United States Patent (19) 11) 4,091,082 Gessell et al. 45 May 23, 1978

54 HYDROCARBON SOLUBLE CATALYST (III) Ammines Chemical Communications, 1970 pp. CONTAINING ONTROGEN OR 875-876 Elson et al. DHYDROGEN TRANSTION METAL The Interaction of Dinitrogen Complexer of Ruthe COMPLEX nium and Osmium with metal salts. Chemical Commu 75) Inventors: Donald Earl Gessell, Baton Rouge, nications, 1970, pp. 90–91, Chatt et al. La; Kirby Lowery, Jr., Lake Bioinorganic Chemistry, Advances in Chemistry Series Jackson, Tex. 100, 79 (1971), Allen. pp. 79-94. Bioinorganic Chemistry, Advances in Chemistry Series 73 Assignee: The Dow Chemical Company, 100, 95 (1971), "Fixation of Molecular Nitrogen Under Midland, Mich. Mild Cond. pp. 95-110. (21) Appl. No.: 693,071 Chemical Reviews, 73 11(1973) Allen et al. pp. 11-20. 22 Filed: Jun. 4, 1976 51) Int. C.? ...... C01B 21/00; B01J 31/00; Primary Examiner-Patrick P. Garvin B01J 27/24: CO1B 11/00 Assistant Examiner-William G. Wright 52 U.S. C...... 423/413; 252/429 A; Attorney, Agent, or Firm-J. G. Carter; M.S. Jenkins 252/429 B; 252/438; 42.3/472; 423/644; 526/159; 526/161; 526/164; 526/169 57 ABSTRACT 58) Field of Search ...... 252/429 A, 429 B, 438; 423/81, 413, 472, 644, 351 Hydrocarbon-soluble compositions useful as the transi tion metal component in the Ziegler polymerization of 56 References Cited a-olefins are provided by reacting molecular nitrogen U.S. PATENT DOCUMENTS or with a transition metal compound such as 1,491,588 4/1924. Duparc et al...... 252/438 titanium trichloride to form a dinitrogen or dihydrogen 3,403, 197 9/1968 Seelbach et al...... 252/429 AX complex of the transition metal compound. OTHER PUBLICATIONS Dinitrogen Complexer of Osmium (III) and Ruthenium 7 Claims, No Drawings 4,091,082 1. 2 tion metal, anionic groups and molecular nitrogen and HYDROCARBON SOLUBLE CATALYST /or molecular hydrogen. With the exception of divalent CONTAINING DENITROGEN OR DIHYDROGEN nickel compounds, the transition metal of the complex TRANSTION METAL COMPLEX has an oxidation state or valence greater than two. In all complexes of this invention, the molecular nitrogen or BACKGROUND OF THE INVENTION molecular hydrogen forms a coordinate This invention relates to new catalytic dinitrogen and with the transition metal. The anionic groups of the dihydrogen complexes of a transition metal and to a complex are preferably halide, most preferably chloride method for preparation of the complexes. or bromide. The number of anionic groups is sufficient In recent years, dinitrogen complexes of certain tran O to satisfy the valence charge on the transition metal. sition metal have been prepared by (1) reacting a coor Due to the high reactivity and instability of the dinitro dination, complex of the transition metal with molecu gen complexes under conditions required for detailed lar nitrogen in the presence of reducing agent, (2) react structural analysis, such complexes are not further char ing a hydride of transition metal in lower oxidation state acterized as to structure. In preferred dinitrogen com with molecular nitrogen or (3) displacing a weaker 15 plexes, it is believed that the ratio of atoms of the transi in a of the transition metal tion metal to molecular nitrogen and/or molecular hy with molecular nitrogen. See, for example, Allen, "De drogen is from about 1:0.3 to about 1:3, more preferably velopments in Inorganic Models of N. Fixation,' Bioi from about 1:1 to about 1:3, most preferably about 1:1, norganic Chemistry, Advances in Chemistry Series, 100, and the atomic ratio of transition metal atoms to anionic 79(1971) and Allen et al., Chemical Reviews, 73, 20 groups is from about 1:2 to about 1:4, preferably about 11(1973). Such complexes have been described as useful 1:3. Such complexes are generally soluble in hydrocar in the fixation of nitrogen. See, for example, Van Tam bon solvents and should be maintained under an atmo elen, "Fixation of Molecular Nitrogen under Mild Con sphere of nitrogen, hydrogen or mixture thereof de ditions,” Bioinorganic Chemistry, Advances in Chemis pending upon whether molecular nitrogen, molecular try Series, 100, 95(1971). 25 hydrogen or combination thereof is part of the complex. Heretofore, however, it has not been recognized that For example, a complex having molecular nitrogen and molecular nitrogen or molecular hydrogen will react in no molecular hydrogen is preferably kept under a nitro the absence of a reducing agent with higher oxidation gen atmosphere. state transition metal compound containing no coordi The dinitrogen complex is prepared by reacting, in nate covalent bonds to form a dinitrogen or dihydrogen 30 the absence of a reducing agent, molecular nitrogen or complex of the transition metal. molecular hydrogen in an inert organic diluent with a transition metal compound, preferably a transition SUMMARY OF THE INVENTION metal halide, which compound contains no coordinate The present invention, in one aspect, is a dinitrogen covalent bond. and/or dihydrogen complex of divalent nickel or a 35 Exemplary transition metal compounds include, for transition metal having an oxidation state greater than example, the halides such as the chlorides, bromides, two. In the complex, the transition metal is bonded by a iodides and fluorides, of the transition metals of Groups to molecular nitrogen and/or 4b, 6b, 7b and 8 of Mendeleev's Periodic Table of Ele molecular hydrogen. For purposes of brevity, the fore ments as set forth in Handbook of Chemistry and Physics, going complex will hereinafter be referred to as "the 40 CRC, 48th Edition (1967-1968). Exemplary metals are dinitrogen complex' and will include both the dinitro titanium, chromium, zirconium, tungsten, manganese, gen and dihydrogen complexes as well as mixtures of molybdenum, ruthenium, rhodium, cobalt, nickel and dinitrogen and dihydrogen complexes. platinum, with titanium and zirconium being preferred. In a second aspect, the invention is a method for In the most advantageous embodiments, the transition preparing the aforementioned complex which com 45 metal compound is insoluble in hydrocarbon diluents prises reacting molecular nitrogen, molecular hydrogen and is rendered soluble by the formation of the dinitro or a mixture thereof under moderate conditions of pres gen complex. Exemplary preferred transition metal sure and temperature with a transition metal compound compounds are titanium trichloride, zirconium tetra containing no coordinate covalent bond. With the ex chloride, tungsten hexachloride, molybdenum penta ception of the suitable divalent nickel compounds, the 50 chloride, nickel dichloride, with the halides, particu transition metal compounds used in the method have an larly the chlorides, of titanium being most preferred. oxidation state greater than two. This reaction is advan The reaction to form the complex is advantageously tageously carried out in the absence of a reducing agent. carried out in an inert organic diluent attemperatures in In a third aspect, the invention is a process for poly the range from ambient to about 200 C by pressuring merizing an a-olefin under conditions characteristic of 55 nitrogen or hydrogen gas into a reactor containing the Ziegler polymerization wherein the dinitrogen complex transition metal compound dispersed in the inert dilu is employed as the transition metal component of a ent. For purposes of this invention, an inert organic Ziegler catalyst. diluent is an organic fluid that does not prevent forma In addition to being useful as a polymerization cata tion of the complex and is non-reactive with the com lyst, the dinitrogen complex of the present invention is plex once it is formed. Accordingly, liquid hydrocarbon also useful as a catalyst for alkylation and hydrogena such as the aliphatic and aromatic hydrocarbons are tion reactions and as a catalyst in the fixation of nitro useful diluents with the acyclic aliphatic hydrocarbons gen. being preferred. Examples of suitable inert organic dilu ents include hexane, isooctane, octane, isononane, no DETAILED DESCRIPTION OF THE 65 nane, decane, cyclohexane, benzene, 2,2,5-trimethyl EMBODIMENTS hexane and mixtures thereof. Preferred diluents are The dinitrogen complex of the present invention is mixtures of isoparaffins, especially those having 8 to 9 broadly characterized as a complex comprising a transi carbon atoms per molecule. Pressures employed in the 4,091,082 3 4. reaction normally range from about 40 to about 300 avoid oversaturation of the solvent with polymer. If psig, preferably from about 60 to about 150 psig, with such saturation occurs before the catalyst becomes de nitrogen and/or hydrogen gas constituting at least 10 pleted, the full efficiency of the catalyst is not realized. mole percent, preferably from about 50 to 100 mole For best results, it is preferred that the amount of poly percent, and especially from about 90 to 100 mole per mer in the carrier not exceed about 50 weight percent cent of the gas phase in the reaction vessel. Although based on the total weight of the reaction mixture. concentration of transition metal compound dispersed The organometallic cocatalyst is suitably any reduc in the inert diluent is not particularly critical, it is gener ing component commonly employed in Ziegler poly ally desirable to employ concentrations in the range merization. For example, the cocatalyst may be any from about 0.1 to about 10, preferably from about 1 to O organometallic reducing compounds employed in con 10, weight percent of transition metal compound in the ventional Ziegler polymerization, preferably an alkyl inert diluent. aluminum compound having at least two alkyl groups In cases wherein the transition metal compound is per aluminum, e.g., aluminum trialkyls or dialkyl alumi insoluble in the organic diluent, it is desirable to agitate num halides. Examples include aluminum triethyl, alu the reaction mixture during the reaction to maintain the 15 minum triisobutyl, aluminum tripropyl, aluminum tri insoluble compound dispersed in the diluent. In all methyl, diethyl aluminum chloride and others wherein cases, sufficient agitation to insure thorough mixing of alkyl has from 1 to 12 carbons and halide is preferably the components is a desirable practice since it promotes chloride or bromide. Preferably, the organometallic contact between the molecular nitrogen and/or hydro reducing compound is present in concentrations suffi gen and the transition metal compound. 20 cient to provide an atomic ratio of reducing metal to In an especially preferred method for preparing the transition metal in the range from about 0.3:1 to about dinitrogen complex, a Friedel-Craft catalyst is em 2000:1, preferably from about 1:1 to about 150:1, espe ployed, usually in amounts from about 5 to about 50 cially from about 1:1 to about 10:1. weight percent based on the transition metal halide, to The a-olefins polymerized in this process are ali accelerate the reaction and to increase yield of dinitro 25 phatic olefins and others which polymerize under con gen complex. Examples of preferred Friedel-Craft cata ventional Ziegler polymerization conditions; e.g., ethyl lysts for this purpose are aluminum trichloride and alu ene, propylene, 1-butene, 1-pentene, 3-methyl-1-pen minum trifluoride. Other known Friedel-Craft catalysts tene, 1-hexene, etc. may be suitably employed. It is understood that inert diluents employed in the The time required to form significant amounts of the 30 polymerization recipe are suitably the diluents used in dinitrogen complex varies with the conditions of the preparation of the complex as hereinbefore. reaction as well as the particular transition metal com The polymerization pressures usually employed are pound. Generally a reaction time in the range from relatively low, e.g., from about 100 to about 500 psig, about 1 to about 8 hours, preferably from 1 to 2 hours, However, polymerization within the scope of the pres is sufficient when operating under the conditions of 35 ent invention can occur at pressures from atmospheric temperature and pressure described hereinbefore. up to pressures determined by the capabilities of the Following the reaction, the hydrocarbon-soluble polymerization equipment. During polymerization it is dinitrogen complex is recovered from the reaction mix desirable to stir the polymerization recipe to obtain ture by decanting the supernatant of the reaction mix better temperature control and to maintain uniform ture from the insoluble transition metal residues and/or polymerization mixtures throughout the polymerization by filtering the solid residue and recovering the filtrate. ZOC, In the practice of the polymerization process of the Hydrogen is often employed in the practice of this present invention, the dinitrogen complex is employed invention to lower molecular weight of the resultant as the transition metal component in an otherwise con polymer. For the purpose of this invention, it is benefi ventional Ziegler polymerization process. Accordingly, 45 cial to employ hydrogen in concentrations ranging from polymerization is effected by adding a catalytic amount about 0.001 to about 1 mole per mole of monomer. The of the reaction product of the dinitrogen complex and larger amounts of hydrogen within this range are found an organometallic cocatalyst to a polymerization zone to produce generally lower molecular weight polymers. containing a-olefin monomer, or vice versa and main It is understood that hydrogen can be added with a tained at temperatures in the range from about 0° to 50 monomer stream to the polymerization vessel or sepa about 300' C, preferably at solution polymerization rately added to the vessel before, during or after addi temperatures, e.g., from about 110' to about 300° C for tion of the monomer to the polymerization vessel, but a residence time of about 10 minutes to several hours, during or before the addition of the catalyst. preferably 15 minutes to 1 hour. It is generally desirable The monomer or mixture of monomers is contacted to carry out the polymerization in an inert diluent and in 55 with the catalyst composition in any conventional man the absence of moisture and oxygen and a catalytic ner, preferably by bringing the catalyst composition and amount of the catalyst composition is generally within monomer together with intimate agitation provided by the range from about 0.0001 to about 1 milligram-atom suitable stirring or other means. Agitation can be con of transition metal per liter of diluent. It is understood, tinued during polymerization, or in some instances, the however, that the most advantageous catalyst concen 60 polymerization can be allowed to remain unstirred tration will depend upon polymerization conditions while polymerization takes place. In the case of more such as temperature, pressure, solvent and presence of rapid reactions with more active catalysts, means can be catalyst poisons and that the foregoing range is given to provided for refluxing monomer and solvent, if any of obtain maximum catalyst yields. Generally in the poly the latter is present and thus remove the heat of reac merization process, a carrier which may be an inert 65 tion. In any event, adequate means should be provided organic diluent or solvent or excess monomer is gener for dissipating the exothermic heat of polymerization. If ally employed. In order to realize the full benefit of the desired, the monomer can be brought in the vapor phase catalyst of the present invention care must be taken to into contact with the catalyst composition, in the pres 4,091,082 5 6 ence or absence of liquid material. The polymerization num triethyl in the foregoing manner catalyzes the pol can be effected in the batch manner, or in a continuous ymerization of ethylene. manner, such as, for example, by passing the reaction As evidenced by the foregoing data of this example, mixture through an elongated reaction tube which is the presence of molecular nitrogen during the prepara contacted externally with suitable cooling medium to tion of the transition metal component of the catalyst maintain the desired reaction temperature, or bypassing yields the desired hydrocarbon soluble titanium com the reaction mixture through an equilibrium overflow plex which when combined with a suitable organome reactor or a series of the same. tallic reducing component catalyzes the polymerization The polymer is recovered by conventional tech of ethylene. niques. For example, the reaction mixture may be 10 quenched with alcohol to deactivate catalyst. Subse quently, the polymer product is washed with alcohol or EXAMPLE 2 mineral acid for further removal of catalyst residues. Following the general procedure of Example 1, a 5-g The following examples are given for the purposes of portion of ATiCl3: AlCls is mixed with 200 ml of Isopar illustrating the present invention and should not be E(R) and heated at 120 C for 2 hours under 100 psig of construed as limiting its scope. In the following exam 15 nitrogen gas. ples, all parts and percentages are by weight unless The reaction mixture is filtered yielding a black fil otherwise indicated. trate containing 4,000 ppm Ti, 110 ppm Al and 1.01 EXAMPLE 1. percent chloride. Analysis for nitrogen indicates an N. 20 concentration of 2,000 ppm which is bonded through a Preparation of Dinitrogen Complex T-bond to titanium. The black filtrate catalyzes the In liter, stainless steel reactor, a 15-g portion of polymerization of ethylene when employed in combina ATiCl, AlCl is mixed with 200 ml of Isopar E(R) (a tion with trialkyl aluminum and subjected to polymeri mixture of saturated isoparaffins having 8 or 9 carbon zation conditions of Example 1. atoms) and refluxed at 120° C for 2 hours in a nitrogen 25 atmosphere at atmospheric pressure. The delta titanium EXAMPLE 3 chloride activated with aluminum chloride (ATiCl Following the procedure of Example 2, a 2-g portion AlCl) is prepared by reducing TiCl, with metallic alu of TiCl3 which has been washed with Isopar E(R) to minum. The Isopar E (E) is purged with nitrogen to remove residual TiCl is mixed with 200 ml of Isopar remove oxygen and then dried with molecular sieves. 30 E(E) and heated under a nitrogen atmosphere. The reaction mixture is decanted and filtered to re The reaction mixture is filtered and the resultant move solid residue including unreacted ATiCl3: AlCls. filtrate contains 320 ppm Ti (III) and <5 ppm alumi Analysis by emission spectroscopy of the resulting fil num. A combination of the filtrate and aluminum tri trate for titanium and aluminum indicates 150 ppm Ti ethyl catalyzes the polymerization of ethylene. and less than 5 ppm Al. The filtered solid residue is 35 added to another 200-ml portion of Isopar E(R) and the EXAMPLE 4 foregoing procedure is repeated. The resultant filtrate Following the procedure of Example 3, a 2-g portion contains 100 ppm Ti and less than 5 ppm Al. Analysis of of tungsten hexachloride is mixed with 200 ml of Isopar the foregoing filtrates for nitrogen by Kjeldahl method E(R) and heated under a nitrogen atmosphere. The fil and infrared spectroscopy indicates presence of nitro 40 trate from the reaction mixture contains 260 ppm tung gen as Ti-N=N (at bonded) in concentration of 2,000 sten as W(VI) in the form of a dinitrogen complex. A ppm. combination of the filtrate and aluminum triethyl cata Polymerization lyzes the polymerization of ethylene. Into a 4-oz serum bottle is added a dilute solution of 45 EXAMPLE 5 aluminum triethyl and the aforementioned solution of the dinitrogen complex. The temperature of the serum Following the general procedure of Example 1, a 3-g bottle is maintained at ambient temperature and the portion of zirconium tetrachloride and 1-g of AlCls is reaction is observed to be complete after 5 minutes. mixed with 400 ml of Isopar E(R) and refluxed at 120°C Following the procedure of a conventional Ziegler 50 for 4 hours under an atmosphere of nitrogen. A brown polymerization, ethylene is polymerized in a paraffin oil is formed at the bottom of the reactor. The remain diluent in the presence of hydrogen and the aforemen ing supernatant liquid (300 ml) is decanted and is found tioned catalyst. The temperature is controlled at 150' C to contain 400 ppm of Zr(IV) and less than 5 ppm of and ethylene pressure is maintained constant at approxi aluminum. Analysis of the supernatant indicates a dini mately 120 psig. Polyethylene is recovered from the 55 trogen complex of zirconium. A combination of super reaction mixture in a conventional manner. natant and aluminum triethyl catalyzes the polymeriza tion of ethylene. Comparative Showing For purposes of comparison, the foregoing procedure EXAMPLE 6 is followed except that an argon atmosphere is substi A 2-g portion of ATiClar AlCl4 as employed in Ex tuted for the nitrogen while refluxing the ATiCl3: ample 1 is slurried with 200 ml of Isopar E(R) in a liter AlClin Isopar E(R). The resulting filtrate is essentially stainless steel reactor under a dry nitrogen atmosphere. colorless and contains 11 ppm of Ti and <5 ppm of Al. The reactor was pressured to 100 psig with hydrogen Analysis of this filtrate indicates Ti is present as TiCl, (instead of N) and subsequently stirred for 2 hours at Repetition of foregoing process three times under argon 65 120 C. The reactor is cooled, contents allowed to set atmosphere yields three filtrates, each containing K15 tle, and the supernatant is removed with a syringe. ppm of Ti and <5 ppm of Al. None of these four fil Analysis of the supernatant by emission spectroscopy trates made under argon when combined with alumi indicates 1700 ppm Ti. A combination of the filtrate and 4,091,082 7 8 aluminum triethyl catalyzes the polymerization of eth 4. The complex of claim 3 wherein the titanium is ylene. bonded only to molecular nitrogen through a coordi What is claimed is: nate covalent bond. 1. A hydrocarbon soluble complex of transition metal 5. A method for preparing the hydrocarbon soluble comprising a transition metal of Groups 4b, 6b, 7b and 8 5 complex of claim 1 which comprises contacting a com of Mendeleev's Periodic Table of Elements having a pound of the transition metal of Groups 4b, 6b, 7b and 8 valence greater than two or divalent nickel, a number of of Mendeleev's Periodic Table of Elements dispersed in halide anionic groups sufficient to satisfy the valence an inert organic diluent with molecular nitrogen and/or charge on the transition metal, and molecular nitrogen molecular hydrogen whereby a dinitrogen or dihydro and/or molecular hydrogen bonded to the transition O gen complex of the transition metal compound is metal through a coordinate covalent bond. formed. 2. The complex of claim 1 wherein the transition 6. The method of claim 5 which is carried out at metal is titanium, chromium, zirconium, tungsten, man temperature in the range from ambient to about 200' C ganese, molybdenum, ruthenium, rhodium, cobalt, and pressure in the range from about 40 psig to about nickel and platinum and the halide anionic group is 15 300 psig in the presence of an acyclic aliphatic hydro chloride or bromide. carbon as the inert diluent, 3. The hydrocarbon soluble complex of claim 2 7. A complex prepared in accordance with the wherein the transition metal is titanium and the anionic method of claim 6. group is chloride. sk 20

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