BE897299A - STABLE HERBICIDE COMPOSITIONS BASED ON M. BIS-CARBAMATES - Google Patents

Abstract

Chemically stable herbicidal compositions based on m. bis-carbamates containing in weight proportions between 90/1 and 1/40 a surfactant or a mixture of surfactants belonging to the class of phosphoric acids mono or di-esterified with alkylphenol and polyethoxylates, having the general formula (1), in which X is a hydroxyl or a group (II) m and n are independent of each other, an integer between 1 and 80, limits included, it being understood that the sum m + n is equal to or less than 80; p is an integer between 1 and 4, preferably equal to 1; R is a linear or branched alkyl radical comprising from 4 to 12 carbon atoms, a bis-alpha-phenyl-ethyl radical or a benzyl radical.

Description

       

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   DESCRIPTIVE MEMORY filed in support of a request for
PATENT OF INVENTION formed by
MONTEDISON S. p. A. for: "Stable herbicidal compositions based on m. Biscarbamates"

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STABLE HERBICIDE COMPOSITIONS BASED ON M. BIS-
CARBAMATES.



   The present invention relates to stable herbicidal compositions and relates more particularly to herbicidal compositions containing m. bis-carbamates, which have been shown to be stable over long periods of time due to the presence of surfactants
 EMI2.1
 belonging to the class of polyoxyethylated alkylphenolphosphoric acids.



   The herbicides called m. bis-carbamates are compounds with good herbicidal activity which have been used for many years for the destruction of weeds in agricultural crops of interest. The m. bis-carbamates can be considered to have the following general formula:
 EMI2.2
 
Representative examples of herbicides of this class are: - Phenmedipham: common name of the compound of formula 1 in which Ri = H,
R2 = 3-tolyl, R3 = CH 3; and,
 EMI2.3
 -: common name of the compound of formula 1 in which Ri = H, R2 = phenyl, R3 = ethyl These herbicides are generally used in the form of liquid compositions, to be diluted before their use, formed of the active substance, an organic solvent and a surfactant.



   Examples of organic solvents which can be used in the abovementioned compositions are aromatic hydrocarbons, alicyclic ketones (cyclohexanon, isophorone), esters, dimethylsulfoxide, dimethylformamide and the like; similarly, examples of surfactants

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 likely to be used are polyethoxylated alkylphenols, alcohols, carboxylic acids and amines as well as salts of alkylbenzenesulfonic acid or naphthalenesulfonic acid.



   A disadvantage of these conventionally prepared compositions is that the active substance tends to decompose, even to a significant extent, during storage so that the herbicide concentrations drop and the herbicidal activity of the compositions is reduced.



   Such compositions are often unstable from the physical point of view since the active substance, especially at high and low temperatures, tends to crystallize and thus give rise to deposits and to separate solid products.



   To overcome these drawbacks, various solutions have been studied which however involve the introduction of complex mixtures (having no less than four constituents) of solvents, stabilizers and surfactants in the compositions.



   U.S. Patent No. 3,898,075 describes a method for stabilizing the herbicide in liquid compositions, such a method consisting in mixing with the compositions an amount of 0.05 to 5% by weight of a chosen organic acid. among the following acids: aliphatic bicarboxylic acids, aliphatic hydroxycarboxylic acids, nitroaromatic monocarboxylic acids, aromatic bicarboxylic acids, aromatic or aliphatic sulfonic acids.



   The aforementioned patent also teaches that other acids, including phosphoric acid, are not suitable for stabilizing the herbicides of formula I.



   In Belgian Patent No. 884,482 to the Société Montedison S. p. A., are also described herbicidal compositions containing as active substance Phenmedipham. These compositions appear to be physically stable for long periods of time both at low and high temperatures.



   By continuing research on the compositions described in the aforementioned Belgian patent, it has been found that a particular composition, which is indicated there by way of example, consisting of phenmedipham (40% by weight), dimethylformamide (30%), xylene (20%) and containing 10% by weight of "Rolfen 10 D" (trade name of ROL Company for a mixture of phosphoric acid mono- and diesterified with nonylphenol and polyoxyethylated with 10 moles of ethylene oxide per mole of substrate) gives

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 considerable chemical stability, because the active substance known as Phenmedipham undergoes negligible degradation over time.



   It has also been found that a series of known surfactants deriving from phosphoric acid mono- and di-esterified with alkylphenol and polyoxyethylated, but having at least one free acid function, as identified below , provides remarkable chemical stability to herbicides based on m. bis-carbamate in compositions intended for agricultural uses.



   The fact that these surfactants derived from phosphoric acid and having at least one free acid function are capable of stabilizing herbicides based on m. bis-carbamate seem particularly surprising in view of the fact that in US Pat. No. 3,898,075 is taught that phosphoric acid is not suitable for fine cat.



   Thus, an object of the present invention resides in herbicidal compositions based on m. bis-carbamates, chemically stable and containing in weight proportions between 90/1 and 1/40, a surfactant or a mixture of surfactants belonging to the class of phosphoric acids mono and diesterified by alkylphenol and polyoxyethylated, having the following general formula:

   
 EMI4.1
 in which :
X is a hydroxyl or a group
 EMI4.2
 m and n independently of each other, are whole numbers between 1 and 80, limits included, such that the sum m + n is less than or equal. a 80; p is an integer between 1 and 4, preferably equal to 1;
R is a linear or branched alkyl radical comprising from 4 to 12 carbon atoms, a bis-a-phenylethyl group or a benzyl group.



   The use of surfactants of formula II as stabilizers in herbicidal compositions containing m. bis-carbamates makes it possible to avoid the use of other additives and offers the considerable advantage of being available stable compositions formed from m. bis-carbamate

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 mainly forming the active substance, an organic solvent and a. surfactant of the aforementioned particular class.



   The present invention relates to stable herbicidal compositions based on m. bis-carbamates composed of:
A.-herbicide m. bis-carbamate of formula l ............................... 0.5 to 45% by weight
B.-a surfactant of formula II ..... 0.5 to 20% by weight C.-an organic solvent chosen from aromatic or alkylaroma hydrocarbons. ticks, alicyclic ketones, esters of carboxylic acids, dimethylsulfoxide, dimethylformamide, monoester glycol or mixtures thereof ..........................

   an amount sufficient to reach 100%, it being understood that, when simultaneously the herbicide of formula I is Phenmedipham, the surfactant is "Rolfen 10 D" and the solvent is a mixture of dimethylformamide and xylol, these substances being in different weight ratios of 40/10/30/20 composition which has already been described in Belgian patent n 884. 482.



   The compositions forming the object of the present invention are stable for long periods of time because, as will appear from the examples, the herbicide undergoes degradation. negligible while in conventional compositions, the degradation is remarkable.



   The compositions according to the present invention are generally self-emulsifying in water due to the presence of compound II which acts both as a stabilizer and as a surfactant.



   However, if the solvent chosen is sparingly soluble in water and if the compound of formula II is used in amounts close to the lower limit, for example less than 4% by weight, it may be useful to add a surfactant. -conventional active ingredient, having a different chemical class, exclusively for the purpose of facilitating lemulsifiability in water of the composition according to the invention.



   Some examples of organic solvents used in the compositions in accordance with the present invention are: benzene, toluene, xylene also in the form of mixtures of isomers, alkylbenzenes comprising from 9 to 12 carbon atoms, also in commercial mixtures, cyclohexanone, isophorone, ethyl acetate, octyl or butyl phthalate, methylcellosolve, cellosolve acetate, etc.

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   The herbicidal amount of formula I in the composition depends on its solubility in the organic solvent chosen.



   The compounds of formula II are known as surfactants also for use in the agricultural field, however, as far as is known, their use for stabilizing herbicides belonging to the m class. bis-carbamate has never been described so far
The surfactants of formula II are readily available commercially as individual compounds or as mixtures, both with respect to the number of moles of ethylene oxide per mole of phosphoric derivative, and for with regard to the substituents on phenol. Also commercially available are mixtures of mono and di-esters of phosphoric acid of formula II having different levels
 EMI6.1
 ethoxylation.



   If it was desirable to have a particular compound of formula II not immediately available commercially, it is possible to prepare it by synthesis according to known techniques. For example, it is possible to react a mono or d-halide of phosphoric acid with one or two moles, respectively, of an alkaline salt (phenate) of the corresponding alkylphenol. The resulting product is then polyethoxylated according to conventional techniques.



   As is known, ethoxylation is very controllable over a wide range although, by its nature, the reaction leads to mixtures of products having a number of moles of ethylene oxide per mole of substrate included in a narrower area so that by the term "rate of ethoxylation" is meant the statistical average of the number of moles of ethylene oxide per mole of substrate.



   The preparation of the compositions according to the invention is accomplished by mixing the constituents in predetermined amounts. The practical uses and the results obtained are very similar to those of known compositions containing the same herbicides.



   In order to better illustrate the present invention, the following examples are given in which the abbreviations have the following meanings: - surfactants of formula II
Tens II-A: it is a phosphoric acid monoesterified with nonylphenol and polyethoxylated at 10 ETO (10 moles of ethylene oxide per mole of substrate); the product with the trade name "Rolfen 10" was used, sold by the company ROL Co.

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   Tens II-B: mixture of phosphoric acid diesterified by nonylphenol and polyethoxylated at 10 ETO with Tens II-A; the product sold under the name "Rolfen 10 D" sold by the company ROL Co. was used



   Tens II-C: phosphoric acid monoestirified by bis-a'phenyl-ethylphenol and polyethoxylated at 10 ETO; the compound sold under the trade name "Rolfen 40" was used by
ROL Co.



   Tens II -0: phosphoric acid monoesterified with nonylphenol and polyethoxylated at 80 ETO; the product sold under the trade name "Rolfen 80" was used by the Company
ROL Co.



  - surfactants for control compositions
 EMI7.1
 OR-25 ETO: polyethoxylated castor oil 25 ETO, DBS-Ca: calcium. dodecylbenzenesulfonate- solvents
DMF: dimethylformamide
DMSO: dimethyl sulfoxide
Xylol: commercial mixture of xylene isomers.



  EXAMPLE 1
A composition in accordance with the invention (composition 1.1) is prepared
 EMI7.2
 by dissolving 5 g of Phenmedipham in 90 g of cyclohexanone and adding to the solution 5 g of Tens II-A. The mixture is stirred at room temperature until it is homogenized.



   Composition 1.1 is placed in a thermostat at 540C and kept there for 14 days. At the end of this heating period, the Phenmedipham is determined quantitatively directly on the sample by high pressure liquid chromatography (HPLC).



   Degradation of less than 0.5% is observed.



  EXAMPLE 2
The compositions according to the invention, prepared in accordance with the method described in Example 1, are mentioned in Table 1 below, while the control compositions not containing surfactants or containing surfactants of a different chemical nature are listed in Table II.

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   TABLE l Compositions according to the invention
 EMI8.1
 
<tb>
<tb> Compositions <SEP> n
<tb> Constituents
<tb> (b)
<tb> 1. <SEP> 1 <SEP> 1. <SEP> 2 <SEP> 1. <SEP> 3 <SEP> 1. <SEP> 4 <SEP> 1. <SEP> 5 <SEP> 1. <SEP> 6 <SEP> 1. <SEP> 7 <SEP> 1. <SEP> 8 <SEP> 1.9 <SEP> 1.10 <SEP> 1. <SEP> 11 <SEP> 1. <SEP> 12 <SEP > 1. <SEP> 13 <SEP> 1.

   <SEP> 14 <SEP>
<tb> Herbicide <SEP> of <SEP> Phenmediphani <SEP> 5 <SEP> 15 <SEP> 30 <SEP> 30 <SEP> 30 <SEP> 45 <SEP> 15 <SEP> 15 <SEP> 15 <SEP > 30 <SEP> 30 <SEP> 30
<tb> formula <SEP> I <SEP> Desmedipham <SEP> 15 <SEP> 30
<tb> Cyclohexanon <SEP> 90
<tb> Isophorone <SEP> 80 <SEP> 65
<tb> DMF <SEP> 60 <SEP> 60 <SEP> 60 <SEP> 45 <SEP> 5 <SEP> 20 <SEP> 20 <SEP> 30 <SEP> 30 <SEP> 30 <SEP> 30
<tb> Solvents <SEP> DMSO <SEP> 80
<tb> Xylol <SEP> 5 <SEP> 55 <SEP> 55 <SEP> 15 <SEP> 15 <SEP> 15 <SEP> 15
<tb> Dioctyl phthalate <SEP> 15 <SEP> 15 <SEP> 15
<tb> Methylcellosolve <SEP> 15
<tb> Tensio-Tens. <SEP> II-A <SEP> 5 <SEP> 5 <SEP> 10 <SEP> 5 <SEP> 10
<tb> active <SEP> of <SEP> Tens. <SEP> II-B <SEP> 10 <SEP> 10 <SEP> 10 <SEP> 10 <SEP> 10 <SEP> 10
<tb> formula <SEP> II <SEP> Tens. <SEP> II-C <SEP> 10 <SEP> 10
<tb> Tens.

   <SEP> II-D <SEP> 10
<tb>
 Legend of Table 1 (a) the quantity of each of the constituents is expressed as a percentage by weight (b) composition No. 1. 1 is described in Example 1.

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   TABLE II Control compositions
 EMI9.1
 
<tb>
<tb> Constituents <SEP> (a) <SEP> Compositions <SEP> nO <SEP>
<tb> Constituents
<tb> 2.1 <SEP> 2.2 <SEP> 2.3 <SEP> 2.4 <SEP> 2.5 <SEP> 2.6 <SEP> 2.7 <SEP> 2.8 <SEP> 2.9 <SEP> 2.10
<tb> Herbicide <SEP> from <SEP> Phenmedipham <SEP> 5 <SEP> 15 <SEP> 30 <SEP> 15 <SEP> 15 <SEP> 30 <SEP> 30 <SEP> 15 <SEP> 15
<tb> formula <SEP> I <SEP> Desmedipham <SEP> 15
<tb> Cyclohexanon <SEP> 95
<tb> Isophorone <SEP> 85 <SEP> 77 <SEP> 65 <SEP> 65
<tb> Solvent <SEP> DMF <SEP> 70 <SEP> 20 <SEP> 30 <SEP> 45 <SEP> 5 <SEP> 5
<tb> DMSO <SEP> 85
<tb> Xylol <SEP> 5 <SEP> 65 <SEP> 40 <SEP> 15 <SEP> 5 <SEP> 5
<tb> Tensio-OR-25 <SEP> ETO <SEP> 10 <SEP> 10 <SEP>
<tb> active <SEP> DBS-Ca <SEP> 3 <SEP> 10 <SEP>
<tb>
 Legend of Table II (a) the quantity of each of the constituents is expressed as a percentage by weight.

   
 EMI9.2
 1

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 EXAMPLE 3
Determination of the chemical stability of the herbicide in the compositions.



   A 100 g batch of each of the compositions in Table 1 (see Example 2) in accordance with the invention and the control compositions in Table II (see Example 2) is placed in a glass container which has been placed
 EMI10.1
 in a thermostat at 54 C.



   After 14 days, the amount of active substance (herbicide) is determined directly on the sample using a high pressure liquid chromatograph (HPLC).



   The results obtained, expressed as a percentage of degradation of the herbicide, are recorded in Table III below. From the data in Table III, it appears that in the compositions according to the present invention, the herbicidal compounds appear to be chemically stable also at high temperatures over a long period of time.



   TABLE III Chemical stability of m-based fungicides. bis-carbamate in different compositions, after 14 days at 54 C.
 EMI10.2
 
<tb>
<tb>



  Composition <SEP> nO <SEP> Degradation <SEP> of <SEP> the herbicide <SEP> (a)
<tb> (cf. <SEP> tables <SEP> 1 <SEP> and <SEP> 2) <SEP> (%) <SEP>
<tb> 1.1 <SEP> <<SEP> 0.5
<tb> 1.2 <SEP> <<SEP> 0, <SEP> 5
<tb> 1.3 <SEP> <<SEP> 0.5
<tb> 1.4 <SEP> <<SEP> 0, <SEP> 5
<tb> 1.5 <SEP> <<SEP> 0, <SEP> 5
<tb> 1.6 <SEP> <<SEP> 0, <SEP> 5
<tb> 1.7 <SEP> <<SEP> 0, <SEP> 5
<tb> 1.8 <SEP> <<SEP> 0, <SEP> 5
<tb> 1.9 <SEP> <<SEP> 0, <SEP> 5
<tb> 1. <SEP> 10- <<SEP> 0, <SEP> 5
<tb> 1. <SEP> 11 <SEP> <<SEP> 0, <SEP> 5
<tb> 1. <SEP> 12 <SEP> <<SEP> 0.5
<tb> 1. <SEP> 13 <SEP> <<SEP> 0, <SEP> 5 <SEP>
<tb> 1.14 <SEP> <<SEP> 0.5
<tb> 2.1 <SEP> 8.3
<tb> 2.2. <SEP> 7.8
<tb> 2.3 <SEP> 69.0
<tb>
 

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 EMI11.1
 
<tb>
<tb> Composition <SEP> nO <SEP> Degradation <SEP> of <SEP> the herbicide <SEP> (a)
<tb> (cf.

   <SEP> tables <SEP> 1 <SEP> and <SEP> 2) <SEP> (%)
<tb> 2. <SEP> 4 <SEP> 38, <SEP> 0
<tb> 2.5 <SEP> 12.3
<tb> 2.6 <SEP> 49, <SEP> 0
<tb> 2.7 <SEP> 53, <SEP> 1
<tb> 2.8 <SEP> 27.2
<tb> 2.9 <SEP> 9.5
<tb> 2.10 <SEP> 7, <SEP> 8 <SEP> - <SEP>
<tb>
 Table III legend
 EMI11.2
 (a) the symbol "<" means "more and the value" <0.5 "less than", that no degradation is observed in the sensitivity range of the analysis method used.


    

Claims (3)

 CLAIMS 1.-Chemically stable herbicidal compositions based on m. biscarbamate containing, in weight proportions between 90/1 and 1/40, a surfactant or a mixture of surfactants belonging to the class of phosphoric acids mono or di-esterified with alkylphenol and polyethoxylates, having the general formula:  EMI12.1  in which : X is a hydroxyl or a group  EMI12.2  m and n are independently of each other, an integer between 1 and 80, limits included, it being understood that the sum m + n is equal to or less than 80; p is an integer between 1 and 4, preferably equal to 1; R is a linear or branched alkyl radical comprising from 4 to 12 carbon atoms, a bis-a-phenyl-ethyl radical or a benzyl radical.  2.-herbicidal compositions according to claim 1, characterized in that the herbicide consisting of m. bis-carbamate is a compound sold commercially under the name of Phenmedipham or Desmedipham.  3.- chemically stable herbicidal compositions according to claim 1, comprising:  EMI12.3   <tb> <tb> A.-herbicide <SEP> formed <SEP> by <SEP> m. <SEP> bis-carbamate ............ <SEP> 0.5 <SEP> to <SEP> 45% <SEP> by <SEP> weight <tb> B.-agent <SEP> surfactant <SEP> of <SEP> formula <SEP> II .............. <SEP> 0.5 <SEP> to < SEP> 20% <SEP> in <SEP> weight <tb>    C. an organic solvent chosen from aromatic or alkylaromatic hydrocarbons, alicyclic ketones, esters of carboxylic acids, dimethyl sulfoxide, dimethyl-  EMI12.4  forlllal1lide, glycol l1Ionoethers or mixtures thereof ......................................  sufficient to reach 100%  <Desc / Clms Page number 13>  it being understood that, when the herbicide used simultaneously is Phenmedipham, the surfactant is a mixture of phosphoric acid mono and di-esterified with nonylphenol and polyethoxylated with 10 moles of ethylene oxide per mole of substrate , the solvent is a mixture of dimethylformamide and xylol, these substances being used in weight ratios other than 40/10/30/20.