Method of producing carboxylates of rare-earth elements

FIELD: chemistry.

SUBSTANCE: method involves reacting oxides of rare-earth elements (REE) with α, α'-branched monobasic carboxylic acids with 8-20 carbon atoms while stirring at high temperature, as well as their mixtures in the presence of water with molar ratio of water to the rare-earth element equal to 1-3:1, with subsequent cooling, addition of solvent and azeotropic drying of the obtained solutions of carboxylates of rare-earth elements through distillation of the azeotropic solvent-water mixture, where the process is carried out while heating to 100°C and further at a rate of 10°C per hour to 150°C, with removal of the bulk of water during synthesis with a stream of inert gas fed to the bottom of the reactor and bubbled through the reaction mixture, without the stage of elutriation from unreacted oxides of rare-earth elements. The proposed method combines high output and purity of the product with simplification of the technique with minimal loss of reagents and minimal consumption of solvent.

EFFECT: obtaining carboxylates of rare-earth elements which are not prone to oligomerisation during azeotropic drying of their solutions and storage, and catalysts based on said compounds can be prepared with or without cooling and have high activity.

8 ex

The invention relates to methods for carboxylates of rare earth elements (REE), which can be used as components of catalysts for the production of diene rubbers with a high content of 1,4-CIS-units.

High stereoregularity rubber provides increased strength, reduced heat buildup and the best resistance of rubber to abrasion.

The carboxylates REE can be obtained in various ways.

Because of the rare earth catalysts of the most intensively studied neodymium catalyst composition: Nd(RCOO)₃/AlEt₂Cl/Al(iBu)₃due to its higher solubility and reactivity, methods of obtaining carboxylates neodymium (Nd).

The neodymium carboxylates obtained exchange reactions between aqueous solutions of nitrate or neodymium chloride and sodium carboxylates, followed by extraction with an organic solvent (Patent US 4520177, US 5220045), characterized by formula (RCOO)₃Nd. The carboxylates are water-soluble sodium salts of carboxylic acids and are obtained by the interaction of carboxylic acids with alkalis. Due to the complexity and multi-stage process of obtaining neodymium carboxylates of the original carboxylic acid remains in the final product, which also contains some number is the number of polar ligands, saturate the coordination sphere neodymium: water, chlorides, nitrates, water-soluble salts of carboxylic acids, hydroxides. The presence in their composition of neodymium carboxylates contributes to the formation of structurally more complex oligomeric systems, which can be deposited from solution in the form of a gel (Patent EP 0599096 A1).

The neodymium carboxylates, received by the exchange reaction between acetate or alcoholate of rare earth element neodymium and carboxylic acids (RCOOH) in the presence of an organic solvent, such as chlorobenzene, are the individual compounds, giving high activity catalytic systems (Patent US 6482930 B1). The authors characterize the obtained in this way neodymium carboxylates of the formula (RCOO)₄HNd. Obtaining neodymium carboxylates characterized by the formula (RCOO)₄HNd is a multistage process, including obtaining preliminary acetate or alcoholate of neodymium and subsequent vacuum distillation of chlorobenzene.

A method of obtaining readingabout components of catalysts for the polymerization of diene hydrocarbons (Patent RU 2247128 C1, MKI 08F 4/52, 01J 37/04) direct interaction of neodymium oxide or its salts with carboxylic acids with 8 to 20 carbon atoms in the environment of the solvent is carried out in the presence of a halogenated acid and/and and Lewis acid with continuous stirring. The result is achieved due to the continuous renewal of the reaction surface, due to the use of technical devices, providing a surface milling 0,055-5.0 m²1 l of the reaction mixture. The interaction is carried out at a molar ratio of carboxylic acid to the neodymium from 3.3:1 to 5.0:1. The disadvantage of this method is the use of sophisticated technical devices, such as ball, disc mill, rotary pulse jet dispersers with shaft speed stirrer 500-2000 min^-1and the use of additional initiation of the reaction substances such as esters, water, hydrogen chloride, acetylchloride, amines, acetylacetone, alkylphosphate, leading to the formation of carboxylates in oligomeric form that can precipitate from solution in the form of a gel.

A method of obtaining carboxylates REE by the interaction of REE oxides and carboxylic acids selected from the group including α-and α,α'-branched and naphthenic acids, in the presence of water at a molar ratio of water to metal of from 5:1 to 200:1 in a solvent (Patent EP 0968992 A1, MKI SS 51/41, 53/128). In the mentioned patent carboxylates REE called lanthanide carboxylates. According to the proposed method the best result is achieved under the conditions of synthesis, when the reaction mixture is taken in a molar ratio of carboxylic acid to m is a metal in the range from 3:1 to 10:1 and water to metal in the range from 20:1 to 78,3:1. The reaction is carried out at 95°C for 2.5 hours in the presence of a solvent. After interaction mixing cease to delamination occurred aqueous and organic phases. The duration of the separation depends on the quantity of water taken for the reaction, and decreasing the amount of water duration of sedimentation increases. Then the aqueous phase is removed. Solutions carboxylates REE in the solvent is dried, fending off the azeotrope solvent is water. The yield of the product, which is characterized by the formula Ln(RCOO)₃is a 90.0-99.5%pure, which is impossible, because a full conversion with a ratio of carboxylic acid to the metal RCOOH:Ln>3 excess of carboxylic acids should remain in the organic phase due to their insolubility in water. The disadvantage of this method is the necessity of using such technological operations, as long advocacy for the separation of the layers of the reaction mixture, followed by separation of the aqueous phase, which significantly complicates the technological process and increases the time of the meeting. In addition, when reducing the amount of water reduced and the yield of the final product (with 99.5 to 95%). When playing this method on the example of receiving neodecanoate neodymium, but at a molar ratio of water to the neodymium equal to 10:1, and neo is Canovas acid to neodymium, equal to 3:1, it was found that the yield does not exceed 90%, and a phase separation requires at least three hours (Patent RU 2209205 C2, MKI SS 51/41).

The closest analogue (prototype) of the proposed method is a method of obtaining carboxylates REE (Patent RU 2209205 C2, MKI SS 51/41) interaction at elevated temperatures of REE oxides and carboxylic acids selected from the group comprising α-branched, α,α'-branched monocarboxylic, naphthenic acid, and mixtures thereof in the presence of water at a molar ratio of water to rare earth element is 1-3:1. The interaction may be carried out in the presence of, or without solvent. In the latter case, the solvent is injected after the interaction. The method consists in that a mixture of REE oxide, carboxylic acid and water with stirring is heated at a temperature of 50-150°C. for 0.5-3 hours. The resulting suspension is dried up, fending off the moisture in the form of an azeotropic mixture with the solvent, to a moisture content of not more than 0.05%, and defend from unreacted oxides, solution carboxylates REE decanted. The output is defined by the number of REE, passed into the solution, is 95-99%. The authors of the patent does not claim the ratio between the carboxylic acid and REE equal to 3:1, but describe it in all the examples. When playing this way is thought, the reaction proceeds with a smaller output. So, in the experiment conducted with a ratio of water to rare earth, equal to 2.5:1, and a temperature of 120°C without solvent, the amount of REE, passed into the solution amounted to 73.2%. In the presence of a solvent at 50 to 100°C, the yield was 43%. The obtained results indicate that for complete conversion of oxides of rare earth carboxylates in this way the ratio between the carboxylic acid and REE equal to 3:1, is insufficient. The disadvantage of this method is the use of relatively large quantities of solvent, as all entered and released during the reaction water is proposed to delete the method of azeotropic dehydration. In connection with the increase of viscosity solutions carboxylates REE during their concentration is inefficient to defend solutions carboxylates from unreacted oxides after carrying out azeotropic dehydration.

The aim of the invention is to obtain carboxylates REE way, combining high yield and purity of the product with the simplification of using the minimum amount of solvent.

This objective is achieved in that the receiving carboxylates REE is the interaction of oxides of rare-earth elements with α,α'-branched monocarboxylic acids with 8 to 20 carbon atoms, and mixtures thereof in the presence of water at a molar ratio of water to RH is, equal 1-3:1. Most preferably the molar ratio of acid to REE equal to 4:1. The method consists in heating a mixture of carboxylic acids, water and REE oxide to 100°C and then at a rate of 10°C per hour to 150°C., with stirring, mechanical stirring and bubbling of inert nitrogen gas, supplied to the bottom of the reactor. The bulk water, is introduced as an initiator and released from the reaction is removed from the reactor during synthesis with a flow of inert nitrogen gas, Bartiromo through the reaction mixture. The resulting carboxylate REE cooled with stirring and diluted with a solvent which is azeotropic dehydration. Cooling is performed to a temperature approximately equal to the boiling point of the azeotropic solvent-water mixture. The dewatering solutions carboxylates REE carry out distillation of the azeotropic solvent-water mixture to a moisture content of not more than 0.05%.

In this way the yield on REE equal to or greater than 99,5%, which allows the synthesis stage without settling solution from the unreacted oxides REE. The method is characterized by an extremely small amount of waste: the proportion of monocarboxylic acids, carry out in the form of a heterogeneous azeotropic mixture with water in a flow of inert nitrogen gas, is about 0.05%. Together with part distilled water these acids m which may be used in the subsequent syntheses.

The carboxylates REE obtained by this method, soluble in toluene, heptane, hexane, isopentane and not prone to gelation during azeotropic drying and storage.

To obtain carboxylates REE used neodymium oxide and the oxide of Didim is a technical mixture of oxides of neodymium and praseodymium in THE HELL 11.46-89. As the carboxylic acids used neodecanoate acid and VIC-AND - technical mixture of α,α'-branched monocarboxylic acids with 8 to 20 carbon atoms in THE 2431-200-00203312-2000.

Below are examples that illustrate the proposed method.

Example a-1.

A mixture of 26.7 g of oxide Didyma (159 mmol REE), 134,1 g VIC (647 mmol) with an acid number 270,4 mg KOH/g and a water content of 0.35% (26 mmol of water) and 2.4 ml of water (133 mmol) was heated to 100°C. and then at a rate of 10°C per hour up to 150°C. At 150°C the mixture is kept for 1 hour. The reaction mixture was stirred with a mechanical stirrer and barbotine through it, the inert gas is nitrogen, supplied to the bottom of the reactor. After cooling to 83°C. with stirring, add 75 ml of toluene and distilled azeotropic mixture of toluene-water until the residual moisture of 0.05%. The output of the carboxylate Didyma equal to 99.5% at a molar ratio of RCOO^-/REE equal 3,96.

Example a-2.

To 80,17 g VIC (387 mmol) of the acid number 270,4 mg KOH/g and a water content of 0.35% (15.6 mmol of water) with stirring was added 1.23 g (96,6 the Nd mmol) of neodymium oxide and 4.9 ml (272 mmol) of water. Stirred and heated as described in example 1. After cooling to 83°C with stirring to 165 ml of toluene and distilled azeotropic mixture of toluene-water until the moisture content of the carboxylate of 0.05%. The output of the neodymium carboxylate is equal to 99.6% at a molar ratio of RCOO^-/Nd equal to Android 4.04.

Example a-3.

To 47,82 g (277,9 mmol) neodecanoic acid containing 0,044% water (1.2 mmol of water)was added to 1.9 ml of water (105,5 mmol) and with vigorous stirring in small portions add 11,81 g (70 mmol Nd) neodymium oxide. Stirred and heated as described in example 1. The reaction mixture is cooled to 60°C., diluted with 75 ml of hexane. From the resulting solution is distilled azeotropic mixture of hexane-water until the residual moisture in the neodymium carboxylate 0,006%. The output of a neodymium carboxylate and 99.8% at a molar ratio of RCOO^-/Nd equal 4,00.

Example a-4.

61,12 g (315 mmol) VIC-AND acid value 289 mg KOH/g and a water content of 0.40% (13,6 mmol of water) is mixed with 3.5 ml of water (194,4 mmol) and 13.25 g (78,9 mmol REE) oxide Didyma. The mixture is stirred and heated as described in example 1. The resulting carboxylate Didyma is cooled with stirring to 90°C., diluted with 75 ml of heptane and dried to a residual moisture of 0.05%, fending off the azeotropic mixture of heptane-water. The output of the carboxylate Didyma of 99.9% at a molar ratio of RCOO^-/REE equal was 4.02.

Example A-5.</>

To 53,37 g (310 mmol) neodecanoic acid containing 0,044% water (1.3 mmol of water) was added 4.8 ml (267 mmol) of water and with stirring 17,83 g (106 mmol Nd) neodymium oxide. In contrast to the proposed method:

1) the Mixture is heated with stirring mixer 80°C and kept at this temperature for 2 hours. After this time, the viscous reaction mixture contains unreacted oxide of neodymium in large quantities. After heating to 120°C. the mixture is stirred for further 0.5 hour;

2) there is No bubbling the reaction mixture with an inert gas nitrogen.

Next, the reaction mixture is cooled to 83°C and diluted with 75 ml of toluene. The resulting product is a bad otchaivaysya suspension. The output of the carboxylate REE content of neodymium in the solution is separated from the reaction mixture by centrifuging, amounted to 73.2% at a molar ratio of RCOO^-/Nd, equal to 4.1.

Obtained by the proposed method carboxylates REE used as components of catalytic systems for the polymerization of isoprene in isopentane solution.

Example B-1.

The preparation of the catalyst is carried out in a pre-heated in a vacuum and filled with an inert gas to the reactor. The reactor was placed a solution of carboxylate Didyma, synthesized in example a-1, piperylene, then after cooling to -10°C and peremeshivaya.prokipevshie impose solutions diisobutylaluminium, diisobutylaluminium and triisobutylaluminum. The molar ratio of reactants is 1:2:10:3:10, respectively. The catalyst can withstand 48 hours without cooling.

Polymerization of isoprene in isopentane solution is conducted from the calculation of the molar ratio of isoprene:REE equal to 15000:1. The polymer yield for 1 hour 91%. The content of CIS-1,4-units 98,8%.

Example b-2.

Preparation of the catalyst is carried out without cooling in the sequence described in example-1 using neodecanoate neodymium synthesized in example a-3, when the molar ratio of components 1:2:9:2,5:9,5 respectively. The catalyst can withstand 48 hours. Out of the polymer during polymerization of isoprene in isopentane solution at a molar ratio of isoprene:REE equal to 15000:1 (95.9% for 2 hours. The content of CIS-1,4-units of 99.2%.

Example b-3.

Preparation of the catalyst is carried out without cooling in the sequence described in example-1 using neodecanoate neodymium synthesized in example A-5, when the molar ratio of components 1:2:9:(2÷3):9,5 respectively. After 48 hours out of the polymer during polymerization of isoprene in isopentane solution at a molar ratio of isoprene:REE equal to 15000:1, these catalysts was 91,5-96,3% for 2 hours. The content of CIS-1,4-units 98,7-99,0%.

Thus, the proposed method will get the carboxylates REE with high yield without long stage of settling from unreacted oxides REE with minimal loss of reagents and minimal consumption of solvent by removing the most part, entered and released by the reaction of water with a flow of inert nitrogen gas when bubbling it through the heated reaction mixture. The carboxylates REE obtained by this method, do not tend to agglomerate when azeotropic drying their solutions and storage. The catalysts obtained on their basis, are homogeneous, can be prepared as with cooling, and without it, have activity similar to the activity of rare earth-based catalysts carboxylates obtained by the method of reaction of aqueous solutions of nitrates of rare-earth elements and sodium carboxylates, followed by extraction with an organic solvent.

The method of obtaining carboxylates of rare earth elements by interaction with stirring and at a high temperature oxides of rare earth elements with α,α'-branched monocarboxylic acids with 8 to 20 carbon atoms, and their mixtures in the presence of water at a molar ratio of water to rare earth element is 1-3:1, followed by cooling, addition of solvent and azeotropic dehydration of the obtained solutions carboxylates of rare earth elements by distillation, azeotropic solvent-water mixture, wherein the process is conducted by heating to 100°C and then at a rate of 10°C per hour to 150°C., with removal of the main mass of water in the course of the synthesis flow enertrag the gas, summed up to the bottom of the reactor and barotrauma through the reaction mixture, without the stage of settling from unreacted oxides of rare earth elements.