CH654173A5 - STABLE LIQUID COMPOSITIONS OF META-BIS-CARBAMATE HERBICIDES. - Google Patents

Description

The present invention relates to stable herbicide compositions and more precisely to herbicide compositions containing m-bis-carbamates which are stable over time thanks to the presence of surfactants belonging to the class of polyoxyethylated alkylphenulfosphoric acids.

The herbicides called m.bis-carbamates are compounds with good herbicidal activity that have been used for several years in the weeding of important agricultural crops. The bisbis-carbamates can be considered included in the following general formula.

OR R1

The /

0 - C - N

rè] v

NH - c - 0 - R

1!

Representative examples of herbicides of this class are Phenmedipham (common name of the compound of formula I in which R1 = H, R2 = 3-tolyl, R3 = CH3) and Desmedipham (common name of the compound of formula I in which R1 = H , R2 = phenyl, R3 = ethyl).

These herbicides are generally used in the form of liquid compositions, to be diluted before use, consisting of the active principle, an organic solvent and a surfactant.

Examples of organic solvents which can be used in the aforementioned compositions are aromatic hydrocarbons, alicyclic ketones (cyclohexhe-none, isophorone), esters, dimethylsulfoxide, dimethylformamide, etc. similarly examples of surfactants that can be used are alkylphenols, alcohols, carboxylic acids and polyoxyethylated amines and alkylbenzene sulphonic or naphthalene sulfonic salts.

A disadvantage of these traditional compositions in the formulation field, consists in the fact that the active principle tends to decompose, even in a very relevant way, during storage and consequently the concentration of the herbicide decreases and the herbicidal effectiveness of the composition is reduced.

Often these compositions are also physically unstable since, especially at high and low temperatures, the active principle tends to crystallize giving rise to solid deposits and separations.

To overcome these drawbacks, various solutions have been studied which however introduce into the compositions complex mixtures (not less than four components) of solvents, stabilizers and surfactants.

In the US patent No. 3 898 075 a method is described for stabilizing the herbicide in liquid compositions, consisting of adding to the compositions a quantity comprised between 0.05 and 5% by weight of an organic acid selected from the following classes: dicarboxylic acids aliphatic, hydroxycarboxylic aliphatic acids, monocarboxylic nitroaromatic acids, dicarboxylic aromatic acids, aliphatic or aromatic sulfonic acids.

In the above patent it is also shown that other acids among which phosphoric acid are not suitable for stabilizing the herbicides of formula I.

In the Belgian patent No. 884 482 in the name of Montedison S.p.A., herbicide compositions having Phenmedipham as active principle are described, among other things. Said compositions are physically stable over time both at high and low temperatures.

Deepening the studies on the compositions described in the aforementioned Belgian patent, we found that a particular composition exemplified therein consisting of Phenmedipham (40% by weight), dimethylformamide (30%, xylene (20%) and containing 10% by weight of «Rolfen 10 D »(Registered trademark of the ROL Company for a mixture of mono and diesterified phosphoric acid with nonylphenol and polyoxyethylate with 10 moles of ethylene oxide per mole of substrate) gives the active principle a remarkable chemical stability as Phenmedipham degrades in a negligible way in time.

We have also found that a series of known surfactants derived from phosphoric acid mono or di-esterified with alkylphenol and polyoxyethylate but having at least a free acid function, as identified below, impart to the m.bis-carbamate herbicides a remarkable stability chemistry in compositions for agricultural use.

The fact that said surfactants derived from phosphoric acid and having at least a free acid function are able to stabilize the herbicides m-bis-carbamates is particularly surprising in consideration of the fact that in the US patent No. 3 898 075 it is reported that the phosphoric acid is not suitable for this purpose.

Therefore, the subject of the present invention are herbicide compositions of chemically stable m.bis-carbamates containing, in a weight ratio between 90: 1 and 1: 40, a ten-

5

10

15

20

25

30

35

40

45

50

55

60

65

3

654 173

sioactive or a mixture of surfactants belonging to the class of mono or di-esterified phosphoric acids with alkylphenol and polyoxyethylates, having general formula:

Q yo - ch2 - CH2) m - o - / qV (R) p HO-r <P)

X

in which:

X represents a hydroxyl or group v. (R)

- (0 - CH2 - CH2) n- 0 - <0 /> P i m and n independently represent an integer between 1 and 80 included so that the sum m + n is less than or equal to 80;

p represents an integer from 1 to 4, preferably 1;

R represents a linear or branched C4-C12 alkyl, a bis-a-phenyl-ethyl group or a benzyl.

The use of the surfactants of formula II as stabilizer of herbicide compositions containing m.bis-carbamates allows to avoid the use of other additives and offers the considerable advantage of having stable compositions of m.bis-carbamates consisting simply of the active principle, an organic solvent and a surfactant of the particular class considered.

Therefore, a second object of the invention are stable herbicide compositions of m.bis-carbamates consisting of A - m-bis-carbamate herbicide of formula I 0.5-45% by weight.

B - surfactant of formula II 0.5-20% by weight

C - an organic solvent selected from aromatic or alkyl aromatic hydrocarbons, alicyclic ketones, carboxylic acid esters, dimethylsulfoxide,

dimethylformamide, glycol-mono-

ethers or their mixtures as required 100%

Without prejudice to the condition 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 xylene, these are in a ratio in weight other than 40: 10: 30: 20 as said composition has been described in the Belgian patent No. 884 482.

The compositions object of the invention are stable over time since, as will appear from the examples, the herbicide degrades in a negligible way while in traditional compositions there is a considerable degradation.

The compositions according to the invention are generally self-emulsifying in water thanks to the presence of compound II in the dual function of stabilizer and surfactant.

However, if the selected solvent is slightly soluble in water and if the compound of formula II is used in quantities close to the lower limit (for example less than 40% by weight), it may be useful to add a conventional surfactant of different chemical class with the exclusive purpose of facilitating the emulsifiability in water of the composition object of the invention.

Examples of organic solvents that can be used in the compositions object of the invention are: toluene, xylene also in commercial isomeric mixtures, alkylbenzenes having from 9 to 12 carbon atoms also in commercial isomeric mixtures, alkylbenzenes having from 9 to 12 carbon atoms also in commercial mixtures , cyclohexanone, isophorone, ethyl acetate, butyl or octyl-phthalate, methylcellosolve, cellosolve acetate, etc. 5 The quantity of herbicide of formula I in the composition essentially depends on its solubility in the selected organic solvent.

The compounds of formula II are known as surfactants also for use in the agricultural field however, to the best of our knowledge, their use in the stabilization of herbicides belonging to the class of m-bis-carbamates had not previously been described.

The surfactants of formula II are readily available on the market as single compounds or as mixtures both as regards the number of moles of ethylene oxide per mole of phosphoric derivative, and as regards the substituents on the phenol. Mixtures of mono and diesters of phosphoric acid according to formula II having different degrees of ethoxylation are also commercially available,

20 If it is desired to have a particular compound of formula II not immediately commercially available, it can be prepared by synthesis according to known techniques.

For example, a mono or dihalide of phosphoric acid can be reacted with one or two moles of an alkali salt (phenate) of the corresponding alkylphenol respectively. The product obtained is then polyoxyethylated according to conventional techniques.

As is known, ethoxylation is well controllable within wide margins however by its nature the reaction provides mixtures of products having a number of moles of ethylene oxide per mole 30 of substrate included in a fairly narrow range and therefore with the term "degree of ethoxylation 'means the statistical average of the number of moles of ethylene oxide per mole of substrate.

The preparation of the compositions according to the invention 35 is carried out by mixing the components in the predetermined quantities.

The practical uses and the results obtained are completely analogous to those of the known compositions containing the same herbicides.

40 With the aim of better illustrating the invention, the following examples are now provided in which the following abbreviations have been used:

Surfactants of formula II 45 Tens II-A = monoesterified phosphoric acid with nonylphenol and polyoxyethylate 10 ETO (10 moles of ethylene oxide per mole of substrate); the product marketed by the ROL company under the brand name «Rolfen 10» was used.

Tens II-B- = mixture of phosphoric acid diesterified with 50 monylphenol and polyoxyethylated 10 ETO with Tens II-A; the product marketed by the ROL company under the brand name "Rolfen 10 D" was used.

Tens II-C = monoesterified phosphoric acid with bis-a-fe-nyl-ethylphenol and polyoxyethylate 10 ETO; Compound 55 was marketed by ROL under the brand name «Rolfen 40».

Tens II-D = monoesterified phosphoric acid with nonyl phenol and polyoxyethylate 80 ETO; the compound marketed by ROL under the brand name «Rolfen 80» was used.

60

Surfactants for comparison compositions

OR - 25 ETO = Polyoxyethylated castor oil 25 ETO

DBS-Ca = calcium dodecylbenzene sulfonate

65 Solvents

DMF = dimethylformamide

DMSO = dimethylsulphoxide

Xylene = commercial mixture of xylene isomers.

654 173

4

Example 1

A composition according to the invention (composition 1.1) is prepared by dissolving 5 g of Phenmedipham in 90 g of cyclohexanone and adding 5 g of Tens II-A to the solution. The mixture is stirred at room temperature to ensure homogenization.

The composition n. 1 is placed in a thermostat at 54 ° C for 14 days. At the end of the heating period, Phenedipham is quantitatively determined directly in the sample by high pressure liquid chromatography (HPLC). I

Degradation of less than 0.5% is observed.

Example 2

In the following table 1 there are reported compositions according to the invention prepared according to what described in example 1 and in Table 2 there are comparative compositions not containing surfactants or containing surfactants of different chemical classes.

TABLE 1 - Compositions according to the invention

Components (a)

Compositions n °

l.l (b)

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

• 1.10

1:11

1:12

1:13

1:14

Herbicide of

phenmedipham

5

15

30

30

30

45.

15

15

15

30

30

30

Formula I

desmedipham

15

30

Cyclohexanone

90

isophorone

80

65

DMF

60

60

60

45

5

20

20

30

30

30

30

DMSO

80

Solvent

Xylene

5

55

55

15

15

15

15

octylphtalate

15

15

15

methylcellosolve

15

Surfactant

Tens. II-A

5

5

10

5

10

of formula II

Tens. II-B

10

10

10

10

10

10

Tens. II-C

10

10

Tens, II-D

10

Note to table 1

(a) The quantity of each component is expressed as a percentage by weight

(b) Composition No. 1.1 is described in Example 1.

TABLE 2 - Comparative compositions

Componenti'3 '

2.1 2.2

2.3

2.4

Compositions n ° 2.5 2.6

2.7

2.8

2.9

2:10

Herbicide of formula I

Phenmedipham Desmedipham

5 15

30

15

15

15

30

30

15

15

solvents

Cyclohexanone

isophorone

DMF

DMSO

Xylene

95

85

70

85

77 5

20 65

30 '40

45 15

65 5

5

65 5

5

Surfactant

OR- 25 ETO DBS-Ca

3

10

10

10

Note, in table 2

(a) The quantity of each component is expressed as a percentage by weight.

5

654 173

Example 3

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

An aliquot of 100 g of each of the compositions of table 1 (see example 2) according to the invention and of the comparative compositions of table 2 (see example 2) was placed in a glass container in a 54 ° C thermostat.

After 14 days the amount of active ingredient (herbicide) was determined directly in the sample by high pressure liquid chromatography (HPLC).

The following table 3 shows the results obtained expressed as a percentage degradation of the herbicide.

From the data reported in table 3 it is clear that in the compositions according to the invention the herbicide compound is chemically stable even at high temperatures for a long period of time.

TABLE 3

Chemical stability of m.bis-carbamate herbicides in different compositions after 14 days at 54 ° C.

Composition n ° Degradation of the herbicide (a)

(see tables 1 and 2)

(%)

1.1

<0.5

1.2

<0.5

10

1.3

<0.5

1-4

<0.5

1.5

<0.5

1.6

<0.5

1.7

<0.5

15

1.8

<0.5

1.9

<0.5

1:10

<0.5

1.11

<0.5

1:12

<0.5

20

1:13

<0.5

1:14

<0.5

2.1

8.3

2.2 •

7.8

2.3

69.0

25

2.4

38.0

2.5

12.3

2.6

49.0

2.7

53.1

2.8

27.2

30

2.9

9.5

2:10

7.8

Note to table 3

(a> The symbol "<" means "less than" and the value "<0.5" indicates that no degradation has been observed within the sensitivity limit of the analysis method.

Claims (3)

654 173 2. Herbicide compositions according to claim I wherein the herbicide m.bis-carbamate is the compound Phenmedipham or Desmedipham. 2 CLAIMS I. Herbicide compositions of chemically stable m.bis-carbamates containing, in a weight ratio between 90: 1 and 1: 40, a surfactant or a mixture of surfactants belonging to the class of mono or di-esterified phosphoric acids with alkyl-phenol and polyoxyethylates having general formula 0 (0, ch2-C "2, b-0 - @ - (B ^ HO - P. X in which: X represents a hydroxyl or group (R) o m and n independently represent an integer between 1 and 80 inclusive so that the sum m + n is equal to or less than 80; P represents an integer from 1 to 4; R represents a linear or branched C4 - Cn alkyl, a bis-a-phenyl-ethyl group or a benzyl. Chemically stable herbicide compositions according to claim 1, consisting of A - herbicide m.bis-carbamate 0.5-45% by weight B - Surfactant of formula II 0.5-20% by weight C - An organic solvent chosen from aromatic or alkyl aromatic hydrocarbons, alicyclic ketones, carboxylic acid esters, dimethylsulfoxide, dimethylformamide, glycol-mono- ethers or their mixtures as required 100%