RU2269509C2 - Ferrous acetate preparation method - Google Patents

Abstract

FIELD: inorganic syntheses.

SUBSTANCE: method consists in that iron powder is oxidized in acetic acid/acetic anhydride (4%) medium with air oxygen bubbled through the medium, while maintaining iron-to-acetic acid molar ratio 5:1 and temperature 17-25°C. Reaction mixture is thoroughly stirred with blade stirrer at speed of rotation 720-1440 rpm until reaction mixture accumulates 0.75-0.96 mol/kg ferric salt. Thereafter, air is replaced by nitrogen and 4% acetic anhydride based on initially charged acetic acid is added, temperature is raised to 35-40°C, and iron is oxidized with ferric salt until full consumption of the latter. Resulting snow-white ferrous acetate suspension is separated from unreacted iron, filtered off, and dried. All above operations are carried out under a nitrogen atmosphere. Filtrate, which is saturated ferric acetate solution in acetic acid/acetic anhydride mixture, is recycled to reactor to be reprocessed or it is used according another destination.

EFFECT: simplified technology and improved economical characteristics of process due to use of inexpensive oxidant.

2 ex

Description

The invention relates to a technology for producing iron (II) acetate and can be used in various fields of industrial and laboratory chemistry, as well as in analytical control.

A known method for producing mercury acetate by the interaction of metallic mercury with peracetic acid formed from acetic acid and hydrogen peroxide directly in the reaction mixture in the presence of a catalyst (US Pat. No. 2873289, CL 556-131, publ. 1960).

Its disadvantage is that peracetic acid and hydrogen peroxide are too strong oxidizing agents so that in their presence iron (II) acetate remains as the target product and does not turn into a more stable iron (III) salt. In addition, the technology proposed in the patent is rather complicated and is based on a catalytic process, which always places high demands on minimizing the content of impurities in the system.

Closest to the claimed is a method for producing acetates of divalent copper, Nickel or cobalt by the interaction of the corresponding metal with acetic acid in a molar ratio of 1: 5.2-5.3 in the presence of oxygen at a temperature of 100-120 ° C and an oxygen pressure of 0.4-0 , 6 MPa (AS USSR No. 1097604).

The disadvantages of this method are:

1. A fairly high temperature of the process at which the solubility of oxygen will be small even at the used high pressure.

2. The use of oxygen instead of air implies certain conditions for the safe conduct of the redox process.

3. For the metals listed in the copyright certificate, the divalent state of the metal in salts is the most stable and common, which cannot be said about salts of ferrous iron. For this reason alone, it can be expected that a similar process for iron is hardly possible.

The objective of this solution is to obtain iron (II) acetate under conditions where iron, acetic acid and atmospheric oxygen will be used as initial reagents, at the same time at lower temperatures and without the use of excess pressure.

The task is achieved by the fact that the process is carried out in two successive stages without changing the reaction apparatus, time-lapse and reloading of reagents, and at the first stage, air is used as an oxidizing agent in the bubbling mode, and this stage is carried out under intense mechanical stirring with high-speed agitator of iron powder and acetic acid at a molar ratio of 5: 1 with the addition of acetic anhydride in an amount of 4% by weight of the loaded acid at a temperature of 17-25 ° C until iron (III) salt is accumulated in the system the amount of 0.75-0.96 mol / kg, after which the air supply is replaced by a nitrogen supply, add 4% of the mass of the initial load of acetic acid of acetic anhydride, increase the temperature to 35-40 ° C and conduct the second stage of the process until all the iron (III) salt accumulated in the first stage to form the iron (II) salt, which is separated in the form of a white suspension in the remaining liquid phase from heavy particles of unreacted iron, filtered and dried in a nitrogen atmosphere, and the filtrate formed during filtration is returned to the reactor for manual ultrasonic inspection process for re-use or for other purposes.

Characteristics of the raw materials used

Reduced iron according to TU 6-09-2227-81

Acetic acid according to GOST 61-75

Acetic anhydride according to GOST 5815-77

Atmospheric air without any additional purification

The process of the claimed method is as follows. The reactor, equipped with a high-speed paddle-type mixer, reflux condenser, bubbler and sampler, load the calculated amounts of acetic acid, acetic anhydride and powdered iron. Mechanical stirring is switched on, air is bubbled in and the process is carried out at ambient temperature until a certain amount of iron (III) salt is accumulated in the reaction mixture. Next, the air is replaced with nitrogen, the temperature is slightly increased, and stirring is continued until the entire iron (III) salt accumulated in the first stage does not turn into the iron (II) salt. At this point, stirring is stopped, the heavy particles of unreacted iron are allowed to settle to the bottom, after which a snow-white suspension of iron (II) acetate is separated from unreacted iron and sent for filtration. The precipitate is dried, and then dried to constant weight. Moreover, all this is done in a nitrogen environment. The filtrate formed during the separation of the solid salt of iron (II) acetate is sent to the reactor for loading for a second process or used for another purpose.

Example No. 1.

In a 483 ml reactor equipped with a paddle-type Teflon stirrer (720 rpm), a reflux condenser providing a free exit of the reactor gas space into the atmosphere, a bubbler and a sampler allowing sampling without stopping mixing, load 205.9 g of ice acetic acid, 8.2 g of acetic anhydride and 38.44 g of reduced iron powder with a maximum linear particle size of not more than 0.6 mm. The molar ratio of acid to reducing agent in the initial charge is 5: 1. The initial temperature is 17 ° C. Mechanical stirring and air bubbling are included with a flow rate of 0.23 l / min. In this mode, the process is conducted until the accumulation in the reaction mixture of iron (III) salts in the amount of 0.96 mol / kg This happened after 139 minutes.

Without stopping mixing, replace the air with nitrogen, increase the temperature of the reaction mixture to 35 ° C, add 8.2 g of acetic anhydride and periodically monitor the content of the iron (II) salt and iron (III) in the reaction mixture. After 87 minutes of the second stage, the analysis showed an almost complete absence of an iron (III) salt in the reaction mixture.

Stirring is stopped, 5 minutes are allowed to settle and localize particles of unreacted iron in the region of the spherical bottom of the reactor, the air outlet from the reflux condenser is blocked, and a snow-white suspension of iron (II) acetate is sent to the filtering unit through the side pipe located near the bottom of the reactor. Automatically, a nitrogen flow is also directed to this assembly, which provides some drying of the filter cake. Subsequently, this precipitate is dried in an oven in a nitrogen atmosphere. And the filtrate, which is a saturated solution of iron (II) acetate in a mixture of acetic acid and acetic anhydride, is sent to the reactor for loading for a second process or for use for other intended purposes.

The dry weight of iron (II) acetate is 56.1 g, the content of iron (II) acetate in the filtrate and in the reactor is 1.2 g. Thus, the product yield is 99.3%.

Example No. 2.

The reactor and its equipment are similar to those described in example 1. The volume of 519 ml, the rotation speed of the stirrer 1440 rpm The mixer is made of stainless steel.

The initial loading of acetic acid 231.81 g, acetic anhydride 9.27 g, reduced iron 43.26 g. The initial temperature of 25 ° C. Air consumption 0.27 l / min. After 103 minutes of conducting the process with stirring under the indicated conditions, the iron salt content in the reaction mixture turned out to be 0.75 mol / kg.

Without stopping stirring, replace the air with nitrogen, add 9.27 g of acetic anhydride, increase the temperature of the reaction mixture to 40 ° C, and after 79 minutes of the second stage, only the iron (II) salt was present in the reaction mixture.

The isolation of the product is similar to that described in example 1. The mass of dry iron (II) acetate was 45.6 g and ~ 2 g remained in the reactor and returned with the filtrate, i.e. yield 99.4%.

The positive effect of the proposed solution is as follows.

1. The process conditions are very soft, the hardware is simple and does not require any special solutions.

2. An available natural oxidizing agent is used.

3. There are no foreign contaminants in the load. Therefore, the purity of the resulting product will be completely determined by the purity of the iron used.

4. Isolation of the product occurs by simple filtration of the suspension.

Claims (1)

A method of producing iron (II) acetate by the interaction of a metal with acetic acid in the presence of an oxidizing agent, characterized in that the process is carried out in two successive stages without changing the reaction apparatus, time-lapse and reagent loading, moreover, air is used as an oxidizing agent in the first stage in bubbling mode, and this stage itself is carried out with intensive mechanical stirring by a high-speed stirrer of iron powder and acetic acid at a molar ratio of 5: 1 with the addition of acetic anhydride in an amount of 4% of m ss of the loaded acid at a temperature of 17-25 ° C until the accumulation of iron (III) salts in the amount of 0.75-0.96 mol / kg, after which the air supply is replaced by a nitrogen supply, 4% of the mass of the initial charge of acetic acid is added acetic anhydride, increase the temperature to 35-40 ° C and lead the second stage until all of the iron (III) salt accumulated in the first stage is completely consumed for the formation of the iron (II) salt, which is separated from heavy particles of unreacted in the form of a snow-white suspension in the remaining liquid phase iron, filtered and dried in the atmosphere nitrogen, and the filtrate formed during filtration is returned to the reactor for loading for a second process or used for another purpose.