Catalysts for the Polymerization of Olefins, Method of Preparing the Same

No prior art disclosing the present catalysts or the use thereof in the homo- and co-polymerization of olefins is known.

An object of the present invention is to provide new catalysts for the (co) polymerization of ethylene and alphaolefins, i.e., olefins containing at least three carbon atoms, to high yields of polymer in gms/gm of Ti, V or Zr used.

This and other objects are achieved by this invention in accordance with which ethylene, alpha-olefins containing at least three carbon atoms, or mixtures thereof, are polymerized in contact with a catalyst prepared as set forth in the foregoing abstract of Disclosures from a complex of formula (I) in which R is preferably an alkyl radical containing from 1 to 10 carbon atoms, a cycloalkyl radical containing from 6 to 8 carbon atoms, or an aryl radical.

Examples of halogen-containing Ti, V or Zr compounds which are useful in preparing the catalysts include: TiCl.sub.3, TiCl.sub.4, TiBr.sub.4, TiI.sub.4, TiCl.sub.3 OCH.sub.3, Ti(O-n-C.sub.3 H.sub.7).sub.2 Cl.sub.2, Ti(O-n-C.sub.4 H.sub.9)Cl.sub.3, Ti(O-n-C.sub.4 H.sub.9).sub.2 Cl.sub.2, Ti(O-n-C.sub.4 H.sub.9).sub.3 Cl, Ti[N(C.sub.2 H.sub.5).sub.2 ]Cl.sub.3, Ti[N(C.sub.6 H.sub.5).sub.2 ]Cl.sub.3, Ti(OOC-C.sub.6 H.sub.5)Cl.sub.3, VCl.sub.4, VOCl.sub.3, ZrCl.sub.4.

Halogen-free, oxygen-containing organic compounds of Ti, V or Zr which can be used in preparing the present catalysts are compounds in which the organic radical contains from 1 to 20, preferably from 1 to 8, carbon atoms and is bound to the metal through an oxygen atom. Examples of the useful compounds of this type include the alcoholates, phenolates, acetylacetonates, and alkyl or polyoxyalkyleneglycol esters of acids derived from the metals. Specific examples include the following: Ti(O-n-C.sub.3 H.sub.7).sub.4 ; Ti(O-n-C.sub.4 H.sub.9).sub.4 ; Ti(OC.sub.6 H.sub.5).sub.4 ; polyoxyethyleneglycol orthotitanates; V(O-n-C.sub.3 H.sub.7).sub.4 ; VO(O-n-C.sub.3 H.sub.7).sub.3 ; V(acetylacetonate).sub.3 ; Zr(O-n-C.sub.4 H.sub.9).sub.4.

Typical examples of the complexes of formula (I) are: MgCl.sub.2.2AlC.sub.2 H.sub.5 Cl.sub.2 ; MgCl.sub.2.2,5Al-i-C.sub.4 H.sub.9 Cl.sub.2 ; MgCl.sub.2.1,5Al-n-C.sub.4 H.sub.9 Cl.sub.2 ; CaCl.sub.2.4AlC.sub.2 H.sub.5 Cl.sub.2 ; and BaCl.sub.2.AlCl.sub.3.AlC.sub.2 H.sub.5 Cl.sub.2.

Decomposition of the complex MX.sub.2.nAlRX.sub.2.pAlX.sub.3 to the product comprising compounds containing at least metal M and halogen, for contacting with the Ti, V or Zr compound to obtain component (A) of the catalysts according to this invention, may be carried out according to various methods. A preferred method consists in reacting the compound of Ti, V or Zr with the complex itself, in a M/transition metal atomic ratio ranging from 0.1 to 50 or higher, at a temperature generally comprised between 0.degree. and 150.degree. C or even below 0.degree. C, but preferably comprised between 20.degree. and 140.degree. C, and in separating the solid reaction product from the liquid phase. Said reaction may be conducted according to various modalities, for example:

(a) the reaction may be conducted in a hydrocarbon diluent, such as n-hexane, n-heptane or cyclohexane, or by dissolving the complex in a compound AlRX.sub.2 in which R and X have the same meaning as in formula (I);

(b) the complex may be pulverized in the presence of the transition metal compound;

(c) the complex, prior to the reaction with the transition metal compound in a hydrocarbon diluent may be activated by grinding.

The extent to which the complex is decomposed by reaction with the Ti, V or Zr compound depends on the operating conditions and on the particular Ti, V or Zr compound used.

According to another embodiment of the invention, component (A) is prepared by direct reaction of the transition metal compound in situ with each individual component of the complex of formula (I), for example by reacting TiCl.sub.4 with MgCl.sub.2 and AlC.sub.2 H.sub.5 Cl.sub.2. That reaction is preferably carried out in an inert hydrocarbon solvent at a temperature higher than 20.degree. C and, generally, at a temperature of from 50.degree. to 120.degree. C. The order in which the reagents are introduced into the reaction zone does not exert any appreciable influence on the activity of the catalysts. An Al/Ti ratio higher than 1.0 is employed.

Other methods of decomposing the complex of formula (I) are the following:

(d) the complex, in suspension in a hydrocarbon solvent, is decomposed by treatment with an excess of gaseous Hcl at room temperature;

(e) the complex, preferably in suspension in a hydrocarbon solvent, is decomposed by reaction with a Lewis base, or with an aliphatic or cycloaliphatic alcohol containing 1 to 20 carbon atoms, at a temperature comprised between -20.degree. and +150.degree. C, or by reaction with an organometallic compound of the metals of Groups I, II or III, in particular with compounds AlR.sub.2 X, in which R is an alkyl, cycloalkyl or aryl radical containing from 1 up to 20 carbon atoms, and X is a halogen or a hydrocarbon group like R, the latter reaction being preferably conducted at the boiling temperature of the hydrocarbon medium.

Because the complex is decomposed by compounds AlR.sub.2 X, which are generally used as component (B) of the catalyst, the transition metal compound is surely, and in any case, in contact with the decomposition product of the complex when the polymerization takes place. The decomposition with the Lewis base may be effected in a wide temperature range. The reaction is more or less complete and yields a complex made up of AlRX.sub.2 and the base. The decomposition products of the complex generally contain metal M, halogen, and, optionally, also Al and R groups. If Al and R groups are not present, the decomposition product consists of the halide MX.sub.2. In the decomposition products containing Al and R groups, the Al/R ratio is higher than in the starting complex.

A particular advantage of the catalysts of this invention consists in that the complex may be dissolved in an excess of Al-alkyl dihalide, and the solution can be used to impregnate an inert carrier containing the transition metal compound, or to which the transition metal compound may be added after the impregnation.

Particularly useful carriers are .gamma.-Al.sub.2 O.sub.3 and SiO.sub.2 having a high surface area and a pores volume exceeding 0.3 cc/g, TiO.sub.2, ZrO.sub.2 or polymers. In this way "supported catalysts" are obtained, which have all of the advantages of these new catalysts plus the advantages of a supported catalyst.

Component (B) of the catalyst is preferably an Al trialkyl or an Al dialkyl monohalide, in which the alkyl radicals contain from 1 to 6 carbon atoms.

Some typical examples of organometallic compounds of the metals of Groups I, II or III to be employed as component (B) of the catalysts are the following: Al(C.sub.2 H.sub.5).sub.3, Al(i-C.sub.4 H.sub.9).sub.3, Al(C.sub.2 H.sub.5).sub.2 Cl, Al.sub.2 (C.sub.2 H.sub.5).sub.3 Cl.sub.3, Al(n-C.sub.3 H.sub.7).sub.2 Cl, Al(i-C.sub.4 H.sub.9).sub.2 H, Al(i-C.sub.4 H.sub.9)H.sub.2, Zn(C.sub.2 H.sub.5).sub.2.

The molar ratio component (B) transition metal compound is higher than 1 and is generally comprised in a wide range: in preferred embodiments the ratio is higher than 100.

The catalysts according to this invention are particularly suitable for the polymerization of ethylene, propylene or mixtures of ethylene and propylene which may contain hydrocarbon compounds having two or more double bonds. The polymerization is carried out in a liquid phase or in a gas phase according to conventional methods. The liquid phase may consist of the monomer to be polymerized or may comprise an inert hydrocarbon diluent, such as butane, pentane, hexane, heptane, cyclohexane, etc.

The polymerization temperature is generally comprised between 0.degree. and 100.degree. C. The (co)polymerization of ethylene and of alpha-olefins is preferably carried out at temperatures between 50.degree. and 90.degree. C, at atmospheric or at a higher pressure.

The present catalysts can be used to polymerize propylene to a polypropylene consisting at least predominantly of isotactic macromolecues, i.e., macromolecules having substantially the isotactic structure and being insoluble in boiling n-heptane. Preferably, to accomplish that purpose, component (B) of the catalyst is an addition product, or complex, with a Lewis base as described in Italian Patent No. 932,438.

The following examples are given to illustrate the invention in more detail and are not intended to be limiting.

The Examples illustrate both the preparation of components (A) of the catalyst and the polymerization of ethylene and propylene in contact with the final catalyst obtained by mixing the component (A) with component (B).

The results of the examples are reported in a number of Tables which show both the data relevant to preparation of component (A) of the catalyst and the results obtained by using the final catalysts in the polymerization of olefins.

In all instances, the polymerization was carried out under the following conditions:

One liter of anhydrous hexane, 1.5 g of Al(i-C.sub.4 H.sub.9).sub.3 as co-catalyst (component B) and, finally, a proper amount of catalyst component (A) prepared from reagents (1) and (2) were introduced, in that order and in a nitrogen atmosphere, into a 2.5-liter autoclave, equipped with a stirrer. The mixture was heated to 85.degree. C, whereupon 3 atm. of hydrogen (molecular weight modifier) and 10 atm. of ethylene were introduced, ethylene being then continuously fed for 4 hours. The suspension was discharged from the autoclave and filtered, and the polyethylene was dried in an oven to constant weight.

The yield is expressed in grams of polymer obtained per gram of transition metal used.

The melt-index of the polymer was measured according to standard ASTM D 1238 (conditions E) and is expressed in g/10 min.

The complex MgCl.sub.2.2AlC.sub.2 H.sub.5 Cl.sub.2 was prepared as follows: 4.65 g of anhydrous MgCl.sub.2 in powder form were mixed, in a glass flask equipped with magnetic stirrer and in a nitrogen atmosphere, with 20 cc of AlC.sub.2 H.sub.5 Cl.sub.2. The mixture was heated to 100.degree. C, with continuous stirring at that temperature for 20 hours. The resulting solution was admixed, after cooling to 20.degree. C, with 300 cc of anhydrous n-heptane. The precipitate which formed was filtered in a nitrogen atmosphere on fritted bottom G 3, then repeatedly washed on such bottom with portions of 50 cc of anhydrous n-pentane for each washing, and finally dried under vacuum (0.5 mm Hg) at 20.degree. C for a few hours. 10.7 g of a white solid powder were obtained, having the formula MgCl.sub.2.2AlC.sub.2 H.sub.5 Cl.sub.2 and a melting point (measured in a tube welded in a nitrogen atmosphere) of 165.degree. C with decomposition.

Analysis - Found: Mg = 6.89%; Al = 15.61%; Cl = 61.50%; ethane (gas volumetric analysis by decomposition with n-octanol) = 16.0%. Calculated: Mg = 6.96%; Al = 15.44%; Cl = 60.91%; ethane = 16.68%.

The other complexes used in the Examples were prepared analogously.

Table I reports the details of Examples 1 to 8 in which catalyst components (A) were prepared by reaction between reagents (1) and (2) in n-heptane, and the utilization of the final catalysts obtained by mixing the catalyst components (A) with component (B) in the polymerization of ethylene. It may be noticed that the catalyst activity increases as the Mg/Ti atomic ratio in the catalyst increases. The catalyst of Example 6 exhibits a particularly high activity, as it was prepared starting from a complex previously activated by grinding, besides having a very favorable Mg/Ti ratio.

150 cc of thoroughly anhydrous n-heptane along with a suitable amount of TiCl.sub.4 were introduced into a 250 cc glass flask equipped with a stirrer and a reflux cooler. A corresponding amount of MgCl.sub.2.2AlC.sub.2 H.sub.5 Cl.sub.2 in powder form was introduced batchwise into the flask, at room temperature and over a period of 30 minutes. The mixture was heated to the boiling point of the solvent (98.degree. C), and held under refluxing for 1 hour. After cooling, the resulting brown solid product was filtered on fritted bottom G3 in a nitrogen atmosphere, thoroughly washed on the filter with n-heptane until the Cl' ions were eliminated from the filtrate, and dried under vacuum at 50.degree. C to constant weight.

6 g of MgCl.sub.2.2AlC.sub.2 H.sub.5 Cl.sub.2 were introduced into a 350 cc porcelain jar containing 5 porcelain balls having a diameter varying from 20 to 40 mm. The jar was fastened in a centrifugal mill, which was rotated at room temperature for 2 hours. 3 g of the solid thus obtained were treated with 0.164 g of TiCl.sub.4 as in Examples 1 to 5, but at the temperature of 20.degree. C instead of 98.degree. C.

Example 6 was repeated, but employing a different Mg/Ti atomic ratio.

Example 6 was repeated, but the reaction with the Ti compound was conducted at 98.degree. C instead of at 20.degree. C.

Table II reports Examples 9 to 12 illustrating the preparation of catalyst components (A) by pulverization of the complex in the presence of reagent (1) in a porcelain jar fastened in a centrifugal mill.

The pulverization was carried out with the same modalities as in Example 6, the only difference consisting in that the time required by such operation was 4 hours.

In these examples, also, it may be noticed that the yield increases as the Mg/Ti atomic ratio increases.

Table III reports the details of Example 13 in which a catalyst component (A) was prepared by reacting, in a solvent, MgCl.sub.2.2AlEtCl.sub.2 with VOCl.sub.3.1.25 g of VOCl.sub.3 dissolved in 50 cc of anhydrous n-heptane were introduced into a 100 cc glass flask, in a nitrogen atmosphere. 5.0 g of MgCl.sub.2.2AlC.sub.2 H.sub.5 Cl.sub.2 were added thereto in 30 min., at room temperature and under stirring. At the conclusion of the addition, the stirring was continued for a further 2 hours. A solid product was thus obtained; it was filtered and washed with n-heptane on the filtering fritted bottom. Finally, the product was dried under vacuum at 40.degree. C to constant weight.

Table IV reports the details of Examples 14 and 15, in which MgCl.sub.2.2AlEtCl.sub.2 (kept in solution in AlEtCl.sub.2 at 100.degree. C) was reacted with TiCl.sub.4 under the following conditions:

A suitable amount of a solution of MgCl.sub.2.2AlEtCl.sub.2 in AlEtCl.sub.2 (such solution contained 15.7% of MgCl.sub.2 and was kept at 100.degree. C to prevent it from solidifying) was dropped, in 15 minutes, under stirring, into a 10% heptane solution of TiCl.sub.4 cooled to -5.degree. C. The resulting brown suspension was brought to room temperature and stirred for a further 2 hours.

Subsequently, the liquid phase was removed by decantation and siphoning, and the solid was washed with n-heptane until the elimination of the Cl' ions from the solvent. The product was then dried under vacuum at 50.degree. C to constant weight.

Table V reports the operating conditions of Examples 16 to 19 in which catalyst components (A) were prepared directly from MgCl.sub.2, AlEtCl.sub.2 and TiCl.sub.4, i.e., the complex MgCl.sub.2.2AlEtCl.sub.2 was not pre-prepared. In these Examples, anhydrous MgCl.sub.2 was used in the form of flakes, having a surface area .ltoreq.1 m.sup.2 /g.

Examples 16 and 17 were carried out as follows: a suitable amount of anhydrous MgCl.sub.2 in flakes was suspended in 50 cc of n-heptane along with TiCl.sub.4 ; keeping a temperature of 10.degree. C, AlEtCl.sub.2 in the form of a heptane solution containing 55.5 g of AlEtCl.sub.2 /100 cc of solution was dropped into the suspension over a period of 30 minutes.

The temperature was then gradually raised to the boiling point of the heptane and the heating was continued under refluxing for 1 hour. The suspension was allowed to cool to room temperature and filtered, the resulting solid was washed 5 times with n-heptane and dried under vacuum at 50.degree. C to constant weight.

Example 16 was repeated, the only difference being that TiCl.sub.4 diluted in 50 cc of n-heptane was dropped into the suspension of MgCl.sub.2 and AlEtCl.sub.2 in 30 cc of heptane (inverted order of addition).

10 g of anhydrous MgCl.sub.2 in the form of flakes were treated with 26.6 g of AlC.sub.2 H.sub.5 Cl.sub.2 (Mg/Al atomic ratio = 1/2) in 50 cc of heptane at 98.degree. C for 1 hour. The reaction product was filtered and repeatedly washed with heptane. 8.8 g of such product reaction product (z) containing Mg = 19.75%; Al = 3.40%; Cl = 73.05% suspended in 50 cc of n-heptane were added, in 30 minutes at room temperature, with 15.7 g of TiCl.sub.4 and the whole was reacted for 1 hour at 98.degree. C.

The resulting suspension was cooled to room temperature and filtered. The solid thus obtained was washed 5 times with heptane and dried under vacuum at 50.degree. C to constant weight.

Table VI gives the details of Examples 20 to 24 in which the catalysts were supported on silicas or on .gamma.-alumina pre-calcined for some hours at 500.degree. to 700.degree. C in a dry nitrogen flow.

In these examples the operations were as follows: a given amount of carrier was introduced into a 250 cc glass flask immersed in an oil bath kept at about 100.degree. C. 25 g of a solution of MgCl.sub.2.2AlEtCl.sub.2 in AlEtCl.sub.2 (at 15.7% by weight of MgCl.sub.2) kept at about 100.degree. C were added to the carrier in 10 minutes, under stirring.

Successively, 150 cc of n-heptane were added, keeping the latter at reflux temperature (98.degree. C) for 1 hour. After cooling, the mixture was filtered, the resulting solid product was repeatedly washed with n-heptane until the Cl' ions were eliminated from the filtrate, and the solid was dried under vacuum at 60.degree. C to constant weight.

A portion of the product thus obtained was introduced into a 250 cc glass flask along with a suitable amount of TiCl.sub.4 dissolved in 50 cc of n-heptane. It was heated to the heptane reflux temperature, maintaining such temperature for 1 hour under stirring. After cooling, it was filtered, the resulting solid product was washed with n-heptane until elimination of the Cl' ions from the filtrate and dried under vacuum at 60.degree. C to constant weight.

In this Example, the carrier was first impregnated with TiCl.sub.4 and then with MgCl.sub.2.2AlEtCl.sub.2.

20.8 g of Al.sub.2 O.sub.3 Grade B produced by AKZO Chemie (calcined at 700.degree. C for 5 hours) and 104 cc of TiCl.sub.4 were introduced into a 250 cc glass flask and, under stirring, the resulting mixture was heated for 1 hour to the reflux temperature of TiCl.sub.4 (136.degree. C).

After cooling, the mass was filtered, and the solid was washed with n-heptane until the TiCl.sub.4 not fixed on the carrier was removed. The product was then dried under vacuum at 60.degree. C.

Subsequently, 10.1 g of the product thus obtained (containing 2.35% of Ti) were impregnated with 12.5 g of a solution of MgCl.sub.2.2AlEtCl.sub.2 in AlEtCl.sub.2, according to the same modalities as described in Examples 20 to 23 for impregnation of the carrier with MgCl.sub.2.2AlEtCl.sub.2.

Table VII gives the details of Examples 25 to 28 in which catalyst components (A) were prepared starting from the MgCl.sub.2.2AlEtCl.sub.2 complex decomposed by treatment with n-butyl ether, AlEt.sub.3, anhydrous HCl or with ethyl alcohol.

The complex MgCl.sub.2.2AlEtCl.sub.2 was treated for 2 hours with anhydrous n-butyl ether (AlEtCl.sub.2 /n-butyl ether molar ratio = 1) at 50.degree. C in 100 cc of heptane. The product obtained after filtration and several washings with heptane had, on analysis, a Mg content of 23.35% and an Al content of 0.55%. It was reacted with TiCl.sub.4 as described in Examples 1 to 5.

A suspension of MgCl.sub.2.2AlEtCl.sub.2 in 100 cc of heptane was gradually added with AlEt.sub.3 dissolved in 50 cc of heptane (AlEtCl.sub.2 /AlEt.sub.3 molar ratio = 1). The mixture was heated to 98.degree. C and held at that temperature for 1 hour. After cooling, it was filtered, the resulting product (a very fine powder containing 24.6% of Mg, 71.8% of Cl and 0.5% of Al) was repeatedly washed with heptane and reacted with TiCl.sub.4 as in Examples 1 to 5.

Anhydrous gaseous HCl in excess was bubbled at room temperature into a suspension of 20.2 g of MgCl.sub.2.2AlEtCl.sub.2 in 100 cc of heptane. A solid decomposition product was thus obtained, in which the Mg/Al atomic ratio was about 1/2. Such solid was washed with n-heptane and 8.0 g of same were reacted with 3.9 g of TiCl.sub.4 diluted with 50 cc of heptane as in Examples 1 to 5.

9.5 g of C.sub.2 H.sub.5 OH diluted with 50 cc of n-heptane were added, over a period of 30 minutes to a suspension of 30.5 g of MgCl.sub.2.2AlEtCl.sub.2 in 150 cc of n-heptane, keeping a temperature of 30.degree. C. The whole was kept under stirring for a further 60 minutes at the same temperature, then filtered, and the resulting solid product was washed 4 times with heptane and dried under vacuum at 50.degree. C.

3.5 g of the product thus obtained were reacted with 51.5 g of TiCl.sub.4 for 1 hour at 136.degree. C. The reaction mass was allowed to cool to room temperature and, after filtration, the resulting solid product was washed 4 times with heptane and dried under vacuum at 50.degree. C to constant weight.

Table VIII records the details of Examples 29 to 31 in which catalyst components (A) were prepared by reaction of .beta.-TiCl.sub.3 in flakes with MgCl.sub.2.2AlEtCl.sub.2 dissolved in AlEtCl.sub.2. The final catalysts prepared from components (A) according to Examples 29 to 31 exhibit an activity considerably higher than that of the catalysts prepared from components (A) in which the Ti compound is .beta.-TiCl.sub.3, and yield polymers having good morphological and free-flowing characteristics.

A certain amount of .beta.-TiCl.sub.3 in flakes (prepared by reduction of TiCl.sub.4 with AlEt.sub.2 Cl and containing 22.0% of Ti and 4.9% of Al) was suspended in 100 cc of n-heptane, and to the suspension, cooled down to -5.degree. C, there was added, under stirring, and in about 15 min., the given amount of a solution of MgCl.sub.2.2AlEtCl.sub.2 in AlEtCl.sub.2 heated to 100.degree. C, in order to keep it in the liquid state (such solution contained 15.7% by weight of MgCl.sub.2). At the conclusion of such addition, the temperature was allowed to rise to 15.degree. C, and held at that temperature for 1 hour. An additional 100 cc of n-heptane were admixed, and the mass was kept under stirring at 15.degree. C for another hour. Finally it was filtered, the solid was repeatedly washed with n-heptane, and dried under vacuum at 50.degree. C to constant weight.

Table IX reports the operating conditions and the results of some runs on the polymerization of propylene in liquid monomer (Examples 32, 33, 34) and in a solvent (Examples 35, 36). These runs were carried out in the presence of the catalysts prepared, respectively, in Examples 26, 3, 11, 3 and 11, employing, as component (B), AlEt.sub.3 mixed with ethyl anisate as complexing agent.

Table X reports the details of Examples 37 and 38, in which catalyst components (A) were prepared by reaction in n-heptane of Ti(O-n-C.sub.4 H.sub.9).sub.4 or V-triacetylacetonate with the complex MgCl.sub.2.2AlC.sub.2 H.sub.5 Cl.sub.2, and the use of same in the polymerization of ethylene.

The operating conditions in said Examples were as follows:

3.10 g of the complex MgCl.sub.2.2AlC.sub.2 H.sub.5 Cl.sub.2 in powder form were introduced into a 250 cc glass flask equipped with stirrer and reflux cooler and cooled to 0.degree. C, whereupon 6.30 g of Ti(O-n-C.sub.4 H.sub.9).sub.4, also cooled to 0.degree. C, were added thereto in 30 minutes.

At the conclusion of the addition, the temperature was brought to 25.degree. C and the mixture was diluted with 150 cc of anhydrous n-heptane. It was then heated up to the solvent boiling point (98.degree. C), and held under refluxing for 1 hour. After cooling, the solid contained was filtered on fritted bottom G3 in a nitrogen atmosphere, thoroughly washed on the filter with n-heptane until the disappearance of Cl' ions from the filtrate, and then dried under vacuum at 50.degree. C to constant weight.

2.5 g of vanadium triacetylacetonate dissolved in 50 cc of anhydrous toluene were introduced, in a nitrogen atmosphere, into a 100 cc glass flask. 5.0 g of MgCl.sub.2.2AlC.sub.2 H.sub.5 Cl.sub.2 were added thereto at room temperature, under stirring and over a period of 30 minutes.

At the conclusion of the addition, stirring was carried on for a further 2 hours. A light green solid product formed. It was filtered and then washed on the filtering bottom first with toluene and successively with n-heptane. Finally, the product was dried under vacuum at 40.degree. C to constant weight.