CS238214B1 - Trans-Dichlorotetrakis (tetrahydrofuran) magnesium complex and process for its preparation - Google Patents

Abstract

The invention relates to inorganic chemistry and chemistry of high molecular weight compounds and solves the preparation of one of the components for the production of highly active catalysts for low-pressure polymerization and copolymerization of olefins. The invention relates to a previously undescribed complex compound of trans-dichloro-tetrakis(tetrahydrofuran)magnesium complex of the general formula [UgCC/jUgO^C^la and methods for preparing this compound by reacting either elemental magnesium with allyl chloride or hydrogen chloride or a Grignard reagent with hydrogen chloride all in a tetrahydrofuran environment and further to a method for isolating the compound by crystallization from the seed. The compound can be used for the synthesis of precursors or catalysts of various organic syntheses.

Description

The invention relates to a previously undescribed chemical compound of trans-dichloro-tetrakis(tetrahydrofuran)magnesium complex of the formula [Mg(C ₄ H _Q O) ₄ d ₂ ] and methods for its preparation.

For the industrial production of various types of polyolefins by polymerization and copolymerization of 1-olefins or their mixtures, various mixtures containing magnesium and titanium compounds together with electron donor compounds, such as various organic acid esters, ethers, amines, alcohols, etc., are very often used as components of catalytically active systems. Precursors of highly active catalytic systems with excellent stereospecific efficiency were obtained using mixtures of magnesium chloride, titanium tetrachloride and tetrahydrofuran in a wide range of component ratios and with various methods of working up and conditioning this reaction mixture. Particularly good results are achieved when preparing precursors from a homogeneous phase, i.e. from tetrahydrofuran solutions of magnesium and titanium chloride. The difficulties caused by the low solubility of anhydrous magnesium chloride in tetrahydrofuran can be circumvented by using in its place the tetrahydrofuran-soluble, but still poorly described and completely unidentified and not further characterized solvates Mgdg.nC^HgO , where n is 1.5 or 2. For similar purposes, a pure chemical individual, trans-dichloro-tetrakis(tetrahydrofuran)magnesium complex [MgCC^HgOj^d^] , which is formed in the Mgdg-tetrahydrofuran system and which is excellently soluble in tetrahydrofuran, has not yet been used. The probable existence of a compound with the general formula Mgdg.éC^HgO has been mentioned only once in the literature.

- 2 _of CH ₉ - CH ₉ ⁰ I '''''CHg ~ ®2 preparation of this compound,

238 214 has been noted (Zeil W., Winter J.: Tagungsber.Chem.Ges. DDK 1954, p. 77; Chem.Zentralblatt 1962, 9270.), but no attempt has been registered to isolate, analyze, physically and chemically characterize it, and no method of its synthesis has been described.

The subject of the invention is the chemical compound trans-dichloro-tetrakis(tetrahydrofuran)magnesium complex of the general formula [kgíC^HgO) ^Clg] 1 of the structural formula

i) i) \ /

CL — Mg — Cl , where D stands for

From \

The subject of the invention is a longer process which consists in reacting either elemental magnesium with allyl chloride in a tetrahydrofuran environment according to the equation

Mg + 2 C ₃ H ₅ CL + 4 C ₄ H _q O -> [MgtC^HgO) ₄ C1^ + CgH^ or a magnesium Grignard reagent of the general formula RMgd, where R is an aliphatic, cyclic or aromatic substituent with up to 8 carbon atoms, preferably 1-butyl, with dry hydrogen chloride in tetrahydrofurane according to the equation

RMgd f HCL + 4 C ₄ H _q O -> [MgíC^gO) ₄ dg] + RH or elemental magnesium with dry hydrogen chloride also in tetrahydrofuran according to the equation Mg + 2 Hd + 4 C ₄ H _q O -[Mg(C ₄ H _g O) ₄ d ₂ ] + Hg

In the preparation method according to the invention, the syntheses are carried out with a starting amount of magnesium of 0.1 to 3.5 moles per liter of tetrahydrofuran (or an equivalent amount of Grignard reagent), preferably 2 to 3 moles per liter of tetrahydrofuran and a stoichiometric238 214

-3 with a small amount of hydrogen chloride or a slightly superstoichiometric amount (up to 10%) of allyl chloride at temperatures of 0 to 60°C, preferably 25 to 30°C and atmospheric pressure with constant effective stirring in a protective atmosphere of dry inert gas (nitrogen or argon). The product is isolated after the reaction by crystallization at temperatures up to 28°C. The product can be purified by recrystallization from tetrahydrofuran solutions under the same conditions. The yields range from 50 to 90% of theory.

The preparation of the compound is demonstrated by the following examples.

Example 1

A dry flask (500 ml) equipped with a reflux condenser and an inert gas inlet and outlet is charged with 12.2 g (0.5 mol) of magnesium turnings and 250 ml of dry tetrahydrofuran. A total of 80.3 g (1.05 mol) of allyl chloride is added to the suspension with constant stirring. The temperature of the reaction mixture is maintained at 28 to 30°C by the rate of allyl chloride addition. After mixing, the reaction mixture is maintained at room temperature with constant stirring until the magnesium present is completely dissolved (3 to 5 hours). The reaction mixture is cooled to 0°C under inert gas and filtered. The precipitated crystals are filtered off sharply with suction and washed with approximately 50 ml of tetrahydrofuran cooled to 0°C. The crude product is dissolved in 600 ml of dry tetrahydrofuran at a temperature of 25 to 28°C, cooled to 0°C and left at this temperature to crystallize. The separated plate-like white crystals are filtered off sharply with suction and washed with 50 ml of cooled tetrahydrofuran. The product is dried in a stream of inert gas only briefly to a clearly free-flowing consistency. The yield is 73 g (38% of theory). After concentration in vacuo at a temperature not higher than 28°C, the following can be obtained from the mother liquors:

238 214

- 4 longer portion of product in the amount of 30 g (15.5% of theory) The second portion is slightly contaminated with traces of the reaction by-product, 1,5-hexadiene.

Example 2

A solution of 1-butylmagnesium chloride prepared from 12.2 g (0.5 mol) of magnesium shavings and 46.3 g (0.5 mol) of 1-butyl chloride in 200 ml of tetrahydrofuran is filtered through a layer of glass wool in the absence of air into a three-necked flask (500 ml) equipped with an inert gas inlet and outlet and a separating funnel. To the solution, 100 ml of a 5 mol/L solution of hydrogen chloride in tetrahydrofuran (total 0.5 mol HCl) is added in small portions over 15 minutes with constant stirring. During the live reaction, the flask is cooled with water and ice. The resulting crystalline mass of the product is then kept for 3 hours at a temperature of 0 to 5°C. The product crystals are then sharply suctioned off, washed with 100 ml of tetrahydrofuran cooled to 0°C and dried in a stream of inert gas to a loose state. Yield 150 g (78% of theory). For the purposes of synthesis of catalytic precursors, the purity of the product prepared in this way is sufficient. Further purification can be carried out by crystallization, as described in Example 1.

The same product was obtained in 65-75% yield using Grignard reagents of formula RMgCL, where R is ethyl, 1-octyl, cyclohexyl or phenyl.

Example 3

A 1000 ml three-necked flask equipped with a reflux condenser and an inert inlet and outlet is charged with 500 ml of a solution of hydrogen chloride in dry tetrahydrofuran (concentration 5 mol«l*^)

- 5,238,214 and a total of 30.4 g (1.25 mol) of aluminum are gradually introduced upstream of the inert. The rate of dosing is controlled by the rate of hydrogen evolution.

As the amount of product increases, the mixture thickens, product crystals precipitate and the dissolution rate decreases. To maintain the optimum reaction temperature (28 to 32° C), the reaction space must be cooled at the beginning of the reaction and heated later. The reaction is terminated by complete dissolution of magnesium. The reaction mixture is then cooled to a temperature of 0 to 5°C and allowed to crystallize. 324 g of crude product is obtained, which is further purified by recrystallization as described in Example 1. Concentration of the mother liquors yields another 106 g of product, so that the total yield is 430 g (90%) of the product.

Example 4

A stream of dry hydrogen chloride gas is introduced into a suspension of 30.4 g (1.25 mol) of magnesium shavings in 500 ml of dry tetrahydrofuran in a three-necked (1000 ml) flask equipped with a reflux condenser and an inert gas inlet and outlet. The reaction is controlled by the amount of dry hydrogen chloride gas. The temperature of the mixture is maintained at 30+2°C. The hydrogen chloride supply is stopped after the magnesium has completely dissolved, which takes 4 to 6 hours depending on the size of the shavings. After the reaction, the slight excess of hydrogen chloride is removed by flushing the reaction mixture with inert gas and by adding a small amount (approx. 0.5 g) of compact magnesium, which is removed mechanically after the neutral reaction is achieved. The reaction mixture is cooled and the precipitated crystals are treated in the same way as described in Example 3. A pure product in the amount of 440 g (92% of theory) is obtained.

Product characterization and identification

Appearance and stability of the product 238 214 [MgCl2HgO2Cl2] forms large plate-like colorless transparent crystals that are indefinitely stable in a closed container below 28°C.

It ventilates very easily in the air and absorbs moisture.

In vacuum, depending on temperature, it easily desolvates to products containing 1.3 or less tetrahydrofuran per formula unit.

Desolvation also occurs when the complex is introduced into inert solvents, such as hexane, paraffin oil, carbon tetrachloride, benzene, etc.

Chemical analysis

The recrystallized product prepared according to the above-described products has a composition corresponding to the formula [Mg(C^H ₈ 0)^Cl ₂ J , as confirmed by the results of chemical analysis shown in Table I.

Table I

Chemical analysis [Lig (Ο^ΗθΟ) ^Clg]

Content of elements and tetrahydrofuran in % Mg Cl c ₄ h ₈ ° Calculated 6,337 18,482 75,181 Found 6.35 18.50 75.15

Powder diffraction pattern of the compound

The compound QdgíC^HgO forms white plate-like well-developed crystals. Powder diffractogram of the compound using

238 214

0.154178 nm gives the diffraction angles 2Θ and the interplanar distances d and relative intensities of the diffraction lines given in Table XI.

Table XI

Powder diffraction parameters [MgCC^HgOjgClJ

Diffraction angle 2Θ, ⁰ relative intensity indexes of planes interplanar distance hkl d, nm

10.2 10

11.4 7

16.7 3

18.9 2

20.4 2

20.8 2

22.2 1

22.9 1

23.3 1

23.6 1

24.3 1

25.4 1

26.3 1

27.4 1

28.2 1

29.9 1

31.0 . 2

31.4 1

32.1 1

40.4 1

49.3 1

002 0.867 100 0.776 111 0.531 112 0.470 004 0.434 0.427 113 0.400 200 0.388 201 0.382 104 0.377 0.367 210 0.351 114 0.339 212,203 0.325 105 0.316 213 0.298 006 0.288 0.285 220 0.279 216,304 0.223 218,403 0.185

The powder diffraction pattern of [MgCC^HgO^Cl^] is almost identical in size and relative intensities of interplanar spacings to the diffraction pattern and consistent with the complete crystal structural

- 8,238,214 by analysis of the homologous compound pαgCC^O^Br^ (Pérucaud M.C., Ducom J., Vallino M.: Compt.Rend. 264. 571, 1967). Both compounds are therefore crystallographically isomorphic and isostructural.

It is highly probable that the molecular structure is identical. The following crystallographic parameters result from the powder diffraction pattern (Table III).

Table III

Crystallographic parameters plg (Ο^ΗθΟ) ^Clg]

habit plates system tetragonal space group P 4g2 2 (probably) From 2 a = b 0.782 nm c 1.734 nm density(calculated) 1206.6 kgm^

Infrared spectra of the compound

The infrared spectrum of the compound in the solid state or in a Nujol suspension cannot be reliably measured due to the low thermal stability of the compound and its easy desolvation by the action of an inert hydrocarbon (Nujol). The spectrum of saturated solutions in tetrahydrofuran in the region of 1400 to 200 cm~^ shows the bands listed in Table IV.

Table IV

238 214

Infrared spectrum of a saturated solution of [(P)2CO3HgO)2O1] in tetrahydrofuran

Wavenumber, •m” ¹ Intensity Assignment 1340 vw CHg-wagging 1292 vw CH ₂ -wagging 1243 vw CH ₂ -wagging 1180 m expanding the circle 1040 vs. _In (00C) in C ₄ H ₈ O...Mg 887 with V _S (COC) in C ₄ H ₈ O...Mg 672 m CH ₂ -rocking 590 vw circle deformation 445 . sh circle deformation 408 m VíblgCl) 348 with V(MgO) 310 sh

vw - very weak, m - medium, s - strong, vs - very strong, sh - shoulder (fold)

Electrical conductivity

The electrical conductivity of solutions of [MgíC^HgOj^d^] in tetrahydrofuran is very low. In the concentration range of 0.02 to 0.20 mol” ¹ the specific conductivity of the solutions is 0.3 to 9.8.10 x ”'cm” at a temperature of 20°C, 0.2 to 6.0.1 θ“^β ^-1 on“ ¹ at a temperature of 30°G and

0.1 to 3.9.10^52. ^-1 cm“ ¹ for 40° C. These values indicate the molecular character of the compound in tetrahydrofuran solutions and indirectly also in the solid state.

Claims (5)

Object of the invention 238 214 trans-Dichlorotetrakis (tetrahydrofuran) magnesium complex in Mg [((Ο ΟθΗ) 4Cl2], structural formula Cl, where (i) means CH _rt / _2V CH _? I ch ₂ 2. A process for the preparation of a compound according to claim 1, characterized in that elemental magnesium is reacted with allyl chloride in a tetrahydrofuran environment. 3. A process for the preparation of the compound according to claim 1, characterized in that the magnesium Grignard reagent of the formula RMgCl, wherein R is an aliphatic, cyclic or aromatic substituent of up to 8 carbon atoms, preferably 1-butyl, is reacted with dry hydrogen chloride in tetrahydrofuran. 4. A process for the preparation of a compound as claimed in claim 1, wherein elemental magnesium is reacted with dry hydrogen chloride in tetrahydrofuran. 5. Process according to claims 2,3 and 4, wherein the product is isolated by crystallization from tetrahydrofuranových solution at 28 ° C _e