifluoromethylbutanesulfonanilide, an oil.

EXAMPLE 4 4-Methylthio-2-trifluoromethylethanesulfonanilide A solution of N-ethylsulfonyl-4-methylthio-2-trifluoromethylethanesulfonanilide and 85 percent potassium hydroxide (10 g., 0.15 mole) in methanol (300 ml.) is stirred for approximately 2.5 days at room temperature. The solvent is evaporated under reduced pressure, and the residue is taken up in hot water, filtered and then acidified with 12N hydrochloric acid. The product is taken up in methylene chloride and dried. Removal of the drying agent and solvent gives an oil that crystallizes on treatment with hexane.

Recrystallization from methylene chloride-hexane gives a golden solid, m.p. 52-55"C.

Analysis: %C %H %N Calculated for CIOH12F3N02S2: 40.1; 4.0; 4.7 Found: 39.9; 4.0; 4.6 Additional compounds prepared utilizing the general method of Example 4 are as follows: 4-n-propylthio-2-trifluoromethylmethanesulfonanilide, b.p. 150-156"C./5 mm.

4-ethylthio-2-trifluoromethylmethanesulfonanilide, m.p. 50-51"C.

4-tert-butylthio-2-trifluoromethylmethanesulfonanilide, m.p. 98-101"C.

4-ethylthio-2-trifluoromethylethanesulfonanilide, an oil 4-isopropylthiol-2-trifluoromethylethanesulfonanilide m p. 51 -53?C.

4-methylthio-2-trifluoromethylpropanesulfonanilide, m.p. 67-70"C.

4-methylthio-2-trifluoromethylbutanesulfonanilide, m.p. 46-55"C.

4-t-butylthio-2-trifluoromethylethanesulfonanilide, m. p. 67-69"C.

EXAMPLE 5 4-Methylsulfinyl-2-trifluoromethylethanesulfonanilide To a stirred solution of 4-methylthio-2-trifluoromethylethanesulfonanilide (3 g. 0.01 mole) in glacial acetic acid (25 ml.) is added 30 percent hydrogen peroxide (1.13 g. 0.01 mole). The solution is stirred overnight at room temperature, heated just to reflux then treated with water. The aqueous mixture is extracted with methylene chloride, washed with water and dried. Removal of the drying agent and solvent gives a yellow oil. Crystallization from methylene chloride-hexane produces a white solid, m.p.

Analysis: %C %H %N Calculated for C,,,H,,F,N02S,: 38.0; 3.8; 4.4 Found: 38.0; 3.8; 4.4 The following compounds are also prepared utilizing the same general method: 4-ethylSulfinyl-2-trifluoromethylmethanesulfonanilide, an oil 4-tert-butylsulfinyl-2-trifluoromethylethanesulfonanilide, m.p. 133-135"C.

4-ethylsulfinyl-2-trifluoromethylethanesulfonanilide, yellow paste.

EXAMPLE 6 4-Methylsulfonyl-2-triflmoromethylethanesulfonanilide To a stirred solution of 4-methylthio-2-trifluorornethylethanesuifonanilide (1.5 g., 0.005 mole) in glacial acetic acid (15 ml.) is added 30 percent hydrogen peroxide (2.3 g., 0.02 mole). The solution is heated at reflux for 2.5 hours, water is added, and the mixture is cooled. The resulting precipitate is collected by filtration, washed with water and dried to give a white solid, m.p. 156-159"C.

Analysis: %C %H %N Calculated for C()Hl2F3NO4S2 36.2; 3.6; 4.2 Found: 36.2; 3.6; 4.1 Additional compounds prepared utilizing the same general method are as follows: 4-ethylsulfonyl-2-tnfiuoromethylmethanesulfonanilide, m.p. 141-144"C.

4-propylsulfonyl-2-trifluoromethylmethanesuifonanilide, m.p. 155-158"C.

4-tert-butylsulfonyl-2-trifluoromethylethanesulfonanilide, m.p. 143-147"C.

4-isopropylSulfonyl-2-trifluoromethylmethanesulfonanilide, m.p. 134-143"C.

4-tert-butylsulfonyl-2-trifluoromethylmethanesulfonanilide, m.p. 195-200"C.

4-ethylsulfonyl-2-trifluoromethylethanesulfonanilide, m. p. 82-86"C.

4-methylSulfonyl-2-trifluoromethylpropanesulfonanilide, m.p. 152-157"C.

4-methylsulfonyl-2-trifiuoromethylbutanesulfonanilide, m.p. 93-113"C.

EXAMPLE 7 4- Thiocyano-2-Hfiu'orornethylanlline To a cold (0-5 C) stirred solution of 2-aminobenzotrifluoride (6.44 g., 0.04 mole) and sodium thiocyanate (9.72 g., 0.12 mole) in methanol (100 ml.) is added dropwise a solution of bromine (6.6 g., 0.42 mole) in methanol (25 ml.) saturated with soalum bromide. The solution is stirred for 20 minutes following the addition of bromine and then poured into water (750 ml.) and neutralized with sodium carbonate. The resulting oil is taken up in methylene chloride and dried. Removal of the drying agent and solvent gives 4-thiocyano-2trifluoromethylaniline as an oil that solidifies on standing (8.4 g., 96 percent yield). A purified sample had a melting point of 52-55sC. and the following analysis.

Analysis: %C NoH %N Calculated for CsH5F3N2S: -44.0; 2.3; 12.8 Found: 43.7; 2.3; 12.9 EXAMPLE 8 4-Methylthio-2-trifluoroinethylan iline A solution of 4-thiocyano-2-trifluoromethylaniline (1.09 g., 0.005 mole) and sodium cyanide (0.125 g., 0.0025 mole) in methanol (50 ml.) is refluxed for about 16 hours.

Methanol is removed from the cool reaction mixture by evaporation under reduced pressure, the residue is taken up in methylene chloride, washed with water and dried'.

Removal of the drying agent and solvent gives the product as a yellow oil (1 g., 91 percent yield).

The following additional compounds are prepared utilizing the same general method: 4-isopropylthio-2-trifluoromethylaniline, an oil 4-n-propylthio-2-trifluoromethylaniline, an oil.

EXAMPLE 9 4-Methylthio-2-trifluoromethylaniline prepared using an alternate procedure A solution of 4-thiocyano-2-trifluoromethylaniline (2.1 g., .01 mole) in ethanol (25 ml.) is added to a stirred solution of sodium sulfide monohydrate (2.4 g., .01 mole) in water (5 ml.) and the mixture is warmed (50 C) for 40 minutes. Methyl iodide (1.55 g., .011 mole) is added to the warm reaction all at once, and stirring is continued for two hours. Thin layer chromatography on silica gel with 50 percent hexane-SO percent methylene chloride diluent alongside an authentic sample shows that all of the thiocyano compound is reacted to produce the desired product.

EXAMPLE 10 4-Bromo-2-trifluoromethylmethanesulfonanilide To a stirred solution of 2-trifluoromethylmethanesulfonanilide (prepared from 2aminobenzotrifluoride utilizing procedures analogous to those of Examples 3 and 4 hereof) in water-ethanol (40 ml.-150 ml.) solvent mixture is added bromine (6.7 g., 0.042 mole) dropwise. The reaction mixture is then heated to reflux and refluxing is continued for two hours. The reaction mixture is cooled and placed under vacuum to remove most of the solvent. The oil which remains is taken up in methylene chloride (100 ml.), and residual water is removed with a separatory funnel, and the methylene chloride solution is dried.

Removal of the drying agent and methylene chloride gives an oil that solidifies on treatment with hexane. The solid is recrystallized from hexane-methylene chloride, m.p. 62-66 C.

Analysis: %C %H Calculated for C8H7BF3NO2S: 30.2; 2.2; 4.4 Found: 30.5; 2.2; 4.4 EXAMPLE 11 4-lsopropylthio-2-trifluoromethylmethanesulfotlanilide Cuprous thioisopropoxide is prepared by stirring a mixture of isopropyl mercaptan (15.2 g., 0.2 mole), cuprous oxide (14.3 g., 0.1 mole) and ethanol (250 ml.) at reflux overnight.

Removal of the solvent by evaporation and washing the residual solid with ethanol gives 26.6 g. of product.

A mixture of cuprous thioisopropoxide (3.1 g.,0.022 mole), 4-bromo-2trifluoromethylmethanesulfonanilide (6.3 g., 0.0198 mole), pyridine (30 ml.) and quinoline (30 ml.) is heated at I90 C for two hours after solution is achieved. The reaction solution is cooled to 1000C. and poured into a 12N hydrochloric acid-wet ice mixture, and the mixture is extracted with chloroform. The chloroform is evaporated, and the residual oil is heated for two hours with 5 percent sodium hydroxide (300 ml.). The basic medium is clarified by treatment wich charcoal, washed with methylene chloride, and then acidified to give an oil.

The oil is extracted with methylene chloride, then combined extracts are dried and stripped to give 4.5 g. of product. Distillation gives 2.3 g. (b.p. 130-150"C./5 mm Hg) of a product which is further purified by recrystallization from hexane-methylene chloride. The resulting product, 4-isopropylthio-2-trifluoromethylmethanesulfonanilide, 'has a melting point of 56-66"C.

Analysis: ,C %C O/oH %N Calculated for CHl4F3NO2S2: 42.2; 4.5; 4.5 Found: 41.6; 4.4; 4.4 4-n-Propylthio-2-trifluoromethylmethanesulfonanilide. b. p 150-156"C. /5 mm Hg, is also prepared utilizing the same general method.

EXAMPLE 12 4-Ethylthio-2-trffluoroinelliylmethan esulfonan ilide N-Methylsulfonyl-4-thiocyano-2-trifluoromethylmethanesulfonanilide (4.5 g. .012 mole). prepared from 4-thiocyano-2-trifluoromethylaniline (of Example 7) utilizing a procedure analogous to that of Example 3 hereof, is added to a solution of 85 percent potassium hydroxide (2.4 g., .036 mole) in ethanol (100 ml.). This solution is stirred at room temperature overnight. the ethanol is then evaporated and the residue heated with water. The aqueous mixture is filtered, and the filtrate is acidified to give an oil. Extraction ot<

Claims (22)

**WARNING** start of CLMS field may overlap end of DESC **. hours. The reaction mixture is cooled and placed under vacuum to remove most of the solvent. The oil which remains is taken up in methylene chloride (100 ml.), and residual water is removed with a separatory funnel, and the methylene chloride solution is dried. Removal of the drying agent and methylene chloride gives an oil that solidifies on treatment with hexane. The solid is recrystallized from hexane-methylene chloride, m.p. 62-66 C. Analysis: %C %H Calculated for C8H7BF3NO2S: 30.2; 2.2; 4.4 Found: 30.5; 2.2; 4.4 EXAMPLE 11 4-lsopropylthio-2-trifluoromethylmethanesulfotlanilide Cuprous thioisopropoxide is prepared by stirring a mixture of isopropyl mercaptan (15.2 g., 0.2 mole), cuprous oxide (14.3 g., 0.1 mole) and ethanol (250 ml.) at reflux overnight. Removal of the solvent by evaporation and washing the residual solid with ethanol gives 26.6 g. of product. A mixture of cuprous thioisopropoxide (3.1 g.,0.022 mole), 4-bromo-2trifluoromethylmethanesulfonanilide (6.3 g., 0.0198 mole), pyridine (30 ml.) and quinoline (30 ml.) is heated at I90 C for two hours after solution is achieved. The reaction solution is cooled to 1000C. and poured into a 12N hydrochloric acid-wet ice mixture, and the mixture is extracted with chloroform. The chloroform is evaporated, and the residual oil is heated for two hours with 5 percent sodium hydroxide (300 ml.). The basic medium is clarified by treatment wich charcoal, washed with methylene chloride, and then acidified to give an oil. The oil is extracted with methylene chloride, then combined extracts are dried and stripped to give 4.5 g. of product. Distillation gives 2.3 g. (b.p. 130-150"C./5 mm Hg) of a product which is further purified by recrystallization from hexane-methylene chloride. The resulting product, 4-isopropylthio-2-trifluoromethylmethanesulfonanilide, 'has a melting point of 56-66"C. Analysis: ,óC %C O/oH %N Calculated for CHl4F3NO2S2: 42.2; 4.5; 4.5 Found: 41.6; 4.4; 4.4 4-n-Propylthio-2-trifluoromethylmethanesulfonanilide. b. p 150-156"C. /5 mm Hg, is also prepared utilizing the same general method. EXAMPLE 12 4-Ethylthio-2-trffluoroinelliylmethan esulfonan ilide N-Methylsulfonyl-4-thiocyano-2-trifluoromethylmethanesulfonanilide (4.5 g. .012 mole). prepared from 4-thiocyano-2-trifluoromethylaniline (of Example 7) utilizing a procedure analogous to that of Example 3 hereof, is added to a solution of 85 percent potassium hydroxide (2.4 g., .036 mole) in ethanol (100 ml.). This solution is stirred at room temperature overnight. the ethanol is then evaporated and the residue heated with water. The aqueous mixture is filtered, and the filtrate is acidified to give an oil. Extraction ot the oil with methylene chloride, drying, washing with water and removal of the methylene chloride gives the desired product as an oil. 4-Isopropylthio-2-trifluoromethylmethanesulfonanilide (an oil) is also prepared utilizing this procedure. WHAT WE CLAIM IS:

1. A compound of the formula

wherein Rl and R2 are independently alkyl groups containing from 1 to 4 carbon atoms and n is 0-2, provided that R1 and R2 are not both methyl, and agriculturally acceptable salts thereof.

2. A compound according to claim 1 wherein n is zero.

3. A compound according to claim 1 wherein n is 1.

4. A compound according to claim 1 wherein n is 2.

5. A compound according to claim 1 wherein R' is methyl and R2 is ethyl.

6. A compound according to claim 1 wherein R1 is ethyl and R2 is methyl.

7. A compound according to claim 1 wherein R1 is ethyl and R2 is ethyl.

8. A compound according to claim 1 wherein R' is methyl and R2 is isopropyl.

9. A compound according to claim 1 wherein Rl is methyl and R2 is tert-butyl.

10. A compound according to claim 1 wherein R1 is ethyl and R2 is tert-butyl.

11. The compound 4-ethylthio-2-trifluoromethylmethanesulfonanilide according to claim 5.

12. The compound 4-ethylsulfinyl-2-trifluoromethylmethanesulfonanilide according to claim 5.

13. The compound 4-ethylsulfonyl-2-trifluoromethylmethanesulfonanilide according to claim 5.

14. The compound 4-methylthio-2-trifluoromethylethanesulfonanilide according to claim 6.

15. The compound 4-methylsulfinyl-2-trifluoromethylethanesulfonanilide according to claim 6.

16. The compound 4-methylsulfonyl-2-trifluoromethylethanesulfonanilide according to claim 6.

17. The compound 4-isopropylthio-2-trifluoromethylmethanesulfonanilide according to claim 8.

18. The compound 4-isopropylsulfonyl-2-trifluoromethylmethanesulfonanilide according to claim 8.

19. A compound according to claim 1 substantially as hereinbefore described in any of Examples 4 to 6, 11 and 12.

20. A method of modifying plant growth using a compound according to any of claims 1 to 19.

21. A composition for modifying the growth of higher plants which comprises a compound according to any of claims 1 to 19 dispersed in an agriculturally acceptable extending medium.

22. A method according to claim 20 and substantially as hereinbefore described.