Abstract: This dialkylmagnesium is represented by the formula R--(CH.sub.2 --CH.sub.2).sub.n --Mg--(CH.sub.2 --CH.sub.2).sub.n' --R', (E--O--E').sub.x, where R and R' each independently represent a C.sub.1 -C.sub.20 hydrocarbon residue, branched or not, substituted or not, of the alkyl, cycloalkyl or aralkyl type; n and n', identical or substantially identical, represent an average number of --CH.sub.2 --CH.sub.2 -- linkages such that the average number of carbon atoms in each of the two chains borne by Mg is greater than 20; E and E', identical or different, each represent an alkyl radical, linear or cyclical, branched or not; and 0.ltoreq.x.ltoreq.2, x being the average value of the number of moles of E--O--E' ether complexed to the dialkylmagnesium. In order to prepare a dialkylmagnesium of this type, ethylene is polymerized in an anhydrous, de-oxygenated hydrocarbonaceous solution by means of a catalyst Cp*.sub.2 MCl.sub.2 Li(OEt.sub.2).sub.

Abstract: This dialkylmagnesium is represented by the formula R--(CH.sub.2 --CH.sub.2).sub.n --Mg--(CH.sub.2 --CH.sub.2).sub.n' --R', (E--O--E').sub.x, where R and R' each independently represent a C.sub.1 -C.sub.20 hydrocarbon residue, branched or not, substituted or not, of the alkyl, cycloalkyl or aralkyl type; n and n', identical or substantially identical, represent an average number of --CH.sub.2 --CH.sub.2 -- linkages such that the average number of carbon atoms in each of the two chains borne by Mg is greater than 20; E and E', identical or different, each represent an alkyl radical, linear or cyclical, branched or not; and 0.ltoreq.x.ltoreq.2, x being the average value of the number of moles of E--O--E' ether complexed to the dialkylmagnesium. In order to prepare a dialkylmagnesium of this type, ethylene is polymerized in an anhydrous, de-oxygenated hydrocarbonaceous solution by means of a catalyst Cp*.sub.2 MCl.sub.2 Li(OEt.sub.2).sub.

Abstract: A catalyst active in the (co)polymerization of .alpha.-olefins is obtained by putting the following components in contact with each other:(i) a "bridged" bis-metallocene derivative of a metal M selected from titanium, zirconium or hafnium, wherein the divalent "bridge" has a rigid structure linked to two .eta..sup.5 -cyclopentadienyl ring with two methylene groups having a distance from each other of less than 3.5 .ANG.;(ii) a co-catalyst consisting of an organic derivative of a metal M' selected from boron, aluminium, gallium and tin.Such a catalyst allows high polymerization rates to be reached and is particularly suitable for high temperature polymerization process and co-polymerization of ethylene with other .alpha.-olefins.

Abstract: This catalyst has the general formula VX.sub.3, mAIX.sub.3, nZ, wherein X is a halogen atom, Z is at least one at least partially halogenated, branched or unbranched, saturated hydrocarbon, m is between 0.1 and 10, and n is between 1 and 300. To prepare it, a vanadium halide VX.sub.2 and/or VX.sub.3 is coground with an aluminum halide AlX.sub.3, and then at least one halogenated hydrocarbon Z is added to the mixture obtained in proportions corresponding to the chosen values of m and n. The invention also relates to the (co)polymerization of alpha-olefins at 20.degree.-350.degree. C. in the presence of a catalyst system comprising at least one catalyst as defined above and at least one organometallic activator.

Abstract: A process is disclosed for the polymerization of olefins, using (i) a catalyst and (ii) an organometallic activator from Groups I, II or III of the Periodic Table at temperatures between 20.degree. and 250.degree. C., and pressure up to 200 bar, in solution, or in suspension in an inert liquid hydrocarbon, at temperatures between 160.degree. and 350.degree. C., under pressures of between 400 and 3000 bar, in a continuous manner in a reactor where the mean residence time of the catalyst is between 1 and 150 seconds. The catalyst comprises at least one titanium compound, at least one halogen-containing organoaluminum compound and at least one inorganic magnesium compound in suspension in at least one .alpha.,.omega.-dihaloalkane. The titanium compound is essentially a titanium (III) compound, the total content of titanium (II) and titanium (IV) being less than or equal to 15% of the total content of titanium.

Abstract: This catalyst consists of the reaction product, with at least one organomagnesium compound and/or organolithium compound R.sup.1 Li (R.sup.1 =alkyl) or ArLi (Ar=phenyl or benzyl), of the reaction product of (Cp).sub.2 MX.sub.2 Li(OR.sub.2).sub.2 (M=lanthanide, Sc, Y; (Cp)=optionally substituted cyclopentadienyl; and R=alkyl), with at least one bidentate ligand, such as .beta.-diketone or .beta.-keto imine CZ.sub.3 COCHZCDCZ.sub.3, Z selected from halogen, alkyl and H, D=O, NH or NR.sup.3 (R.sup.3 =alkyl or aryl); and phosphorus ylid R.sup.2.sub.3 P.dbd.CA--CO--R.sup.2, R.sup.2 chosen from alkyl and aryl; A=alkyl or H. It advantageously takes the form of a solution at least partially containing an aromatic hydrocarbon. The process for the polymerization of ethylene may be carried out at 20.degree.-250.degree. C. at a pressure which may range up to approximately 200 bars, in solution or in suspension in an at least C.sub.

Abstract: Process for the preparation of a catalytic composition for the polymerization of olefins. At least partial electrochemical oxidation of aluminum in a solvent of .alpha.,.omega.-dihalogeno-alkane and simultaneously the electrochemical reduction of a compound of titanium (IV) occur in process.The catalytic composition comprises at least one titanium compound, at least one halogenated organo-aluminum compound and at least one inorganic magnesium compound in suspension in at least one .alpha.,.omega.-dihalogeno-alkane. The titanium compound is essentially a titanium (III) compound. The overall content of titanium (II) and titanium (IV) is less than or equal to 15% of the total titanium content.

Abstract: The process comprises, in a first step, the reduction of a titanium (IV) compound in an .alpha.,.omega.-dihalogenoalkane using a molar excess of at least one halogenated organoaluminium compound in the absence of an ether, and then in a second step, the addition of a reaction mixture of a compound capable of forming a magnesium halide in-situ, without additional reduction of the titanium compound obtained in the first step. The catalyst contains at least one titanium compound, at least one halogenated organoaluminium compound and at least one inorganic magnesium compound in suspension in at least one .alpha.,.omega.-dihalogenoalkane; the titanium cmpound is essentially a titanium (III) compound, the total titanium (II) and titanium (IV) content being less than or equal 15% to the total titanium content. It may also contain at least one vanadium compound, an inert solvent, at least one partially polymerized .alpha.

Abstract: Process for the preparation of a catalytic composition for the polymerization of olefins. At least partial electrochemical oxidation of aluminum in a solvent of .alpha., .omega.-dihalogeno-alkane and simultaneously the electrochemical reduction of a compound of titanium (IV) occur in process.The catalytic composition comprises at least one titanium compound, at least one halogenated organs-aluminum compound and at least one inorganic magnesium compound in suspension in at least one .alpha.,.omega.-dihalogeno-alkane. The titanium compound is essentially a titanium (III) compound. The overall content of titanium (II) and titanium (IV) is less than or equal to 15% of the total titanium content.

Abstract: Process for the preparation of a catalytic composition for the polymerization of olefins. At least partial electrochemical oxidation of aluminum in a solvent of .alpha.,.omega.-dihalogeno-alkane and simultaneously the electrochemical reduction of a compound of titanium (IV) occur in process.The catalytic composition comprises at least one titanium compound, at least one halogenated organo-aluminum compound and at least one inorganic magnesium compound in suspension in at least one .alpha.,.omega.-dihalogeno-alkane. The titanium compound is essentially a titanium (III) compound. The overall content of titanium (II) and titanium (IV) is less than or equal to 15% of the total titanium content.

Abstract: A process for the continuous manufacture of homopolymers of an ethylene monomer and copolymers of an ethylene monomer with at least one .alpha.-olefin containing 3 to 8 carbon atoms. The monomers and a catalytic system are introduced into a first stage reactor to form a reaction medium for polymerizing the monomers. During a first stage, when the polymerization is substantially complete, a first compound, which is capable of reducing a transition metal of the catalytic system, is introduced into the reaction medium.

Abstract: The process, which comprises a first stage for (co)polymerizing ethylene at 180.degree.-320.degree. C. and 300-2,500 bars in the presence of a Ziegler type catalytic system, a second stage for separation, a third stage for recycling unreacted monomers, and a fourth, recompression stage, is characterized by introducing into the stream of recycled monomer(s) during the third stage, at least one compound selected from the amides of the saturated or unsaturated organic acids containing from 12 to 22 carbon atoms, polyalkylene polyols containing from 4 to 500 carbon atoms, and compounds containing at least two epoxide functions, with a molecular weight greater than approximately 200. Preferably from 0.005 to 0.1 mole of the selected compound is introduced per ton of recycled monomer.This process makes it possible to avoid the formation of high molecular weight polymers in the recycle circuits.

Abstract: A catalyst system for use in the polymerization of ethylene under high pressure and temperature containing an alkyl-aluminum or alkylsiloxalane activator and a compound of the formula:(TiCla) (MgCL.sub.2).sub.y (AlCl.sub.3)z (RMgCl).sub.bin whicha is from 2 to 3;y is 2 or more;z is from 0 to 1/3;b is from 0 to 1; andR is an aliphatic or aromatic hydrocarbon radical.

Abstract: A catalyst for the polymerization of ethylene comprising at least one halogenated compound of a transition metal of Groups IV to VI of the Periodic System and at least one aromatic silicon compound having the formula .phi..sub.n Si(OH).sub.4-n, in which .phi. is a substituted or unsubstituted aromatic or polyaromatic ring compound having from 6 to 15 carbon atoms and 1.ltoreq.n.ltoreq.3, said silicon compound being present in a molar ratio of between 0.2 and 2 inclusive with respect to said transition metal. Polymerization of ethylene may be carried out under a pressure of between 200 to 2500 bars and at a temperature of between 170.degree. and 300.degree. C. with the catalyst of this invention.

Abstract: A catalyst for the polymerization of ethylene comprising at least one halogenated compound of a transition metal of Groups IV to VI of the Periodic System and at least one aromatic silicon compound having the formula .phi..sub.n Si(OH).sub.4-n, in which .phi. is a substituted or unsubstituted aromatic or polyaromatic ring compound having from 6 to 15 carbon atoms and 1.ltoreq.n.ltoreq.3, said silicon compound being present in a molar ratio of between 0.2 and 2 inclusive with respect to said transition metal. Polymerization of ethylene may be carried out under a pressure of between 200 to 2500 bars and at a temperature of between 170.degree. and 300.degree. C. with the catalyst of this invention.

Abstract: A polymerization activator for polymerizing ethylene comprising a dialkylaluminum monofluoride mixed with minor amounts of at least one of dialkylaluminum hydride or halide and a trialkylaluminum. The activator preferably corresponds to the general formula (AlR.sub.2 F)(AlR.sub.2 H).sub.b (AlR.sub.3).sub.c or the general formula (AlR.sub.2 F)(AlR.sub.2 X).sub.a wherein R is an alkyl group having 1 to 12 carbon atoms, 0.1.ltoreq.b.ltoreq.0.4, 0.05.ltoreq.c.ltoreq.0.2, X is a halogen other than fluorine, and 0.1.ltoreq.a.ltoreq.0.4. The activator is used in a catalytic system including at least one halide of a transition metal of Group IVB to VIB, the valency of the metal in the halide being not more than 3 and the atomic ratio of aluminum in the activator to transition metal in the catalyst lying between 0.1 and 10. The catalytic system is used in a high pressure and temperature process for polymerizing or copolymerizing ethylene.

Abstract: A process for polymerizing ethylene in the presence of a catalyst system comprising at least two halogen compounds of transition metals, one of which has the formula (TiCl.sub.3,Y3 AlCl.sub.3)(MY.sub.3).sub.x (MgYZ).sub.y, where M is a transition metal of Group VB or V1B, X is a halogen and 0.3.ltoreq.x.ltoreq.3, 0.ltoreq.y.ltoreq.20, and a Group I to III hydryde or organometallic activator and the mean residence time of the catalyst system in the polymerization reactor is between 2 and 100 seconds.

Abstract: A catalyst comprising the product obtained by bringing into contact (a) a compound of magnesium comprising at least one species selected from the group consisting of magnesium monohalides (MgX), halo-magnesium hydrides (HMgX) and magnesium hydride (MgH.sub.2), X being a halogen and the said species MgX or HMgX being obtained by thermal decomposition of a powdery organo-magnesium halide R.sub.1 MgX wherein R.sub.1 is an organic radical; and (b) at least one halide of a transistion metal selected from the group consisting of titanium and vanadium, the valency of said metal in said halide being lower than or equal to 3, the quantities of (a) and (b) being such that the atomic ratio of magnesium to said transistion metal is between 1 and 25, and a catalyst system including the catalyst that is suitable for use in the polymerization of olefins and particularly ethylene.

Abstract: An organometallic halide having the formula:(RMX) (MX.sub.2).sub.a (MR.sub.2).sub.b (MH.sub.2).sub.cwherein a.ltoreq.0.45, b.ltoreq.0.15, and c.ltoreq.0.30, X is a halogen, R is a hydrocarbon radical, and M is a metal selected from the group consisting of magnesium, zinc, beryllium, and calcium is prepared by a continuous dry process by reacting an organic monohalide RX and a metal M in the form of convex solid grains of a size between 1 and 15 mm. The reaction temperature is lower than the temperature at which decomposition of the organometallic halide RMX begins and at least 10.degree. C. higher than the boiling point of the organic monohalide. The reaction may also take place in the presence of an organometallic derivative comprising a hydroxy group or an enolysable ketone group. The resulting organometallic halide may be used for the synthesis of anhydrous magnesium halide or for the reduction of titanium tetrachloride.

Abstract: A polymerization activator for polymerizing ethylene comprising a dialkylaluminum monofluoride mixed with minor amounts of at least one of dialkylaluminum hydride or halide and a trialkylaluminum. The activator preferably corresponds to the general formula (AlR.sub.2 F)(AlR.sub.2 H).sub.b (AlR.sub.3).sub.c or the general formula (AlR.sub.2 F)(AlR.sub.2 X).sub.a wherein R is an alkyl group having 1 to 12 carbon atoms, 0.1.ltoreq.b.ltoreq.0.4, 0.05.ltoreq.c.ltoreq.0.2, X is a halogen other than fluorine, and 0.1.ltoreq.a.ltoreq.0.4. The activator is used in a catalytic system including at least one halide of a transition metal of Group IVB to VIB, the valency of the metal in the halide being not more than 3 and the atomic ratio of aluminum in the activator to transition metal in the catalyst lying between 0.1 and 10. The catalytic system is used in a high pressure and temperature process for polymerizing or copolymerizing ethylene.