FR2472341A1 - Seed dressing contg. a methyl benzimidazolyl carbamate salt - dissolved in an alcohol ether - Google Patents

Abstract

A homogeneous liquid seed dressing for grain and seeds contains as fungicide methyl benzimidazol-2-yl-carbmate (carbendazim) as a salt with one or more of hydrochloric, hydrobromic, hydroiodic or perchloric acids, dissolved in an alcohol ether of formula (I) R1-(OCHR2.CHR3)n-OH (I) (R1 is Me, Et, nPr, iPr, or -CHR3.CHR2.OH; R2 and R3 are H or Me; n is 1 or 2). The dressing may also contain other fungicides or insecticides particularly 1- beta-(allyloxy)-2,4-dichlorophenethyl -imidazole (imazalil) in similar salt form. It is possible without addition of excess acid to produce stable solutions containing up to 20% carbendazim. No inhibition of germination has been noted with the dressing.

Description

To protect seeds and seeds against
cryptogamic diseases, it has been used since
number of years of products containing compounds
organic mercury. Such products come under
powder form, on the one hand, and in the form of liquids, on the other hand: part. The latter are preferable, because we thus obtain a better adhesion of the product to the seeds and we avoid
nuisance caused by dusts resulting from the use of powders. The preparation of liquid disinfectants
It is not difficult to contain organic mercury compounds since the compounds generally used for this purpose are soluble in water or in the usual organic solvents.

However, the use of organic mercury compounds for the disinfection of seeds and seeds is not
without danger, due, on the one hand, to the toxicity of the compounds
and on the other hand, the risk of contamination of organisms and soil by mercury compounds.

Carbendazim (methylbenzimidazol-2-yl-carbamate)
is known as an effective fungicide against a number
diseases attacking germinating seeds and seeds,
and dry disinfectants containing carbendazim alone
or with other fungicides are known.

It is also known to use suspensions of
carbendazim in a slug or other liquid agent for combating fungal diseases. The use of suspensions, however, has obvious disadvantages, particularly because of their tendency to precipitation, and it is therefore desirable to be able to prepare homogeneous liquid disinfectants containing carbendazim in sufficient concentration to obtain a satisfactory fungicidal effect.

 For disinsection of grains with a liquid disinfectant, a disinfectant dose of 100-500 ml - preferably 100-250 ml - per 100 kg of seed is appropriate. Amounts of less than 100 ml are difficult to evenly distribute on 100 kg of seeds, and a dose greater than 500 ml / 100 kg of seed may wet the seeds to the point of substantially reducing the operating capacity of the equipment. seed treatment.

 However, the preparation of a homogeneous liquid disinfectant agent based on carbendazim faces serious difficulties because carbendazim is practically insoluble in all the usual solvents. For example, its solubility is 36 mg / l in benzene and 300 mg / l in ethanol.

 It is known that carbendazim, which is a very weak base, can form salts with acids and that these salts are soluble in water or aqueous acids. When these salts are dissolved in water, hydrolysis with precipitation of free carbendazim is rapidly produced. This precipitation can be prevented by adding an excess of acid, but such strongly acidic solutions (about pH 3) are not suitable for use as seed disinfectants, since the excess of acid has the effect of to prevent germination, and that excess acid may also have a corrosive effect on the seed treatment equipment.

 Instead of water or aqueous acids, it has been proposed to use fluids such as ketones, acid amides, xylene, alcohols, alkylated naphthalene or glycols. Solutions in such fluids, however, are not suitable as seed disinfectants because, on the one hand, it is not possible to obtain the necessary concentrations of carbendazim in the disinfectant and, on the other hand, that said solvents can have a detrimental effect on germination.

 In the description of Danish Patent Application No. 2165/74, it has been proposed to prepare fungicidal agents containing carbendazim including seed disinfectants, by first preparing a carbendazim and acid addition product. sulphonic acid having at least 8 carbon atoms, after which, from a water-insoluble adduct, the agents used in practice are prepared, for example solutions in organic solvents. In particular, disinfectants are provided with solutions in dimethylformamide (DMF) or dimethylsulfoxide.

 The need to separately prepare this carbendazim adduct complicates and makes more expensive the production of said disinfectant solutions and this production is made even more expensive by the fact that the adduct preparation is carried out with a loss. not negligible carbendazim which is a product quite expensive in itself. In addition, the use of solvents such as DMF or dimethylsulfoxide in liquid disinfectants is unfortunate, because of the risk of adverse effects on the seed germination capacity. It is the same for a number of other organic solvents proposed especially for liquid fungicidal agents, such as for example methylpyrrolidone.

Surprisingly, it has now been found according to the invention that salts of carbendazim with hydrochloric acid, hydrobromic acid, hydroiodic acid and perchloric acid are readily soluble in alcoholic ethers of the type

<tb> where <SEP> R1 <SEP> stands for <SEP><SEP><SEP> groups <SEP> CH3, <SEP> C2H5, <SEP> C2H5-CH2, <SEP> (CH3) 2-CH
<tb> or <SEP> HO-CH-CH, <SEP> R2 <SEP> and <SEP> R3 <SEP> represent <SEP> each <SEP> separately <SEP> H <SEP> or <SEP> CH3,
<tb><SEP> E2 <SEP> each <SEP> separately <SEP> H <SEP> t3
<tb><SEP> RR
<tb> and n is 1 or 2.

 It is therefore possible with said salts and said alcohol ethers, and without the addition of excess acid, to prepare stable homogeneous solutions containing up to about 20% of carbendazim, which is quite sufficient for the purpose of disinfecting seeds. No inhibitory effect of the agent on germination was observed.

 Accordingly, the invention relates to a homogeneous liquid disinfecting agent for seeds and seeds containing the fungicide carbendazim (methylbenzimidazol-2-yl-carbamate) and optionally other fungicides or insecticides, this agent being characterized in that it contains the carbendazim in the form of a salt with one or more of hydrochloric, hydrobromic, hydroiodic or perchloric acid, dissolved in an alcoholic ether of the aforementioned type.

 Unlike the process according to Application No. 2165/74, it is not necessary to first prepare an addition product which entails complications and costs, since the preparation of the disinfecting agent according to the invention can easily be for example, by stirring the carbendazim in the chosen alcoholic ether and then adding, while stirring, the selected acid in the molar ratio of 1: 1. Shortly thereafter, carbendazim is dissolved as the corresponding salt. The dissolution process can be accelerated by using a small excess of acid. An important excess of acid should be avoided, not only because of the disadvantages mentioned above, but also because the solubility of the carbendazim salt is reduced as a result of an interaction of ions.

 It is not necessary to use the acids in question in their anhydrous form. It is easy to use, for example, 30% aqueous HCl. 45% aqueous HBr or 70% aqueous HC104. It is not appropriate, however, for the disinfecting agents to have a water content substantially higher than that which is thus obtained, as this results in a reduction of the solubility of the carbendazim salts.

The homogeneous liquid disinfecting agent may, in addition to carbendazim, contain other fungicides or insecticides, if these are soluble in the alcoholic ethers in question or form soluble salts with the acids in question. Thus, the disinfecting agent according to the invention may, in addition to carbendazim, contain the fungicide "Imazalil" (1-6
(allyloxy) -2,4-dichlorophenethyl-imidaz as a salt with one or more of the indicated acids.

The invention will be illustrated in more detail by the
following examples
Example 1
A solution is prepared from the following components
Carbendazime, 90% techn. 10.0 g
Ethylene glycol methyl ether 83.8 g
Hydrobromic acid, aqueous 47.7% 9.0 g
Rhodamine (dye) 0.4 g
103.2 g = 100 ml
The preparation is carried out by stirring the carbendazim in ethylene glycol methyl ether, after which the hydrobromic acid is added. Even after leaving the solution at rest for a long time, precipitation does not occur.

 The solution is suitable for the treatment of wheat against decay (Tilletia caries) and the treatment of rye against uracysts (Urocystis occulta), and for these two species of cereals against Fusariuni nivale and Septoria nodorum. It is recommended to use a 200 ml dose of disinfectant.

 for 100 kg of seed.

Example 2
In the same way as in Example 1, a solution is prepared from the following components
Carbendazime, 90% techn. 10.0 g
Ethylene glycol monoethyl ether 82.6 g
Perchloric acid, aqueous 69.8% 7.3 g
Rhodamine 0.2 g
100.1 g = 100 ml
No crystallization of the solution occurs after a fairly long storage at -100C. The solution can
be used as in Example 1.

Example 3
In the same way as in Example 1,
a solution from the following components
Carbendazime, 90% techn. 5.0 g
Imazalil, 99% techn. 5.0 g
Ethylene glycol monoethyl ether 84.5 g
Hydrobromic acid, aqueous 61.5% 5.9 g
rhodamine
100.8 g = 100 ml
The solution is cold-resistant to -100C. It can be used for the treatment of barley against helminthosperiosis (Helmintosporium gramineum) and Fusarium nivale at a dose of 100 ml per 100 kg of barley.

Example 4
In the same manner as in Example 1, a solution is prepared from the following components:
Carbendazime, 90% techn. 3.7 g
Imazalil, 99% techn. 3.4 g
Concentrated hydrochloric acid 37% 3.1 g
Ether ethylene glycol methyl 88.5 g
Rhodamine 0.3 g
99.5 g = 100 ml
The solution is cold-resistant up to -10 C. It can be used for the treatment of barley against helminthos- periosis and Fusarium nivale at a dose of 150 ml per 100 kg of barley.

Example 5
In the same way -as in the previous examples, a solution is prepared from the following components
Carbendazime, 90% techn. 5.6 g
Hydrogen iodide, aqueous 57.5% 6.1 g
88.1 g ethylene glycol monoethyl ether
Rhodamine 0.2 g
100.0 g
No crystallization occurs by cooling down to -100C. The field of application and the doses are the same for this solution as in Example 1.

Example 6
In the same way as in the previous examples, a solution is prepared from the following components
Carbendazime, 90% techn. 6.6 g
Hydrobromic acid, aqueous 47.7% 5.6 g
Diethylglycol monoethyl ether93.4 g
Rhodamine 0.2 g
105.8 g = 100 ml
The field of application of the solution is the same as in Example 1. The dose is about 300 ml per 100 kg of seeds. The solution is cold-resistant to -100C.

Claims (2)

 1. Homogeneous liquid disinfecting agent for seeds and seeds containing the fungicide carbendazime (methylbenzimidazol-2-yl-carbamate) and optionally other fungicides or insecticides, characterized in that it contains carbendazim in the form of a salt with one or more hydrochloric, hydrobromic, hydroiodic or perchloric acids, dissolved in an alcoholic ether of the type.

where R1 represents one of the groups CH3, C2Hq, C2H5-CH2, (CH) -CH R2 and R) are each H or CH3, and n is 1 or 2.  2. Disinfecting agent according to claim 1, characterized in that it contains the fungicide of 1- (allyloxy) -2,4-dichlorophenethyl-imidazol in the form of a salt with one or more of the abovementioned acids.