RU2255082C2 - Heterometallic neodymium (iii) and iron (iii) malate and a method for preparation thereof - Google Patents

Abstract

FIELD: inorganic synthesis.

SUBSTANCE: invention provides heterometallic neodymium (III) and iron (III) malate having formula I:

appropriate for synthesis of mixed oxides with perovskite structure, which are used as catalysts in oxidative catalysis of unsaturated acyclic hydrocarbons and as materials used in microwave frequency technology and in computer memory materials. Preparation consists in electrolysis of concentrated aqueous solution of neodymium (III) chloride and malic acid at 1:3 ratio in presence of pyridine with pressed reduced iron anode and inert cathode at anode current density 1 A/cm², followed by separating precipitate and washing it with organic solvent before drying.

EFFECT: enlarged assortment of oxidation catalysts.

2 cl, 1 dwg, 2 tbl

Description

The invention relates to coordination chemistry, more specifically to the production of heterometallic neodymium (III) malate and iron (III) of formula 1

used to obtain mixed oxides with a perovskite structure, which are widely used as catalysts in the oxidation catalysis of unsaturated acyclic hydrocarbons and as materials in microwave technology and computer storage devices.

Known heteronuclear containing d-elements of salicylidensemicarbazidates of rare earth elements [Samus N.M., Tsapkov V.I., Khoroshun I.V., Petrenko P.A., Gulya A.P. // Coord. chemistry. 2000, vol. 26, No. 4, S.300-304], of the general formula LnL ₃ · M (NO ₃ ) ₂ · nH2O, where Ln is the lanthanide (III) ion, M is Co (II), Ni (II) , L is a salicylidensemicarbazide ion obtained by adding to a suspension containing 10 mmol of rare earth salicylidensemicarbazidate in 50 ml of purified chloroform, with constant stirring on a magnetic stirrer, 10 mmol of cobalt (II) nitrate or nickel (II) nitrate dissolved in a minimum amount of methanol, s subsequent heating at 50-55 ° C under reflux for 1.5-2.0 hours, cooling, filtering, washing with chloroform, high Shivani in vacuo over silica gel. The isolated compounds are used to obtain mixed oxides with a perovskite structure, however, due to the high cost of the starting organic reagent, obtaining the desired product is not economically feasible.

The main heteronuclear acetate Fe (III) and Mg (II) of the composition [Fe ₂ MgO (CH ₃ COO) ₆ (H ₂ O) ₃ ] · 2H ₂ O is known [Antony B. Blake, Ahmad Yavari, William E. Hatfield, Sethulekshmi CN // J. Chem. Soc. Dalton trans 1985], obtained by adding to the solution of sodium acetate trihydrate (11 g in 8 ml of water) a solution of magnesium chloride (II) 0.01 mol and iron nitrate (III) 0.02 mol in 9 ml of water, separating the red-brown precipitate after 24 hours, filtering washing with water and alcohol and drying in air.

The closest analogue to the claimed compound are bridged hexa-nuclear complexes Ln (III) -Cr (III) of the general formula [Ln ₂ (μ-Ox) {Cr (Diru) (μ-Ox) (Ox)} ₄ (H ₂ O) ₆ ] · 13H ₂ O, where Ox-oxalate dianion, Ln = Pr, Gd, obtained by the interaction of complex particles [Cr (Dipy) (Ox) ₂ ] ^- with Ln (III) ions in the presence of dipyridine. [Zhang Xing, Cni Youg, Zhend Fakun, Huang Jinshun // Chem. Letl, 1999, No. 10, C.1111-1112].

The above compounds are used to obtain mixed oxides with a spinel structure, which, unlike mixed oxides with a perovskite structure, have not been widely used in optoelectronics.

A known method for producing heterometallic complex compounds with organic ligands described in [Garnovsky AD, Vasilchenko IS, Garnovsky D.A. Modern aspects of the synthesis of metal complexes. Basic ligands and methods. Rostov-on-Don, LaPO, 2000], which includes ion exchange reactions between the starting reagents. The disadvantage is the inability to obtain heterometallic iron malate (III) and neodymium (III) with malic acid in the above manner.

The closest analogue to the claimed method of obtaining is a method of obtaining complex compounds with REE [US Pat. 2191190 RF, IPC (7) C 07 F 5/00, C 07 C 49/92. A method of producing rare earth acetylacetonates / V.Yu. Frolov, V.T. Panyushkin, V.I. Zelenov. - No. 2001102640/04; Stated January 29, 2001; Publ. 10/20/2002; Priority 01/29/2001 // BIPM. - No. 29. - 4 pp.], According to which the REE acetylacetonates of the general formula Ln (AA) ₃ , where Ln is the lanthanide ion and AA is acetylacetone, were obtained by electrolysis of acetylacetone and lithium chloride in acetonitrile, taken in the ratio (1: 1: 500) with a rare-earth metal anode and an inert cathode with anode potential in the range of 0.5-1 V, using a single semiconductor diode connected in series with the electrolyzer to create an asymmetric alternating current. The precipitate formed as a result of electrolysis is separated, washed with absolute alcohol and dried.

The disadvantages of the prototype include the impossibility of obtaining in the described conditions a heterometallic malate of iron (III) and neodymium (III), and in addition the use of an expensive solvent of acetonitrile.

None of the proposed methods the claimed compound of formula 1 was not obtained.

An object of the invention is to obtain iron (III) malate and neodymium (III), during the pyrolysis of which mixed oxides with a perovskite structure are formed, in a simple, one-step method.

To solve the technical problem, it is proposed by electrolysis of a concentrated aqueous solution of neodymium (III) chloride and malic acid, taken in a ratio of 1: 3 in the presence of pyridine with an anode pressed from reduced iron and an inert cathode at an anode current density of 1 A / cm ² , s subsequent precipitation of the precipitate, washing it with an organic solvent and drying to obtain iron (III) malate and neodymium (III) malate of the general formula 1 NdFe (C ₄ H ₄ O ₅ ) ₃ · 5H ₂ O.

The proposed production method differs from the closest analogue in that it allows one to isolate the compound described by formula 1 by electrolysis of a solution of neodymium (III) chloride and malic acid in a ratio of 1: 3 in water instead of acetonitrile, in the presence of pyridine, with an anode pressed from reduced iron brand “h.ch” instead of an anode of rare-earth metal, the resulting solid product is separated, washed with ethanol and diethyl ether instead of absolute alcohol.

The drawing shows a diagram used to implement the proposed method.

The electrosynthesis of heterometallic neodymium (III) malate and iron (III) is carried out as follows:

make up an electric circuit (shown in the drawing), containing as a current source an adjustable step-down transformer 1 at 220 V, an electrolyzer 2, a rectifier diode 3 connected in series with a series of cd 226, an ammeter 4 at 100 mA, a voltmeter 5 at 100 V.

The electrolyzer 2, composed of a glass vessel (a thermostatically controlled beaker (298 K), in which two electrodes are placed - one pressed from reduced iron, the other from platinum or graphite (not shown), is filled with an electrolyte consisting of an aqueous solution of neodymium chloride (III) and malic acid, taken in a ratio of 1: 3, in the presence of pyridine.

The transformer 1 is set to the minimum output voltage, included in the AC circuit at 220 V 50 Hz and adjusted so that the voltmeter 5 shows the voltage between the electrodes 1-20 V, the current passing through the electrolyzer 2 should correspond to the anode current density of 1 A / cm ² calculated according to the ammeter 4. The use of diode 3 allows us to simplify the procedure for obtaining an asymmetric current, which leads to a decrease in the adhesion of the resulting compound to the anode. The product obtained by electrolysis is separated, washed with alcohol and diethyl ether, and dried.

Concrete example

Electrolyzer 2, equipped with two electrodes - one pressed from reduced grade “h.” Grade iron, the other from smooth platinum, was filled with an electrolyte consisting of an aqueous solution of neodymium (III) chloride 0.3 M and malic acid 0.9 M in the presence of pyridine, connected through a diode 3 to the transformer 1, the voltage established on the voltmeter 5 so that the density of anodic current, controlled by the ammeter 4, was 1 a / cm ^2, which is separated, after electrolysis formed precipitate was washed with ethyl alcohol and diethyl ether and sushi Whether in the air to a constant weight.

The metal content in the obtained compound was determined complexometrically: by joint titration of iron (III) and neodymium (III) EDTA with the xylenol orange indicator in urotropin buffer, in the presence of ascorbic acid; and titration of iron (III) EDTA with sulfosalicylic acid pH = 2-3 at 70 ° C; the content of neodymium (III) was found by difference. To determine the content of malate ions, an ion exchange reaction was used between the compound and KU-2-8 cation exchanger followed by titration of malic acid with alkali and phenolphthalein. The ratio of components in the compound was Fe: Nd: (C ₄ H ₄ O ₅ ) = 1: 1: 3. In addition, the complex compound contains 5 water molecules. The individuality of the obtained compound was confirmed by IR spectroscopic (see table. 1) and thermal analysis method (see table 2).

Formula of the compound: NdFe (C ₄ H ₄ O ₅ ) ₃ · 5H ₂ O

IR spectroscopic analysis method. A sample for recording IR spectra was prepared by pressing the test substances with KBr (10 mg of the substance per 200 mg of the total weight of the tablet)

From the data in Table 1, it follows that absorption bands are absent in the region of 1700-1750 cm ^-1 , and appear in the region of 1630-1500 cm ^-1 , which indicates the formation of an average salt.

Thermal analysis method. The heating rate of 10 deg / min, the temperature range of 20-1000 ° C.

table 2 Data of thermal analysis of NdFe (C ₄ H ₄ O ₅ ) ₃ · 5H ₂ O Δ T, ° C T _s ° C Δ m,% Δ N 65-230 13.8 230-255 245 5.3 > 0 255-325 6.4 325-385 340 20.2 > 0 385-450 420 5.3 > 0 450-600 560 12.73 > 0 65-1000 63.78

Thermal analysis showed that in the range of 65-230 ° C NdFe (C ₄ H ₄ O ₅ ) ₃ · 5H ₂ O loses crystallization water, and at a temperature of about 300 ° C it passes into mixed carbonate, which starts at a temperature above 325 ° C decompose and at 600 ° C turns into oxide.

A one-step, simple electrochemical method for the synthesis of heterometallic iron (III) malate and neodymium (III) is proposed. The proposed method is distinguished by the possibility of obtaining a high-purity target product of formula 1 in one step using more affordable and cheaper reagents: pyridine instead of dipyridine, water instead of acetonitrile, neodymium (III) chloride instead of metal neodymium, safety, which contributes to the further use of the method to obtain the desired product in industry.

Claims (2)

1. Heterometallic malate of neodymium (III) and iron (III) of the formula 1

used to produce mixed oxide with perovskite structure. 2. A method of obtaining a compound described by formula 1, comprising electrolysis of a solution of the starting components, taken in certain proportions, with an inert cathode, at an anode current density of 1 A / cm ² , precipitation, washing and drying, characterized in that the starting components are taken concentrated aqueous solutions of neodymium (III) chloride and malic acid in a ratio of 1: 3 in the presence of pyridine with an anode pressed from reduced iron; washing was carried out with alcohol with diethyl ether.