RU2177910C1 - Method of preparing anhydrous iron (ii) chloride containing blend - Google Patents

Abstract

FIELD: chemical industry, more particularly organic and organometallic compounds. SUBSTANCE: device provided with stirrer and cooling jacket is charged with mixture of iron (III) chloride, aluminium powder and inert material, e. g. activated carbon, Al₂O₃ or SiO₂ at weight ratio of 100.0: (4.0-6.0): (4.0-7.0) of said components, and the whole is agitated till homogeneous mixture is formed. Mixture is thermally initiated with red hot nichrome spiral or thermal match. Process then occurs authomatically and heat is liberated to prepare anhydrous iron II chloride-containing blend which comprises, wt %: FeCl₂; 82.0-84.4; FeCl₃, 0.0-1.5; AlCl₃, 6.3-8.9; and inert material, 7.6-9.3. Blend is used without additional treatment. Yield of ferrocene is increased to 84% and yield of dicyclopentadiene up to 85.75% of theoretical amount. EFFECT: simplified method and reduced process temperature. 2 cl, 7 ex, 1 dwg, 1 tbl

Description

 The invention relates to chemical technology, in particular to the production of anhydrous iron (II) chloride, and can be used in the processes of producing organic and organometallic compounds, for example, for the monomerization of dicyclopentadiene and the production of ferrocene.

Well-known methods for producing iron (II) chloride (FeCl ₂ ), in which the following reactions are realized:
Fe + 2CHl (decomp.) 9 -> FeCl ₂ + H ₂ ; (1)
FeO + 2НСl (decomp.) -> FeCl ₂ + Н ₂ O; (2)
Fe (OH) ₂ + 2HCl (decomp.) -> FeCl ₂ + 2H ₂ O; (3)
2 FeCl ₃ + 2H ₂ 0 + S0 ₂ -> FeCl ₂ + H ₂ SO ₄ + 2HCl; (4)
2 FeCl ₃ + Fe -> 3 FeCl ₂ ; (5)
2FeCl ₃ + 2KI -> 2FeCl ₂ + I ₂ + 2KCl; (6)
In these methods, to obtain anhydrous iron (II) chloride, the next stage of the process is the evaporation of water and dehydration in an inert gas stream at a temperature above 230 ^o C.

 The use of non-aqueous solvents, for example tetrahydrofuran, somewhat simplifies the process, but is associated with the use of toxic and flammable substances, which limits their use.

Anhydrous iron (II) chloride can be directly obtained by the implementation of the following reactions:
2FeCl ₃ + H ₂ -> 2FeCl ₂ + 2HCl (T = 250-300 ^° C); (7)
2 FeCl ₃ + 2H ₂ S -> FeS ₂ + FeCl ₂ + 4HCl; (8)
Fe + 2HCl -> FeCl ₂ + H ₂ (Т = 500 ^o С). (9)
In methods 7-9 it is necessary to create high temperatures, significant energy consumption, and the use of toxic and fire hazardous reagents (Н ₂ , H ₂ S, НСl) entails certain difficulties in their industrial use (R. A. Lidin, V. A. Molochko, L. L. Andreeva. Chemical properties of inorganic substances, 11 edition, M.: Chemistry, 1997).

A known method of producing anhydrous iron (II) chloride, mainly used for monomerization of dicyclopentadiene, by reacting iron (III) chloride with chlorobenzene at a temperature of 135-140 ^o C in a stream of nitrogen for 5-6 hours. Iron (II) chloride is filtered off, washed with benzene and dried (M.E. Pozin. Technology of mineral salts, fertilizers, pesticides, industrial salts, acid oxides. Part I. L.: Chemistry, 1974).

 This method involves the use of toxic and flammable chlorobenzene, as well as the need for disposal of the resulting dichlorobenzenes and hydrogen chloride. In addition, this method is energy-intensive, significant production waste, and the use of expensive reagents increases the cost of products of subsequent processes.

Closest to the claimed is a method for producing anhydrous iron (II) chloride, used subsequently in the form of the obtained mixture in the reaction of synthesis of ferrocene, by direct dechlorination of iron (III) chloride at a temperature of at least 500 ^o C for 2-3 hours. Heating and cooling the mixture is carried out in a stream of nitrogen with constant mixing of the mixture. The chlorine released during this is trapped by alkali.

 The resulting mixture contains up to 5-10% of iron (III) chloride. (R. A. Lidin, V. A. Molochko, L. L. Andreeva. Chemical properties of inorganic substances, 11 ed., M.: Chemistry, 1997, p. 420). The disadvantage of this method is its extreme energy intensity and the need for disposal of the released chlorine.

 The objective of the present invention is to simplify the method of producing iron (II) chloride by reducing the process temperature and energy consumption.

 The second objective of the invention is to obtain anhydrous iron (II) chloride, which without further processing can be used in further processes of the synthesis of ferrocene and monomerization of dicyclopentadiene.

 The problem is solved in that anhydrous iron (II) chloride-containing mixture is obtained by dechlorination of iron (III) chloride in the presence of aluminum powder and inert material, taken in a ratio of 100: 4-6: 4-7 (wt.), Respectively , and the process is conducted in a stream of nitrogen by thermal initiation of the said mixture.

 As an inert material, activated carbon, alumina, silica are used.

In the claimed method, the following reactions are implemented:
3FeCl ₃ + Al -> 3FeCl ₂ + AlCl ₃ ; (10)
2FeCl ₃ -> 2FeCl ₂ + Cl ₂ ; (eleven)
2Al + 2Cl ₂ -> 2AlCl ₃ , (12)
moreover, reactions 10, 12 proceed with the release of heat, and reaction 11 with its absorption. The heat generated in reactions 10, 12 is sufficient to carry out reaction 11 and sublimate the resulting aluminum (III) chloride.

 The drawing shows a General diagram of a plant for producing iron chloride (II) -containing charge. The process is conducted as follows.

 In the reactor 1, equipped with a stirrer and a cooling jacket, is loaded a mixture consisting of anhydrous iron (III) chloride, aluminum powder and an inert material. Inert material is introduced to slow down the reaction rate and loosen the mixture. As an inert material, quartz sand, aluminum oxide or activated carbon is used. The use of activated carbon is preferable, since it has a less abrasive effect with respect to the walls of the reactor, and also sorbes chlorine released on its surface. Next, nitrogen is supplied to reactor 1 to displace air and a stirrer is turned on to average the composition of the charge.

 The next stage is the thermal initiation (ignition) of the charge. For this, a “ignitor” is introduced into the cavity of the reactor until it comes into contact with the charge, which is a hot nichrome spiral. As a pilot light, you can use a termite match burning without access to air.

 After ignition, the reaction proceeds autothermally with heat. In this case, the formed aluminum chloride, iron (II) chloride and unreacted iron (III) chloride are partially distilled off in a stream of nitrogen. After completion of the reaction (about 1 h), the products are cooled by feeding a refrigerant to the jacket and discharged from the reactor. The anhydrous aluminum and iron chlorides removed from the reactor 1 are sublimated and precipitated in the collector 2. The iron and aluminum chlorides that have passed through the collector 2 and a possible small amount of chlorine are absorbed by water in the absorber 3.

 Iron (II) chloride-containing mixture obtained by thermal initiation of a mixture of iron (III) chloride, aluminum powder and activated carbon taken in predetermined proportions is characterized by the content of iron (II) chloride, iron (III) chloride, aluminum (III) chloride in it and activated carbon in ratios, respectively, wt. %: 62.5-84.4: 0.0-24.4: 6.3-8.9: 4.6-8.1.

 The following examples illustrate the claimed method.

The process was carried out using the following reagents: iron (III) chloride (FeCl ₃ ), TU 6-00-5763450-129-91; aluminum powder (Al), GOST 5494-95; activated carbon AGI-2, TU 6-17-05795748-179-9.

Example 1. In a steel apparatus equipped with a stirrer and a cooling jacket, 800 g of iron (III) chloride, 32 g of aluminum powder and 32 g of activated carbon (reagent ratio (parts by weight) of 100: 4: 4) are placed and mixed until formation homogeneous mixture. The mixture is ignited (thermally initiated). For this, a “igniter” is introduced into the reactor cavity until it comes into contact with the charge, which is a hot nichrome spiral or a termite match burning without air. Next, the process goes automatically with heat. As a result of the exothermic process, 685.3 g of iron chloride (II) -containing charge of the composition, wt. %: FeCl ₂ - 62.5; FeCl ₃ - 24.4; A1Cl ₃ - 8.5; activated carbon - 4.6.

 Examples 2-7 of obtaining anhydrous chloride of iron (II) -containing charge are summarized in table.

 Use for thermal initiation of components in ratios higher or lower than those specified (examples 6, 7) leads to spontaneous combustion of the mixture or complete absence of its combustion.

 Iron (II) chloride-containing charge can be used in various processes of organic and organometallic chemistry, where anhydrous iron (II) chloride is required. The method is simple to perform and does not require additional costs for the absorption of chlorine. The generated heat can be disposed of.

 When using iron chloride (II) -containing a mixture obtained according to the claimed method, for the synthesis of ferrocene, the yield of the latter rises to 84%. This reduces the time of the process, reduces resin formation due to the catalytic effect of aluminum chloride contained in the mixture.

During the monomerization of dicyclopentadiene, iron (II) chloride-containing mixture inhibits the polymerization process and increases the yield of cyclopentadiene to 85.75% of theoretical at 150-200 ^o C.

Claims (2)

 1. The method of obtaining anhydrous chloride of iron (II) -containing charge by dechlorination of iron (III) chloride in a stream of nitrogen, characterized in that the dechlorination of iron (III) chloride is carried out in the presence of aluminum powder and inert material taken in a mass ratio of 100: ( 4-6): (4-7), respectively, and the process is conducted by thermal initiation of the mixture.  2. The method according to p. 1, characterized in that as an inert material using activated carbon, aluminum oxide or silicon oxide.

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