SU953008A1 - Process for producing metal alcoholates - Google Patents

Description

(54) METHOD FOR PRODUCING METAL ALCOHOLATES

one

The invention relates to an improvement in the process for the production of metal alcoholates, which are valuable intermediates for the preparation of catalysts and oxide ceramics used in the electronics industry.

A known method for the preparation of Ta, Ge, Si, Ti, and Zr ethylates is by electrochemical anodic dissolution of the corresponding metal in the electrolyte containing SEC or (Cll). The electrolysis is carried out with a direct current at the boiling of the electrolyte, with a voltage of 40-60 V, current of 2 A, using a graphite cathode. 70-78% 1.

However, this method is feasible for a limited number of metals.

There is also known a method for producing silicon ethylates by electrochemical anodic dissolution of a ferrosilicon anode in a drainage solution of the electrolyte Fe2 (804) 3 or using a graphite cathode. The electrolysis is carried out at a voltage of 70 V, a current of 2 A, and the desired product is obtained with a yield of 60% 2,

The disadvantage of this method is 1; cue yield of the desired product.

In addition, a method of producing ethylates of iron, cobalt and nickel is known by electrochemical-anodic dissolution of the corresponding metals in an alcohol electrolysis solution containing lithium perchlorate and lithium bromide. The electrolysis is carried out at the boiling of the electrolyte, a voltage of 50-60 V, current of 1.5 A,

10 using a graphite cathode. Exit 75% 3.

In this case, the implementation of the method is also limited by a small amount of metals.

15

The closest to the invention to the technical essence is a method of producing metal alcoholates with atomic numbers 14-82 by electrochemical anodic dissolution of the corresponding metals by direct current in an electrolyte containing alcohol and an electrically conductive additive of the formula, where R is hydrogen or alkyl, X -halogen.

25 For synthesis, a cell with unseparated anodic and cathodic spaces is used, equipped with a stirrer, and two electrodes — one of graphite (cathode) and the other of the corresponding metal (anode). Electrochemical dissolution of the andes occurs at a current of 0.5-2, and a voltage of 40-60-V. NH.ce and (. Electrosynthesis is carried out at the boiling point of electrolyte. The yield of the final products is 68-78%. 4. The disadvantage of this method is the complexity of the hardware design of the synthesis, the inability to synthesize the alcohol of a number of metals , comparatively low yields of final products. The purpose of the invention is to simplify the process and increase the yield of alcoholics. The goal is achieved by a method for producing alcohols of the metals of the general formula M (OR) n, where M is a metal selected from the group of titanium, magnesium, alum ini, scandi, yttri, gallium, zirconium, hafnium, niobium, tantalum, iron, cobalt, nickel, lanthanum; R is normal or iso-alkyl; n is an integer from 2 to 5, by electrochemical solution of anode from the corresponding metal or its alloy in the electrolyte containing alcohol and an electrically conductive additive, in which salts of the general formula KX are used, where K is a cation selected from the group of alkali metal, aluminum, or quaternary ammonium base, X is chlorine, bromine, iodine, BF, PF, taken in an amount of 2-20 wt.% at the boiling point of the electr and performing that process by using the AC power frequency. It is advisable to add acetonitrile, dimyl sulfoxide, dimethylformamide, and benzene in an amount of 1–20 wt.% To the electrolyte. Additionally added solvents, e.g. acetonitrile, dimethylformamide, dimethyl sulfoxide, lead to; an increase in the electrical conductivity of the solution, since polar solvents have a dielectric constant higher than that of some alcohols (especially higher alcohols); The introduction of nonpolar solvents (benzene, toluene) into the electrolyte leads to the fact that this solvent is well adsorbed on the electrode and thereby improves the dissolution of alcohols, which are poorly soluble in alcohol. Carrying out the process according to the proposed method allows to simplify the process by eliminating the use of alternating current rectifiers and to increase the yield of metal alcohols obtained by electrochemical method (PL). The synthesis of alcohols at a constant current is carried out in two. Din: anodic process — synthesis of alkoxohalides of the corresponding metals (halogen ion from an electrically conductive additive) and cathodic process; recovery of intermediate intermediates at the cathode to form the target product — an alcoholate of the corresponding metal. According to known data, in the cathode reduction of metal chlorides in alcoholic solutions at the cathode, hydrogen evolution and the formation of metal alcoholates are observed. Thus, for the synthesis of alcohols of metals on a constant current, the intermediate alkoxohalides migrate from the anode to the cathode, which requires intensive mixing. In addition, as a result of a local (anode) increase in the concentration of alkoxohalides, an anode potential increases and, as a result, alcohol decomposes to form olefins and oxo or hydroxo compounds are formed on the anode, which contaminate the product and reduce the current and substance output. The use of direct current also prevents the synthesis of a number of alcohols, whose intermediate products — alkoxohalides are insoluble in the electrolyte and cannot be transferred from the anode to the cathode. When the process is conducted in alternating current, intermediate products (metal alkoxohalides) are formed in the anodine: half period, and their recovery to the corresponding alcohols is observed in the cathode n-period. In this case, there is no need for intensive mixing, since both stages of the synthesis occur in the cell (on the electrode surface); there is no need for solubility of these intermediate intermediates; the rapid change in the potential of the electrode surface does not create a local excess of the concentration of alkoxohalides and does not lead to the decomposition of alcohol. Example 1. For electrolysis, a glass cell equipped with a thermostating jacket, a thermometer immersed in an electrolyte, and two flat titanium electrodes are used. The electrolyte contains 100 ml of absolute ethyl alcohol, pre-dried with calcium or aluminum alcoholate, and 5% tetraethylammonium bromide. The electrolysis is carried out at 70 ° C using an alternating current with a frequency of 50 Hz (± 10%) with a current of 0.5 A and a voltage of 220 V. During 13 P min of electrolysis, 1.6 g of tetraethoxytitanium are obtained with a mp. 40c, bp 135/5 mm. The resulting product was distilled in vacuo. The yield of tetraethok of a sitan with respect to the effective current is 72%, and with respect to the substance - 91%. The effective current output is determined as follows. The output of r8-Jf 100%, At mol weight: weight of the obtained product, g; the number of electrons (corresponds to the number of OR groups); AC amplitude. BUT; duration of electrolysis, h; mole weight is the molecular weight of the produced alcoholate. The substance yield is determined by reducing the weight of the electrodes by the formula atom weight. where m is the weight of the obtained product, g; 01 - loss of weight of the electrodes, g; mole weight is the molecular weight of the alcohol produced; atom weight is the atomic weight of the metal used. 10 Examples 2-14. Analogously to example 1, the synthesis of metal alkoxides is carried out. Table 1 shows the material of the anode, the process temperature, the composition of the electrolyte, the target product, the output (current and substance) and its characteristics. The separation of liquid alcohols at room temperature is carried out by distillation in vacuo. The crystalline alcohols are isolated by filtering the solution after it is cooled to room temperature. Table 2 shows the elemental analysis data of the compounds obtained. Comparative examples 16-22. For comparison, the electrosyntheses of a number of metal alkoxides were carried out analogously to example 1, but using direct current. In these synthees, anodes from the corresponding metal are used, and short-circuit cathodes of graphite, platinum, or metal, similar to the anode. The substance yield in these experiments cannot be accurately determined due to partial incidence of the anode material. If you do not take into account the precipitation, the outputs are in the range of 67-82%. As can be seen from the data of Table 1, the yield of the target products by electrolysis using alternating currents is 87-97%. As for the synthesis of alumina lanthanum, its synthesis is possible only with the use of alternating current — the use of direct current leads to the electrode surface of the non-conductive oxide film, which inhibits the process and the current stops.

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Claims (5)

Claim 1, A method for producing alcohols of talles of general formula M (OR) f ,. a metal selected from the group of titanium, magnesium, aluminum scandium, yttri, gallium, qi, horses, hafnium, niobium, tantalum, iron, cobalt, nickel, lanthanum; R is alkyl of normal or organic structure; p is an integer from 2 to 5, by electrochemical dissolution of the anode from the corresponding metal or its alloy in the electrolyte containing alcohol and an electrically conductive additive at the boiling point of the electrolyte, characterized in that, in order to simplify the process and increase the yield of alkoxides, the process is conducted with using an alternating current using salts of the general formula KX as an electrically conductive additive, where K is a cation selected from the group of alkali metal, ammonium or a quaternary base, .13 95300 X is chlorine, bromine, iodine, VHz, PF, ССОц, in amounts ve 2-20 wt.%. 2. The method according to claim 1, about tl and h ayusch and the fact that the process is conducted in an electrolyte containing acetonite-5 reel, dimethyl sulfoxide, dimethylformamide, benzene in an amount of 1-20 wt.%. Sources of information taken into account in the examination 1. The patent of Germany 2.121.732,10 ll. From 07 s, publish. 1972. 814 2. Patent of Great Britain No. 1.136016, published. 1968. 3. Canadian patent 1.024.466, cl. 204-43,5, pub. 1978 4. French patent 2,091.299, cl. From 07 F, published. 1972 (prototype) 5. Charmetant, S., Paris, R., Compt.rend.220, 314-316 (1945). Electrolysis of some metal chlorides in methyl and ethyl alcohols.