KR20000022046A - Process for the production of alkaline metal salts and earth alkali metal salts of aryloxy-c1-c4-alkane carboxylic acids - Google Patents

Abstract

PURPOSE: A process for preparation alkaline metal salts and earth alkali metal salts of aryloxy-C1-C4-alkane carboxyl acids is provided to prevent the extrudates from agglomerating or deliquescing and hinder the fluidity of them from continuously dropping. CONSTITUTION: Alkaline metal salts and earth alkali metal salts of aryloxy-C1-C4-alkanecarboxyl acids are prepared by reacting the basic aryloxy-C1-C4-alkane carboxyl acids with alkaline metal bases or earth alkalimetal bases in the melt, by extruding a mixture of the aryloxy-C1-C4-alkane carboxyl acid and an at least stoichiometric quantity of an alkaline metal base or an earth alkali metal base, which are partially or completely converted in the reaction conditions into volatile substances. The extrudates containing an aryloxy-C1-C4-alkane carboxyl acid with herbicidal action are used for restraining undesired plant growth.

Description

Method for producing alkali metal salts and alkaline earth metal salts of aryloxy-C1-C4-alkanecarboxylic acids

The invention aryloxy -C ₁ -C ₄ - alkali metal salt of an alkane carboxylic acid and an alkaline earth metal salt-alkane-carboxylic acid by reacting an alkali metal salt or alkaline earth metal base with the melt aryloxy -C ₁ -C ₄ It relates to a manufacturing method.

The present invention also relates to salts obtained by this method, and to the undesirable use of plant growth inhibition of such salts containing herbicidal crop protection activity, such as aryloxy-C ₁ -C ₄ -alkancarboxylic acids.

German patent application P 44 46 387.1 describes a process for the preparation of solid, free-flowing, water-soluble salts of aryloxy-C ₁ -C ₄ -alkanecarboxylic acids, in which the carboxylic acid is reacted with a salt forming base as a melt.

EP-A 238 240 describes a process for continuously reacting an acidic form of a crop protection active compound with Brünsted base in an extruder to obtain a salt of the active compound. Suitable bases are alkali metal hydroxides, alkaline earth metal hydroxides, ammonia and amines.

However, products made by these known methods tend to absorb moisture from the surrounding air, forming lumps and / or deliquescent. Indeed, this leads to the problem that the quality, in particular the flowability of this product, decreases continuously in open containers.

It is therefore an object of the present invention to provide a process for the preparation of alkali and alkaline earth metal salts of aryloxy-C ₁ -C ₄ -alkanecarboxylic acids which can make products without these disadvantageous properties.

We aim to extrude a mixture of aryloxy-C ₁ -C ₄ -alkanecarboxylic acids and stoichiometric amounts of alkali metal bases or alkaline earth metal bases, which are partially or fully converted to volatile materials under reaction conditions. that, aryloxy -C ₁ -C ₄ includes-alkane carboxylic standing by reacting the acid with an alkali metal base or an alkaline earth metal base with the melt aryloxy -C ₁ -C ₄ - alkane carboxylic acid of an alkali metal or alkaline earth It has been found that this is achieved by the method for preparing metal salts.

In addition, the inventors have found the use of inhibiting the plant growth of salts obtainable by this method and those salts containing herbicidal crop protection activity such as aryloxy-C ₁ -C ₄ -alkancarboxylic acids.

Suitable aryloxy-C ₁ -C ₄ -carboxylic acids preferably have activity against undesirable plant growth (IUPAC name and common name are described in ["The Pesticide Manual", The British Crop Protection Council, 9th edition, London). , 1991), for example: (RS) -2- (2,4-dichlorophenoxy) propionic acid (dichlorprop), R-2- (2,4-dichlorophenoxy) Propionic acid (dichlorprop-P, D-2,4-DP), 2,4-dichlorophenoxyacetic acid (2,4-D), 4- (2,4-dichlorophenoxy) butyric acid (2,4 -DB), 4- (4-chloro-o-tolyloxy) acetic acid (MCPA), 4- (4-chloro-o-tolyloxy) butyric acid (MCPB) and (R) -2- (4-chloro-o -Tolyloxy) propionic acid (mecoprop-P, D-CMPP).

D-2,4-DP, MCPA and especially D-CMPP can preferably be reacted by the process according to the invention to give an extrudate of its alkali metal or alkaline earth metal salts.

Particularly advantageous handling is exhibited by granules prepared from hygroscopic aryloxy-C ₁ -C ₄ -alkanecarboxylic acids, for example mecoprop-P, by the process according to the invention.

Mixtures of two or three aryloxy-C ₁ -C ₄ -carboxylic acids can be used, for example: dichlorprop-P and 2,4-D; Dichlorprop-P and MCPA; Mecoprop-P and 2,4-D; Mecoprop-P and MCPA; MCPA and 2,4-D; Mecoprop-P, dichlorprop-P and MCPA.

It is also possible to use racemates thereof in place of optically active aryloxy-C ₁ -C ₄ -carboxylic acids.

It is also possible to mix aryloxy-C ₁ -C ₄ -carboxylic acids with other herbicides: ventazone and 2,4-D; Ventazone and dichlorprop-P; Ventazone and mecoprop-P; Ventazone and MCPA; Ventazone and MCPB; Ventazone, MCPB and MCPA; Ventazone and 2,4-DB; Ventazone and MCPA.

Preferred alkali metal bases and alkaline earth metal bases which are partially or completely converted under the reaction conditions to volatiles are acetates which give acetic acid during the reaction of alkaline earth metals and especially alkali metals, formate to give formic acid and in particular carbonates and hydrogencarbonates ( Formation of carbon dioxide), for example sodium acetate, potassium acetate, sodium formate, potassium formate, preferably sodium carbonate, sodium bicarbonate and potassium hydrogen carbonate, very particularly preferably potassium carbonate.

Mixtures of the foregoing alkali metal bases and alkaline earth metal bases are also suitable.

The base according to the invention is at least in stoichiometric amount, preferably in excess and in particular in excess of 1 to 40 mol% and very particularly preferably from 2 to 30 mol, based on aryloxy-C ₁ -C ₄ -carboxylic acids. Used in excess of%.

Excessive use of the base according to the invention generally produces oily products of varying concentrations, but with stoichiometric amounts of the base according to the invention and very particularly in excess, it is well poured and has storage stability and at the same time in water A product of granular structure with good solubility and dissolution rate is obtained.

Volatile substances contained in the starting material and / or formed in the reaction, such as water, carbon dioxide, acetic acid, etc., are generally volatilized from the product during the reaction or further after the reaction if the product remains in the extruder at a sufficiently high temperature.

The reaction in the extruder can be carried out in the presence of a trapping agent to assist the evaporation of water upon evaporation.

Suitable trapping agents are cyclohexane, toluene and petroleum ether. Low molecular weight alcohols are preferred, in particular C ₁ -C ₇ -alkanols and C ₁ -C ₇ -alkanediols. Very particular preference is given to primary, secondary and tertiary alcohols, for example methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, tert-butanol, pentanol, hexanol, heptanol and mixtures thereof.

In a preferred embodiment of the process according to the invention, the molten aryloxy-C ₁ -C ₄ -alkanecarboxylic acid is prepared by mixing thoroughly with the solid base according to the invention in an extruder.

In a further preferred embodiment of the process according to the invention, solid aryl-C ₁ -C ₄ -alkanecarboxylic acid is added to the extruder to melt and react with the solid base according to the invention.

Bases according to the invention can also be used dissolved or suspended in a collecting agent.

The solid starting material may be prepared by the solid itself or as a paste or dissolved or suspended in a solvent and fed to the extruder. The solvent is chosen such that its volatility is maximized during the production of the extrudate according to the invention. Preferably the solvent used is one or more of the foregoing collectors.

Depending on the physical properties, all starting materials can be premixed early before the reaction. For example, premixes of liquid and solid products have the advantage that the solid material is prewet. Advantageous fluidity in the case of starting materials is generally attributable to this.

If fluidity problems occur during premixing, flow aids or antiblocking agents can be used, such as calcium carbonate, tricalcium phosphate, colloidal silica gel and talc.

Mechanical aids such as vibrators and stirrers can be used in addition to the handling of the premix.

The nature of the extruder in the process according to the invention is not critical. Single-screw, counter- and co-rotating, mesh screw and multi-shaft extruders are suitable. Such machines are familiar to those skilled in the art and thus require no further explanation (see eg EP-A-238 240).

Preferred extruders for the process according to the invention are co-rotating, meshed twin-screws.

In the case of hygroscopic or reactive starting materials and / or products the extruder is deactivated with nitrogen or carbon dioxide prior to the reaction.

The reaction is often completed after less than 3 minutes of residual time of the reaction mixture in the reaction zone of the extruder.

The reaction in the extruder and the subsequent drying of the extrudate can be carried out at ordinary pressure or at elevated or reduced pressure and at 0 to 250 ° C, in particular at 80 to 150 ° C.

Depending on the reaction temperature process, the product during the reaction in the extruder is obtained in the form of particles or plastic masses which can be formed by methods known per se.

The procedure is preferably obtained using particles with an average diameter of 0.1 to 5, preferably 0.1 to 3 cm.

If the extrudate still has volatiles, the volatiles can be removed from the extrudate according to the invention by conventional (dry) methods.

The extrudate produced by the process according to the invention is based on herbicidal crop protection active compounds of the aryloxy-C ₁ -C ₄ -carboxylic acid compound class and is used for the inhibition of undesirable plant growth.

To this end, this extrudate is usually dissolved in water or suspended in water and the spray mixture thus obtained is allowed to act on the crop, its habitat and / or its seeds using methods known per se. The preparation and application of this type of spray mixture on the other hand is known to the person skilled in the art (see German patent application P 44 46 387.1) and no further explanation is necessary.

The process according to the invention is particularly suitable for the preparation of relatively large particles of aryloxy-C ₁ -C ₄ -alkanecarboxylic acids.

<Production example>

In the following, "D + L" refers to the content of the D- + L- isomer of a specific compound as a whole. "D: L" represents the ratio of these isomers.

For the production of extrudates a co-rotating mesh twin-screw machine (ZSK 30 from Werner & Pfleiderer, Stuttgart, Germany) is used, which consists of eight separate heating or cooling chambered areas. It is. In the following, the zones are denoted as "zone 1", "zone 2" and the like as if the starting material entered zone 1 and exit zone 8. Zone 1 was cooled with water (temperature of water flowing out: 38 ° C.). Zone 2 was operated at 80 ° C. and zones 3 and 4 at 138 ° C. for the entire experimental period. Zone 4 also leaves the top open so that volatiles and vapors formed in the reaction can escape in the form of gases. Zones 5, 6, 7 and 8 are 28 (zones 5), 21 (zones 6), 21 (zones 7) and 20 ° C (zone 8) which flow out to cool with water.

The active compound content of the product is independent of the amount of base and the residual moisture content, in particular the quality of the aryl-C ₁ -C ₄ -alkanecarboxylic acids used.

<Example 1>

Preparation of calcium salt of D-4-chloro-2-methylphenoxypropionic acid (D-CMPP, Mecoprop-P)

532 parts (3.855 moles) of potassium carbonate and 1380 parts of D-4-chloro-2-methylphenoxypropionic acid (D-CMPP, mecoprop-P; D + L = 97.6% by weight, D: L = 94.7: 5.3) (6.434 moles) was put into the belt wagon with a screw in zone 1 of the extruder every hour at a rotation speed of 36 rpm. The extruder was run for 40 hours to yield 69 kg of D-CMPP potassium salt. D-CMPP was completely reacted in this apparatus to obtain potassium salt. The product could be characterized as follows:

Active compound content D + L = 75.3 wt%

Enantiomer ratio D: L = 94.8: 5.2

Moisture content = 2.3% by weight

The extrudate of the potassium salt of D-CMPP containing 71.3% by weight of the active compound obtained by the corresponding process consists of granules which are easily soluble in coarse granular water, further characterized as follows:

The bulk weight after tamping (method CIPAC MT 169) was 614 g / l. Moisture content was 2.6 wt%. The particle size of the water soluble granules was 0.25 cm to 2 cm. The product was almost dust free. Water is added at 20 ° C. to ensure complete wetting immediately. The product was dissolved completely in water with stirring within 2 minutes to give a solution which was 1% by weight of the active compound (method CIPAC MT 174).

Water soluble granules were ground in a mortar to make a comparative sample and screened portions of less than 0.02 mm were used for testing after screening.

10 g of product was weighed and placed in a petri dish 10 cm in diameter. This sample and the comparative sample (powder) were exposed to air of 86-96% relative humidity in the chamber. The measurement temperature was 20 ° C. After 15 minutes in the chamber, the increased weight and their flowability in the samples were tested.

Table: Results of the potassium salt of D-CMPP prepared according to the invention in humid air compared to powder

Water soluble granule powder Particle size (cm) 0.25-2 <0.02 Weight increase (%) 0.306 0.564 liquidity Free-flow Bunch together

<Example 2>

Preparation of Potassium Salt of D-2,4-Dichlorophenoxypropionic Acid (D-2,4-DP)

6.1 kg (25.95 moles) of D-2,4-dichlorophenoxypropionic acid (D + L = 98.8 wt%, D: L = 93.1: 6.9) was prepared in the same manner as in Example 1 with 1.9 kg of potassium carbonate ( 13.768 moles). After an additional 2 hours of operation, a total of 22 kg of D-2,4-dichlorophenoxypropionic acid potassium salt of the following composition was obtained:

Active compound content D + L = 75.0 wt%

Isomer ratio D: L = 93.1: 6.9

Moisture content = 3.6% by weight

<Example 3>

Preparation of Potassium Salt of 2-methyl-4-chlorophenoxyacetic acid (MCPA)

Similar to Example 1, potassium salt of 2-methyl-4-chlorophenoxyacetic acid having the following composition was reacted by reacting 3.67 kg (18.3 mol) of 2-methyl-4-chlorophenoxyacetic acid with 1.33 kg (9.64 mol) of potassium carbonate. 27 kg were prepared per hour in a 6 hour procedure:

Active compound content = 74% by weight

Water content = 4.4% by weight

Claims (10)

Aryloxy, comprising extruding a mixture of aryloxy-C ₁ -C ₄ -alkanecarboxylic acids with at least stoichiometric amounts of alkali metal bases or alkaline earth metal bases, which are partially or fully converted to volatile materials under reaction conditions A _{process for} reacting an -C ₁ -C ₄ -alkane carboxylic acid with an alkali metal base or an alkaline earth metal base as a melt to produce an alkali metal or alkaline earth metal salt of aryloxy-C ₁ -C ₄ -alkane carboxylic acid. The method of claim 1 wherein the aryloxy -C ₁ -C ₄ used-alkane-carboxylic acid aryloxy -C ₁ -C ₄ having the herbicidal activity-alkane-carboxylic acid method. The process according to claim 1 or 2, wherein the alkali metal base used is an alkali metal carbonate. The method according to claim 3, wherein the alkali metal carbonate used is potassium carbonate. The process according to claim 1, wherein the molten aryloxy-C ₁ -C ₄ -alkane carboxylic acid is reacted thoroughly by mixing with a solid alkali metal base or alkaline earth metal base in an extruder. 6. The process according to claim 1, wherein the solid aryl-C ₁ -C ₄ -alkanecarboxylic acid is added to the extruder to melt and react with complete mixing with the solid alkali metal base or alkaline earth metal base. 7. The process according to any one of claims 1 to 6, wherein the reaction is carried out in the presence of a collecting agent suitable for azeotropic removal of water in the extruder. 8. The method of claim 7, wherein the trapping agent exits the mixture during extrusion. An alkali metal or alkaline earth metal salt of aryloxy-C ₁ -C ₄ -alkane carboxylic acid, obtainable by any of the methods of claims 1 to 8. Using at least _one alkali metal salt or alkaline earth metal salt of aryloxy-C ₁ -C ₄ -alkane carboxylic acid having herbicidal activity according to claim 9 in crops, their habitat and / or seeds thereof. , Method of inhibiting undesirable plant growth.