US3906017A - Preparation of diarene chromium compounds - Google Patents

Preparation of diarene chromium compounds Download PDF

Info

Publication number
US3906017A
US3906017A US381428A US38142873A US3906017A US 3906017 A US3906017 A US 3906017A US 381428 A US381428 A US 381428A US 38142873 A US38142873 A US 38142873A US 3906017 A US3906017 A US 3906017A
Authority
US
United States
Prior art keywords
chromium
process according
reactor
alkyl group
pressure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US381428A
Other languages
English (en)
Inventor
Robert Middleton
Peter Leslie Timms
Geoffrey Moorhouse Gibson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
British Chrome and Chemicals Ltd
Original Assignee
British Chrome and Chemicals Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by British Chrome and Chemicals Ltd filed Critical British Chrome and Chemicals Ltd
Application granted granted Critical
Publication of US3906017A publication Critical patent/US3906017A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F11/00—Compounds containing elements of Groups 6 or 16 of the Periodic Table

Definitions

  • ABSTRACT Diarene chromium compounds where each arene separately is an alkyl benzene or optionally alkyl substituted diphenyl, tetralin or indane molecule are prepared substantially pure by condensing gaseous chromium atoms with the arene or mixture thereof at a pressure of less than 10 torr and at a temperature compatible with maintaining that pressure.
  • the diarene chromium compounds may be thermally decomposed to deposit a layer comprising chromium.
  • the product typically obtained when employing cumene as the alkyl benzene comprises a liquid mixture having the apparent composition 7% dibenzene chromium, 43% dicumene chromium, 34% mixed bis (diisopropyl benzene) chromium, and 16% bis (tri isopropyl benzene) chromiums.
  • ethyl benzene as the alkyl benzene, a mixture of diarene chromiums is obtained, each compound having as the arene part, two ethylbenzene, diethylbenzene or triethylbenzene molecules, one benzene and one ethylbenzene molecule, or one ethylbenzene and one diethylbenzene molecule. It has been reported (Metody Poluch. Anal. Veshchestv. Osobvi. Chist. Tr. Vses, Konf. 1968, pl 16; Chem. Abs. 1971,75 63925) that under very carefully controlled conditions it is possible to make pure bis(ethyl benzene) chromium by the Friedel-Crafts route, but the process is completely unsuitable for industrial application.
  • Timms (Chem. Comm. 1969, 1033) has described a process of reacting gaseous chromium atoms with benzene vapour at a low pressure and collecting the bis benzene chromium product on a cooled surface.
  • the present invention provides a process for preparing diarene chromium compounds, which process comprises condensing gaseous chromium atoms with at least one aromatic compound of formula Ar or Ar", or a mixture thereof, at a pressure of less than torr and at a temperature compatible with maintaining said pressure, Ar representing an alkyl benzene molecule, in which the benzene ring is substituted by one or more alkyl groups, preferably 1 3 groups, each preferably of l 6 carbon atoms, especially branched chain alkyl groups of at least 3 carbon atoms, and Ar representing a diphenyl tetralin or indane molecule, each of which is unsubstituted or substituted by one or more alkyl groups, each preferably of 1 6 carbon atoms.
  • This process enables arene chromium compounds to be formed without substantial isomerization or disproportionation and is particularly applicable when the arene contains at least one alkyl group of 2 or more, usually 3 or more
  • the pressure in the system should be less than 10' torr; preferably it is below 10' torr and optimally below 2 X l0- torr. lf high speed pumping is employed this dynamic pressure will be below the equilibrium pressure for the system. It is of course the dynamic pressure in the system which is the pressure referred to herein. It is necessary to keep the pressure in the system at these low levels in order to prevent the reaction of the chromium atoms with themselves or other undesired species which might be present if a high vacuum were not maintained.
  • the reaction is carried out in a reactor having walls maintained at a temperature compatible with the need to maintain the pressure at less than 10 torr and stop volatilization of the aromatic compound.
  • the wall temperature is less than for less volatile aromatic compounds such as diphenyl for a constant pressure.
  • the pressure can be greater and still less than 10 torr in the case of the volatile compound then it may be possible for the wall temperature to be the same in both cases.
  • Chromium atoms for condensing with the aromatic compound maybe obtained by any convenient means of which many are known for example by volatilisation (typically as sublimation) of massive chromium or from a chromium arc or other plasma, or by the action of an electron or laser beam on massive chromium. lf volatilisation techniques are employed it may be possible to employ not only pure chromium metal as the source but also ferrochrome or certain compounds such as chromium carbide. Normally such material will be heated by conventional electrical resistance heating in a molybdenum or tungsten crucible.
  • the process can be carried out by a cocondensation route by passing gaseous chromium atoms and vapour of the aromatic compound or compounds in a reactor on to the chilled surface of the reactor, preferably one chilled to at least 60C, such as 60C to 00C, but especially 'l60C to 200C.
  • a temperature of about C can be maintained with a mixture of solid carbon dioxide and an organic solvent such as ethanol or acetone.
  • a temperature of l80C to 200C can be maintained with liquid air or liquid nitrogen (b.p. 196C). Slightly lower temperature from the values of about 80C and lC can be obtained by forced cooling.
  • any other temperature and method of cooling can be used so long as the chilled surface can be maintained at a temperature compatible with maintaining the pressure of less than 10" torr.
  • the actual temperature of the cooling bath surrounding the reactor needed to maintain the inner surface of the reactor at the necessary temperature depends on the wall thickness, heat losses and other similar parameters.
  • the temperature of the inner surface is less, preferably 20C to 60C less, than that necessary to keep the vapour pressure of the aromatic compound or compounds sufficiently low to avoid any substantial volatilization under the pressure employed.
  • the process of the invention can be carried out in a liquid phase route by condensing gaseous chromium atoms in a reactor on to a continually regenerated surface of a liquid, which comprises the aromatic compound. or compounds and is maintained at a temperature compatible with the need to keep the pressure in the reactor of less than 10 torr.
  • the temperature is usually -60C to 150C, preferably 70C to lC, especially 80C to 90C e.g. about -80C with cooling by a bath of solid carbon dioxide and an organic solvent such as acetone or ethanol.
  • the liquid phase can be the aromatic compound (or compounds) alone or diluted with a solvent having itself a sufficiently low vapour pressure at the temperature of the liquid.
  • solvents for use with temperatures of the order of -60C to 100C and 0 to 25C respectively are di-isooctyl ether and hydrocarbon vacuum pump oils such as Apiezon BW.
  • the liquid phase is preferably agitated e.g.
  • the liquid may also be stirred by magnetic or ultrasonic means. Alternatively external agitation can be avoided if desired, by passing the liquid through at least one port in the side wall of the reactor and thence down the wall and out through an exit port in the base, or the liquid can be fed in at the upper side of a sloping base to the reactor and out at the lower side of the base.
  • the liquid entering the reactor is prechilled to enable the necessary pressure of less than torr to be retained.
  • the entry and exit ports to the reactor are provided with vacuum locks to keep the reduced pressure in the reactor,
  • the liquid phase route is very suitable for use on an industrial scale with continuous feeding and withdrawal of the liquid as mentioned above.
  • the diarene chromium compounds prepared bythe process of the invention generally and by both of its preferred embodiments can be separated from the unreacted aromatic compound in any convenient manner, for example in the case of the cocondensation route by solvent extraction followed by distillation.
  • An alternative method which we have found useful is simply to permit the walls of the reactor to heat up to room tem' perature and simply to pump off the unreacted aromatic compound.
  • the desired chromium compound can be obtained either directly from the walls of the reactor by solvent extraction or by heating the reactor whilst keeping the pressure very low.
  • the chromium compound sublimes under these conditions and may be collected by means of a cold finger in the vacuum system line.
  • the product is a mixture of the desired chromium compound, colloidal chromium and massive chromium as well as unreacted aromatic compound.
  • the techniques described above of evaporation of the unreacted aromatic compound followed by sublimation or distillation of the chromium compound can be used to work up the liquid phase product, as can initial evaporation followed by solvent extraction and then evaporation of solvent, if
  • an inert gas e.g. nitrogen can be admitted to the reactor to bring the pressure back to atmospheric and then the liquid phase filtered to remove massive chromium and probably some of the colloidal chromium.
  • the filtrate is treated with water containing an oxidizing agent such as oxygen (e.g. as air) or hydrogen peroxide to convert the chromium compound into its cation and form a chromium containing sludge which is then separated.
  • the diarene chromium cation in the water can then be converted into an insoluble salt e.g. the tetra phenyl boron salt and separated, or can be reduced to the diarene chromium (0) compound with an appropriate reducing agent e.g.
  • the chromium (0) compound being extracted into an organic solvent at least partially immiscible with water, such as aromatic hydrocarbons e.g. benzene, toluene, and chlorinated hydrocarbons. Evaporation of the organic solvent leaves the chromium arene compound.
  • the present invention also provides bis arene chromium compounds of the formula ArCrAr, Ar" CrAr", or Ar Cr Ar” wherein Ar and Ar" are as defined above except that both Ar" are not diphenyl molecules, and both Ar" are not ethyl benzene molecules, in the substantial absence of any disproportionation or rearrangement product thereof in the case of the compounds of formula ArCrAr'.
  • alkyl benzene molecules represented by Ar, Ae" or Ar examples include toluene, 0-, mand p-xylene, ethylbenzene, mesitylene (and isomers thereof), cummene, m di isopropyl benzene, cymene (p-isopropyl toluene) and tert. butyl benzene.
  • a particularly important compound is di cumene chromium, which when pure is a solid of melting point about 46C in contrast to its mixture with its rearrangment or disproportionation products as a result of the F riedel-Crafts reaction process which mixture is a liquid of freezing point 218C and boiling point 297C.
  • Another important compound is bis m (di isopropyl) benzene chromium which is a solid of melting point about 55C.
  • the diarene chromium compounds of the invention or produced by the process of the invention can be used as reactive intermediates and also in the wide range of uses to which the presently available impure compounds may be put.
  • they may be used as components of Ziegler Natta catalysts, but their main use lies in their thermal decomposition to deposit a layer comprising chromium on a heated surface of a substrate.
  • a layer comprising chromium is deposited on the surface; this layer also contains free carbon, enhancing the corrosion resistance to acids of the layer over that obtained from electrolytic or vacuum deposited chromium.
  • thermal decomposition in the liquid phase at about 200C in the presence of a catalyst can also be used.
  • FIG. l is a diagrammatic section through an apparatus suitable for carrying out the cocondensation process
  • FIG. 2 is a diagrammatic section through an apparatus suitable for carrying out the liquid phase process.
  • the apparatus of FIG. 1 has a reaction vessel made of e.g. stainless steel surrounding which is a cooling jacket 2 into which coolant e.g. liquid nitrogen can be put.
  • a middle member 11 having a vacuum exit line 7 and line 8, line 7 being connected to a .vacuum pump directly and line 8 being connected to a vacuum pump by way of a cold trap (not shown).
  • flanges 12 and 13 Mounted on middle member 11 by means of flanges 12 and 13 islid .14, in which are held vapour inlet pipe 5 and waterpipes l5 and 16. Vapour pipe 5 divides into three equally spaced limbs 6 (only two of which are shown).
  • Water pipes 15 and 16 are formed at their lowest point into a cooling jacket 17 centrally located in the reactor and in which jacket is mounted a furnace I8.
  • Furnace 18 consists of an open ended coil 19 of tungsten wire, which, in use contains chromium source 34, and which has two molybdenum heat shields 20 loosely fitting thereover. Chromium 34' is retained in the 'coil by a molybdenum strip 21 across the bottom of coil 19.
  • the water pipes 15 and 16 are separated by an insulated joint of alumina tube 22 and'electrical leads 23 pass from the coil 19 to each of the pipes 15 and 16 as power conductors.
  • FIG. 1 also showsproduct 24 collecting on the inside of reactor 1. l
  • the reactor is first evacuated to the desired degree of vacuum using line 7. Liquid nitrogen is then introduced into the jacket 2. Chromium metal in chip form is heated in the furnace 18 by resistance heating to e.g. 1600C, evaporates and by means of heat shields 20 the atoms are directed downwards towards the reactor.
  • the desired aromatic compound is volatilised elsewhere, for example by heating, and introduced to the reactor via pipe 5.
  • the vapour of the aromatic compound condenses on the liquid nitrogen cooled walls of the reactor in the vicinity of the outlets of the limbs 6.
  • the heating is switched off and the liquid nitrogen pumpedfrom the jacket 2. Whenroorn temperature is reached the unreacted aromatic compound may be separated by simply pumping it off at low pressure. If desired it may be collected in a liquid nitrogen trap which replaced the cold trap in line 8.
  • the desired product may be obtained by heating the reactor whilst maintaining the pressure at a low value by pumping through line 8, the product being collected by condensation on the cold finger.
  • the apparatus shown in FIG. 2 can be used for the liquid phase route.
  • the apparatus is basically the same as that shown in FIG. 1, the differences lying in the different furnace assembly, the absence of inlet pipe 5 and limbs 6, and the presence of a stirrer and valve closed outlet in the base of the reactor. Otherwise the remaining features of the apparatus are the same and will not be further described.
  • the furnace 18 present in FIG. 1 is unsatisfactory in the liquid phase route because it does not give a sufficiently collimated beam of chromium atoms.
  • the furnace 25 in FIG. 2 has an inverted alumina crucible 26 wound with molybdenum wire 27 and coated with alumina cement.
  • Chromium 34 is held in the crucible 26 by molybdenum strip 28 slotted into slits 29 in the crucible walls.
  • the bottom part of crucible 26 provides a degree of collimation for the beam of chromium atoms.
  • a stirrer shaft 30 having a paddle 31 is mounted off centre on lid 14 and is reciprocated by means of a motor (not shown).
  • the reactor 1 has in its base an outlet 32, closed by a valve (not shown).
  • the paddle 31 is immersed in liquid 33 in the bottom of the reactor 1. In use the liquid phase is placed in the bottom of thereactor 1, outlet 32 being closed.
  • the reactor is closed and its walls cooled to the necessary temperature e.g. l90C or about -80C by cooling medium in the jacket 2.
  • the reactor is then evacuated to the desired pressure, the stirrer reciprocated and the heating of the chromium started.
  • the heating is switched off, jacket 2 removed and an inert gas e.g. nitrogen passed into the apparatus.
  • the liquid phase is then passed out through outlet 32, the -valve being opened, and the liquid worked up to isolate the arene chromium compound.
  • the prechilled liquid may be fed into the reactor continuously in the presence or absence of the stirrer with continuous withdrawal of reaction liquid through outlet 32.
  • EXAMPLE 1 2.1 parts by weight of chromium were placed in the furnace of the apparatus shown in FIG. 1 and the apparatus was then sealed for evacuation. The pressure in the reactor was reduced to less than 2 X 10 torr. The crucible was heated by passing a current of 40 amps at 9 volts, m-Di-isopropyl benzene (30.2 parts by weight) was volatilised by heating to about C and drawn into the reactor overa period of 20 minutes. After completion of the reaction a black solid was obtained, which on vacuum sublimationgave bis m di isopropyl benzene with a melting point of about 55C.
  • Example 1 The product of Example 1 was mixed with a waterhexane'mixture, followed by reaction with nitric acid, which results in freeing the alkyl benzene compound from the chromium components, and then solution of the alkyl benzene compound in hexane.
  • Gas chromatography on the hexane extract after removal of hexane showed only one peak identified as m di isopropylbenzene.
  • EXAMPLE 2 The process was carried out as in Example 1 using cumene (volatilised at about 50C) as the alkylbenzene compound. In this case the crucible was heated using 34 amps at 0.8 volts. The cumene was fed in for 30 minutes enabling 62.3 g. of cumene to be employed. The product obtained was a dark solid which on vacuum sublimation gave bis cumene chromium having a melting point of about 46C. The product was decomposed with acid and extracted as in Example 1 and gas liquid chromatography showed only one peak. Mass spectroscopy on the bis cumene chromium showed only one peak corresponding to a parent compound, which peak had a m/e of 292 as expected.
  • EXAMPLE 3 A saturated solution of diphenyl in m di isopropyl benzene was placed in the bottom of the reactor of an apparatus as shown in FIG. 2 and cooled to C to -C by means of an acetone/solid carbon dioxide bath in jacket 2. The reactor was then evacuated to a pressure of 10 torr, the stirrer started and the chromium in the crucible heated to l500 l600C. The reaction was carried out for 30 mins, after which the heating and stirring were stopped, the jacket removed and the reactor filled with nitrogen. The liquid was passed through outlet 32 and massive chromium separated by filtration anaerobically.
  • a diphenyl m di isopropyl benzene chromium compound can be isolated by evaporation of the hydrocarbons from the filtrate and distillation of the residue. Alternatively the liquid filtrate is evaporated to remove the hydrocarbons and the residue distributed between hexane and dilute nitric acid and the hexane extract evaporated. Gas liquid chromatography of the residue showed only diphenyl and m di isopropyl benzene peaks, showing that the residue from the filtrate contained both these molecules combined with chromium.
  • a process for preparing diarene chromium compounds comprising condensing gaseous chromium atoms with at least one aromatic compound of formula Ar or Ar, or a mixture thereof, at a pressure of less than torr and at a temperature compatible with maintaining said pressure, wherein Ar is an alkylbenzene molecule in which the benzene ring is substituted by one or more alkyl groups, and Ar" is a diphenyl, tetralin or indane molecule, each of which is unsubstituted or substituted by at least one alkyl group.
  • each alkyl group has at least 3 carbon atoms.
  • a process according to claim 2 which comprises passing gaseous chromium atoms and vapour of the aromatic compound or compounds in a reactor onto a chilled surface of the reactor.
  • a process for producing a diarene chromium compound comprising contacting in a reactor gaseous chromium atoms with a continually regenerated surface of a liquid aromatic at a pressure of less than 10" torr at a temperature compatible with maintaining said pressure in the reactor,
  • said liquid aromatic being at least one aromatic compound of formula Ar or Ar", or a mixture thereof, wherein Ar is an alkylbenzene molecule in which the benzene ring is substituted by one or more alkyl groups, and Ar is a diphenyl, tet'ralin or indane molecule, each of which is unsubstituted or substituted by at least one alkyl group,
  • reaction product comprising said diarene chromium compound in said liquid aromatic are produced.
  • liquid is m di isopropyl benzene or a mixture thereof with another alkylbenzene having at least 3 cabon atoms in the alkyl group and is maintained at a temperature of C to C.
  • liquid aromatic having the formula Ar contains at least one alkyl group of at least two carbon atoms.
  • each alkyl group contains at least two carbon atoms.
  • each alkyl group contains at least two carbon atoms.
  • each alkyl group contains at least two carbon atoms.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
US381428A 1972-07-24 1973-07-23 Preparation of diarene chromium compounds Expired - Lifetime US3906017A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB3455172A GB1415508A (en) 1972-07-24 1972-07-24 Diarene chromium compounds

Publications (1)

Publication Number Publication Date
US3906017A true US3906017A (en) 1975-09-16

Family

ID=10367033

Family Applications (1)

Application Number Title Priority Date Filing Date
US381428A Expired - Lifetime US3906017A (en) 1972-07-24 1973-07-23 Preparation of diarene chromium compounds

Country Status (4)

Country Link
US (1) US3906017A (OSRAM)
JP (1) JPS4992052A (OSRAM)
DE (1) DE2337393A1 (OSRAM)
GB (1) GB1415508A (OSRAM)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4155925A (en) * 1978-02-16 1979-05-22 E. I. Du Pont De Nemours And Company Hexakis- and dihydridopentakis(phosphite ester)chromiums
US4292253A (en) * 1979-04-03 1981-09-29 Ozin Geoffrey A Organo-metal catalysts and processes for their preparation
US4333881A (en) * 1979-03-07 1982-06-08 Anic S.P.A. Process for reducing metal alkoxides, and the use of the compounds so obtained
US4526724A (en) * 1983-09-30 1985-07-02 Standard Oil Company (Indiana) Process for the preparation of zero valent bis-arene transition metal compounds
US4552855A (en) * 1982-12-30 1985-11-12 Ozin Geoffrey A Metal zeolite catalyst preparation
WO2015199698A1 (en) * 2014-06-26 2015-12-30 Swan Lew Essential oil distillation systems, devices, and methods

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2985640A (en) * 1959-09-15 1961-05-23 Union Carbide Corp Polymerization catalyst and process

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2985640A (en) * 1959-09-15 1961-05-23 Union Carbide Corp Polymerization catalyst and process

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4155925A (en) * 1978-02-16 1979-05-22 E. I. Du Pont De Nemours And Company Hexakis- and dihydridopentakis(phosphite ester)chromiums
US4333881A (en) * 1979-03-07 1982-06-08 Anic S.P.A. Process for reducing metal alkoxides, and the use of the compounds so obtained
US4292253A (en) * 1979-04-03 1981-09-29 Ozin Geoffrey A Organo-metal catalysts and processes for their preparation
US4552855A (en) * 1982-12-30 1985-11-12 Ozin Geoffrey A Metal zeolite catalyst preparation
US4526724A (en) * 1983-09-30 1985-07-02 Standard Oil Company (Indiana) Process for the preparation of zero valent bis-arene transition metal compounds
WO2015199698A1 (en) * 2014-06-26 2015-12-30 Swan Lew Essential oil distillation systems, devices, and methods

Also Published As

Publication number Publication date
GB1415508A (en) 1975-11-26
JPS4992052A (OSRAM) 1974-09-03
DE2337393A1 (de) 1974-02-28

Similar Documents

Publication Publication Date Title
US8101787B2 (en) Method of preparing organometallic compounds
Eisch et al. Stereochemistry and Orientation in the Reactions of 1-Phenylpropyne with Diisobutylaluminum Hydride1
Eisch Organometallic Compounds of Group III. II. the Reaction of Gallium Alkyls and Alkyl Hydrides with Unsaturated Hydrocarbons
Muetterties Synthesis of organoboranes
US3906017A (en) Preparation of diarene chromium compounds
Siedle et al. Solvolysis of dimethylzirconocene by trialkylaluminum compounds
JP3880025B2 (ja) 高純度トリメチルインジウムおよびその合成方法
Mochida et al. Activation of carbon-hydrogen bonds of aromatic rings using calcium atoms
KR20110091457A (ko) 유기금속 화합물의 제조방법
KR20110091460A (ko) 유기금속 화합물의 제조방법
EP0108469B1 (en) Preparation of organometallic indium and gallium compounds
Mendenhall et al. Di-and tri-tert-butylmethyl, two aliphatic radicals of unusual stability
US4725342A (en) Photochemical dimerization and functionalization of alkanes, ethers, primary alcohols and silanes
Buchanan III et al. Generation of arenium ions by a self-protonation reaction in an aprotic molten salt medium
Gaines et al. Synthesis and characterization of 1-(Cl2B) B5H8 and 1-(Cl2B)-2-ClB5H7: a new boron-boron. sigma. bond
US3255167A (en) Olefin polymerization in presence of a reduced titanium halide supported on gamma alumina and an organometallic compound
US2614130A (en) Oxidative condensation of alkyl aromatic hydrocarbons and of nuclearly chlorinated alkyl aromatic hydrocarbons
US5380895A (en) Method for the synthesis of metal alkyls and metal aryls
Mangette et al. Thiadisilacyclopropanes: Stereospecific Formation from Disilenes and Solid State Structures
Domrachev et al. Reactions of transition metals in the atomic state
US3155493A (en) Method for manufacturing high purity aluminum
Tanuhadi et al. Stabilization of reactive rare earth alkyl complexes through mechanistic studies
EP0258973A2 (en) Process for propylene dimerization
US3114781A (en) Alkylation of aromatic compounds
FR2650273A1 (fr) Cycloalkylation de composes aromatiques sur zeolithes