RU2046093C1 - Double cobalt-manganese hydrophosphates and process for preparing thereof - Google Patents

Abstract

FIELD: agriculture. SUBSTANCE: double cobalt-manganese hydrophosphates of the general formula: Co_1-xMn_xHPO₄·1,5H₂O, wherein 0<X≅ 5,5, used as fungicides having prolonged activity. Reagents used for preparing these salts include a 40-80% phosphoric acid solution, a mechanical mixture of cobalt and manganese hydroxocarbonates at a Co to Mn ratio of (10-1,5):1 and a 20-30% hydrogen peroxide solution. Reactants are fed under continuous agitation at a hydroxocarbonate mixture to H₂O, weight ratio of (5-3):1, respectively to a reactor thermostated at 25-60 C. The reactor contains water acidified with phosphoric acid and the pH of the reaction mixture is maintained constant at 2.6 to 3.2. The resulting precipitate is removed by filtration, washed with water and dried. EFFECT: improved properties of the title compounds. 3 cl, 5 tbl

Description

The invention relates to the synthesis of new chemical compounds, in particular to cobalt-manganese double hydrophosphates of the general formula Co _{1 x} Mn _x HPO ₄ ˙ 1.5H ₂ O (0 <x ≅ 0.45) used in forestry as prolonged action fungicides to prevent infectious lodging (fusarium) of conifers.

In the literature from among double manganese and cobalt containing phosphates, which can be considered as analogues of the claimed compounds, are known:
1. Double phosphates of the composition Co _{3 x} Mg _x (PO ₄ ) ₂ ˙ 8H ₂ O
(0 <X ≅ 1.00) [1]
2. Double magnesium-manganese hydrogen phosphates composition
Mg _1-x Mn _x HPO ₄ ˙ 3H ₂ O (0 <x <1.00) [2]
However, the first synthesized cobalt-manganese double hydrophosphates differ from the known double phosphates in such an important indicator as the crystal structure. The named double phosphates have different crystal lattices, different spatial groups, unit cell sizes, number of formula units, qualitative and quantitative composition of atoms. The difference in chemical composition follows from the formulas of these salts. This causes significant differences in the properties of these compounds and, first of all, in their solubility in aqueous and citrate solutions. Table 1 shows the comparative crystallochemical characteristics and properties of double phosphates, emphasizing their significant differences.

Cobalt-manganese double phosphate is obtained by reacting a mixture of sulfate aqueous solutions of cobalt and manganese salts with sodium phosphate solution [1] Magnesium-manganese double hydrogen phosphates are obtained by neutralizing a mixture of hydroxycarbonates with phosphoric acid [2]
The closest in technical essence to the proposed cobalt-manganese double hydrogen phosphates one and a half hydrates are manganese-cobalt double dihydrogen phosphates of the general formula Mn _1-x Co _x (H ₂ PO ₄ ) ₂ ˙ 2H ₂ O (0 <x <1.00) (prototype) [3] They are polycrystals of monoclinic syngony (Table 1). The basis of their crystal lattice is the octahedron, the coordination environment of which includes four phosphate tetrahedra and two molecules of crystallization water. The strength of hydrogen bonds between OH groups of water molecules and phosphate tetrahedra is 64.9 kJ / mol. This predetermines many physicochemical properties of the compounds and, in particular, thermal behavior and solubility in standard agrochemical solutions.

Manganese-cobalt double dihydrogen phosphates are obtained by crystallization from concentrated phosphoric acid solutions using a mechanical mixture of cobalt and manganese hydroxocarbonates and concentrated phosphoric acid (64.15% P ₂ O ₅ ). The synthesis is carried out at 20-25 ^about C, feeding a mixture of hydroxocarbonates in portions with continuous stirring in the reaction vessel. The precipitate formed is separated from the mother liquor, washed and dried at 40-50 ^o C to constant weight [3]
The solubility of double manganese-cobalt dihydrogen phosphates in water, in a 2% solution of citric acid and in a solution of ammonium citrate reaches 100%. Double manganese-cobalt dihydrogen phosphates are used as a mineral feed additive [3]
The invention consists in the creation of a number of new chemical compounds of the general formula Co _1-x Mn _x HPO ₄ ˙ 1.5H ₂ O (0 <x ≅ 0.45), which can be used, in particular, in forestry as prolonged fungicides containing trace elements, and the development of a method for their preparation.

The solution of this problem is achieved by co-precipitation of Co ²⁺ and Mn ^{2+ ions} with the hydrophosphate ion HPO ₄ ^2- from dilute phosphoric acid solutions obtained by the interaction of a mechanical mixture of cobalt and manganese hydroxocarbonates taken in a specific ratio with phosphoric acid at a fixed concentration of hydrogen ions.

To obtain cobalt-manganese double hydrophosphates, water (predominantly 2.8) at 25-60 ^o C (predominantly 40 ^o C) is thoroughly homogenized with continuous stirring in a reaction vessel containing acidified with phosphoric acid to a pH of 2.6 to 3.2 a mixture of cobalt and manganese hydroxocarbonates, taken in an atomic ratio of Co: Mn from 10: 1 to 1.5: 1, a solution of phosphoric acid 40 of 80% concentration (mainly 55%) and a 20-30% solution (mainly 25%) hydrogen peroxide, taken in relation to a mixture of hydroxocarbonato in 1: 3 1: 5. The pH of the reaction medium is monitored using a pH meter and kept constant (2.6-3.2), by adjusting the supply of H ₃ PO ₄ (automatic titration unit BAT-15) and a mechanical mixture of hydroxocarbonates. The duration of the synthesis is 3-4 hours. The precipitate formed is separated from the mother liquor by filtration, washed with water (T: G 1: 5) and dried at room temperature for 10-12 hours.

The specified method allows to obtain double cobalt-manganese hydrophosphates one and a half hydrates of the general formula Co _1-x Mn _x HPO ₄ Н 1.5H ₂ O. The values of x determined according to the results of chemical analysis vary within 0 <x ≅ 0.45. In the table. Figure 2 shows the characteristics of the synthesized double hydrophosphates depending on their composition on the preparation conditions (Co: Mn ratio in the mixture of starting reagents). According to Table 2, the content of cobalt and manganese in the composition of double hydrophosphates can be controlled in a controlled manner, changing the composition of the initial hydroxocarbonates during the synthesis.

The content of all ingredients in cobalt-manganese double hydrophosphates is as follows (in terms of oxides), wt. Phosphorus 38.74-38.95 Cobalt 39.07-23.17 Manganese 2.07-17.86 Water Else up to 100%
The fact of the formation of a new chemical compound of the general formula Co _1-x Mn _x HPO ₄ x 1.5H ₂ O (0 <x ≅ 0.45) is confirmed by the results of physicochemical studies and, in particular, the data of chemical and x-ray phase analyzes (Table 2 , 3).

Table 3 shows the x-ray characteristics of two representatives of the synthesized series of new double hydrogen phosphates. The data obtained allow us to conclude that the synthesized compounds are individual, that is, they contain phosphorus, cobalt and manganese in one crystal lattice and do not contain extraneous impurities. The established limits in the variation of x values characterize the obtained hydrophosphates as a limited number of substitutional solid solutions. An extremely saturated member of this series is double hydrophosphate of the composition Co _0.55 Mn _0.45 HPO ₄ ˙ 1.5H ₂ O. No double cobalt-manganese hydrophosphates, the value of x in which exceeds 0.45, are formed. Under conditions when the Co: Mn ratio in the mixture of the starting hydroxocarbonates is less than 1.5: 1 (1.3: 1), a mechanical mixture of two crystalline phases is formed (Table 2).

 To decipher the structure of the obtained cobalt-manganese double hydrophosphates of sesquihydrate, precision x-ray studies were performed. It is established that they are polycrystals of pseudomonoclinic syngony. The basic structure-forming unit of their crystal lattice is the octahedron, the coordination environment of which is composed of oxygen atoms of phosphate tetrahedrons and oxygen atoms of crystallization water molecules. Using infrared spectroscopic studies, it was found that one of the water molecules is common to two neighboring octahedra. The energy of the most loaded hydrogen bond, realized in the structure of cobalt-manganese double hydrophosphates of sesquihydrate, is 46.75 kJ / bond. The properties of the synthesized double hydrophosphates are given in table 1.

Compliance with the inventive step is due to:
1. The difference in the type of crystalline structures of the inventive double hydrophosphates of cobalt-manganese sesquihydrate and prototype. Pseudomonoclinic syngony (space group Pm, Z 2-8) for Co _{1 x} Mn _x HPO ₄ ˙ 1.5H ₂ O, unlike monoclinic syngony (space group P2 / n, Z 2) for Mn _{1- x} Co _x (H ₂ PO ₄ ) ₂ ˙ 2H ₂ O (prototype). This determines a number of distinctive features and, in particular:
different mutual arrangement of atoms in the crystal lattice of compounds;
excellent parameters and volume of their unit cells, angles between atomic planes;
various types and nature of bonds realized in the crystal lattice, their strength, the number of bonds of the same type in the unit cell (three Me-OH bonds in hydrogen phosphate and 6 bonds in dihydrogen phosphate, 2 times more in dihydrogen phosphate and P-OH bonds);
2. The difference in the qualitative and quantitative composition of the compared compounds;
3. The difference in chemical properties. The thermal behavior, for example, of Co _1-x Mn _x HPO ₄ ˙ 1.5H ₂ O, is fundamentally different from the thermolysis of Mn _1-x Co _x (H ₂ PO ₄ ) ₂ x 2H ₂ O. Their solubility in standard nutrient solutions is also different ( table 1).

Compliance with the inventive step of the proposed method for producing new double hydrophosphates due to:
1. The difference in the starting reagents. To obtain Co _{1 x} Mn _x HPO ₄ ˙ 1.5H ₂ O, hydrogen peroxide (20 30% concentration) is additionally used, a mixture of hydroxycarbonates hydrogen peroxide 5 1 3 1, without which it is impossible to obtain a finished product, not contaminated, is used impurity phases;
2. The difference in the concentration of phosphoric acid used (40 80% solution of H ₃ PO ₄ for Co _1-x Mn _x HPO ₄ ˙ 1,5H ₂ O in contrast to 87% for Mn _1-x Co _x (H ₂ PO ₄ ) ₂ x 2H ₂ O, which ensures the purity of the target product);
3. The difference in the concentration of hydrogen ions (pH) of the reaction medium. With _{1 x} Mn _x HPO ₄ ˙ 1.5H ₂ O, is obtained at any fixed pH from 2.6 3.2. This prevents the formation of H ₂ PO ₄ ^- ions and ensures the formation of NRA ₄ ² - precipitating ions. In the synthesis of Mn _1-x Co _x (H ₂ PO ₄ ) ₂ ˙ 2H ₂ O, the pH is not fixed, they are obtained by crystallization from concentrated solutions of H ₃ PO ₄ ;
4. The difference in the temperature regime of the process. With _1-x Mn _x HPO ₄ ˙ 1.5H ₂ O was prepared at 25-60 ^{° C} (preferably ^at 40 ° C). This allows you to significantly accelerate the process of deposition. Dual dihydrogenphosphate was prepared at ²⁵ ° C;
5. The difference in the duration of the process (the precipitation of double hydrophosphates requires 3-4 hours, in contrast to double dihydrophosphates, the crystallization of which takes 12-15 hours);
6. The difference in hardware design. The process of producing double hydrophosphates is partially automated: the target pH of the reaction mixture is controlled and maintained by a constant supply of H ₃ PO ₄ using an automatic titration unit.

 To obtain double cobalt-manganese hydrophosphates of one and a half hydrates, initial mechanical mixtures of hydroxocarbonates with different cobalt and manganese contents were prepared. The synthesis was carried out as described above. The preparation conditions and composition characteristics of the synthesized cobalt-manganese double hydrophosphates of sesquihydrate are presented in Table 2.

Table 4 gives the rationale for the selection of the parameters of the proposed method for producing double cobalt-manganese hydrogen phosphates of sesquihydrate. From the data table. 4 it follows that the synthesis of double hydrophosphates Co _1-x Mn _x HPO ₄ ˙ 1.5H ₂ O must be carried out under the following conditions: pH 2.6 3.2; 25 ^o C 60 ^o C; concentration of H ₃ PO ₄ 40 80% concentration of H ₂ O ₂ 20-30% ratio of the mixture of hydroxocarbonates to H ₂ O ₂ = 3: 1 5: 1; Co: Mn ratio in the mixture of the starting hydroxocarbonates 10: 1, 1.5: 1. Failure to at least one of these synthesis conditions does not allow to obtain the target product in the form of an individual compound.

EXAMPLES EXAMPLE 1 In a thermostated ^at 40 ° C reactor containing 200 ml of water is supplied 55% solution of H ₃ PO ₄ (0.4 ml) until a pH 2.8 solution. A mechanical mixture of cobalt hydroxocarbonates (CoOH) ₂ CO ₃ ˙ mH ₂ O (10.00 g) and manganese (MnOH) ₂ CO ₃ ˙ nH ₂ O (1.02 g), 15 20 ml is fed into the resulting solution in portions with constant stirring. 55% H ₅ PO ₄ solution in such a ratio that the set pH of the reaction medium remains constant, and 3-4 ml of a 25% H ₂ O ₂ solution. The resulting solid phase is filtered off, washed with water (T Ж 1 5), dried at room temperature for 8 10 hours. A product of the composition Co _0.99 Mn _0.01 HPO ₄ ˙ 1.5H ₂ O is obtained. Content in it, wt. CoO 39.07; MnO 2.07; P ₂ O ₅ 38.80; H ₂ O, 20.00. Yield (phosphorus) 97.6%
PRI me 2. In a thermostatically controlled at 40 ^about With a vessel containing 200 ml of water, serves 0.3 ml of a 55% solution of H ₃ PO ₄ to achieve a pH of 3.0. Then, analogously to example 1, serves a mixture of 10.00 g (CoON) ₂ CO ₃ ˙ mH ₂ O and 5.10 g (MnOH) ₂ CO ₃ x xnH ₂ O, 15-20 ml of a 55% solution of H ₃ PO ₄ and 5 6 ml of a 25% solution of H ₂ O ₂ . Further operations are carried out analogously to example 1. Get the product composition, wt. CoO 28.37; MnO 12.78; P ₂ O ₅ 38.95; H ₂ O 19.78, which corresponds to the formula Co _0.68 Mn _0.32 HPO ₄ x x1.5H ₂ O. Yield (by phosphorus) 98.9%
PRI me R 3. In a temperature-controlled reactor at 45 ^about C, containing 200 ml of water, serves 0.2 ml of a 55% solution of H ₃ PO ₄ to achieve a pH of 3.2. In the resulting solution, analogously to example 1, a mechanical mixture of 10.00 g of cobalt hydroxocarbonate (CoOH) ₂ CO ₃ ˙ mH ₂ O and 7.79 g of manganese hydroxocarbonate (MnOH) ₂ CO ₃ подают nH ₂ O, 18 22 ml 55% a solution of H ₃ PO ₄ and 6-7 ml of a 25% solution of H ₂ O ₂ . Further operations are carried out analogously to example 1. Get double hydrogen phosphate composition, wt. CoO 23.17; MnO 17.86; P ₂ O ₅ 38.88; H ₂ O 20.01, which corresponds to the formula Co _0.55 Mn _0.45 HPO ₄ ˙ 1.5H ₂ O. The yield of the target product (phosphorus) 98.5%
PRI me R 4. In a temperature-controlled reactor at 40 ^about With a reactor containing 200 ml of water, serves 0.5 ml of a 55% solution of H ₃ PO ₄ to achieve a pH of 2.5. Further operations are analogous to example 3. Get the product in the form of a mechanical mixture of two phases With _{1 x} Mn _x HPO ₄ ˙ 1,5H ₂ O + Co (H ₂ PO ₄ ) ₂ x x2H ₂ O.

PRI me R 5. The same as in example 3, but the reactor is thermostated at 25 ^about C. Further operations are similar to example 1. The duration of the synthesis is increased to 6-8 hours. Get the product composition With _0.55 Mn _{0, 45} HPO ₄ ˙ 1.5H ₂ O. The yield of the target product (phosphorus) 98.0%
One of the possible areas of use of cobalt-manganese double hydrophosphates of sesquihydrate is forestry, where the compounds obtained can be used as fungicides to prevent infectious lodging of coniferous seedlings when grown in the sowing department of forest nurseries.

To study the fungicidal effect of cobalt-manganese double hydrophosphates of one and a half hydrates, experiments were carried out when sowing ordinary pine seeds in the closed ground of the sowing department of the Kostopolsky basic plant nursery Rovnoles. The experimental design provided for the comparison of double hydrophosphates with the mixture of salts SOSO ₄ ˙ 7H ₂ O and MnSO ₄ ˙ 7H ₂ O [4] taken in amounts corresponding to the content of manganese and cobalt in double hydrophosphates and fundozole [5]. The control was carried out on areas without any substances. In addition, an experiment was conducted in which the effect of double dihydrogen phosphate of the composition Mn _1-x Co _x (H ₂ PO ₄ ) ₂ xx 2H ₂ O as a fungicide was studied. Experience has shown that in connection with 100% aqueous solubility, comparing it with a prolonged-release fungicide is incorrect, because fungicidal properties are manifested in this case only at the initial stage of development of seedlings. Table 5 shows the test results, according to which the total percentage of elongation of pine seedlings when using the test substance is 2.5% versus 4.2 and 6.2% when using a mixture of sulfates and fundozole, respectively. Thus, an experimental verification showed that cobalt-manganese double hydrophosphates one and a half hydrates are promising fungicides that prevent infectious lodging of coniferous seedlings.

Claims (2)

1. Double hydrophosphates of cobalt manganese sesquihydrates of the General formula
Co _{1 - x} Mn _x NRA ₄ · 1,5N ₂ O,
where 0 < _x ≅ 0.45,
used as prolonged action fungicides. 2. The method of obtaining double hydrophosphates of cobalt manganese sesquihydrate of the General formula
Co _{1 - x} MP _x HPO ₄ · 1,5H ₂ O,
where 0 < _x ≅ 0.45,
consisting in the fact that a 40-80% solution of phosphoric acid, a mechanical mixture of cobalt and manganese hydroxocarbonates with an atomic ratio of Co: Mn = (10 ^° C, 1.5): 1 and 20-30% hydrogen peroxide solution are fed simultaneously with continuous stirring and with a mass ratio of a mixture of hydroxocarbonates and H ₂ O ₂ (3 ^o C5) 1, respectively, in a temperature-controlled reactor at 25-60 ^o C containing acidified water with phosphoric acid, maintaining a constant pH value of 2.6-3.2, formed the precipitate is filtered off, washed with water and dried.

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