RU2307118C1 - Methods for preparing ferric complexes with one salicylic acid anion - Google Patents

Abstract

FIELD: coordination compound chemistry.

SUBSTANCE: invention relates to technology of complexes of iron with salicylic acid suitable for use in a variety of technical areas and in medicine. Title complex is obtained via interaction of metal with acid using air oxygen as oxidant. Salicylic acid is used in butyl acetate or n-butyl alcohol solution with dissolved molecular iodine or potassium iodide. Iron is provided in the form of steel or cast iron shell, shaft, and blade of mechanical mixer as well as, agitated by the mixer, reduced iron powder fractions, broken cast iron or broken steel cuttings, cast iron or steel filings. Process is carried out at stirring with high-speed mechanical stirrer and air bubbling allowing self-heating of reaction mixture to 70-80°C until 1.72-1.85 mole/kg iron compounds is accumulated in reaction mixture in the form of suspension, whereupon mixing is stopped. Suspension is freed of unreacted fine iron and/or alloy(s) thereof and subjected to hot filtration, Filtrate is warmed to eliminate precipitated solid phase and then slowly cooled to ambient temperature. Precipitated solid phase is filtered off, dried, and recrystallized, while filtrate is recycled.

EFFECT: improved technology required only accessible starting materials and increased yield of desired product.

2 cl, 4 ex

Description

A method of obtaining a complex of iron (III) with one anion of salicylic acid

The invention relates to the production and isolation of iron complexes with salicylic acid and can be used in various fields of industrial and laboratory practice, in the analytical control of the course of various processes, with the stabilization of certain polymers and lubricating oils, in medicine and in other fields of scientific and practical activity .

A known method of producing salicylate complexes of iron (III) by the exchange interaction between water-soluble salts of salicylic acid and iron (III)

(Handbook of Chemical Equilibria in Analitical Chemistry, Chichester, U.K., Ellis Horwood Limited, 1985, p.163).

(Handbook of Chemical Equilibria in Analitical Chemistry, Chichester, UK, Ellis Horwood Limited, 1985, p. 163).

The disadvantage of this method is that the resulting complexes are contaminated with anions of the starting iron salt and cations of the taken salt of salicylic acid, and therefore require appropriate purification. In addition, the starting salts are not natural compounds and require appropriate preliminary preparation, isolation and purification, which is not such a simple matter.

Closest to the claimed is a method for producing basic iron (III) acetate (positive decision on the application No. 2004108558/04, published 09.09.05), in accordance with which powdered iron is individually or together with the adjacent iron shell adjacent to the reactor vessel into an intensive contact with acetic acid in the absence or in the presence of a stimulating additive of acetic anhydride under conditions of intensive air bubbling at 17-25 ° C until product accumulation with the content of basic iron (III) acetate in the amount of 2.70-3.51 mol / kg followed by stopping the mixing and bubbling of gas, separating the suspension of the reaction mixture from the heavy particles of unreacted iron deposited to the bottom, filtering the basic iron (III) acetate and returning the filtrate to the reactor for loading for a second process.

The disadvantages of this method are:

1. Acetic acid is a low molecular weight fatty acid capable of individually composing a liquid loading phase with an acid concentration of ~ 16 mol / kg. Aromatic salicylic acid, substituted in the o-position, solid at room temperature, noticeably higher molecular weight. It cannot independently form the liquid phase of the system at room and close to them temperatures. An additional solvent is needed, which is rarely indifferent to the ongoing process. In addition, the solubility of salicylic acid in many solvents is small (2-4 mol / kg should be considered good solubility). Consequently, salicylic acid concentrations close to acetic acid cannot be created under any conditions.

2. When carrying out the process with salicylic acid, it will inevitably have to evaluate the role of the additional solvent, not only on the rate and duration of the process, but also on the composition of the products obtained. In particular, the formation of iron (II) and iron (III) salts (basic and normal) is possible in acetic acid. With salicylic acid, the iron (III) cation forms complexes with the number of acid anions from 1 to 3. Not everything is simple with respect to iron (II) compounds. In other words, the replacement of the nature of the acid leads to a different nature of the products of the transformation, which cannot but affect the characteristics of the process and cannot be predicted and taken into account in advance.

3. In the process being analyzed as a prototype, the stimulating additive is acetic anhydride, known as a rather effective dewatering agent. When switching to a system with salicylic acid, it makes no sense to use such a stimulating additive. Firstly, acetic acid formed from it will compete with salicylic acid, which will require additional separation and purification of the conversion products. Moreover, it is not at all obvious that in systems with salicylic acid, the same deep dehydration is needed as in systems with acetic acid, and whether it is necessary at all.

4. To facilitate the isolation of the product by filtration in the analyzed system with acetic acid, the salt content of the product is adjusted to 2.70-3.51 mol / kg. In systems with salicylic acid, it is impossible to accumulate such quantities of the product due to the lack of an acid reagent for these purposes. Therefore, the reaction mixture will contain much smaller amounts of product. Moreover, it is not at all obvious that the main part of such a product will be in the solid phase, which can be easily filtered.

The objective of the proposed solution is to select such a solvent, a stimulating additive and conditions for the oxidation of iron in the presence of atmospheric oxygen and dissolved salicylic acid, in which the latter would be practically quantitatively spent on the formation of an iron (III) complex with one acid anion.

The problem is achieved in that as a liquid phase of loading, a solution of salicylic acid and molecular iodine or potassium iodide in butyl acetate or n-butyl alcohol with a concentration of 1.8-1.9 mol / kg and 0.04-0.08 mol / kg, respectively, iron is taken in the form of a cast iron or steel shell, a shaft and a blade of a mechanical mixer, as well as reduced iron powder moved by the mixer, fractions of broken cast iron or broken steel shavings, cast iron or steel sawdust, and the process is carried out with stirring at a high speed by a mechanical stirrer and bubbler of air with a flow rate of 2.5-5.7 l / (min · kg loading of the liquid phase) during spontaneous heating of the reaction mixture to 70-80 ° C until the accumulation of iron compounds in the reaction mixture suspension 1.72-1, 85 mol / kg, after which stirring and bubbling are stopped, the suspension of the reaction mixture is separated from unreacted finely divided iron and (or) its alloy (s) and sent to hot filtration, where it is purified from carbon impurities from the reacted iron alloys, the filtrate is heated to eliminate precipitated solid phases And then allowed to cool slowly to room temperature, the precipitated solid is filtered and sent for drying or recrystallization, and the filtrate (a solution mainly iron compounds (III) with impurities of iron compounds (II)) is sent to re-boot process.

In this case, the precipitate filtered by hot filtration is accumulated, and then the target product is separated from finely dispersed carbon during recrystallization.

Characteristics of the raw materials used

Iron reduced according to TU 6-09-2227-72;

Steel 45 according to GOST 1050-74;

Gray cast iron grade SCh 15-32 according to GOST 1412-70;

Salicylic acid according to GOST 5844-51;

Crystalline iodine according to GOST 4159-65;

Potassium iodide according to GOST 4232-65;

Butyl acetate according to MRTU 6-09-5743-68;

n-Butyl alcohol according to GOST 6006-51.

The process of the claimed method is as follows. In the reactor with an iron (steel) or cast-iron shell around the entire height, equipped with a high-speed mechanical stirrer, a condenser-reflux condenser and an air supply system for bubbling, the calculated amounts of a pre-prepared solution of salicylic acid and an iodine-containing stimulating additive in butyl acetate or n-butyl alcohol are loaded. The formation of this solution is possible directly in the reactor, for which a solvent, solid acid, iodine or potassium iodide are dosed separately, they include mechanical stirring and the solid components are dissolved at room temperature. After the liquid phase is introduced into the reactor or obtained directly therein, iron powder or fractions of beaten cast iron and / or broken steel chips or generally sawdust or mixtures are loaded in any ratio. The amount of such a reducing agent is selected based on the power of the used mixer. With regard to stoichiometry, it is naturally redundant. It is important that the surface developed by such a moving reducing agent is as large as possible. And to protect the reactor vessel from impacts of heavy particles moved by the mixer, the steel or cast-iron shell with the lower attached bottom just serves.

After the loading of the reagents and the solvent is completed, mechanical stirring is turned on and air is supplied to the bubbler. They stabilize the air flow at a given level and monitor the temperature change in the reaction zone. Some time after the air supply, it begins to grow, first auto-accelerated, then the growth rate slows down, the temperature reaches a maximum and begins to fall.

As soon as a noticeable increase in temperature begins, a sample of the reaction mixture is taken, in which the content of iron (II) and (III) compounds is analyzed. Subsequently, sampling is continued and the moment is fixed when the amount of iron compounds in the reaction mixture (in moles or mol / kg) approaches the initial acid content. At this point, the mixing and bubbling of air is stopped, the reaction mixture is separated from unreacted iron and (or) its alloys, subjected to hot filtration, the filtrate is heated until the precipitated solid phase passes into the solution, after which the resulting solution is allowed to slowly cool to room temperature. The precipitated product is filtered off and sent to drying or recrystallization, and the filtrate is returned to the loading process again.

Example 1

Into a reactor consisting of a glass casing with an annular lid, in which a steel shell protruding at the top of 173 mm high and an inner diameter of 53 mm is enclosed, closed by an autonomous lid with a stuffing box for a high-speed (1560 rpm) vane-type mechanical stirrer and slots for a reflux condenser -condenser and sampler, as well as with a loading hatch, and an attached steel bottom with a thrust bearing for the free end of the shaft of the mechanical mixer (shaft and blade material steel 45, blade thickness 3.2 mm), cc 150 g of a pre-prepared solution of salicylic acid in butyl acetate with a concentration of 1.8 mol / kg and containing 0.006 moles of molecular iodine are used as a stimulant. Mechanical stirring is turned on and 25.3 g of reduced iron powder is charged. An air flow is supplied to the bubbling with a flow rate of 5.11 l / (min · kg of the liquid loading phase) and this moment is taken as the beginning of the process. Observe the temperature change in the reaction zone. As soon as it begins to grow, and in this case it occurs 10 minutes after the start of air sparging, a sample of the reaction mixture is taken without stopping mixing and immediately analyzed for the content of iron (II) and iron (III) compounds in it. It turned out to be 0.21 and 0.16 mol / kg, respectively. Samples taken at 20, 40, 60, 80, 100, 140 and 180 min gave the results of 0.31 and 0.25; 0.29 and 0.73; 0.33 and 0.90; 0.10 and 1.11; 0.05 and 1.40; ~ 0.01 and 1.70 mol / kg. At the same time, the temperature of the reaction mixture passed through a maximum of 74 ° C, per 83 min of the process.

For 185 minutes, air bubbling and stirring with a mechanical stirrer are stopped. At this moment, the content of iron (III) compounds as the target product was 1.72 mol / kg. Part of this product is in the solid phase, which characterizes the final reaction mixture as a suspension. A magnet to hold particles of unreacted iron powder is attached to the bottom of the glass reactor vessel, previously disconnected from the condenser-condenser and the air supply system for bubbling and removed from its workplace on the frame frame, and the reaction mixture is carefully poured onto the filter of the hot filter installation, where the product in the solid phase with carbon impurities is separated from the shell that has reacted during the steel process, the mixer and its shaft in the contact zone with the mixed action mix. The obtained filtrate with precipitated during the operation of the hot filtration solid phase is slightly heated until the solid phase is completely dissolved and left to slowly cool to room temperature for 12 hours. This is necessary to facilitate separation of the precipitated solid phase by filtration and to reduce the degree of capture of the liquid phase by such a solid phase. The resulting product precipitate is dried or immediately sent for additional recrystallization. The precipitate after hot filtration is also sent for recrystallization. If it is not enough, then preliminary accumulation from several experiments is carried out. The filtrate of the last filtration is subjected to analysis for the residual content of iron compounds (II and III) and salicylic acid and sent to download a second process. Sometimes it is combined with a similar filtrate of another experience before this.

Example 2

The reactor and its elements are similar to those described in example 1. The solution-liquid phase is prepared directly in the reactor. For this, 108.41 g of n-butyl alcohol, 38.54 g of salicylic acid and 3.05 g of solid crystalline iodine are loaded into it. Mechanical stirring is turned on and after 24 minutes a solution is obtained with a concentration of salicylic acid and iodine of 1.86 and 0.08 mol / kg, respectively. Through the loading hatch in the lid of the steel shell without stopping mixing, 14 g of the fraction of broken cast iron and 11 g of the fraction of broken steel chips with linear particle sizes of 4 mm or less are introduced. They give air current, and this moment is taken as the beginning of the experiment. The air flow rate is stabilized at 2.5 l / (min · kg of the liquid phase) and after 25 minutes a sample of the reaction mixture is taken. The temperature of the reaction mixture at this moment was 28 ° C. Analysis of a sample of the reaction mixture showed the presence of 0.16 mol / kg of iron (II) compounds and 0.06 mol / kg of iron (III) compounds. The samples for 60 ^minutes, 100 ^minutes, 150 ^minutes, 200 ^minutes min showed an iron content of (II) and iron (III), respectively, 0.31 and 0.18; 0.33 and 0.48; 0.20 and 1.21; 0.15 and 1.60 mol / kg. Stirring is continued for another 20 minutes to obtain an iron salt content of 1.78 mol / kg in the reaction mixture. Then, all operations are performed to isolate the solid product and prepare it for recrystallization, as described in example 1.

Example 3

The reactor and its elements, as well as the loading mass of the liquid phase, are similar to those described in Example 1. A cast iron shell, wall thickness 5 mm. The liquid phase is 82 g of the filtrate of example No. 2, 29.8 g of n-butyl alcohol, 37.9 g of salicylic acid and 0.3 g of crystalline iodine. The concentration of acid in the liquid phase is 1.91 mol / kg, iron (II and III) compounds are 0.11 mol / kg, and iodine is 0.040 mol / kg. After preparing this liquid phase by dissolving the solids (stirring in the reactor for 28 minutes at room temperature), 25.7 g of cast iron sawdust is introduced without stopping mixing. An air flow is supplied to sparge, stabilize the flow rate at the level of 4.3 l / (min · kg of the liquid phase) and monitor the temperature increase and the accumulation of iron (II) and (III) compounds during the process. The maximum temperature was reached for 100 min and amounted to 80 ° C. By 180 min, the process was practically completed: the content of iron (III) compounds reached 1.85 mol / kg. Further processing of the reaction mixture is similar to that described in example 1.

Example 4

The reactor and its elements are similar to those described in example 1. The liquid phase is represented by a solution of salicylic acid and potassium iodide in n-butyl alcohol with concentrations of 1.94 and 0.08 mol / kg. The mass of the loaded liquid phase is 150 g. The steel shell. The metal moved by the mechanical stirrer is represented by 25.2 g of reduced iron powder. Air consumption for bubbling is 5.7 l / min · kg of the liquid loading phase. The content of iron (II) and (III) salts in time changed as follows (τ _samples , min, mol / kg of Fe ²⁺ compounds and mol / kg of Fe ³⁺ compounds): 40, 0.15, 0.14; 100, 0.14, 0.32; 150, 0.12, 0.75; 200, 0.09 1.05; 300, 0.08, 1.37; 400, 0.07, 1.72. The termination of the process and the processing of the reaction mixture are similar to those described in example 1.

The filtered precipitates during hot filtration of examples 2-4 are combined and are aimed at cleaning carbon from iron alloys during recrystallization.

The positive effect of the proposed solution is as follows:

1. The target product is obtained directly from the metal or its alloy and acid in the presence of atmospheric oxygen and a stimulating additive, which is much more profitable than from metal salts of the corresponding oxidation state and acids that must be additionally obtained from the same metal and the same acid. At the same time, crushed waste from other industries can be used as metal.

2. The target product is separated by simple filtration and is easily purified from carbon alloys of iron during recrystallization.

3. The method does not require external heat. On the contrary, with increased loads, removal of reaction heat is required, which can be disposed of.

4. The reaction mixture remaining after separation of the product does not require separation and disposal of components. It can be returned entirely to the download of the repeated process.

5. The proposed method is quite simple in execution, carried out at temperatures close to room temperature and without restrictions on the free exit to the atmosphere. Pretty simple and hardware design process. In particular, the reactor, shaft and blade of a mechanical stirrer can be made of available steels. The case can be reliably protected by a shell and an attached bottom. And the shaft and the blade of the mixer as they wear due to the consumption of metal in the process, periodically simply replace.

Claims (2)

1. A method of producing a complex of iron (III) with one anion of salicylic acid by direct interaction of a metal with an acid in the presence of atmospheric oxygen as an oxidizing agent, characterized in that a solution of salicylic acid and molecular iodine or potassium iodide in butyl acetate or n-butyl alcohol with a concentration of 1.80-1.94 mol / kg and 0.04-0.08 mol / kg, respectively, iron is taken in the form of a steel or cast iron shell, a shaft and a blade of a mechanical stirrer, as well as moved by a stirrer a piece of reduced iron, fractions of broken cast iron or broken steel shavings, cast iron or steel sawdust, and the process itself is carried out with stirring by a high-speed mechanical stirrer and sparging of air with a flow rate of 2.5-5.7 l / (min · kg of liquid phase) during spontaneous heating the reaction mixture to 70-80 ° C until the accumulation of iron compounds in the reaction mixture suspension of 1.72-1.85 mol / kg, after which stirring and bubbling are stopped, the suspension of the reaction mixture is separated from unreacted finely divided iron and (or) its alloy ( s) and on They are divided into hot filtration, where they remove carbon impurities from the reacted iron alloys, the filtrate is heated until the precipitated solid phase is eliminated, after which it is allowed to cool slowly to room temperature, the product precipitated into the solid phase is filtered and sent for drying or recrystallization, and the filtrate (solution mainly iron (III) compounds with impurities of iron (II) compounds are sent to download the second process. 2. The method according to claim 1, characterized in that the precipitates filtered by hot filtration are accumulated, and then the target product is separated from the finely dispersed carbon during recrystallization.