GB1576681A - Process for preparing organic sulphone compounds - Google Patents

Description

(54) PROCESS FOR PREPARING ORGANIC SULFONE COMPOUNDS (71) We, UNION CARBIDE CORPORATION, a Corporation organised and existing under the laws of the State of New York, United States of America, of 270 Park Avenue, New York, State of New York 10017, 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 a process for preparing certain organic sulfone compounds. More particularly, this invention relates to an improved process for oxidizing certain organic sulfide compounds in a relatively simple and efficient manner to the corresponding organic sulfone compound.

Organic sulfone compounds as well as oxidation processes for their preparation are well known in the art. Heretofore, organic sulfone compounds generally have been prepared by one of two oxidation processes which employ a peracid as the oxidizing agent. One process, the so-called "generator process", involves separately generating an anhydrous peracid oxidizing agent to be used for the oxidation of the organic sulfide compound at some later time. The other process, the so-called "in-situ" process is a one-step process which calls for the generation of the peracid oxidizing agent in-situ in the presence of the organic sulfide compound sought to be oxidized. Although they are relatively simple and efficient, both known processes suffer from a number of inherent disadvantages. For example, it is generally recognized that both of the previously disclosed peracid oxidation processes usually give rise to organic sulfone compounds that are contaminated with unacceptably large amounts of the corresponding sulfoxide compound as a by-product. This makes it necessary to carry out elaborate and cumbersome purification procedures which result in relatively small yields of the sulfone product. In addition, the generator process suffers from a further disadvantage in that it requires the generation and handling of the generally unstable and potentially hazardous anhydrous peracid. The conventional "in-situ" process, although simple and safe to operate, generally requires expensive high boiling reaction solvents, extended reaction periods, and high reaction temperatures with concomitant increased probability of thermal degradation products. Consequently, there exists a need for a more effective process for converting organic sulfide compounds in organic sulfone compounds with enhanced sulfone yields coupled with lower reaction temperatures and shorter reaction periods.

According to the present invention there is provided an improved process for preparing organic sulfone compounds as hereinafter defined by reacting the corresponding organic sulfide compound with a mixture of (a) an excess amount of hydrogen peroxide and (b) a carboxylic acid, the improvement which comprises conducting the reaction in the presence of a catalytically effective amount of a mineral acid or an organic sulfonic acid.

It has been found that the oxidizing agent employed in the process of this invention not only provides excellent conversion activity under mild reaction conditions but at the same time exhibits superior selectivity in the oxidation of the sulfide linkage to the exclusion of other oxidizable moeties that may be present in the molecule. The process of this invention is extremely valuable in that it provides a high yield of a high quality organic sulfone compound which is relatively free of sulfoxide contaminants and other reaction by-products, while at the same time employing mild reaction conditions, short reaction periods and low reaction temperatures.

The organic sulfide reactants which are employed in the present invention are those of the general formula

wherein: n is 0 to 5; R1 is alkyl, phenyl, phenylalkyl, alkenyl, alkynyl, cycloalkyl or cycloalkenyl all of which may be substituted with one or more chloro, fluoro, bromo, cyano, nitro, alkyl, alkoxy, alkylthio, alkylsulfinyl, alkylsulfonyl, or alkoxyalkyl substituents; R2 and R3 are individually hydrogen or either substituted or unsubstituted alkyl wherein the permissible substituents are one or more chloro, fluoro, bromo, cyano, nitro or alkoxy substituents; R2 and R3 preferably being individually hydrogen or alkyl having from 1 to 4 carbon atoms; R4 is hydrogen, chloro, fluoro, bromo, cyano, alkyl, alkylsulfonyl, alkoxy, alkylthio, alkylsulfinyl, carboalkoxy, alkoxyalkyl, alkylthioalkyl, alkylsulfonylalkyl or alkylsulfinylalkyl, in which any alkyl moiety may be substituted with one or more chloro, bromo, fluoro, cyano, amido or nitro substituents; R4 preferably being hydrogen or alkyl being from 1 to 4 carbon atoms; and Z is hydrogen or

wherein: R5 and R6 are individually hydrogen or either substituted or unsubstituted alkyl, phenyl or phenylalkyl wherein the permissible substituents are one or more chloro, fluoro, bromo, nitro, cyano, alkyl or alkoxy substituents.

The product is an organic sulfone compound of the general formula:

wherein n, R1, R2, R3, R4 and Z are as defined above.

Examples of suitable organic sulfide reactants are: 2-Methyl thiopropionaldehyde N-methylcarbamoyloxime,2-Ethylthiopropionaldehyde N-methylcarbamoyloxime, 2-n-Propylthiopropionaldehyde N-methylcarbamoyloxime, 2-Isopropylthiopropionaldehyde N-methylcarbamoyloxime, 2-n-Butylthiopropionaldehyde N-methylcarbamoyloxime, 2-sec-Butylthiopropionaldehyde N-methylcarbamoyloxime, 2-t-Butylth iopropionaldehyde N-methylcarbamoyloxime, 2-Isobutylthiopropionaldehyde N-methylcarbamoyloxime, 2-Hcptylthiopropionaldehyde N-methylcarbamoyloxime, 2-Dcclythiopropionaldehyde N-methylcarbamoyloxime, 2-Vinylthiopropionaldehyde N-methylcarbamoyloxime, 2-2-Propenylthio)propionaldehyde N-methylcarbamoyloxime, 2-3- Butenylthio)propionaldehyde N-methylcarbamoyloxime, 2-Hexcnylthiopropionaldehyde N-methylcarbamoyloxime, 2-Fthynylthiopropionaldehyde N-methylcarbamoyloxime, 2-Phcnylthiopropionaldehyde N-methylcarbamoyloxime, 2-(a -Naphthylthio)propionaldehyde N-methylcarbamoyloxime, 2-Bcnzylthiopropionaldehyde N-methylcarbamoyloxime, 2-(4 -Chlorophenylthio)propionaldehyde N-methylcarbamoyloxime, 2-(2.4 -Dichlorophenylthio)propionaldehyde N-methylcarbamoyloxime, 2-Methyl-2 -methylthiopropionaldehyde N-methylcarbamoyloxime, 2-Methyl-2 -ethylthiopropionaldehyde N-methylcarbamoyloxime, 2-Methyl-2-n -Propylthiopropionaldehyde N-methylcarbamoyloxime, 2-Methyl-2-isopropylthiopropionaldehyde N-methylcarbamoyloxime, 2-Mcthyl-2-butylthiopropionaldehyde N-methylcarbamoyloxime 2-Methyl-2-heptylthiopropionaldehyde N-methylcarbamoyloxime, 2-Methyl-2 -decylthiopropionaldehyde N-methylcarbamoyloxime, 2-Methyl-2 -vinylthiopropionaldehyde N-methylcarbamoyloxime, 2-Methyl-2 -(2-propenylthio)propionaldehyde N-methylcarbamoyloxime, 2-Methyl-2-(3 -butenylthio)propionaldehyde N-methylcarbamoyloxime, 2-Methyl-2 -hexenylthiopropionaldehyde N-methylcarbamoyloxime, 2-Methyl-2 -ethynylthiopropionaldehyde N-methylcarbamoyloxime, 2-Methyl-2 -phenylthiopropionaldehyde N-methylcarbamoyloxime 2-Methyl-2-(a -naphthylthio)propionaldehyde N-methylcarbamoyloxime, 2-Methyl-2 -benzylthiopropionaldehyde N-methylcarbamoyloxime, 2-Methyl-2- 2 -chlorophenylthio propionaldehyde N-methylcarbamoyloxime, 2-Methyl-2- 4 -chlorophenylthio propionaldehyde N-methylcarbamoyloxime, 2-Methyl-2- 2,4 -dichlorophenylthio)propionaldehyde N-methylcarbamoyloxime, 2-Methylthiobutyraldehyde N-methylcarbamoyloxime, 2-Methylthiopentanaldehyde N-methylcarbamoyloxime, 2-Methylthiohexanaldehyde N-methylcarbamoyloxime, 2-Methylthioheptanaldehyde N-methylcarbamoyloxime, 2-Methylthiodecanaldehyde N-methylcarbamoyloxime, 2-Methyl-2 -methylthiobutyraldehyde N-methylcarbamoyloxime, 2-Ethyl-2 -methylthiobutyraldehyde N-methylcarbamoyloxime, 2-Butyl-2 -methylthioheptanaldehyde N-methylcarbamoyloxime, 2-Octyl-2-methylthiodecanaldehyde N-methylcarbamoyloxime, Carboxylic acids useful in the conduct of the process of this invention are well known to those skilled in the synthetic art and will correspond to the following generic formula:

wherein R is either substituted or unsubstituted aromatic or aliphatic group such as alkyl, aryl, arylalkyl or alkylaryl group. Permissible substituents include but are not limited to halogen. cyano, and nitro groups. Examples of carboxylic acids useful in the conduct of the process of this invention are benzoic acid,p-chlorophenoxyacetic acid, acetic acid, butanoic acid, heptanoic acid, formic acid,p-methoxybenzoic acid, toluic acid, valeric acid, propionic acid, p-naphthoic acid, 4-(1-naphthyl)-4 -butanoic acid, and 3-(2-naphthyl)butyric acid. In general, to achieve acceptable results it is necessary to employ at least one mole of carboxylic acid per equivalent of the divalent sulfide functional unit present in the organic sulfide compound. The preferred amount of carboxylic acid is from 1 to 4 moles of acid per equivalent sulfide functional unit present in the sulfide reactant. The particularly preferred amount of carboxylic acid employed is from 1.5 to 2.0 moles per mole of sulfide functional unit. In order to achieve a satisfactory conversion of the sulfide compound to the sulfone compound an excess of hydrogen peroxide should be employed. The preferred amount of hydrogen peroxide is from 2 to 5 moles of hydrogen peroxide per equivalent of sulfide functional unit present in the sulfide reactant. The particularly preferred amount of hydrogen peroxide is from 2.3 to 2.0 moles per mole of sulfide function unit.

The process of this invention is always conducted in the presence of a conventional mineral acid or organic sulfonic acid. Examples of suitable mineral acids that can be employed in the conduct of the process of this invention are phosphoric acid, nitric acid, sulfuric acid, hydrochloric acid, boric acid. perchloric acid, and hypochloric acid. Examples of useful organic sulfonic acids are benzenesulfonic acid, p-toluenesulfonic acid, p-nitrobenzenesulfonic acid, and 1-naphthalensulfonic acid.

The quantity of acid catalyst employed in conduct of the process of this invention can be varied over a wide range. In general, the reaction proceeds satisfactorily when employing as little as 0.010 weight percent of the acid catalyst based on the quantity of the reactants. The upper concentration limit can be quite high, such and as for example 10.0 weight percent, and higher. In the preferred embodiments of this process, an acid catalyst concentration of from 0.10 to 7.0 weight percent based on quantity of the reactants is useful.

The reaction temperature is not critical and can be varied over a wide range. The process is normally conducted at a temperature in the range of from about 0 C. and upwards to approximately 120"C. Preferred reaction temperatures are from 25 C. to 75 C. At temperatures below 25 C. the rate of reaction becomes markedly slower, while at temperatures above 75"C. product degradation may occur.

The process can be carried out neat or in solution. A normally liquid organic solvent is preferably employed as the reaction medium. In general any organic solvent inert to oxidation by mild oxidative agents may be used. Examples of the organic solvents which are suitable as reaction solvents in the practice of the preferred embodiments of this invention are saturated and unsaturated aliphatic and aromatic hydrocarbons, e.g. hexane, cyclohexane, octane. dodecane. naphtha, decal in, kerosene, tetrahydronapthalene, cycloheptane, alkylcycloalkane. benzene. toluene. xylene, naphthalene, or alkylnaphthalene; ethers such as tetrahydrofuran. tetrahydropyran. diethyl ether, dioxane, 1,2-methyoxybenzene, 1,2 ethoxybenzene, and the mono and dialkyl ethers of ethylene glycol, of dipropylene glycol, of butylene glycol, of diethylene glycol, and of dipropylene glycol. Preferred solvents for the conduct of the process of this invention are chlorinated aliphatic hydrocarbons and as for example, chloroform, methylene dichloride, 1,1-dichloroethane, or carbon tetrachloride Reaction pressures are not critical. The process of this invention can be conducted at either subatmospheric, atmospheric or superatmospheric pressure. For convenience, the reaction is usually conducted at atmospheric or autogenous pressure.

The process of this invention is effected over a period of time sufficient to produce the desired organic sulfone compound. In general, residence times can vary from a few minutes to approximately 24 hours or longer. In most instances, when employing preferred reaction conditions, reaction times will be found to vary from 2 hours to 4 hours. Reaction time is influenced to a significant degree by the reaction temperature, the concentration and choice of acid catalyst, the choice and concentration of diluent and other factors known to those skilled in the synthetic art.

The process of this invention can be conducted in a batch, semicontinuous or continuous fashion. The reaction can be conducted in a single reaction zone or in a plurality of reaction zones, in series or in parallel or it may be conducted intermittently or continuously in an elongated tubular zone or series of such zones. The materials of construction employed should be inert to the reactants during the reaction and the fabrication of the equipment should be able to withstand the reaction temperatures and pressure.

The process is preferably conducted in either glass lined, stainless steel 316 or Hastelloy (Registered Trade Mark) C-276 reaction equipment. The reaction zone can be fitted with one or more internal and/or external heat exchanger(s) in order to control undue temperature fluctuations, or to prevent any possible "runaway" reaction temperatures. In preferred embodiments of the process, agitation means to vary the degree of mixing the reactions mixture can be employed. Mixing by vibration, shaking, stirring, rotation, oscillation, or ultrasonic vibration are all illustrative of the types of agitation means contemplated. Such means are available and well known to those skilled in the art.

The acid catalyst may be initially introduced into the reaction zone batchwise or it may be continuously or intermittently introduced in such zone during the course of the proces. Means to introduce and/or adjust the quantity of reactants introduced, etiher intermittently or continuously into the reaction zone during the course of the reaction can be conveniently utilized in the process especially to maintain the desired molar ratio of the solvent and reactants.

In accordance with the preferred embodiments of the process of this invention, an organic sulfide compound is treated with an aqueous mixture of hydrogen peroxide, a carboxylic acid, and a catalytic amount of a mineral acid or an organic sulfonic acid in a suitable reaction solvent. The manner and order in which the reaction components are mixed is not critical. In general, the organic sulfide reactant carboxylic acid and a suitable reaction solvent are placed in a suitable reaction vessel and hydrogen peroxide and the acid catalysts are added in consective order, preferably with moderate agitation and the reaction mass heated to the desired temperature.

One preferred and representative embodiment of the process of this invention involves adding an aqueous solution of hydrogen peroxide to a mixture or an organic sulfide compound and formic acid in a chlorinated aliphatic hydrocarbon under ambient conditions.

After the additions. either sulfuric, phosphoric orp-toluenesulfonic acid either in the form of a concentrated solution or as a 50 percent aqueous solution is then added followed by refluxing at temperature of about 50"C. The reaction product can be isolated employing standard processing equipment and conventional isolation techniques as for example distillation. crystalization, or decantation.

The manner of practicing the process of the present invention and advantages obtained thereby will be illustrated by the following specific Examples which are merely illustrative and are not intended. in any manner, to limit the scope of the invention.

EXAMPLE I Procedure: 55 grams of a 30 percent aqueous hydrogen peroxide solution was added dropwise to a mixture of 55 grams of 2-methyl-2 -(methylthio)propionaldehyde 0-(methylcarbamoyl)oxime and 15 grams of formic acid in 200 grams of methylene chloride solution over a 15-20 minute period. The temperature rose from 25"C. to 400 C. during the addition. When the addition was complete 3 grams of concentrated sulfuric acid was added dropwise to maintain a gentle reflux followed by an additional 2 hours of reflux at 40-450C.

After the reaction period was over, methylene chloride solvent was evaporated under reduced pressure. The mixture was cooled to 50C and filtered. The solid obtained was washed with 200 ml of water and dried to give 37 grams 2-methyl-2 -(methylsulfonyl)propionaldehyde 0-(methylcarbamoyl)oxime m.p. 145-147"C. The yield was 90.5 percent based on 2-methyl-2-(methylthio)propionaldehyde O-(methylcarbamoyl)oxime.

The product was found to contain 0.05 weight percent of 2-methyl-2 -(methylsulfinyl)propionaldehyde 0-(methylcarbamoyl)oxime (sulfoxide) by liquid-liquid chromatographic analysis.

EXAMPLE H Procedure: 15 grams of an 88 percent aqueous solution of formic acid was added to a mixture containing 30 grams of 2-methyl-2 -(methylthio)propionaldehyde 0-(methylcarbamoyl)oxime in 70 grams of methylene chloride solution. To the mixture was added 56 grams of a 30 percent aqueous hydrogen peroxide over a 15-20 minute period.

During the course of addition, the reaction temperature rose from 25 to 400C. with a gentle reflux of methylene chloride. After the addition of the peroxide solution, 6.0 grams of concentrated sulfuric acid was added dropwise at a rate to maintain the reflux at 400 C. When the addition was complete, the mixture was stirred for an additional 2.5 hours at 40.450C.

When the oxidation was over, 60-70 grams of the methylene chloride solvent was removed by evaporation under reduced pressure. The mixture was cooled to 50C. and filtered. The solid reaction Product was then washed with 25-30 grams of cold water and dried to constant weight. 2-Methyl-2 -(Methylsulfonyl)propionaldehyde 0-(methylcarbamoyl)oxime was obtained, m.p. 144-145"C, having a 2-methyl-2 -(methylsulfinyl)propionaldehyde O-methylcarbamoyloxime (sulfide) content of less than 0.10 percent.

EXAMPLE III Procedure: The reaction of EXAMPLE I was repeated using 3.0 grams of phosphoric acid instead of sulfuric acid, as the catalyst, the reaction conditions and recovery procedure being otherwise the same. The 2-methyl-2 -(methylsulfonyl)propionaldehyde O-(methylcarbamoyl)oxime product obtained was 27.7 grams, representing a 79 percent yield based on 2-methyl-2 -(methylthio)propionaldehyde O-(methylcarbamoyl)oxime. The product had a 2-methyl-2 -(methylsulfinylpropionaldehyde O-(methylcarbamoyl)oxime (sulfoxide) content of 1.95%.

EXAMPLE IV Procedure: The reaction of EXAMPLE I was repeated with 4.0 grams of p-toluenesulfonic acid as catalyst and a reaction contact time of 5 hours. The reaction conditions and recovery procedure otherwise being the same. The 2-methyl-2 -(methylsulfonyl)propionaldehyde 0-(methylcarbamoyl)oxime reaction product obtained was 23.0 grams, representing a 66 percent yield based on 2-methyl-2 -(methylthio)propionaldehyde 0 (methylcarbamoyl)-oxime reactant. The reaction product had a 2-methyl-2 -(methylsulfinyl)propionaldehyde 0-(methylcarbamoyl)oxime (sulfoxide) content of less than 0.1%.

EXAMPLE V Procedure: Formic acid (88 percent, 4.5 grams) was added to a mixture containing 10 grams of 3,3-dimethyl-1 -(methylthio(-2-butanone 0-(methylcarbamoyl)oxime in 30 grams of methylene chloride solution. To the mixture was added 16.5 grams of a 30-percent aqueous hydrogen peroxide over a 20-30 minute period. During addition the reaction temperature rose from 25 to 35"C. When the addition was complete, a mixture containing 1 gram of concentrated sulfuric acid and 1 grams of water was added dropwise to the reaction mixture and the mixture was then refluxed at 40-42"C. for 2 hours. After reflux about 75 grams of methylene chloride was added to dilute the mixture and the organic layer was separated by decantation. The organic layer was washed once with water and then evaporated to dryness under reduced pressure. A total of 11 grams of a residual product was obtained which was identified by spectral analysis as 3,3-dimethyl-l -(methylsulfonyl) -2-butanone 0-(methylcarbamoyl)oxime. The yield was 95.9 percent. The product had a 3,3-dimethyl-1 -(methylsulfinyl-2-butanone 0-(methylcarbamoyl)oxime (sulfoxide) content of less than .10%.

The reactions of Examples VI-XIV were conducted utilizing the procedure of EXAM PLES I-V. In each of these Examples, 100 grams of a 30 percent 2-methyl-2 -(methylthio)propionaldehyde 0-(methylcarbamoyl)oxime methylene chloride solution, an 88 percent aqueous formic acid solution and a 30 % aqueous hydrogen peroxide solution were used as the starting materials. The contact time was 2.5 hours at a temperature of 40-43"C.

2-(Methyl-2 -(methylsulfonyl)propionaldehyde 0-(methylcarbamoyl)oxime (sulfone) was obtained as one crop, whose 2-methyl-2-(methylsulfinyl)propionaldehyde 0-(methylcarbamoyl)oxime (sulfoxide) content was determined by the liquid-liquid chromatographic technique. The results of EXAMPLES VI-XIV are set forth in TABLE I below: TABLE I ACID CATALYZED "IN-SITU" OXIDATION PROCESS grams of grams of Yield 88% Formic 30% H2O2grams of Percent Example Acid Solution Acid Catalyst Sulfone Product Sulfone Sulfoxide Content VI 15g 56g 1.0g(H2SO4) 21.0g 61 8.24% VII 15g 56g 2.0g(H2SO4) 27.0g 77 2.35% VIII 15g 40g 2.0g(H2SO4) 26.0g 74 3.59% IX 15g 56g 4.0g(H2SO4) 28.5g 81 0.1 % X 15g 56g 9.0g(H2SO4) 27.1g 77 0.1 % XI 12g 56g 3.0g(H2SO4) 29.2g 83 0.1 % XII 10g 56g 3.0g(H2SO4) 28.6g 82 0.1 % XIII 15g 65g 4.0g(H2SO4) 26.3g 75 0.1 % XIV 12g 56g 4.0g(p-CH3C6H4SO3H) 23.0g 66 1.0 % To demonstrate more particularly the increased efficiency of the peracid oxidation process of this invention in comparison with known peracid oxidation processes, the experimental results of three representative examples of the process of this invention were compared with the experimental results from an example of a known process. The comparison data is set forth in TABLE II hereinbelow. The known peracid oxidation process was conducted as described in EXAMPLE XV below.

EXAMPLE XV Procedure: 56 grams of a 30 per cent aqueous hydrogen peroxide solution was added dropwise to a mixture of 30 grams of 2-methyl-2 -(methylthio)propionaldehyde 0-(methylcarbamoyl)oxime and 15 grams of an 80% aqueous formic acid solution in 70 grams of methylene chloride. After the addition the reaction mixture was refluxed for 2 hours at a temperature of 40-45"C. The methylene chloride solvent was then evaporated under reduced pressure and the reaction mixture was then cooled to 50C. and filtered. The 2-methyl-2 -(methylsulfonyl) propionaldehyde 0-(methylcarbamoyl) oxime reaction product, m.p. 137-138"C., obtained was 12.6 grams which represented a 34 percent yield. The reaction product had a 2-methyl-2 -(methylsulfinyl)propionaldehyde 0-(methylcarbamoyl)oxime (sulfoxide) content of 15.28 pe ient.

TABLE II COMPARISON DATA grams of 88% grams of 30% grams of percent Aqueous Formic Aqueous H2O2 grams of sulfone Yield of Sulfoxide Example Acid Solution Acid Catalyst Product Sulfone Product Content I 15 56 3.0g of H2SO4 28.0 80 0.05% IV 15 56 4.0g of (p-CH3C6H4SO3H) 23.0 66 0.1 % XV 15 56 Og of Acid 12.69 34 15.28% The data presented in TABLE II hereinabove clearly illustrates the greatly increased efficiency of the peracid oxidation process of this invention in comparison with known peracid oxidation processes. For example, the known process of EXAMPLE XV which was conducted without a mineral acid or a sulfonic acid catalyst had a 34% yield of the organic sulfone product which contaminated with 15.28% sulfoxide by-product. This results is to be contrasted with EXAMPLES I and IV which employ the process of this invention. Note that the sulfone product of EXAMPLES I and IV was produced in an 80% and 66% yield, respectively. Further, EXAMPLES I and IV which were conducted with an acid catalyst yield an organic sulfone product which was contaminated with only 0.10% of the sulfone byproduct. This represents over a two-fold increase in the %yield of the sulfone and a 152.8 fold decrease in the degree of sulfoxide by-product contamination.

The organic sulfone compounds prepared in accordance with the process of this invention have wide utility and are valuable for a number of useful purposes. Some of the organic sulfone compound prepared in accordance with the process of the inventions exhibited outstanding insecticidal, nematocidal and miticidal acticity and may be utilized as insecticides, miticides and namatocides according to methods known to those skilled in the pesticidal art. These compounds are also relatively non-toxic to plants and mammals when used in amounts sufficient to kill insects, mites and nematodes. Thus, for example, 2methyl-2-(methylsulfonyl) propionaldehyde 0-(methlcarbamoyl)oxime an outstanding pesticide may be conveniently prepared by the process of this inve tion. Accordingly, the present invention also provides pesticidal compositions whenever comprising an organic sulfone compound prepared by the process of the invention together with a non-toxic carrier. It should be pointed out, however, that other organic sulfone compounds prepared by the process of this invention are not limited to use as pesticides but in addition are extremely useful for other purposes which are known to those skilled in the art.

Claims (23)

WHAT WE CLAIM IS:

1. A process for preparing an organic sulfone compound of the general formula:

which comprises treating a compound of the general formula:

with a mixture of (a) an excess amount of hydrogen peroxide and (b) a carboxylic acid in the presence of a catalytically effective amount of a mineral or organic sulfonic acid, wherein: n is 0 to 5; Rl is alkyl, phenyl, phenylalkyl, alkenyl, alkynyl, cycloalkyl, or cycloalkenyl all of which may be substituted with one or more chloro, fluoro, bormo, cyano, nitro, alkyl, alkoxy, alkylthio, alkylsulfinyl, alkysulfonyl or alkoxyalkyl groups; R2 and R3 are individually hydrogen or either substituted or unsubstituted alkyl; wherein the permissible substituents are one or more chloro, fluoro, bromo, cyano, nitro or alkoxy substituents; R4 is hydrogen, chloro, fluoro, bromo, cyano, alkyl, alkysulfonyl, alkylthio, alkysulfinyl, alkoxy. carboalkoxy, alkoxyalkyl, alkythioalkyl, alkylsulfonylalkyl or alkylsulfinylalkyl in which any alkyl moiety may be substitued with one or more chloro, bromo, fluoro, cyano, amido or nitro groups; and p Z is hydrogen or -CNR5R6 wherein: R5 and R6 are individually hydrogen or either substituted or unsubstituted alkyl, phenyl or phanylalkyl wherein the permissible substituents are one or more chloro, fluoro, bromo, nitro, cyano, alkyl or alkoxy groups.

2. A process as claimed in claim 1 wherein R1 is alkyl.

3. A process as claimed in claim 1 or claim 2 wherein n is 0, 1 or 2.

4. A process as claimed in any one of the preceeding claims wherein R2 and R3 are individually hydrogen or alkyl having from 1 to 4 carbon atoms.

5. A process as claimed in any one of the preceding claims wherein R4 is hydrogen or alkyl having from 1 to 4 carbon atoms.

6. A process as claimed in any one of the preceding claims wherein Z is hydrogen.

7. A process as claimed in any one of claims 1 to 5 wherein Z is

wherein: R5 and R6 are individually hydrogen or alkyl.

8. A process as claimed in any one of the preceding claims wherein the acid catalyst is a mineral acid.

9. A process as claimed in claim 8 wherein the acid catalyst is sulfuric acid, nitric acid, perchloric acid, hydrochloric acid or phosphoric acid.

10. A process as claimed in any one of claims 1 to 7 wherein the acid catalyst is an organic sulfonic acid.

11. A process as claimed in claim 10 wherein the acid catalyst is benzensulfonic acid p-toluene-sulfonic acid, p-nitrobenzenesulfonic acid or 1-naphthalene-sulfonic acid.

12. A process as claimed in any one of the preceding claims which is conducted in the presence of from 0.010 to 10.00 weight percent of acid catalyst based on the total weight of the reactants.

13. A process as claimed in claim 12 which is conducted in the presence of from 0.10 to 7.0 weight percent of acid catalyst based on the total weight of the reactants.

14. A process as claimed in claim 1 which is for preparing a compound of the formula:

which comprises treating a compound of the formula:

with a mixture of (a) an excess amount of hydrogen peroxide and (b) a carboxylic acid in the presence of a catalytically effective amount of a mineral or sulfonic acid, wherein:

15. A process as claimed in claim 14 wherein the acid catalyst is a mineral acid.

16. A process as claimed in claim 14 wherein the acid catalyst is an organic sulfonic acid.

17. A process as claimed in claim 15 wherein the acid catalyst is sulfuric acid, nitric acid, perchloric acid. hydrochloric acid or phosphoric acid.

18. A process as claimed in claim 16 wherein the acid catalyst is benzenesulfonic acid, p-toluenesulfonic acid, p-nitrobenzenesulfonic acid, or 1-naphthalenesulfonic acid.

19. A process as claimed in any one of claims 14 to 18 which is conducted in the presence of from 0.01 to 10.0 weight percent of acid catalyst based on the total weight of the reactants.

20. A process as claimed in claim 19 which is conducted in the presence of from 0.1 to 7 weight percent of acid catalyst based on the total weight of the reactants.

21. A process as claimed in claim 1 substantially as hereinbefore described in any one of Examples I to XIV.

22. Organic sulfone compounds whenever prepared by a process as claimed in any one of the preceding claims.

23. Pesticidal compositions whenever comprising an organic sulfone compound as claimed in claim 22 and a non-toxic carrier.