GB1574600A

GB1574600A - Herbicidal compositions

Info

Publication number: GB1574600A
Application number: GB1114476A
Authority: GB
Original assignee: Imperial Chemical Industries Ltd
Current assignee: Imperial Chemical Industries Ltd
Priority date: 1976-03-19
Filing date: 1976-03-19
Publication date: 1980-09-10
Also published as: JPS6135964B2; JPS52114021A; IT1075577B; AU505086B2; FR2344225A1; DE2712032A1; FR2344225B1; DE2712032C2; AU2311477A

Description

(54) IMPROVED HERBICIDAL COMPOSITIONS (71) We, IMPERIAL CHEMICAL INDUSTRIES LIMITED, Imperial Chemical House, Millbank, London SWIP 3JF, a British Company, 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 concentrated herbicidal compositions containing a herbicidal bipyridylium quaternary salt as an active ingredient.

Over the years, a large range of pesticides has been developed for agricultural use in the control of fungal and insect pests and weeds. While these substances are necessarily toxic to certain forms of life, when used with due care and in accordance with governmentally approved codes of practice, they present no hazard to human life. However, in spite of efforts to encourage those concerned with pesticides to adopt safe handling practices, instances of misuse of pesticides do occur. One particular unsafe practice in the case of liquid pesticides is for an operator to transfer a small amount of the concentrated pesticide to a domestic container such as a beverage bottle for subsequent use at home.

The risk attached to these practices is of course that a child or incautious adult coming upon the bottle may swallow the contents with possibly serious consequences.

U.K. Patent Specfication No. 1,406,881 discloses herbicidal compositions comprising an aqueous solution of a salt of a herbicidal bipyridylium quaternary cation and an odorant comprising the substance pyridine base which comprises a mixture of alkyl pyridines. The unpleasant smell of the odorant acts as a warning that the composition is not a beverage; with the consequential reduction in the likelihood of accidental swallowing of these herbicides in the circumstances described above.

Our copending U.K. Patent Application No. 2174/76 (Serial No. 1,570,981) discloses aqueous herbicidal compositions comprising a salt of a herbicidal bipyridylium quaternary cation and an alkyl carboxylic acid as an odorant.

The choice of an odorant for admixture with bipyridylium quaternary cation herbicides is greatly restricted by the exacting technical requirements which such an odorant must meet. For example, the odorant must be sufficiently soluble in concentrated bipyridylium solutions, it must be physically and chemically compatible with the bipyridylium cation, it must have sufficient stability on storage for long periods and it must possess an odour not to be confused with the characteristic odour of other commercial products.

The use of the substance pyridine base referred to hereinabove imposes a burden on the manufacturer since the composition of the pyridine base varies according to its source and it is necessary to monitor the composition to check that it meets with the appropriate standard. An odorant material available in substantially pure form would therefore be advantageous.

The use of an alkyl, carboxylic acid as an odorant, referred to above, is limited to use in aqueous solutions having a pH not greater than 5, due to a decrease in the odour of the composition on storage.

We have now discovered that a bipyridylium composition having satisfactory deterrent properties can be obtained.

According to the present invention, there is provided a concentrated herbicidal composition comprising an aqueous solution of a salt of a herbicidal bipyridylium quaternary cation and an odorant comprising tetrahydrothiophen (I).

The unpleasant smell of the odorant acts as a warning that the composition is not a beverage.

Preferably the composition also comprises a surface-active agent. The herbicidal bipyridylium quaternary salts for use in the compositions of the invention are those of the following formulae:-

wherein R and Rt, are selected independently from the group consisting of alkyl radicals of from 1. to 4 carbon atoms and alkyl radicals of 1 to 4 carbon atoms substituted by a radical selected from the group consisting of hydroxyl, halogen, carboxyl, lower alkoxy, lower alkyl carbonyl, lower alkoxycarbonyl, vinyl, carbamoyl or N - lower alkyl substituted carbanoyl; [X]"- represents an anion and n is an integer from 1 to 4 inclusive. By lower alkoxy, alkoxycarbamoyl, alkylcarbonyl, or alkyl, is meant radicals containing an alkyl group of 1 to 4 carbon atoms; this definition also applies in the claims at the end of this specification.

Particularly preferred herbicidal bipyridylium quaternary salts are those listed below: 1,1 - dimethyl - 4,4' - bipyridylium di (methylsulphate) (paraquat methosulphate) I,I' - ethylene - 2,2' - bipyridylium dibromide (diquat dibromide) 1,1' - dimethyl - 4,4' - bipyridylium dichloride (paraquat dichloride) 1,1' - di - 2 - hydroxyethyl - 4,4' bipyridylium dichloride - (2 - hydroxyethyl) - 1' - methyl 4,4' - bipyridylium dichloride 1,1' - di - carbamoylmethyl - 4,4' bipyridylium dichloride 1,1' - bis - N,N - dimethylcarbamoyl methyl - 4,4' - bipyridylium dichloride 1,1' - dimethyl - 4,4' - bipyridylium sulphate (paraquat sulphate) 1,1' - bis - N,N - diethylcarbamoyl methyl - 4,4' - bipyridylium dichloride 1,1' - diacetonyl - 4,4' - bipyridylium dichloride 1,1' - diethoxycarbonylmethyl - 4,4' bipyridylium dibromide I, I ' - diallyl - 4,4' - bipyridylium dibromide The names in brackets alongside some of the compounds in the above list are the accepted common names for the cationic portion of these compounds. Thus 'paraquat' is the common name for the 1.1' - dimethyl - 4,4' - bipyridylium cation.

Paraquat is a particularly preferred bipyridylium cation for use in the compositions of the invention.

Since the herbicidal effect of a bipyridylium quaternary cation is independent of the nature of the associated anion, the choice of the anion is a matter of convenience, depending, for example, on cost. Preferably the anion is one which gives rise to a salt of convenient water solubility.

Examples of anions, which may be mono- or polyvalent, include acetate, benzenesulphonate, benzoate, bromate, bromide, butyrate, chlorate, chloride, citrate, formate, fluorosilicate, fumarate, fluoroborate, iodide, lactate, malate, maleate, methylsulphate, nitrate, propionate, phosphate, salicylate, sulphamate, succinate, sulphate, thiocyanate, tartrate, and p toluenesulphonate. The salt of the herbicidal bipyridylium cation may be formed from a number of similar anions or mixtures of different ones. A salt having any particular desired anion may be prepared either by direct synethesis from reactants which include the desired anion, or by exchanging the anion of a previously prepared salt for the preferred anion by methods well knows in the art, for example by passage of a solution of the previously prepared salt through an ion-exchange resin. For reasons of convenience and economy, the chloride anion is a particularly preferred anion.

Since the characteristic herbicidal activity of a salt of a herbicidal bipyridylium quaternary cation resides in the cation only, it is customary to quote concentrations of active ingredient and rates of application in terms of the amount of bipyridylium quaternary cation used, thus avoiding the inconvenience of having to quote different application rates for different salts of the same bipyridylium quaternary cation.

Application rates and concentrations quoted in this specification therefore relate to the amount of herbicidal bipyridylium quaternary cation unless otherwise stated.

The amount of herbicidal bipyridylium quaternary cation present in the compositions of the invention is preferably from 0.5 to 3.0 pounds per Imperial gallon (50 grams to 300 grams per litre) and more preferably from 1.0 to 2.5 pounds per Imperial gallon (100 to 250 grams per litre).

Surface active agents may be cationic, non-ionic or anionic. Generally speaking cationic and non-ionic surface-active agents are preferred to anionic surface active agents for use in the compositions of the invention, since the latter may interact undesirably with the bipyridylium quaternary salt in the composition.

Examples of non-ionic surface-active agents for use in the compositions of the invention include the condensation products of ethylene oxide with alkyl phenols such as octylphenol, nonylphenol and octylcresol.

Other non-ionic agents are the partial esters derived from long chain fatty acids and hexitol anhydrides, for example sorbitan monolaurate; the condensation products of salts and condensates of ethylene oxide and the lecithins. Examples of cationic surface-active agents incude quaternary salts and condenstates of ethylene oxide with amines, for example the substances sold under the Trade Marks "Ethomeen", "Ethoduomeen", "Duoquad" and "Arquad".

Particularly preferred surface-active agents are the combinations of surfaceactive agents described in U.K. Patent No.

998,264 for use in formulations of herbicidal bipyridylium quaternary salts.

The amount of surface-active agent present in the composition is preferably from 20 to 100 grams per litre of the composition.

The choice of an odorant for an aqueous composition comprising a herbicidal bipyridylium salt is by no means a simple matter. For reasons of economy in transport and storage it is desirable for the compositions to be sold in the form of a concentrate, which may be diluted with water as required to form a solution of suitable strength for application. Such concentrates may contain for example from 5% to 20% by weight of herbicidal bipyridylium quaternary cation. Many substances are not miscible with or soluble in solutions of bipyridylium salts of this concentration with the result that the excess of odorant floats on the surface of the concentrate. This results in uneven distribution of the odorant when the concentrate is re-packed into small containers from bulk. Insoluble substances are therefore unsuitable as odorants.

Furthermore, the odorant must not react chemically with the active ingredient, or otherwise impair the herbicidal properties of the latter. Since many months may elapse between the formulation of the herbicidal concentrate and its use, it is essential for the odorant not to deteriorate on storage.

Compositions according to the invention in storage tests have been found to maintain their repulsive smell.

Compositions according to the invention preferably contain from 0.1% to 5% by weight of the tetrahydrothiophen used as the odorant. Preferably the amount of tetrahydrothiophen used is from 0.1 -' to 1% by weight.

The formulations of our invention are corrosive. They must be handled with care, to avoid splashing of the eyes or skin, and they should not be allowed to come into contact with corrodable metals prior to dilution.

The compositions according to the invention may also comprise coloured dyestuff compounds to give them a characteristic or distinguishing colour.

Examples of such dyestuffs for use in the practice of the invention are "Monastral Blue BNV Paste" and "Lissamine Turquoise VN 150".

If desired, the tetrahydrothiophen may be incorporated in the formulations of herbicidal bipyridylium quaternary salts described in our British Patent Specification No. 1,395,502. These formulations comprise an aqueous solution of a herbicidal bipyridylium quaternary salt containing a gelling agent, for example finely divided silica, or a combination of the xanthan gum sold under the Trade Mark "Kelzan" with sodium metaborate. Xanthan gum is a complex polysaccharide.

The inclusion of the odorant in compositions according to the invention has no adverse effect upon the herbicidal activity of the compositions. The invention is illustrated by the following Examples.

EXAMPLE 1 This Example illustrates a composition according to the invention which comprises tetrahydrothiophen as odorant in aqueous solution. The composition comprises the following ingredients.

Ingredients % w/v Paraquat concentrate x Sodium metaborate 1.3 Sodium benzoate 2.0 Lissapol NX 1.1 DS 4392 4.1 Silcolapse M5000 0.06 Tetrahydrothiophen 0.1 Water to 100 ml (where x gives 200+5 g/litre paraquat ion) Paraquat concentrate is a solution of paraquat dichloride containing 25 /" to 30% by weight of 1,1' - dimethyl - 4,4' bipyridylium cation. The amount used was chosen to give a composition containing 20% weight/volume of paraquat cation.

"Lissapol" NX is a Trade Mark for a surface-active agent comprising a condensate of from 7 to 8 molar proportions of ethylene oxide with I molar proportion of p - nonylphenol.

DS 4392. This is a code number for a surface-active agent comprising a mixture of amines derived from soya bean fatty acids condensed with approximately 15 molar proportions of ethylene oxide.

'Silcolapse" is a Trade Mark for an anti foaming agent comprising a silicone derivative.

The composition described above was prepared by simple agitation of the ingredients together.

EXAMPLE 2 This Example illustrates a composition according to the invention which comprises a gelling agent in addition to the terahydro thiophen added as odorant. The composition comprises the following ingredients.

Amount Ingredients in Grams Paraquat concentrate x "Kelzan" 0.4 (added as 1% solution in water) Sodium metaborate 0.014 Lissapol NX 1.1 DS 4392 4.1 Tetrahydrothiophen 0.1 Silcolapse 5000 0.01 Water to 100 ml (where x gives 200+5 g/litre paraquat ion) The composition described above was prepared by simple agitation of the ingredients together and was sufficiently fluid when prepared to be poured into containers. On standing for 15 to 20 minutes the composition formed a gel and was not pourable unless vigorously shaken.

WHAT WE CLAIM IS: 1. A concentrated herbicidal composition, comprising an aqueous solution of a salt of a herbicidal bipyridylium quaternary cation selected from the group consisting of compounds of the formula:-

wherein R and R' are selected independently from the group consisting of alkyl radicals of from I to 4 carbon atoms and alkyl radicals of from 1 to 4 carbon atoms substituted by a radical selected from the group consisting of hydroxy, halogen.

carboxyl, lower alkoxy, lower alkylcarbonyl, lower alkoxycarbonyl, vinyl, carbamoyl and N-lower alkyl substituted carbamoyl; [X]n- represents an anion and n. is an integer of from 1 to 4 inclusive; together with an odorant comprising tetrahydrothiophen.

2. A composition as claimed in Claim 1 in which the salt of the herbicidal bipyridylium quaternary cation is 1,1 - dimethyl - 4,4 bipyridylium di(methylsulphate).

3. A composition as claimed in Claim 1 in which the salt of the herbicidal bipyridylium quaternary cation is 1,1' - ethylene - 2,2' bipyridylium dibromide.

4. A composition as claimed in Claim 1 in which the salt of the herbicidal bipyridylium quaternary cation is 1,1' - dimethyl - 4,4' bipyridylium dichloride.

5. A composition as claimed in Claim 1 in which the salt of the herbicidal bipyridylium quaternary cation is 1,1' - dimethyl - 4,4' bipyridylium sulphate.

6. A composition as claimed in any one of the preceding claims which further comprises a surface-active agent.

7. A composition as claimed in any one of the preceding claims in which the odorant is present in the proportion of from 0.1% to 5% by weight of the composition.

8. A composition as claimed in any one of the preceding claims in which the amount of herbicidal bipyridylium cation present is 50 to 300 grams per litre.

9. A composition as claimed in any one of the preceding claims which further comprises a gel forming amount of a gelling agent.

10. A composition as claimed in Claim 8 in which the gelling agent comprises a combination of Xanthan gum with a borate salt.

11. A composition as claimed in any one of the preceding claims which further comprises a coloured dyestuff or pigment compound.

12. Herbicidal compositions substantially as hereinbefore described with reference to the Examples.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. The composition described above was prepared by simple agitation of the ingredients together. EXAMPLE 2 This Example illustrates a composition according to the invention which comprises a gelling agent in addition to the terahydro thiophen added as odorant. The composition comprises the following ingredients. Amount Ingredients in Grams Paraquat concentrate x "Kelzan" 0.4 (added as 1% solution in water) Sodium metaborate 0.014 Lissapol NX 1.1 DS 4392 4.1 Tetrahydrothiophen 0.1 Silcolapse 5000 0.01 Water to 100 ml (where x gives 200+5 g/litre paraquat ion) The composition described above was prepared by simple agitation of the ingredients together and was sufficiently fluid when prepared to be poured into containers. On standing for 15 to 20 minutes the composition formed a gel and was not pourable unless vigorously shaken. WHAT WE CLAIM IS:

1. A concentrated herbicidal composition, comprising an aqueous solution of a salt of a herbicidal bipyridylium quaternary cation selected from the group consisting of compounds of the formula:-