IL25486A - Derivatives of 2,6-dichlorothiobenzamide,their preparation and use - Google Patents

Description

'JHUJI }713 ΤϊΙΠΓ'Ί m PATENT ATTORNEYS · O ' D I D S ' 3111) PATENTS AND DESIGNS ORDINANCE SPECIFICATION Novel derivatives of 2,6-dic lorothiobenaaa.ide, their preparation and use I (we) SHELL IKTEHHATIONALE RISEAKCH MAATSCHAPPIJ N.V., of , Carel van Bylandtlaan, The Hague, a Netherlands Company do hereby declare the nature of this invention and in what manner the same is to "be performed, to he particularly described and ascertained in and by the following statement: - This invention relates to novel herbicidal derivatives of 2,6-dichlorothiobenzamide, methods for their preparation, herbicidal compositions containing them, and to a method for combating weeds.

The novel derivatives of 2, 6-dichlorothiobenzamide ac-cording to the invention have the general formula: - wherein R represents an alkyl or haloalkyl group, said group preferably containing 1-6 carbon atoms, and X represents an alkyl, aryl or alkaryl sulphate or sulphonate ion. Examples of the sul-phonate ion are the methanesulphonate, ethanesulphonate, benzene-sulphonate and toluenesulphonate, for example the p-toluenesulphonate ion. Examples of the sulphate ion are the methyl sulphate, ethyl sulphate, isopropyl sulphate and nonyl sulphate ion.

The haloalkyl group which R may represent is preferably a chloro or bromoalkyl group, for example a 2-chloroethyl, 3-bromopropyl or 2-chlo obutyl group.

The compounds of the invention are active pre-emergence herbicides. The methyl sulphate salt of S-methyl-2, 6-dichloro-thiobenzimidate combines a high herbicidal activity with a low mammalian toxicity. Accordingly, it is the preferred compound of the invention.

The compounds of the invention may be used in the manner known for herbicides, that is to say, they may be applied in admixture with an inert diluent which may contain a surface-active agent. The invention also includes therefore a herbicidal composition which comprises a compound of the invention and a carrier, or a surface -active agent, or both a carrier and a surface-active agent .

The carrier may be a solid, a liquid or a compressed gas. Examples of suitable solid carriers are clays, silicates, synthetic hydrated silicon oxides, resins, waxes, synthetic polymeric materials, carbon and sulphur. Examples of suitable liquid carriers are water, alcohols, ketones, aromatic hydrocarbons, chlorinated hydro of suitable compressed gases are those normally employed in aerosols, for example trichloromonofluoromethane or dichlorodifluoromethane.

The surface-active agent may be anionic, cationic or nonionic and may take the form of an emulsifier, wetting agent, dispersing agent or a sticker. Examples of suitable surface-active agents are alkyl aryl sulphonates alkyl sulphates containing more than 10 carbon atoms, alkylphenol/ethylene oxide condensates, sor-bitan esters of fatty acids, alkylamide sulphonates and ethylene oxide/fatty acid ester condensates.

The compositions of the invention may be formulated as a wettable powder, a dust, granules, a concentrate, a solution, an emulsifiable concentrate, a conventional emulsion, an invert emulsion, an aerosol, or an encapsulated material.

The novel compounds of the invention may also be used in combination with each other or with other substances, for example, known pesticides and/or fertilizers.

The invention also contemplates a method of combating weeds which comprises applying to said weeds and/or their habitat a compound of the invention or a herbicidal composition containing it.

The novel compounds of the invention may be prepared by techniques known to the chemical art. They may be prepared, for example, by reacting 2, 6-dichlorothiobenzamide with the appropriate ester cf an oxy-sulphur acid. According to the invention, the novel compounds having the general formula:- may be prepared by reacting 2, 6-dichlorothiobenzamide with a compound of the formula HX wherein R and X have the meanings hereinbefore specified. Thus when, for example, dimethyl sulphate is reacted with 2, 6-dichlorothiobenzamide, the following compound is obtained:- The reaction may be carried out in the absence of a reaction medium but is preferably carried out in the presence of an inert reaction medium which may be organic or inorganic, for example acetone or water. In some cases better yields are obtained when the reaction is carried out at elevated temperature, suitably in the range 6θ°- 100°C for example at the reflux temperature of the reaction mixture.

All aspects of the invention are further illustrated in the Examples that follow in which parts by weight (w) and parts by volume (v) bear the same relation as the kilogram to the litre.

EXAMPLE I Preparation of S-methyl-2,6-dichlorothio- benzimidate methyl sulphate CI © Θ CH S0 SCH.

CI (i) Without a reaction medium 2, 6-Dichlorothiobenzamide ( 20.6 w) and dimethyl sulphate ( 1 2.6 w) were heated together at 100°C for three hours and then left at room temperature for sixteen hours. The mixture was ground up with acetone ( 50 v) and filtered. The desired product ( 28 w), .p. 1 88°- 1 89°C, was obtained in 85$ yield. ( ii ) With water as reaction medium 2, 6-Dichlorothiobenzamide ( 20.6 w), dimethyl sulphate ( 1 .6 w) and distilled water (80 w) were stirred at 80°-90°C until a solution was formed. The hot solution was filtered and the filtrate was allowed to cool. The resulting solid was filtered off, washed with acetone ( 50 v) and dried. The desired product ( l 8.5 w), m.p. l 89°- 190°C, was obtained in 6 yield. (iii) With acetone as reaction medium and acetone ( 150 v) were mixed together and refluxed for one hour. A white solid was obtained which was filtered, washed firstly with acetone and then with ether. The desired product ( 28 w), m.p. 189°- 190°C was obtained in 85$ yield.

Analysis Found : C 32.2; H 3.4; N 4.5; S 19 -0; CI 2^.^ C.Hl1Cl N0.,S requires: C 32.5 H 3-3; N 4. 2; S 19-3; CI 21 . # 9 1 I . 4 EXAMPLE II Preparation of S-ethyl-2, 6-dichlorothiobenzitnidate ethyl sulphate 2, 6-Dichlorothiobenzamide (20 w), diethyl sulphate (20 w) and acetone (100 v) were mixed together and refluxed for 12 hours. The acetone was evaporated from the reaction mixture and the residue was crystallized from ethyl acetate affording the desired product, m.p. 149°-1 51°C.

Analysis Pound : C 36. H . ; N .9; S 17-8; CI 19· 5# EXAMPLE III Preparation of S-ethyl-2, 6-dichlorothiobenzimidate methanesulphonate 2, 6-Dichlorothiobenzamide ( 21 w) and ethyl methanesulphonate ( 1 2.5 w) were heated together on a water bath for three hours. The mixture was cooled, acetone added, and a white solid crystallized on standing. The solid (22 w) was filtered and washed with acetone and then with ether. Yield 66%, m.p. 176°-178°C.

Analysis Found : C .4 H 4.0; S 19.2; CI 21 .5# C H N0 S C1 requires: C 36.4; H 3-9; S 19.4; CI 21 .556 In the same way the following compounds were prepared:- m.p. 166°-168°C (68j6) Pound : C 47-1; H 4.4; 3-4; S 15-7; CI 17-7$ C16H17N0^S2C12 requires: C 47-3; H 4.2; N 3-4; S 15-8; CI 17-5$ 1¾°-134°C (6 £) Pound : C 49-5 H 4.9; S l4.3; CI ΐ6.¾ί EXAMPLE IV Preparation of S-n-butyl-2, 6-dichlorothiobenzimidate methanesulphonate 2., 6-Dichlorothiobenzamide (20.6 w) and butyl methanesulphonate (15-2 w) were heated together at 100°C for 2 hours. The mixture was dissolved in acetone (50 v) and allowed to crystallize overnight. The white crystals were filtered and washed giving the product (15 w) m.p. 110O-112°C. A further quantity (8 w) of material was obtained by pouring the filtrate into ether (100 v). Total yield 64$.

Analysis Found : C 40 H 4-5; N 3-9 S 17-9; CI 20.0$ requires: C 40.2; H 4.7; N 5-9 S 17-9; CI 19.8# In the same way the following compound was prepared:- m.p. 141°-143°C Found : C 48.4; H 4.4; N 3-2; S 15-2 C17HigCl2Nt3S2 requires: C 48.6; H 4.5; N 3-3; S 15-2$ EXAMPLE V Preparation of S-methyl- 2, 6-diehlorothio- benzimidate ethane sulphonate 2, 6-Dichlorothiobenzamide (21 w), methyl ethanesulphonate (12.5 w) and acetone (150 v) were refluxed together for 20 hours. The reaction mixture was then cooled and a white solid crystallized from the mixture. It was filtered and the residue washed with acetone and then ether. Yield 17 w, m.p. 174 -176 C.

Analysis Found : C 36.4; H 4.0; N 4.2; S 19-2; CI 21.7 C1£)H.^C12N0^S2 requires: C 36.4; H 3-9; N 4.2; S 19-4; CI 21.

In the same way the following compound was prepared :- m.p. 178°-l80°C Found : C 44-3; H 3-4; N 3-7; S 17-2; CI 19-0$ requires: C 44.4; H 3-4; N 3-7; S 16·9; CI 18.85G EXAMPLE VI Preparation of S-n-propyl-2, 6-dichlorothio- benzimidate p-toluenesulphonate 2, 6-Dichlorothiobenzamide ( 21 w) and n-propyl p_-toluene-sulphonate (22 w) were heated together on a water bath for 2 hours. The reaction mixture was cooled and washed with ether yielding a sticky solid. A small amount of acetone was added and a white solid separated out; this was filtered and then washed with acetone. Yield 1 5 w, m.p. 1410- 143°C.

Analysis Pound : C 48.7 H 4.7; S 14.9; CI l6.9?6 Cl7H19Cl2N0 32 requires: C 48.6; H 4.5; S 1 5- 2; CI l6.9# In the same way the following compound was prepared:- m.p. 1 29°- 131°C Found : C 45. 2; H 4.2; S 1 4.2; CI 2J>.J> C17H18C12N05S2 requires: C 44- 9; H 3,9; S 14. 1 ; CI 2J. % EXAMPLE VII Preparation of S-methyl-2, 6-dichlorothio benzimidate p-toluenesulphonate 2, 6-Dichlorothiobenzamide (20 w), methyl p-toluenesulphonate ( 18 w) and acetone (100 v) were refluxed together for 6 hours. The reaction mixture was left at room temperature for 16 solution. Yield 12 w.

Analysis Found : C 5.6; H 3-7; S 16.6; CI l8.0# C1t-H.cCl_N0-.S requires: C 5.9; H 3-8; S 16.3; CI 18.1$ EXAMPLE VIII Preparation of S-(2-chloroethyl)-2,6- dichlorothiobenzimidate p-toluenesulphonate 2, 6-Dichlorothiobenzamide (21 w) and 2-chloroethyl p-toluenesulphonate ( · 5 ) were heated on a water bath for 6 hours. The reaction mixture was cooled and ether was added; a small amount of solid precipitated which was filtered off. The filtrate was allowed to stand overnight; pale yellow crystals were obtained. They were filtered, combined with the first portion, and washed with acetone. Yield 6 w, m.p. 1 4°-156°C.

Analysis Found : C 3-8 H -9 CI 24.5$ requires: C 43-6; H 3-6; CI 24.2$ EXAMPLE IX Preparation of an Emulsifiable Concentrate An emulsifiable concentrate was prepared by mixing the following ingredients :- S-methyl-2, 6-dichlorothiobenz- imidate methyl sulphate (Example I) 20.2$ w/v Surface-active agent (Tensiofix D 120) 5-0$ w/v Carrier (N-methyl pyrrollidone) to 100 v (Tensiofix D 1 0 is a commercially available surface-active agent and comprises an alkyl aryl polyether alcohol).

EXAMPLE X Preparation of a Wettable Powder A wettable powder was prepared by mixing the following ingredients :- S-methyl-2, 6-dichlorothiobenz- imidate methyl sulphate 0. w/w Carrier (Clay GTY) 39 - 5$ w/w (Nonipol CS 50 s a water-soluble, non-ionic surface-active agent and comprises a polyethylene glycol ether; Aerosol OT/B is a surface-active and wetting agent and comprises sodium dioctyl sulpho succinate; Clay GTY is a kaolinite china clay).

EXAMPLE XI Herbicidal Activity The compounds of the invention are essentially pre-emergence herbicides and their degree of activity was determined by the following method.

Seeds of Oat ( 0) , ryegrass (RCJ), sweet corn (SC), pea (P), sugar beet (SB), linseed (L) and mustard (M) were sown arid allowed to germinate in sterile John Innes compost. The soil was sprayed at a volume equivalent to 50 gallons per acre with the following compositions : - Acetone 0# by volume Water 60$ by volume Surface-active agent (Triton X- 1 55) 0· 5¾ by weight Active ingredient varying amounts (Triton X- 1 55 is a commercially available surface-active agent and comprises an alkyl aryl polyether alcohol). Control tests were also carried out.

After 1 2 days the phytotoxic effect of the compound applied was assessed by determining the reduction in fresh weight of stem and leaf of the emerging plants over the control plants and plotting a regression curve relating the growth inhibition (CI) and the dosage of compound applied. The dosage required for 90 growth inhibition (i.e. that weight of compound required to give a reduction in the fresh weight of plants leaf and stem of 90$) is given in the following Table in pounds per acre.

TABLE TABLE (cont'd)

Claims (26)

1. ΗΑ'νΙΚΠ- ΟΎ particularly described and ascertained nature of our said invention and in what manner the s^me in be performed, we declare that ¾rhat we claiw is Compounds having the general formula:- CI CI wherein R represents an alkyl or haloalkyl group and X represents an alkyl, aryl or alkaryl sulphate or sulphonate ion.

2. Compounds as claimed in claim \, wherein R represents an alkyl or haloalkyl group containing 1-6 carbon atoms.

3. · Compounds as claimed in claim 1 or 2, wherein R represents a chloro- or bromo-alkyl group.

4. S-methyl-2, 6-dichlorothiobenzimidate methyl sulphate.

5. · S-methyl-2, 6-dichlorothiobenzimidate ethanesulphonate.

6. S-methyl-2, 6-dichlorothiobenzimidate benzenesulphonate.

7. - S-methyl-2, 6-dichlorothiobenzimidate p-toluenesulphonate.

8. S-ethyl-2, 6-dichlorothiobenzimidate methanesulphonate .

9. · S-ethyl-2, 6-dichlorothiobenzimidate ethyl sulphate.

10. S-ethyl-2, 6-dichlorothiobenzimidate p-toluenesulphonate.

11. S-(2-chloroethyl)-2, 6-dichlorothiobenzimidate p-toluenesulphonate.

12. S-(n-propyl)-2, 6-dichlorothiobenzimidate p-toluenesulphonate.

13. · S- (3-chloropropyl)-2, 6-dichlorothiobenzimidate p-toluenesulphonate.

14. 1 . S-(n-butyl) -2, 6-dichlorothiobenzimidate methanesulphonate.

15. S-(n-butyl) -2, 6-dichlorothiobenzimidate benzenesulphonate.

16. S-(n-butyl) -2, 6-dichlorothiobenzimidate p-toluenesulphonate.

17. any one of claims 1 - 16, wherein 2, 6-dichlorothiobenzamide is reacted with a compound of the formula RX wherein R represents an alkyl or haloalkyl group and X represents an alkyl, aryl or alkaryl sulphate or sulphonate ion*

18. A process as claimed in claim 17, wherein the reaction is carried out in an inert reaction medium.

19. · A process as claimed in claim 18, wherein the inert reaction medium is acetone or water.

20. A process as claimed in claim 17* 18 or 19* wherein the reaction is carried out at an elevated temperature.

21. A process or the preparation of compounds specif ed in any one of claims 1 - 16, substantially as hereinbefore described

22. A process for the preparation of compounds specified in any one of claims 1 -16, substantially as hereinbefore described with reference to any of Examples I-VIII.

23. 3- A herbicidal composition comprising a compound as specified in any one of claims 1 -16, a carrier, a surface-active agent, or both a carrier and a surf ce-active agent.

24. A composition as claimed in claim 23, formulated as a wettable powder, a dust, granules, a concentrate, a solution, an emulsifiable concentrate, a conventional emulsion, an invert emulsion, or an encapsulated material.

25. · A composition as claimed in claim 23, substantially as hereinbefore described.

26. A composition as claimed in any one of claims 23-2 * substantially as hereinbefore described in Examples IX and X. 27· A method of combating weeds which comprises applying to said weeds and/or their habitat a compound as claimed in any one of claims 1 -16 or a composition as claimed in any one of claims 23-26. Dated this 29th day of ¾rch, 1966 R11