Octacarbonyl, cobalt

Ethanol can also be obtained by the reaction of methanol with synthesis gas at 185°C and under pressure (6.9—20.7 MPa or 68—204 atm) in the presence of a cobalt octacarbonyl catalyst (177). However, although ethanol was the primary product, methyl formate, methyl, propyl and butyl acetates, propyl and butyl alcohols, and methane were all present in the product. 

Tri-iron dodecacarbonyl was prepared according to (l8) bis (cyclopentadienyldicarbonyliron) was prepared according to (19) tri-ruthenium dodecacarbonyl and di-cobalt octacarbonyl were supplied by Strem Chemicals. 

Provided [P(C6H5)3] > 2 [Co2(CO)8] the reaction is independent of phosphine concentration and first-order in cobalt octacarbonyl indicating that reaction (2) is the rate-controlling step so that the observed first-order rate coefficient is k2. 

THE DECOMPOSITION OF COBALT OCTACARBONYL AND SUBSTITUTED BINUCLEAR COBALT CARBONYL DERIVATIVES IN THE PRESENCE OF TRIPHENYL PHOSPHINE... 

Aryl methyl ketones have been obtained [4, 5] by a modification of the cobalt-catalysed procedure for the synthesis of aryl carboxylic acids (8.3.1). The cobalt tetracarbonyl anion is converted initially by iodomethane into the methyltetra-carbonyl cobalt complex, which reacts with the haloarene (Scheme 8.13). Carboxylic acids are generally obtained as by-products of the reaction and, in several cases, it is the carboxylic acid which predominates. Unlike the carbonylation of haloarenes to produce exclusively the carboxylic acids [6, 7], the reaction does not need photoinitiation. Replacement of the iodomethane with benzyl bromide leads to aryl benzyl ketones in low yield, e.g. 1-bromonaphthalene produces the benzyl ketone (15%), together with the 1-naphthoic acid (5%), phenylacetic acid (15%), 1,2-diphenylethane (15%), dibenzyl ketone (1%), and 56% unchanged starting material [4,5]. a-Bromomethyl ketones dimerize in the presence of cobalt octacarbonyl and... 

Cobalt octacarbonyl reacts with polydiynes obtained by Co y-irradiation to give metallated products in which 50% of the available alkyne moieties are coordinated. Reactions with M(CO)2Cp 2 (M = Mo, W) also gave partly characterized polymeric metallated products, together with significant amounts of M(CO)3Cp 2. °... 

Cobalt octacarbonyl is used as a catalyst in the Oxo process (see Carbon Monoxide). It also is used as a catalyst for hydrogenation, isomerization, hydrosilation and polymerization reactions. The compound is also a source of producing pure cobalt metal and its purified salts. 

Cobalt octacarbonyl is prepared by the reaction of finely divided cobalt with carbon monoxide under pressure ... 

Cobalt octacarbonyl forms complexes with many types of ligands, replacing one or more CO groups. 

Metal derivatives of cobalt carbonyl hydride such as Tl[Co(CO)4], Zn[Co(CO)4]2, or Cd[Co(CO)4]2 are formed upon reaction of cobalt octacarbonyl with these metals in the presence of carbon monoxide under pressure. Reaction with halogens (X) produces cobalt carbonyl halides, Co(CO)X2. 

Cobalt octacarbonyl decomposes when treated with nitric acid, forming cobalt nitrate. A similar reaction occurs with sulfuric acid or hydrochloric acid, but at a slower rate. 

Elemental composition Co 32.47%, C 28.10%, O 37.43%. Cobalt octacarbonyl may be digested with nitric acid, diluted appropriately, and analyzed by AA, ICP, or other instrumental methods (see Cobalt). The compound may be dissolved in methanol and the solution analyzed by GC/MS. 

Cobalt octacarbonyl is toxic by ingestion, inhalation, and other routes of... 

Additional support for the carbon monoxide-alkoxycobalt insertion reaction is found in the reaction of tert-butyl hypochlorite with sodium cobalt carbonyl. This reaction, if carried out at — 80°C. in ether solution under nitrogen or carbon monoxide, leads to about a 10% yield of /er/-butoxycarbonylcobalt tetracarbonyl which has been isolated as the monotriphenylphosphine derivative. The major product seems to be cobalt octacarbonyl, possibly formed by decomposition of an intermediate JerJ-butoxycobalt tetracarbonyl (34). This reaction appears to be a true insertion reaction although a direct attack of a coordinated carbonyl group upon oxygen cannot be ruled out. 

Compounds with Metal-Metal Bonds. There is one clear example of the addition of a compound with a metal-metal bond to an olefin. Cobalt octacarbonyl reacts with tetrafluoroethylene to form a symmetrical adduct (102). 

Compounds with Metal—Metal Bonds. Additions of compounds with metal-metal bonds to acetylenes are rare. Perhaps the addition of acetylenes to cobalt octacarbonyl (29) should be considered an insertion reaction even though the metal-metal bond is not broken since the acetylene finally is bonded to both metal atoms. 

One complex with a metal—metal bond that has been added to an olefin is cobalt octacarbonyl. It reacts with tetrafluoroethylene and it seems reasonable that this is an insertion reaction but again it has not been proved. 

The l-propargyl-4-vinylazetidine derivative 374 undergoes Pauson-Khand cyclization at room temperature when reacted with cobalt octacarbonyl and trimethylamine /V-oxidc (TMANO) to give the tricyclic azetidine 375 (Equation 50). But when l-allyl-4-ethynylazetidine 376 is used, product 377 is obtained (Equation 51). In both cases, moderate yields with the formation of a single isomer of the products is achieved <1996TL6901, 1998JOC6786>. 

Pauson-Khand cyclization of vic-enyne derivatives of /3-lactams gave good yields of fused tricyclic compounds. The 1,4-disubstituted 2-azetidinone 391 and cobalt octacarbonyl gave the alkyne-cobalt carbonyl complex, which on thermolysis gave the tricycle 392 in 95% yield (Equation 54). When the complexes of 393 with cobalt octacarbonyl were treated with TMANO, a lower yield (65%) of 394 was obtained (Equation 55). A single diastereoisomer was formed in each case <1996TL6901>. 

The Pauson-Khand reaction has been used to obtain 4/5/5 systems from /3-lactams having unsaturated 3,4-substituents. Thus, the reaction of 443 with cobalt octacarbonyl in the presence of TMANO gave 444 in 80% yield C1996TL6901, 1998JOC6786>. 

The Pauson-Khand reaction provides a route to the 4/6/5 system from 3,4-disubstituted /3-lactams having both alkenyl and alkynyl groups, and will allow the presence of some functional groups on the substituents. The reaction of cobalt octacarbonyl and TMANO with 448 furnished 449 in 55% yield as a mixture of diastereoisomers in a ratio of 70 30 <1998JOC6786>. 

D. W. Slocum Chfmkcts from Coal the Cobalt Octacarbonyl Catt yzeti... 

The chemoselective 1,2-reduction of a 3-unsaturated carbonyl compounds has been carried out with metal hydride or by hydrogenation. However, chemoselective 1,4-reduction of a (B-unsaturated carbonyl compounds is challenging. Recently, a(B-unsaturated carbonyl compounds 1.23, 1.25 and 1.27 were selectively reduced to the corresponding saturated carbonyl compounds 1.24, 1.26 and 1.28, respectively, by cobalt octacarbonyl and water [Co2(CO)8-H20 system]... 

CARBONYLHEXACARBONYLDI-, (CO-CO) COBALT OCTACARBONYL COBALT TETRACARBONYL COBALT TETRACARBONYL DIMER DI-MU-CARBON-YLHEXACARBONYLDICOBALT DICOBALT CARBONYL DICOBALT OCTACARBONYL OCTACARBONYLDICOBALT... 

COBALT NITRATE see CNC500 COBALT(2+) NITRATE see CNC500 COBALT(II) NITRATE see CNC500 COBALT OCTACARBONYL see CNB500 COBALTOUS ACETATE TETRAHYDRATE see CNA500... 

Decomposition of methanesulphonyl azide in aromatic solvents (methyl benzoate or benzotrifluoride), in the presence of transition metal compounds (e.g. copper(ri) acetylacetonate, manganese(ii) acetylacetonate, di-cobalt octacarbonyl, tri-iron dodecacarbonyl, and iron pentacarbonyl) led to a marked decrease in the aromatic substitution product compared with thermolysis, and, with the iron carbonyls, to an increased yield of methanesulphonamide . In addition, the aromatic substitution products shifted from mainly ortAo-substitution with no additives to mainly w ia-substitution in the presence of the additives mentioned above. 

CojMoOkChHk, Cobalt, octacarbonyl(ti -cy-clopentadienyl)-(jirethyl [Pg.385]

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