Cobalt tetracarbonyl dimer

Synonyms dicobalt octacarbonyl cobalt carbonyl cobalt tetracarbonyl dimer... 

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

Synonyms/Trade Names di-mu-CarbonylhexacarbonyIdicobalt, Cobalt octacarbonyl. Cobalt tetracarbonyl dimer. 

Synonyms Cobalt carbonyl Cobalt octacarbonyl Cobalt tetracarbonyl dimer Dicobalt carbonyl Dicobalt octacarbonyl Octacarbonyidicobalt... 

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... 

Carbonvlation of Benzyl Halides. Several organometallic reactions involving anionic species in an aqueous-organic two-phase reaction system have been effectively promoted by phase transfer catalysts(34). These include reactions of cobalt and iron complexes. A favorite model reaction is the carbonylation of benzyl halides using the cobalt tetracarbonyl anion catalyst. Numerous examples have appeared in the literature(35) on the preparation of phenylacetic acid using aqueous sodium hydroxide as the base and trialkylammonium salts (Equation 1). These reactions occur at low pressures of carbon monoxide and mild reaction temperatures. Early work on the carbonylation of alkyl halides required the use of sodium amalgam to generate the cobalt tetracarbonyl anion from the cobalt dimer(36). 

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