RU2256602C1 - Method for preparing calcium polysulfide solution - Google Patents

Abstract

FIELD: inorganic chemistry, chemical technology, agriculture, building materials.

SUBSTANCE: invention relates to a method for preparing calcium polysulfide aqueous or alcoholic solutions. Method involves continuous feeding gaseous hydrogen sulfide at stirring to reaction mass containing calcium oxide or hydroxide and elemental sulfur in aqueous or alcoholic medium that results to formation active calcium sulfide in the reaction mass that reacts easily with sulfur to form calcium polysulfide solution. This allows significant intensifying the process and to carry out its under milder temperature conditions, to enhance the yield of calcium polysulfide and avoid formation of by-side calcium thiosulfate. Method is simple and suitable for realization as far as prepared solutions of calcium polysulfide doesn't depend on raw quality and the solvent nature. Prepared calcium polysulfide shows biological activity comparable with that of the known preparation. Calcium polysulfide can be used as acaricide and insecticide-fungicide for protection of forest and agricultural plants against pests and diseases, as water-repellent for water-sensitive building materials and so on.

EFFECT: improved method for preparing, valuable properties of product.

2 tbl, 8 ex

Description

The invention relates to a method for producing solutions of calcium polysulfide, which are used as acaricides and insectofungicides to protect forest and agricultural plants from pests and diseases, water repellent agent for water-sensitive building materials, etc.

The following methods are known for the synthesis of polysulfides of alkali and alkaline earth metals: the production of Na ₂ S _{n by} direct interaction of the metal with sulfur at high temperatures (250-350 ° C) [1], the interaction of sulfur with aqueous solutions of alkalis at 100 ° C with the formation of metal thiosulfate as a by-product or by the interaction of sulfur with a metal sulfide under the same conditions without the formation of side sulfite and metal thiosulfate [2]. The use of water-soluble amines in the case of the last two reactions allows you to speed up the process and lower the temperature to 60 ° C [3].

For polysulfides of alkaline earth metals, in particular calcium, there are limitations in the application of the above methods. Direct synthesis from calcium and sulfur is not possible due to the insufficiently high stability of calcium polysulfides CaS _n at elevated temperatures. The reaction of sulfur with calcium sulfide is also difficult, since, firstly, the synthesis of the initial CaS is an energy-intensive high-temperature process (1000-1200 ° C) [4], secondly, CaS is poorly soluble in water and, thirdly, decomposes on air.

Closest to the invention is a method for producing calcium polysulfide by the interaction of calcium oxide CaO with sulfur in water at 100 ° C and a ratio of components by weight: S: CaO: H ₂ O = 10: 5: 85 [5]. CaO is preliminarily reacted with part of the water (slaking lime), and then sulfur is introduced in the form of a paste obtained by thoroughly grinding lump sulfur with water additives. The reaction produces CaS ₄ and CaS ₅ (64-67%) and by-products - calcium thiosulfate CaS ₂ O ₃ (23-28%) and calcium carbonate CaCO ₃ (0.3-1.1%), and also remains 5-11% of unreacted sulfur. The resulting solution settles out from the lime sediment and is used under the name of lime-sulfur broth.

The disadvantages of this method are the significant length of the process, including both the reaction time (several hours) and the time required to extinguish the lime and prepare the aqueous sulfur paste, a sufficiently high reaction temperature (100 ° C), a large formation of by-products (one third) .

The aim of the present invention is a method for producing solutions of calcium polysulfide, devoid of these disadvantages, i.e. allowing to intensify the process, reduce the reaction temperature and increase the yield of the main product.

This goal is achieved in that the process of producing CaS _{n is} carried out with continuous bubbling of gaseous hydrogen sulfide into a reaction mass containing calcium oxide or hydroxide and sulfur in an aqueous or alcoholic medium. The use of hydrogen sulfide (both commercial gas and gas generated during the hydrotreating of various raw materials from sulfur can be used) provides easy formation of calcium sulfide, which, when in active form, interacts with elemental sulfur under mild temperature conditions with the formation of calcium polysulfide with high exit. The use of hydrogen sulfide can reduce the process temperature to 50-80 ° C and reduce the time to produce CaS _n to 30-90 minutes. The decrease in temperature and synthesis time compared with the prototype contributes to greater selectivity of the process and avoids the formation of side calcium thiosulfate. In addition to the function of the reagent, hydrogen sulfide also plays the role of a protective air cushion, preventing unwanted contact of the reaction mass with oxygen.

As initial components, technical lump sulfur in the form of coarse powder and technical calcium oxide with any content of the basic substance, i.e. the reaction is not sensitive to impurities. Perhaps the use of slaked lime Ca (OH) ₂ . The process is carried out both in water and in lower alcohols (methanol, ethanol), but the use of water is preferable, given the predominant practical use of aqueous CaS _n solutions and the release of water during the interaction of calcium oxide with hydrogen sulfide.

It should be noted that the process according to the proposed method can be carried out at room temperature in an alcoholic environment, but in this case its duration increases by 2-3 times.

The polysulfide CaS _{n is} regulated by the ratio of CaO and S (from 2 to 4) and has values characteristic of this substance.

The invention is illustrated by the following examples.

Example 1. In a suspension containing 56.1 g of CaO (with a basic substance content of 71.1%) and 32.1 g of powdered sulfur (molar ratio of CaO: S = 1: 1) in 300 g of water, with stirring, bubbled under a small the pressure is gaseous H ₂ S. The process is exothermic, the reaction mixture is heated. The temperature of the reaction mixture is maintained between 60-70 ° C. The reaction ends after the sulfur has completely dissolved, while the solution acquires an intense dark cherry color. To remove residual H ₂ S, the solution was purged with nitrogen at 60 ° C. After cooling and settling, the calcium polysulfide solution is filtered, placed in an airtight container and analyzed. The density of the solution, the content of CaS _n and the degree of its polysulfide are determined by the iodometric method. The data are given in table. 1.

Examples 2-8 were carried out analogously to example 1, only in example 7, methyl alcohol was used instead of water, in example 8, ethyl alcohol. The ratio of the components in examples 2-8 and the properties of the obtained CaS _n solutions are given in table. 1.

From the above table. 1 data we can draw the following conclusions.

1. The proposed method for the synthesis of CaS _n provides acceleration of the process - the reaction lasts 30-90 minutes compared to several hours in the prototype.

2. The process goes under milder temperature conditions - 50-80 ° C against 100 ° C in the prototype.

3. Provides greater process selectivity and an increase in the yield of CaS _n to 85-100%, which is indirectly confirmed by higher density values of the obtained CaS _n solutions. The density of the solutions according to the claimed method is 1.32 for aqueous and 1.16 kg / m ³ for alcohol, and the maximum density of the aqueous CaS _n solution obtained by the prototype is 1.285 kg / m ³ provided that high-quality starting ingredients are used [6]. Moreover, in the obtained CaS _n solutions, unlike the prototype, calcium thiosulfate is practically absent. The claimed method allows to obtain sufficiently concentrated solutions of the drug (27-36%), ready for practical use after dilution.

4. The method is simple and convenient for implementation, since the quality of the obtained CaS _n solutions does not depend on the quality of the raw material (CaO) and the nature of the solvent.

The biological activity of the obtained CaS _n solutions corresponds to the biological activity of preparations based on CaS _n (the so-called calcareous broths) obtained by the prototype method. In particular, in laboratory conditions, the activity of the preparation obtained according to Example 3 (Table 1) is shown in relation to fungi causative agents of pine disease - common and snow shute. When making the drug in an amount of 8% in a nutrient medium containing a culture of the pathogen fungus, an inhibitory effect was observed, which manifested itself in a decrease in the diameter of the fungal colonies (Table 2).

From the table. Figure 2 shows that under comparable conditions the activity of CaS _n preparations is approximately the same and exceeds the activity of sulfur and the control experiment.

Sources of information

1. USSR copyright certificate No. 1129186, cl. C 01 B 17/22, 1983.

2. Synthetic rubber, ed. I.V. Garmonova, Leningrad: Chemistry. 1983.

3. Copyright certificate of the USSR No. 1137075, cl. C 01 B 17/22, 1983.

4. Copyright certificate of the USSR No. 1476877, cl. S 09 K 11/56, 1987.

5. M.E. Pogodin. The technology of mineral salts. T.1, Moscow: Chemistry, 1974.

6. A. Razumov. Grapes: growing and processing at home. Uzbekistan, 1978, 243 p.

Table 1
Synthesis conditions and properties of CaS _n solutions No. Ratio
Reagents
CaO *: S: H ₂ S: solvent ** Tempe
ratrata
p-tion
° C Time
p-tion
min Koncen
traction
solution,% Exit
CaS _n ,%
from theor. N value
in CaS _n ,
calc / exp Density
solution
CaS _n , kg / m ³ 1 1: 1: excess: 16.5 60-70 thirty 27.0 89.8 2.0 / 1.7 1.23 2 1: 2: excess: 16.7 60-70 thirty 29.8 85.9 3.0 / 2.4 1.28 3 1: 3: excess: 15.4 60-70 60 33.9 90.3 4.0 / 3.5 1.32 4 1: 3: excess: 15.4 50-60 90 33.9 90.0 4.0 / 3.5 1.32 5 1: 3: excess: 15.4 70-80 40 34.0 90.5 4.0 / 3.5 1.32 6 1: 3: excess: 16.8 60-70 60 32,7 85.9 4.0 / 3.3 1.30 7 1: 3: excess:
8.0 60-70 60 36,2 92.2 4.0 / 3.6 1.16 8 1: 3: excess:
6.6 60-70 60 29.3 ~ 100 4.0 / 4.4 1.10 ^* - in examples 1-5 used CaO with a basic substance content of 71.1%, in examples 6-8 used CaO with a basic substance content of 87.4%.
^** - in examples 1-6, the solvent is water, in example 7, the solvent is methyl alcohol, in example 8 the solvent is ethyl alcohol.

table 2
The biological activity of sulfur and calcium polysulfides A drug The diameter of the colonies of mushrooms for 7 days, mm Common shute Snow shute The control 65 61 Colloidal sulfur fifty 49 CaS _n - prototype 12 eleven CaS _n - obtained in
conditions of example 3 10 12

Claims (1)

A method of obtaining calcium polysulfide solutions by the interaction of calcium oxide and sulfur in a solvent, characterized in that, in order to intensify, reduce the reaction temperature and increase the yield of the target product, the process is carried out by continuously supplying hydrogen sulfide gas to the solution at a reaction mass temperature of 50-80 ° C.