COBALT ETHYLENED

Cobalt atom reactions with ethylene were also studied (121). By using techniques similar to those described for Cu (122) and Ni (101), it has proved possible to synthesize a novel series of mononuclear and binuclear cobalt-ethylene complexes, Co(C2H4) , = 1, or 2, and... 

While the 2,6-bis(imino)pyridine ligand frame has continued to lead the way, the past 10 years has also seen the development of alternative ligand sets that can act as compatible supports for iron and cobalt ethylene oligomerisation/polymerisation catalysts (Table 4) [46, 50, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192,193,194,195,196,197,198,199,200, 201,202,203,204,205, 206,207,208, 209] active catalysts based on bimetallic iron and cobalt precatalysts have also started to emerge (Table 5) [54, 210, 211, 212, 213, 214, 215], In the main, these systems show lower activities than the prototype bis(imino)pyridine-based catalysts, although several of these systems have significantly started to approach their catalytic performances (e.g. 65/MAO [46, 188], 69/MAO [191,192,193], 70/MAO [194], 71/MMAO [195]). 

Cobalt vapor was generated by directly heating a 0.01-in. ribbon filament of the metal and cocondensed with C2H4/Ar matrices at 12-15K. A series of mono- and binuclear cobalt-ethylene complexes Co(C2H4) (where / = 1, 2) and Co2(C2H4)OT (where m = 1, 2) as well as a suspected tetranuclear species Co4(C2H4)f have been detected by spectroscopic methods. 

Soshnikov IE, Seirukolenova NV, Bushmelev AN et al (2009) Investigating the nature of the active species in bis(imino)pyridine cobalt ethylene polymerisation catalysts. Organometallics 28 6003-6013... 

Britovsek GJP, Bruce M, Gibson VC, Kimberley BS, Maddox PJ, Mastroianni S, McTavish SJ, Redshaw C, Solan GA, Stroemberg S, White AJP, Williams DJ (1999) Iron and cobalt ethylene polymerization catalysts bearing 2,6-bis(imino)pyridyl ligands synthesis, structures and polymerization studies. J Am Chem Soc 121(38) 8728-8740... 

FLUORINECOBTPOUNDS,ORGANIC - PERFLUORINATED ETHYLENE-PROPYLENE COPOLYBffiRS] pol 11) Chloropentakis(ethanol) cobalt (II) [32354-52-2]... 

This reaction is rapidly replacing the former ethylene-based acetaldehyde oxidation route to acetic acid. The Monsanto process employs rhodium and methyl iodide, but soluble cobalt and iridium catalysts also have been found to be effective in the presence of iodide promoters. 

EG may also be pioduced via glycolic acid using catalysts containing strong acids (66), cobalt carbonyl (67—69), rhodium oxide (68), or HE solvent (70,71) (see Glycols, ETHYLENE glycol). 

MMA and MAA can be produced from ethylene [74-85-1/ as a feedstock via propanol, propionic acid, or methyl propionate as intermediates. Propanal may be prepared by hydroformylation of ethylene over cobalt or rhodium catalysts. The propanal then reacts in the Hquid phase with formaldehyde in the... 

The mechanism of the cobalt-cataly2ed oxo reaction has been studied extensively. The formation of a new C—C bond by the hydroformylation reaction proceeds through an organometaUic intermediate formed from cobalt hydrocarbonyl which is regenerated in the aldehyde-forrning stage. The mechanism (5,6) for the formation of propionaldehyde [123-38-6] from ethylene is illustrated in Figure 1. 

Fig. 1. Mechanism for the unmodified cobalt oxo reaction which produces propionaldehyde from ethylene.

Polyether Polyols. Polyether polyols are addition products derived from cyclic ethers (Table 4). The alkylene oxide polymerisation is usually initiated by alkah hydroxides, especially potassium hydroxide. In the base-catalysed polymerisation of propylene oxide, some rearrangement occurs to give aHyl alcohol. Further reaction of aHyl alcohol with propylene oxide produces a monofunctional alcohol. Therefore, polyether polyols derived from propylene oxide are not truly diftmctional. By using sine hexacyano cobaltate as catalyst, a more diftmctional polyol is obtained (20). Olin has introduced the diftmctional polyether polyols under the trade name POLY-L. Trichlorobutylene oxide-derived polyether polyols are useful as reactive fire retardants. Poly(tetramethylene glycol) (PTMG) is produced in the acid-catalysed homopolymerisation of tetrahydrofuran. Copolymers derived from tetrahydrofuran and ethylene oxide are also produced. 

With Unsaturated Compounds. The reaction of unsaturated organic compounds with carbon monoxide and molecules containing an active hydrogen atom leads to a variety of interesting organic products. The hydroformylation reaction is the most important member of this class of reactions. When the hydroformylation reaction of ethylene takes place in an aqueous medium, diethyl ketone [96-22-0] is obtained as the principal product instead of propionaldehyde [123-38-6] (59). Ethylene, carbon monoxide, and water also yield propionic acid [79-09-4] under mild conditions (448—468 K and 3—7 MPa or 30—70 atm) using cobalt or rhodium catalysts containing bromide or iodide (60,61). 

Choline Bitartrate. This substance [87-67-2] is a white crystalline material possessing an acid taste. It melts at 149—I53°C. Analysis by cobaltous chloride shows more than 99% as the bitartrate. Free ethylene glycol is less than 0.25%, with free alkaU at 0.0%. 

Hydroformylation. In hydroformylation, the 0x0 reaction, ethylene reacts with synthesis gas (CO + H2) over a cobalt catalyst at 60—200°C... 

Silver-containing catalysts are used exclusively in all commercial ethylene oxide units, although the catalyst composition may vary considerably (129). Nonsdver-based catalysts such as platinum, palladium, chromium, nickel, cobalt, copper ketenide, gold, thorium, and antimony have been investigated, but are only of academic interest (98,130—135). Catalysts using any of the above metals either have very poor selectivities for ethylene oxide production at the conversion levels required for commercial operation, or combust ethylene completely at useful operating temperatures. 

Oxidation catalysts are either metals that chemisorb oxygen readily, such as platinum or silver, or transition metal oxides that are able to give and take oxygen by reason of their having several possible oxidation states. Ethylene oxide is formed with silver, ammonia is oxidized with platinum, and silver or copper in the form of metal screens catalyze the oxidation of methanol to formaldehyde. Cobalt catalysis is used in the following oxidations butane to acetic acid and to butyl-hydroperoxide, cyclohexane to cyclohexylperoxide, acetaldehyde to acetic acid and toluene to benzoic acid. PdCh-CuCb is used for many liquid-phase oxidations and V9O5 combinations for many vapor-phase oxidations. 

In the case of ester exchange for the manufacture of poly(ethylene terephthalate), a low molecular weight diester, known as the monomer , is first prepared by reacting 1 mol of dimethyl terephthalate with about 2.1-2.2 mol ethylene glycol at about 150°C in the presence of catalysts such as antimony trioxide and cobaltous acetate ... 

Elastomers, plastics, fabrics, wood and metals can be joined with themselves and with each other using nitrile rubber/epoxy resin blends cured with amines and/or acidic agents. Ethylene-propylene vulcanizates can also be joined using blends of carboxylated nitrile rubber, epoxy resin and a reactive metal filler (copper, nickel, cobalt). However, one of the largest areas of use of nitrile rubber modified epoxy systems is in the printed circuit board area [12]. 

The first example of homogeneous transition metal catalysis in an ionic liquid was the platinum-catalyzed hydroformylation of ethene in tetraethylammonium trichlorostannate (mp. 78 °C), described by Parshall in 1972 (Scheme 5.2-1, a)) [1]. In 1987, Knifton reported the ruthenium- and cobalt-catalyzed hydroformylation of internal and terminal alkenes in molten [Bu4P]Br, a salt that falls under the now accepted definition for an ionic liquid (see Scheme 5.2-1, b)) [2]. The first applications of room-temperature ionic liquids in homogeneous transition metal catalysis were described in 1990 by Chauvin et al. and by Wilkes et ak. Wilkes et al. used weekly acidic chloroaluminate melts and studied ethylene polymerization in them with Ziegler-Natta catalysts (Scheme 5.2-1, c)) [3]. Chauvin s group dissolved nickel catalysts in weakly acidic chloroaluminate melts and investigated the resulting ionic catalyst solutions for the dimerization of propene (Scheme 5.2-1, d)) [4]. 

Vinyl chloride is an important monomer for polyvinyl chloride (PVC). The main route for obtaining this monomer, however, is via ethylene (Chapter 7). A new approach to utilize ethane as an inexpensive chemical intermediate is to ammoxidize it to acetonitrile. The reaction takes place in presence of a cobalt-B-zeolite. 

For cobalt phthalocyanines (PcCo, PcCoX), besides the most common method starting with phthalonitrile and cobalt(II) chloride in ethylene glycol, 130-277 279 some other methods have been employed. Other cobalt compounds used are cobalt(II) acetate127 or acetylacetonate.279 Besides using solvents like 2-ethoxyethanol279 and 2-(dimethylamino)ethanol,121 the reaction has also been performed without solvent.137,262 The central metal may exhibit the oxidation states +11 (PcCo) and + III (PcCoX).279... 

Some data are also available (5) on the use of metallic cobalt and nickel supported on charcoal for high polymerization of ethylene. However, the application and investigation of these catalysts were not subsequently developed. 

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