Method for preparing ferrous (ii) acetate

FIELD: chemical technology.

SUBSTANCE: invention relates to a method for preparing acetic acid salts, in particular, anhydrous ferrous (II) acetate. Method for preparing anhydrous ferrous (II) acetate involves interaction of metallic iron with acetic acid in the presence of oxidizing agents of ferric oxide Fe₂O₃ or Fe₃O₄ and molecular iodine in the mole ratio acetic acid : acetic anhydride : iron oxide = 100:(6-20):(2-2.5), respectively, and in the mole ratio iron oxide : iodine = 100:6.3. The process is carried out at temperature 80°C in the beaded mill of vertical type with high-rotation blade mixer and reflux condenser in the mass ratio of glass beads and liquid phase in the charge = 1:1. The process is carried out with periodic taking off samples of the end product solid phase by filtering and the following recover filtrate and feeding with acetic acid and iron oxide. For compensation of components loss of liquid phase in filtering there are recovered into reactor to the repeated process that is carried out for four times at a time. All procedures of the basic process and filtration are carried out in nitrogen medium. Preferably, method involves using hematite, γ-oxide, iron minium, magnetite or Fe₃O₄ x 4 H₂O as the iron oxide source. Invention provides possibility for preparing anhydrous ferrous (II) acetate and simplifying method due to excluding the evaporation stage in isolation of salt.

EFFECT: improved preparing method.

3 cl, 2 tbl, 8 ex

The invention relates to a technology for obtaining salts of acetic acid, in particular acetate anhydrous iron (II), which is used in various industries, analytical and applied chemistry.

A method of obtaining acetates of divalent copper, Nickel or cobalt dissolution of metals in acetic acid under oxygen pressure of 0.4-0.6 MPa at 100-120°and the molar ratio of metal:acetic acid 1:5,2÷5,3 (A.S. USSR №1097604).

The downside of it is quite high-temperature process in which the solubility of oxygen as oxidant in the liquid phase is very small, even when using high pressure.

Closest to the claimed is a method of producing acetate cobalt (A.S. USSR № 1728222), according to which as oxidant use hydrogen peroxide or peracetic acid, which is mixed with acetic acid in a molar ratio of 1:2 served continuously in the upper part of the column is filled with the metal cobalt with a specific surface area 1-1000 cm²/g with simultaneous selection of the bottom of the column an aqueous solution of cobalt acetate and evaporation of the latter with the aim of identifying the product by crystallization.

The disadvantages of this method are:

1. In anorganische environment determine udalenie the target product by evaporation, that is a separate process (or stage), very energy intensive and also long, and with the melt, the prospects for utilization of steam.

2. From water-organic media crystallizes only hydrated, in this case, for example, With(C₂H₃O₂)₂·4H₂O, but not the anhydrous salt.

3. Used oxidant (hydrogen peroxide, in particular) in no way reflected in the weight of the resulting product, although it takes a direct part in the intermediate stages of this complex multi-stage redox process.

4. Cobalt with a specified specific surface need to get.

5. The model of this process is unlikely to be implemented for iron, because the acetate of iron (II) in solution is very sensitive to oxygen and is easily oxidized in basic acetate of iron (III). Hydrogen peroxide and percolate oxidize acetate iron (II) salt of iron (III) almost instantly. Therefore, even in an inert atmosphere, but with such oxidizing agents more realistic receive basic acetate of iron (III), but not acetate iron (II), not anhydrous and hydrated.

The objective of the proposed solutions is to receive acetate anhydrous iron (II), to avoid a stage evaporation in the allocation of the specified salt is the quality of the target product, and to use an oxidizer, which would bring a significant contribution to the mass produced product.

This object is achieved in that the oxidizer take iron oxide Fe₂About₃or Fe₃O₄and molecular iodine in the initial molar ratio of 100:6,3, and the process is conducted in a reactor of the type bead mill with glass beads in a mass ratio of the liquid phase of 1:1 with high-speed mechanical stirrer and reflux-condenser in a nitrogen atmosphere with the use of iron in the form of a coiled-type shells tape with equal working height of the side surface of the reactor height and initial loading of acetic acid, acetic anhydride and iron oxide in a molar ratio of 100:(6÷20):(2÷2,5) at 80°With periodic sampling of the solid phase of acetate of iron (II) by filtration in a nitrogen atmosphere, returning the filtrate together with the feed consumed by the formation of acetate of iron (II) acetic acid and iron oxide, as well as compensation of losses of acetic acid anhydride and iodine during the filtration process in the reactor to repeat the process. The Fe₂About₃take hematite, γoxide, iron oxide red, and as Fe₃O₄magnetite and Fe₃O₄·4H₂Oh, and repeated the process carried out at least four times in a row.

Characteristics of ispolzuemogo raw materials

The reactive iron in THE 6-09-2227-81

Iron carbonyl radio brand R-20 GOST 13610-79

The iron oxides:

hematite according to GOST 4173-77

minium on THE 113-00-38-160-96

γoxide according to GOST 3 540-82

magnetite according to GOST 26475-85

Iodine crystal according to GOST 4159-79

Acetic acid according to GOST 61-75

Acetic anhydride according to GOST 5815-77

Steel 3 on CMTU 1-84-67

The process of the inventive method the following. In ball mill vertical type with glass (for reactive product purity) or steel (for technical product) housing and the agitator vane type of dense and inert plastic or steel, and with a reflux-condenser is placed with a small gap to the chassis bent-type shell of iron or steel tape with a height that meets the working height of the reactor. Connect the mill shell with cover with stuffing box mixers, accessories for temperature control, sampling and providing gas flow and loading nozzle. Through the latter enter the estimated amount of the mixture of acetic acid and acetic anhydride, and oxide of iron, iodine and glass beads as pereirago agent. Include stirring and heating. Then organize duct nitrogen through the gas space of the bead mill. The exit temperature is URS the specified mode remains of the oxygen in the air is almost completely spent on chemical transformations and, from this point, the main raw material for producing acetate become iron oxide and iron. The solubility of acetate of iron (II) in the selected environment and conditions, it is quite small and after a short time all resulting in further salt goes into the solid phase. From this point, the reaction mixture turns into a corresponding complex suspension with solid phases of iron oxide and salt. Upon reaching almost total consumption of iron oxide suspension acetate iron (II) through a grid at the bottom of the pipe mill to separate from the glass beads is directed to filtration, then the filtrate is recycled back to the reactor, hold enter another portion of iron oxide, as well as recharge spent on the formation of acetate of iron (II) acetic acid and compensation of loss of components of the liquid phase during the filtration, then repeated the process of obtaining the target salt. Recharge acetic anhydride and iodine for such compensation shall be allowed to not every time. The process stops if necessary, recharge the tape or after obtaining the required amount of salt.

Drying the filtered salts is carried out in a nitrogen atmosphere.

Example 1

In the glass case vertical bead mill type internal diameter of 63.7 mm and a height of 109 mm insert a shell of the floor is si iron of a thickness of ˜ 0.8 mm with an external diameter of ˜62 mm, height 65 mm and weight 77,85, After this case is connected to the fixed stationary on the frame cover with a mechanical stirrer vane type of Teflon and reflux-condenser. Through the loading hatch in the lid consistently give 110,85 g of glass beads with a diameter of 0.9÷1.6 mm, 100 g of glacial acetic acid, 10.2 g of acetic anhydride, to 6.67 g of hematite and 0,667 g of molecular iodine. Close the loading door, down a liquid heating bath from below so that the working part of the bead mill was immersed in a preheated to 65°With fluid again include heating in the bath include mechanical stirring agitator bead mill with the speed of 1260 rpm and serves duct nitrogen through the gas space of the reactor with a flow rate of 0.28 l/min After 20 min the temperature in the reaction zone reaches 80°C. Stabilize the temperature at this level and carry out the process within 140 min, holding control over the expenditure of the oxide by the method of sampling and analysis of samples. During this time, almost all the input hematite have time to fully react in salt, the bulk of which is in the solid phase.

The resulting suspension with a uniformly distributed through the volume of the solid phase direct in nitrogen atmosphere for filtration, then the filtrate to the number of 91.6 g return in a bead mill to repeat the process. With him is injected into the reactor 19 g of glacial acetic acid and 6.7 g of hematite as compensation unreacted reagents and loss of the liquid phase during the filtration process. Stabilize the temperature at 80°and conduct proceedings for 110 min, which all entered the second time hematite time to change into acetate of iron (II). Spend again the separation of the reaction mixture from beads, filtration of the solid phase of acetate of iron (II), the return of the filtrate in number to 91.1 g of bead mill, enter a new portion of hematite aid of acetic acid and other components of the liquid phase. Next, perform a stabilization of the temperature, the following process for 135 min, then the cycle departments, aid, following repeated the process, etc.

In particular, in the second, third and fourth re-processes the input hematite amounted to 6.7 g each time, the input of acetic acid was 20, 20, and 22 g of acetic anhydride, 1.5 g of molecular iodine on 0,114 g before the third and fourth re-processes. The duration of the second, third and fourth re-processes 114, 97, and 105 minutes For five consecutive processes the received 104,7 g dried in nitrogen atmosphere acetate iron (II). The content of acetate of iron in suspension before filtration fluctuated in the range of 1.00-1.15 mol/kg Further accumulation of the product in suspension was necelesobrazno the output due to a sharp reduction in the flow speed of the chemical interactions in such conditions.

Examples 2-7.

The reactor, the boot order of the reagents, the sequence of operations of the process, separating the suspension from the beads and solid acetate of iron in the slurry, the temperature mode, the number of retry processes similar to those described in example 1. Different nature of the iron oxide and the molar ratio of acetic acid: acetic anhydride: iron oxide, dozagruzki to repeat the process. The results obtained are summarized in table 1

Example No. 8.

In a ball mill made of stainless steel which has the dimensions: diameter 80 mm, height 200 mm, wall thickness 11 mm, with a smaller gap insert a shell of steel 3 height 110,9 mm and weight 384,5, the Housing shell is connected to the lid with a paddle stirrer, reflux-condenser and a loading opening. The agitator shaft with a flexible coupling connected to an electric motor rigidly mounted on the upper platform of the skeleton frame. Through the charging port injected 350 g of glass beads with a diameter of 0.9÷2.1 mm and 350 g of a mixture containing 298,4 g of glacial acetic acid and 50 g of acetic anhydride. Next enter 1,60 g of solid iodine and 23,15 g of magnetite. The molar ratio of acetic acid: oxsny anhydride: iron oxide 100:9,86:2 and the molar ratio of iron oxide: iodine 100:6,3. Close C the loaders hatch, serves duct nitrogen with a flow rate of 0.36 l/min through the gas space of the bead mill, the last case is placed in moving along the longitudinal axis of the reactor, heating the liquid bath, include heating the latter and mechanical stirring in a bead mill, paddle mixer with a speed of 1440 rpm Deduce the temperature at 80°, which took 37 minutes Stabilize the temperature at this level and in such conditions continue stirring for 75 minutes the Results of the control method of sampling show that by this time, almost the entire magnetite reacted and content of molecular iodine in the reaction mixture is close to zero.

Stop stirring bead mill, the heating bath is lowered down so that the drain pipe of the mill building, containing in the upper part of a screen to separate the beads from the suspension of the reaction mixture, was available for connection to the node filtering, perform this connection, using it as a cooler for cooling the suspension, open the shutoff valve on inlet and conduct filtering acetate iron (II). When this duct nitrogen through the gas space of the bead mill is redirected to the node filtering.

The filtrate is returned to repeat the process, increasing its mass by the addition of 52 g of uksosn the th acid and 3 g of acetic anhydride in order to compensate for the expenditure of the first to the formation of salt as well as inevitable during the filtration loss (wetted sediment, the walls of the filter, the receiving tank and so on). Metered and 23.2 g of magnetite, and then perform all operations on output and temperature stabilization, process control, an end to the separation of the solid product, the actual separation by filtration and repetition just described for the second repeated the process. Just spent four repeated process, although restrictions on the possible number of them are not identified. The question is, how fully and successfully conducted the compensation of acetic acid, acetic anhydride and iodine before each repeated the process. Made options are summarized in table 2

Table 2

For these five processes received 331,7 g of dry solid acetate iron (II), n is that spent 534 min (re-processes: the first 23+84, the second 27+77, the third 19+80 and fourth 21+91) of them at the conclusion of temperature on the mode 127 minutes also remained 308 g of the solution of acetate of iron (II) in a mixture of acetic acid and acetic anhydride with the addition of iodine (mostly in the form of FeJ₂), which can be used to continue the process in the subsequent repeated the process.

The positive effect of the proposed solution is as follows:

1. This process does not require high temperatures and is quite simple in hardware design. It uses the available raw materials, and not necessarily reactive purity.

2. The selection of product is not an independent phase, and occurs during the process. Thus instead of energy-intensive and prolonged evaporation is used much more easy filtering.

3. Received the product in anhydrous environment does not contain water of crystallization. Therefore, do not need special stage to remove it.

4. Major contamination of the product is accounted for iodide iron (II) and to a lesser extent on the molecular iodine. These impurities can be removed by recrystallization of the product from a mixture of acetic acid and acetic anhydride. Moreover, obtained after separation of the recrystallized product, the filtrate is returned to the main process either as the original liquid medium, either as podpitat what's liquid phases.

1. The method of obtaining acetate iron (II), the interaction of metallic iron with acetic acid in the presence of an oxidizer, wherein the oxidizer agents take iron oxide Fe₂O₃or Fe₃O₄and molecular iodine in the initial molar ratio of 100:6,3, and the process is conducted in a reactor of the type bead mill with glass beads in a mass ratio of liquid phase loading 1:1, with high-speed mechanical stirrer and reflux-condenser in a nitrogen atmosphere with the use of iron in the form of a coiled-type shells tape a height equal to the working height of the side surface of the reactor, and the initial loading of acetic acid, acetic anhydride and iron oxide in a molar ratio of 100:(6÷20):(2÷2,5) at 80°C, with periodic sampling of the solid phase of acetate of iron (II) by filtration in a nitrogen atmosphere, returning the filtrate together with the feed consumed by the formation of acetate of iron (II) acetic acid and iron oxide, as well as compensation of losses of acetic acid anhydride and iodine during the filtration process in the reactor to repeat the process.

2. The method according to claim 1, characterized in that the iron oxide used hematite, γoxide, red iron oxide, magnetite and Fe₃O₄·4H₂O.

3. The method according to claim 1, characterized in that the re process PR is lead not less than four times in a row.