DK155301B - PROCEDURE FOR THE PREPARATION OF SOLID, CORNED, HERBICIDE PREPARATIONS CONTAINING A BIPYRIDYLIUM SALT - Google Patents

Description

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DK 155301 B

The present invention relates to a process for the preparation of solid compositions of bipyridyl human herbicides.

In British Patent Nos. 785,732, 813,531 and 813,542 5 various herbicidal quaternary bipyridylium salts are disclosed. Generally, these compounds are prepared for use in agriculture in the form of concentrated aqueous solutions. When used, these concentrated solutions are diluted with water to form a solution which is then sprayed onto unwanted plants. For various reasons, e.g. for convenient packaging, it would be appropriate for bipyridyl ium herbicides to be delivered in solid form rather than as aqueous solutions. Various methods have been proposed for the preparation of solid compositions of herbicidal, quaternary bipyridyl aluminum salts, but so far none of these compositions have proved suitable for extensive industrial use in agriculture. British Patent Specification No. 813,532 discloses e.g. dust preparations comprising a mixture of a herbicide quaternary bipyridylium salt with an inert powdered diluent, e.g. talc, porcelain, plaster or basic slag. Such preparations are not convenient for the application of bipyridylium herbicides in agriculture and have not been adapted for industrial use.

British Patent Specification No. 1,086,937 discloses a process for the preparation of solid herbicidal compositions in which an aqueous solution of a herbicidal quaternary bipyridylium salt is mixed with a hydrate-forming salt in such proportions that the hydrate-forming salt is associated with a sufficient amount of it. water present to give a solid preparation. The preparations prepared in this way have been accepted in the retail market for use in gardens. However, they are not suitable for large scale use in agriculture. Thus, the amount of active ingredient is relatively low and the product does not dissolve quickly enough. Another method of preparing solid herbicidal compositions is described in Japanese Patent Application Laid-Open No. 3381/73. As a result of this process, an aqueous solution of a bipyridyl acid is absorbed.

DK 155301 B

2 umberbicide in pre-formed grains of a water-soluble salt. As is the case with the process of British Patent Specification No. 1,086,937, only compositions with relatively low concentration of active ingredient can be prepared.

5

According to the invention, there is now found a process in which it is possible to prepare a solid, granular composition containing a relatively high amount of the quaternary bipyridylium salt used as an active ingredient.

10

The invention discloses a process for the preparation of a solid, grainy, herbicidal composition containing a herbicidal, diquaternary bipyridylium salt together with a solid diluent, and the process is characterized by the characterizing part of claim 1.

The term fluidized bed is well known in the chemical art, it relates to processes in which a gas species is passed through a layer of solid particulate material at such a rate that the particles are dynamically suspended in the gas stream. The layer (i.e., the bed) of material assumes a strong turbulent state similar to a boiling liquid. In the present invention, it is preferred to use air as a gas species to fluidize the solid part into cold-formed materials. However, other gases (eg nitrogen) can be used if desired. The fluidized bed is maintained at an elevated temperature by heating the gas stream which fluidizes the bed.

The temperature of the heated gas stream is preferably in the range 30 to 100 to 250 ° C, e.g. from 120 to 150 ° C. The temperature of the fluidized beds may be from e.g. 50 to 100 ° 0. The aqueous solution of the quaternary bipyridylium salt can be introduced into the identified bed by spraying through one or more spray nozzles. The aqueous solution can itself be heated if desired, but they do not benefit therefrom. The concentration of the quaternary bipyridylium salt solution is preferably high, e.g. over 200 g per liter of quaternary bipyridylium cation, so that it water to be evaporated is reduced.

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3

Surprisingly, it is not necessary for the solid particulate diluent to be insoluble in water. The evaporation of water from the aqueous solution proceeds so rapidly that when a water-soluble diluent is used, e.g. sodium-chloride, there are no difficulties in dissolving the grains in the aqueous solution of quaternary bipyridylium salt.

Thus, while theoretically both water-soluble and water-insoluble diluents can be used, diluents which are freely water-soluble are used according to the invention, so that when the solid composition of the invention is to be used to kill unwanted plants, it can be completely and quickly dissolved in water to form a syringe solution. The inorganic salt is essentially free of crystallization water, as hydrate in serified salts can decrepitate when placed in the heated air stream. Salts which react as alkalis in aqueous solution, e.g. salts having a pH of more than approx. 8, when dissolved in water (e.g. sodium carbonate), are not used as solid diluents of the invention because of the detrimental effects they may have on the active ingredients of the agent, since quaternary bipyridylium salts are less stable in solutions with high pH.

The rate of air flow required to fluidize the solid particulate diluent depends on various factors, e.g. of the particle size of the diluent and of its density. A suitable speed is readily ascertained in carrying out the process, the fluidized bed technology being well known to those skilled in the art, but as an example, a linear air velocity of 0.9 to 1.1 m / sec. has proved suitable for holding a bed of sodium chloride 30 in fluidized state.

Herbicidal, quaternary bipyridylium salts which can be used as active ingredients in the compositions of the invention include those of the following formulas 35 l J 0 0 '' η 2 [[Γ Γ Γ CK31 [χΓ_ + nch2ch2 +

DK 155301 B

Wherein R and R, which may be the same or different, are each an alkyl or alkenyl radical of 1-4 carbon atoms which may be substituted by a hydroxy, carboxy, alkoxy, alkylcarbonyl, alkoxycarbonyl, carbamoyl - or R-alkyl-substituted carbamoyl radical or a halogen atom, [x] n 'represents an anion and n is 1, 2, 5 or 4. Preferred alkoxy groups are those containing 1-4 carbon atoms. Preferred alkylcarbonyl and alkoxycarbonyl groups are those containing from 2 to 5 carbon atoms. Preferred R-alkyl-substituted carbamoyl radicals are those wherein the R-alkyl substituent or substituents 10 contain from 1 to 4 carbon atoms.

Examples of herbicidal diquaternary bipyridylium salts include those listed below: 1,1'-ethylene-2,2 * -bipyridylium dibromide (diquat dibromide) 1,1'-dimethyl-4,4'-bipyridylium dichloride (paraquat dichloride) 1 1,1-di-2-hydroxyethyl-4,4'-bipyridylium dichloride 1,1'-bis-3,5-dimethylmorpholinocarbonylmethyl-4,4'-bipyridylium di = chloride (morphamquat dichloride) 1- (2-hydroxyethyl) -1 * -methyl-4,41-bipyridylium dichloride 1,1 * -dicarbamoylmethyl-4,4'-bipyridylium dichloride 1,1'-bis-R, R-dimethylcarbamoylmethyl-4,4'-bipyridylium dichloride 1,1'-bis -R, R-diethylcarbamoylmethyl-4,4'-bipyridylium dichloride 1,1-di- (piperidinocarbonylmethyl) -4,4'-bipyridylium dichloride 1,1'-diacetonyl-4,4'-bipyridylium dichloride 1,1'-diethoxycarbonylmethyl-4 , 4'-bipyridylium dibromide 1,1 »-diallyl-41-bipyridylium dibromide.

The rows in parentheses of some of the compounds in the above list are accepted common names for the cationic portion of the compounds. Thus, "paraquat" is the common name for the 1,1'-dimethyl-4,4'-35 bipyridylium cation. Paraquat is a particularly preferred bipyridylium compound for use in the compositions of the invention.

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5

Since the herbicidal action of a quaternary bipyridylium ion is independent of the nature of the associated anion, the choice of anion is a matter of convenience, e.g. depends on the price. Preferably, the anion is one which provides a salt of appropriate water solubility. Examples of anions that may be monovalent or polyhydric include acetate, benzenesulfonate, benzoate, bromide, butyrate, chloride, citrate, fluorosilicate, fumarate, fluoroborate, iodide, lactate, malate, maleinate, methyl sulfate, nitrate, propionate. phosphate, salicylate, succinate, sulfate, thiocyanate, tartrate and p-toluenesulfonate. The salt of the herbicidal 10 bipyridylium cation can be formed by a number of similar anions or mixtures of different. A salt having a given desired anion can be prepared either by direct synthesis of the reaction participants containing the desired anion, or by exchanging the anion in a previously prepared salt with the preferred anion in ways well known in the art. eg. by passing a solution of the previously prepared salt through an ion exchange resin. For convenience and economic reasons, the chloride anion is a particularly preferred anion.

Since the characteristic herbicidal activity of a salt of a herbicide, 20 quaternary bipyridylium cation lies in the cation alone, it is common to mention the concentrations of active ingredient and the amounts of application expressed in the amount of quaternary bipyridylium cation used, so as to avoid the inconvenience of mentioning various application rates for different salts of the same quaternary bipyridium cation. Application rates and concentrations mentioned in the present disclosure therefore relate to the amount of quaternary bipyridylium cation, unless otherwise stated.

In carrying out the process of the invention, it is preferred, as mentioned above, to use an aqueous solution containing a high concentration of quaternary bipyridylium cation, e.g. at least 200 g per liter. Concentrations as high as 360 g / ml liter can be conveniently used. The product of the process may also contain a relatively high amount of the bipyridylium cat = 35 ion used as active ingredient. Eg. concentrations of 20 wt.% of the bipyridylium cation are readily obtained and also higher concentrations, e.g. up to $ 28 weight or more, can be conveniently manufactured. Preferably, the product contains at least 10 wt.% Bipyridylium cation.

DK 155301 B

6

The process of the invention can be operated either portionwise or as a continuous process.

The time taken to complete the manufacture of the product depends on e.g. of the temperature and velocity of the heated air stream.

By way of example, in a typical batch preparation, 5 kg of sodium chloride fluidized in an air stream at a velocity of 60 m / min and a temperature of 130 ° C on the inlet side of the fluid ice is bed. A solution of paraquat dichloride (6 liters, 360 g 10 paraquat per liter) was injected into the fluidized bed through a nozzle for a period of 1 hour. The product collected after this time was a non-dusting, free-flowing, grainy solid containing $ 27 weight paraquat and it was free of moisture. The average particle size of the grains was in the range 1 to 2 15 mm and the bulk weight was 0.88 g / ml.

If desired, other ingredients can be incorporated into the composition of the invention, e.g. surfactants. This can be done in different ways. E.eks. For example, a surfactant may be incorporated into the aqueous solution of bipyridylium salt introduced into the fluidized bed. Alternatively, the bipyridylium solution and the surfactant solution may be introduced separately from each other in the fluidized bed. The amount of surfactant used may be e.g. from 10 to 20% by weight of the amount of bipyridyl = 25 µm cation in the composition, but greater or lesser amounts may be appropriate depending on the intended use of the product.

Preferably, the surfactant used is a cationic or nonionic surfactant. The choice of a suitable surfactant is within the skill of the art. By way of example, however, it may be mentioned that nonionic surfactants useful in the compositions of the invention include the condensation products of ethylene oxide with fatty alcohols, such as oleyl alcohol and cetyl alcohol, or with alkyl phenols such as octylphenyl, nonylphenol and octylresol. Other nonionic agents are the partial esters derived from long chain fatty acids and hexanite anhydrides, e.g. sorbitan monolaurate, the condensation products of these partial esters with ethylene oxide and the lecithins. Examples of cationic surfactants 7

DK 155301 B

agents include quaternary salts and ethylene oxide condensates with amines, e.g. the substances sold under the trademarks "Ethome" Ethoduomeen "," Duoquad "and" Arquad ".

The process of the invention can be carried out in a conventional fluidized bed reaction apparatus. The fluidized bed technology is well known to those skilled in the art. The reactor itself comprises a generally tubular or cylindrical container disposed with its long axis vertical and having a perforated plate closing the lower end. The solid particulate material to be fluidized is filled into the real tower and rests on the perforated plate. The gas used to fluidize the material is forced through the perforated plate under pressure and goes upward through the material. It is preferred to maintain the pressure below the perforated plate in the direction of flow, slightly below the atmospheric pressure outside the apparatus, e.g. by means of a fan arranged to extract the outflow air from the reactor. In this way, the avoidance of fine particles from the a is prevented if a leakage develops in its walls. In the process of the invention, it is preferred to pass the effluent air from the reactor through an apparatus (e.g., a cyclone) to collect fine dusty particles that are too small to become the fluidized bed and are flushed through the reactor of air flow but. As mentioned above, the aqueous solution of the bipyridylium salt can be introduced into the fluidized bed by spraying through one or 25 or more nozzles. These can, e.g. be mounted in the wall of the fluidised bed reactor or in the center of the perforated plate.

Conveniently, the solution may be pumped through a metering pump to enable measurement and regulation of the amount introduced.

30

The apparatus is shown schematically in block diagram in the drawing.

The following example illustrates the invention.

35 8

DK 15530i B

Example

The process of the invention was carried out using grainy calcium chloride and sodium chloride as solid particulate ε diluents. The bipyridylium salt used was paraquat dichloride at a concentration of 360 g paraquat per liter. In the sodium chloride test, a surfactant comprising a condensate of from 7 to 8 molar amounts of ethylene oxide with p-nonylphenol and marketed under the trademark "Lissapol11 EX was mixed with the solution 10 of paraquat dichloride in 4 parts paraquat to 1 part" Lissapol The products from the two experiments were uniform, free-flowing, non-dusting grains with an average particle size in the range of 1 to 2 mm. The operating conditions are summarized in Table 1.

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Try Thinning Time Temperature Average Air Speed No. Mean (Min.) In Bearing ° C Bearing Temperature np / sec.

20 1 Calcium = 85 130 93 1.1 Chloride 2 Eetrium = 70 130 86 1.0 Ehloride 25

The analysis and yield of the product are listed in Table 2.

30 35 9

DK 15530 1 B

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Claims (7)

A process for preparing a solid, granular, herbicidal composition containing a herbicidal, diquaternary bipyridylium salt together with a solid diluent, characterized in that an aqueous solution of a herbicidal diquaternary bipyridylium salt optionally containing a surfactant , is introduced into a fluid bed of 10 particles of a solid diluent consisting of a water-soluble inorganic salt which is substantially free of crystal water and having a pH of not more than 8 when dissolved in water, which fluidized bed of the solid diluent particles are kept at an elevated temperature whereby the solution of the bipyridylium salt rapidly evaporates and deposits the bipyridylium salt and any surfactant on the solid diluent particles and the solid granular preparation thus obtained is collected. 2 0 Process according to claim 1, characterized in that the fluidized bed is maintained at a temperature of 50-100 ° C. Process according to claims 1 and 2, characterized in that the herbicidal diquaternary bipyridylium salt is a compound of the formula: -O-O Η ΙΧΓ or Q-Q ® [X] n_ + \ / + Wherein R and R, which may be the same or different, are each an alkyl or alkenyl radical of up to 4 carbon atoms, optionally substituted with a hydroxy, carboxy, alkoxy, alkylcarbonyl, alkoxycarbonyl, carbamoyl - or N-substituted carbamoyl radical or a halogen atom, X is an anion and n is 1, 2, 3 or 4. DK 155301 B Process according to one of the preceding claims, characterized in that the herbicidal diquaternary bipyridylium salt is paraquat dichloride or paraquatdi (methyl sulfate). Process according to one of the preceding claims, characterized in that the solid diluent is an inorganic salt. Process according to claim 5, characterized in that the solid diluent is sodium chloride or calcium chloride. A solid, grainy, herbicide preparation prepared by a method according to any one of the preceding claims. 15 20 25 30 35