RU2335488C1 - Method of obtaining water-free acetylacetonates of refractory metals - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method involves reaction of metal oxychloride with ammonium hydrocarbonate and acetylacetone in water with further cooling of reaction mix, precipitation separation, flushing, dehydratation and drying of obtained product. The process is performed by continuous or gradual feeding, along with continuous stirring, of water metal oxychloride solution to water ammonium hydrocarbonate with at feed rate under 2.5 ml of water metal oxychloride solution per minute per each 100 ml of water ammonium hydrocarbonate solution, followed by acetylacetone feeding at the mol ratio of metal oxychloride:ammonium hydrocarbonate:acetylacetone from 1.0:2.8:4.4 to 1.0:3.0:4.4, cooling of reaction mix at (-4) - (-6)°C for 7-9 hours, sequential precipitation flushing with water and acetone, dehydratation and drying of obtained product in air at 60-70°C for 4-6 hours. Water zirconium or hafnium oxychloride solution is used as water metal oxychloride solution.

EFFECT: simplified technology and higher environmental safety of the process.

2 ex

Description

The invention relates to the production of anhydrous refractory metal acetylacetonates, in particular anhydrous zirconium and hafnium acetylacetonates, which are used as starting reagents for producing oxide films and coatings in CVD processes in the production of thermoerosion-resistant composite materials, in preparative chemistry, and also in other fields.

So it is known the use of zirconium acetylacetonate in the compositions of the adhesive compositions / RU 2139314 / and in the method for producing the encapsulated crosslinking agent / RU 2002101621 /, and it is also known to use zirconium and hafnium acetylacetonates in the oxidation catalyst of a hydrocarbon, alcohol or ketone to a carboxylic acid / RU 98106628 /.

A known method of producing metal acetylacetonates by the interaction of a water-soluble metal salt with acetylacetone in an aqueous medium in the presence of an equimolecular amount of ammonia. The resulting product does not have sufficient purity / SU 330746 /.

A known method of producing complex compounds of metals with acetylacetone (acac) of the general formula M (acac) _n , where M is a metal cation selected from the group consisting of Fe, Co, Ni, Cu, Zn, Al, Ca, Mg, Mo, Ru, Re, U, Th, Ce, Na, K, Rb, Cs, V, Cr and Mn, “n” - corresponds to the electrovalency of the metal, by reacting the corresponding metal hydroxide, hydrated metal oxide or metal oxide with a stoichiometric amount of acetylacetone and further separation of the product / GB 2411654 /. However, this source of information does not mention the preparation of zirconium and hafnium acetylacetonates.

A known method for producing anhydrous zirconium and hafnium acetylacetonates by reacting metal oxonitrates in an aqueous medium with a twofold excess of acetylacetone in the presence of sodium hydroxide as a neutralizing agent, followed by extraction with benzene and isolating the product by distillation of the solvent / Bert Allard, Journal of Inorganic & Nuclear Chemistry, 38 (11) 2109 (1976) /.

This method allows you to get small batches of high quality product for physico-chemical, etc. studies, but the use of significant amounts of toxic and combustible benzene as an extractant and the need for labor-intensive extraction and solvent recovery operations preclude the possibility of using this method for the industrial production of anhydrous zirconium and hafnium acetylacetonates.

A known method for producing anhydrous zirconium acetylacetonate from metal zirconium by conducting an electrolytic process in an acetonitrile medium / J.H. Greenberg, Journal of Physical Chemistry, 60 (4), 1044 (1986) /.

This method can be used for the industrial production of anhydrous zirconium and hafnium acetylacetonates in a continuous cycle of factory production, but has all the disadvantages of electrolytic processes in non-aqueous media: high energy consumption, complicated hardware, work with large amounts of toxic electrolyte, the need for periodic regeneration and purification from sludge etc.

A known method of producing metal acetylacetonates by heating a mixture of 2-10 moles of 2,4-pentanedione and one weight equivalent of metal oxide or hydroxide in the absence of water and organic solvents. The resulting vapor mixture can be condensed and directed to the isolation of a layer of 2,4-pentanedione, which is returned to the reaction zone, adjacent to the watered layer. Metal acetylacetonate can be isolated by cooling to 0-50 ° C / FR 1576711 /. However, this method also does not allow with sufficient efficiency to obtain the target product of the required purity.

The closest in technical essence to the present invention is a known method for producing anhydrous refractory metal acetylacetonates by the interaction in the aqueous medium of metal oxychloride with ammonium bicarbonate and acetylacetone, followed by cooling of the reaction mixture, separation of the precipitate, its

washing, dehydrating and drying the resulting product. According to the prototype method, the product is obtained by reacting zirconium oxychloride with a 30% excess of acetylacetone (compared to the total molar content of zirconium oxychloride and ammonium bicarbonate) using ammonium bicarbonate as a neutralizing agent, followed by a long (48 hours) cooling of the reaction mass, and separating the precipitate of zirconium decahydrate, washing the latter with water, recrystallizing from a water-alcohol solution and dehydrating the product in vacuo at 25-30 hPa over anhydrous potassium carbonate at 35 ° C / J.Dobrovolski, Badanie warunkow otrzymywania i oczyszczania acetyloacetonianu cyrkonu (IV), Zeszyty Naukowe Politechniki Slaskiej, Chemia, 639 (93), 73 (1980) /.

The specified method allows to obtain anhydrous zirconium acetylacetonate of high quality with a high yield, but has significant disadvantages, namely:

- high consumption of acetylacetone, which is currently a custom imported reagent and environmentally hazardous component,

- the need for a laborious and highly waste recrystallization stage,

- the use at the final stage of vacuum equipment, significantly complicating the process when using this method in an industrial environment.

The technical task of the invention is the development of an industrial method for the preparation of anhydrous zirconium and hafnium acetylacetonates while eliminating these drawbacks.

The technical result of the invention is to simplify the process technology by eliminating the recrystallization stage and increasing the environmental safety of the process by reducing the consumption of acetylacetone and eliminating the waste from the recrystallization stage.

The specified technical result is achieved by the fact that in the method for producing anhydrous refractory metal acetylacetonates by the interaction of metal oxychloride with ammonium bicarbonate and acetylacetone in an aqueous medium, followed by cooling of the reaction mixture, separation of the precipitate, washing, dehydration and drying of the obtained product, the process is carried out by introducing portionwise with continuous stirring or a continuous stream of an aqueous solution of metal oxychloride in an aqueous solution of ammonium bicarbonate at a rate of the amount not exceeding 2.5 ml of an aqueous solution of metal oxychloride per minute for every 100 ml of an aqueous solution of ammonium bicarbonate, the subsequent introduction of acetylacetone with a molar ratio of metal oxychloride: ammonium bicarbonate: acetylacetone from 1.0: 2.8: 4.4 to 1 , 0: 3.0: 4.4, cooling the reaction mixture at (-4) - (-6) ° C for 7-9 hours, sequentially washing the precipitate with water and acetone, dehydrating and drying the resulting product in air at 60- 70 ° C for 4-6 hours, moreover, an aqueous solution of approx. zirconium chloride or hafnium oxychloride.

The above order of mixing the reagents, as well as the introduction of a metal oxychloride solution at a certain low speed, the use of acetone in the last stage of washing the precipitate, provide a high yield and purity of the target product and the ability to eliminate the laborious and highly waste recrystallization stage, the need to use special vacuum equipment at the dehydration stage with a decrease of 3 times the excess acetylacetone (10-12%) and 6 times the cooling time of the reaction mixture compared to the nearest their analogue, without reducing quality, to maintain the yield of the target product at a level of at least 95 wt.% for metal, which allows you to successfully use the method on an industrial scale.

Example 1

45 g (0.569 M) of ammonium bicarbonate are dissolved in 120 ml of distilled water; with vigorous stirring, a solution of zirconium oxychloride is introduced at a rate of about 2.4 ml per minute (at the rate of 2 ml per minute per 100 ml of ammonium hydrogen carbonate solution), obtained by dissolving 65 g (0.202 M) of zirconium octahydrate in 110 ml of distilled water.

At the end of the neutralization reaction (pH = 6.5), 92 ml (0.893 M) of acetylacetone are added, after which the reaction mixture is stirred vigorously for 1 h at room temperature and placed in a refrigerator for 8 h - cooling at -5 ° C. The molar ratio of zirconium oxychloride: ammonium bicarbonate: acetylacetone is 1.0: 2.8: 4.4 (excess acetylacetone 11.6%).

The resulting precipitate of zirconium acetylacetonate decahydrate is separated on a Buchner funnel and washed first with 100 ml of cold distilled water, and then with 50 ml of acetone. Dehydration and drying of zirconium acetylacetonate is carried out in air in an oven at 65 ° C for 5 hours.

The product yield on zirconium is 130 g (96%). Mass fraction of zirconium acetylacetonate - 99.5%. The composition of the product is confirmed by spectral analysis.

Example 2

50 g (0.632 M) of ammonium bicarbonate are dissolved in 120 ml of distilled water; with vigorous stirring, a solution of hafnium oxychloride is introduced at a rate of about 3.0 ml per minute (based on 2.5 ml per minute per 100 ml of ammonium hydrogen carbonate solution), obtained by dissolving 85 g (0.208 M) of hafnium oxychloride octahydrate in 110 ml of distilled water.

At the end of the neutralization reaction (pH = 6.5), 95 ml (0.922 M) of acetylacetone are added, after which the reaction mixture is stirred vigorously for 1 h at room temperature and placed in a refrigerator for 8 h - cooling at -5 ° C. The molar ratio of hafnium oxychloride: ammonium bicarbonate: acetylacetone is 1.0: 3.0: 4.4 (excess acetylacetone 10.0%).

The precipitate of hafnium acetylacetonate decahydrate formed is separated on a Buchner funnel and washed first with 100 ml of cold distilled water and then with 50 ml of acetone. The dehydration and drying of hafnium acetylacetonate is carried out in air in an oven at 65 ° C for 5 hours.

The hafnium product yield is 155 g (96%). The mass fraction of hafnium acetylacetonate is 99.5%. The composition of the product is confirmed by spectral analysis.

Claims (1)

The method of obtaining anhydrous refractory metal acetylacetonates by the interaction in the aqueous medium of metal oxychloride with ammonium bicarbonate and acetylacetone, followed by cooling of the reaction mixture, separation of the precipitate, washing, dehydration and drying of the obtained product, characterized in that the process is carried out by introducing with continuous stirring portionwise or continuous stream an aqueous solution of metal oxychloride in an aqueous solution of ammonium bicarbonate at a rate of administration not exceeding 2.5 ml of aqueous a solution of metal oxychloride per minute for every 100 ml of an aqueous solution of ammonium bicarbonate, subsequent administration of acetylacetone in a molar ratio of metal oxychloride: ammonium bicarbonate: acetylacetone from 1.0: 2.8: 4.4 to 1.0: 3.0: 4, 4, cooling the reaction mixture at (-4) - (-6) ° C for 7-9 hours, sequentially washing the precipitate with water and acetone, dehydrating and drying the resulting product in air at 60-70 ° C for 4-6 hours moreover, as an aqueous solution of metal oxychloride, an aqueous solution of zirconium oxychloride or hafnium oxychloride is used .